ORCID Profile
0000-0003-2734-9475
Current Organisation
University of Wollongong
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 10-2003
Abstract: Robust evidence exists that the brain functioning of children and adolescents with attention-deficit/hyperactivity disorder (AD/HD) differs from that of normal controls. The purpose of this study was to further investigate whether event-related potential (ERP) measures of brain function could be used to reliably classify normal controls versus children and adolescents with two subtypes of AD/HD. Behavioural and topographic ERP data from children aged 8-12 years (n = 75) and adolescents aged 13-18 years (n = 75) were entered into stepwise discriminant function analyses separating controls and subjects with AD/HD, and also subjects with AD/HD-Predominantly Inattentive type (AD/HDin) from those with AD/HD-Combined type (AD/HDcom). For children aged 8-12 years, controls and children with AD/HD could be separated with an overall classification accuracy of 73.3%, and the AD/HD subtypes were classified with 69.4% overall accuracy. For adolescents aged 13-18 years, 58.7% of the control vs. AD/HD subjects were correctly classified, and 62.7% of subjects in the subtypes. Classification function coefficients for each of these discriminations are presented for the purposes of cross-validation. In children aged 8-12 years, analysis of ERP data may aid a clinician in diagnosing AD/HD, although the clinical utility of ERP analysis is reduced for adolescents aged 13-18 years. Suggestions are made to combine ERP measures with other measures of brain function in order to improve classification accuracy, and also to predict drug response in children diagnosed with AD/HD.
Publisher: Springer Science and Business Media LLC
Date: 12-10-2017
DOI: 10.1038/S41598-017-13383-3
Abstract: Research suggests that listening to white noise may improve some aspects of cognitive performance in in iduals with lower attention. This study investigated the impact of white noise on new word learning in healthy young adults, and whether this effect was mediated by executive attention skills. Eighty participants completed a single training session to learn the names of twenty novel objects. The session comprised 5 learning phases, each followed by a recall test. A final recognition test was also administered. Half the participants listened to white noise during the learning phases, and half completed the learning in silence. The noise group demonstrated superior recall accuracy over time, which was not impacted by participant attentional capacity. Recognition accuracy was near ceiling for both groups. These findings suggest that white noise has the capacity to enhance lexical acquisition.
Publisher: Elsevier BV
Date: 10-1998
DOI: 10.1016/S0165-1781(98)00072-9
Abstract: This study investigated differences in the EEG between children with Attention-Deficit/Hyperactivity Disorder of the Combined Type, Attention-Deficit/Hyperactivity Disorder of the Predominantly Inattentive Type and control subjects. All subjects were between the ages of 8 and 12 years, and groups were matched on age and gender. The EEG was recorded during an eyes-closed resting condition from 21 monopolar derivations and these were clustered into nine regions prior to analysis. One minute of trace was analysed using Fourier transformation to obtain both absolute and relative power estimates in the delta, theta, alpha and beta frequency bands. The patient groups were found to have greater levels of theta and deficiencies of alpha and beta in comparison to the control group. Children with Attention-Deficit/Hyperactivity Disorder of the Predominantly Inattentive type were found to be significantly different from those of the Combined type in the same measures, appearing to be closer to the normal profiles. The general results support a maturational lag model of the central nervous system in Attention Deficit/Hyperactivity Disorder. The differences between the subtypes suggest a difference in the severity of the disorder rather than a different neurological dysfunction.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.IJPSYCHO.2014.07.003
Abstract: Previous research has shown that as the stimulus-to-matching-stimulus interval (including the target-to-target interval, TTI, and nontarget-to-nontarget interval, NNI) increases, the litude of the P300 ERP component increases systematically. Here, we extended previous P300 research and explored TTI and NNI effects on the various ERP components elicited in an auditory equiprobable Go/NoGo task. We also examined whether a similar mechanism was underpinning interval effects in early ERP components (e.g., N1). Thirty participants completed a specially-designed variable-ISI equiprobable task whilst their EEG activity was recorded. Component litudes were extracted using temporal PCA with unrestricted Varimax rotation. As expected, N1, P2, and P3b litudes increased as TTI and NNI increased, however, Processing Negativity (PN) and Slow Wave (SW) did not show the same systematic change with interval increments. To determine the origin of interval effects in sequential processing, a multiple regression analysis was conducted on each ERP component including stimulus type, interval, and all preceding components as predictors. These analyses showed that matching-stimulus interval predicted N1, P3b, and weakly predicted P2, but not PN or SW SW was determined by P3b only. These results suggest that N1, P3b, and to some extent, P2, are affected by a similar temporal mechanism. However, the dissimilar pattern of results obtained for sequential ERP components indicates that matching-stimulus intervals are not affecting all aspects of stimulus processing. This argues against a global mechanism, such as a pathway-specific refractory effect, and suggests that stimulus processing is occurring in parallel pathways, some of which are not affected by temporal manipulations of matching-stimulus interval.
Publisher: Elsevier BV
Date: 11-2005
DOI: 10.1016/J.CLINPH.2005.08.008
Abstract: This study examined the use of caffeine to manipulate arousal level without the confounds associated with task-related activation. From previous work in our laboratory, an increase in skin conductance level (SCL) and EEG alpha frequency, together with a global decrease in alpha power, were used as markers of arousal increase, and we sought to identify these effects with caffeine ingestion. We examined the effect of a single oral dose of caffeine (250 mg) in a randomised double-blind placebo-controlled repeated-measures cross-over study. Eighteen healthy university students (mean age 21 years 13/18 females) participated in two sessions 1 week apart. EEG and autonomic data (SCL, heart rate, systolic and diastolic blood pressure, and respiration rate) from a 2 min eyes-closed epoch, commencing approximately 30 min after ingestion of caffeine or placebo, were examined. Caffeine was associated with increased SCL, a global reduction in EEG power in the alpha band, and a global increase in alpha frequency. There were no cardiovascular effects. The positive results are consistent with recent electrodermal and EEG studies of arousal and suggest that caffeine may be utilised as a task-free means of manipulating arousal in future investigations. Further work is necessary to clarify the absence of cardiovascular effects, and to integrate those data with emerging conceptualisations of arousal and activation. The present data support the use of caffeine as a simple tool to explore the role of arousal in both normal and atypical functioning, and this may be useful in determining the validity and importance of supposed hyper- or hypo-arousal in such syndromes as attention-deficit/hyperactivity disorder (AD/HD).
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.IJPSYCHO.2014.07.005
Abstract: This study examined the occurrence of preferred EEG phase states at stimulus onset in an equiprobable auditory Go/NoGo task with a fixed interstimulus interval, and their effects on the resultant event-related potentials (ERPs). We used a sliding short-time FFT decomposition of the EEG at Cz for each trial to assess prestimulus EEG activity in the delta, theta, alpha and beta bands. We determined the phase of each 2 Hz narrow-band contributing to these four broad bands at 125 ms before each stimulus onset, and for the first time, avoided contamination from poststimulus EEG activity. This phase value was extrapolated 125 ms to obtain the phase at stimulus onset, combined into the broad-band phase, and used to sort trials into four phase groups for each of the four broad bands. For each band, ERPs were derived for each phase from the raw EEG activity at 19 sites. Data sets from each band were separately decomposed using temporal Principal Components Analyses with unrestricted VARIMAX rotation to extract N1-1, PN, P2, P3, SW and LP components. Each component was analysed as a function of EEG phase at stimulus onset in the context of a simple conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). The predicted non-random occurrence of phase-defined brain states was confirmed. The preferred states of negativity, negative driving, and waxing were each associated with more efficient stimulus processing, as reflected in litude differences of the components. The present results confirm the existence of preferred brain states and their impact on the efficiency of brain dynamics in perceptual and cognitive processing.
Publisher: Elsevier BV
Date: 04-2002
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.IJPSYCHO.2006.02.001
Abstract: This study investigated ERPs to auditory targets amidst visual standard stimuli in an inter-modal oddball task. Twenty subjects completed three tasks in random order: 1) an inter-modal oddball, 2) an auditory oddball, 3) and a single tone task. Target stimuli were identical in each task. In the inter-modal condition the auditory N100, N130 and P200 components were not substantially affected by the presence of the visual standard stimulus. In contrast, the later components P250, P300 and P350 differed between conditions. It is suggested that the processing of auditory targets in the inter-modal oddball occurs in two-stages--with initial auditory processing occurring independently of the visual standards, followed by activity indicative of an integration of stimulus characteristics. Furthermore, these data indicate that the context in which stimuli are presented affects the ERP. These results are discussed in light of previous findings in inter-modal research.
Publisher: Springer Science and Business Media LLC
Date: 03-1981
DOI: 10.3758/BF03326965
Publisher: Elsevier BV
Date: 05-1979
DOI: 10.1016/0301-0511(79)90045-0
Abstract: Recent studies have generated a four-system structure proposed as a replacement for Sokolov's unitary OR concept. This conceptualisation developed from a logical consideration of stimulus--response relationships based upon mean response magnitudes over subjects, and paid no attention to in idual response types. It is conceivable that no in idual subject exhibited responses compatible with such a formulation. This paper addressed that problem by using factor analysis as a means of descriptively summarising the data of each subject, and examining its compatibility with both unitary and four-system structures. Of 72 subjects, none exhibited a factor structure compatible with Sokolov's unitary concept, while 70 exhibited structures compatible with the four-system structure. These results support the validity of the structure proposed to replace the unitary OR.
Publisher: Elsevier BV
Date: 02-1997
DOI: 10.1016/S0167-8760(96)00713-1
Abstract: Overlapping phasic skin conductance responses (SCRs) obtained using short interstimulus interval (ISI) paradigms such as those employed in cognitive research, confound measurement of each discrete phasic SCR as well as the tonic skin conductance level (SCL). We report a method of resolving this problem using a modelling technique that takes advantage of the stereotyped nature of the within-subject SCR waveform. A four-parameter sigmoid-exponential SCR model that describes the entire response, was developed and extended to five-, six- and eight-parameter skin conductance (SC) models. These SC models were successfully curve-fitted to more than 60 SC segments, each containing one SCR or two overlapping SCRs on a sloping baseline obtained from 20 normal subjects. The SC segments were consequently decomposed into their components: the tail of the previous response, one or two SCRs and the SCL. The SCRs free of the complication of overlap were then quantified. The raw SCRs of the same data set were also measured using a standard method. The standard measurement showed a significant reduction of 15% in litude and 140 ms in peak latency compared to our method. The basic four SCR model parameters--onset time, rise time, decay time constant and gain--showed increasing inter-subject variability in that order. These SCR model parameters may be studied as variables in normal and patient groups and as indices of treatment response. This quantitative method also provides a means to assess the relationships between central and autonomic psychophysiologic measures.
Publisher: Wiley
Date: 23-04-2012
DOI: 10.1111/J.1469-8986.2012.01367.X
Abstract: Sokolov's classic works discussed electroencephalogram (EEG) alpha desynchronization as a measure of the Orienting Reflex (OR). Early studies confirmed that this reduced with repeated auditory stimulation, but without reliable stimulus-significance effects. We presented an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time-frequency analysis of electrooculogram (EOG)-corrected EEG was used to explore prestimulus levels and the timing and litude of event-related increases and decreases in 4 classic EEG bands. Decrement over trials and response recovery were substantial for the transient increase (in delta, theta, and alpha) and subsequent desynchronization (in theta, alpha, and beta). There was little evidence of dishabituation and few effects of counting. Expected effects in stimulus-induced alpha desynchronization were confirmed. Two EEG response patterns over trials and conditions, distinct from the full OR pattern, warrant further research.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.IJPSYCHO.2013.05.002
Abstract: For 35 years, some researchers have argued that CNV resolution may affect or even produce the increased P3 for NoGo compared to Go trials, and thus that no 'inhibitory' NoGo P3 exists. This is based on the work of Simson et al. (1977b), the scalp topography of potentials in auditory and visual Go/NoGo tasks. Electroencephalography and Clinical Neurophysiology, 43, 864-875, which compared Go and NoGo topography after CNV was subtracted from NoGo trials only. Specifically, the NoGo P3 topography showed the distinctive frontocentral maximum, which is often linked to motor inhibition, when referenced to a pre-target baseline. This NoGo topography changed to a more parietal maximum, similar to that on Go trials, when referenced to a pre-cue baseline. Many researchers have cited this study, while failing to use the delayed response design on which Simson et al. based their argument. We attempted to replicate Simson et al.'s experiment with delayed responses and also with immediate responses, as are more often used. As expected, the litudes of CNV and P3 to both Go and NoGo trials were increased when immediate compared to delayed responses were required, but we failed to replicate the topographic shift of NoGo P3 with different baselines for both delayed and immediate responses. That is, subtraction of the CNV from NoGo P3 did not change the distinctive frontocentral topography of this component. The results suggest that CNV may affect the litude and measurement of the NoGo P3, but that NoGo P3 anteriorisation is not caused by CNV resolution.
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.CLINPH.2009.08.006
Abstract: Recent work on arousal vs. activation in adults showed that skin conductance levels (SCLs) increased, and global alpha levels decreased, from eyes-closed to eyes-open resting baseline conditions. This study explored whether similar effects occur in children. EEG activity was recorded from 30 children aged 8-12 years during counterbalanced eyes-closed and eyes-open resting conditions SCL was measured as an index of arousal. SCLs were negatively correlated with mean alpha levels in the eyes-closed condition, and increased significantly from eyes-closed to eyes-open. Reductions were found in across-scalp mean absolute delta, theta, alpha, and beta from eyes-closed to eyes-open. Topographic changes were evident in all bands except alpha. Results confirm the use of mean alpha level as a measure of resting-state arousal under eyes-closed and eyes-open conditions. Focal changes in the other bands suggest that these reflect differences in activation, rather than the simple increase in arousal shown in alpha. This child study confirms the generality of eyes-closed vs. eyes-open non-alpha EEG measures differing in mean power levels and topography, the latter indicating brain activity related to visual processing. Such differences should be considered when evaluating EEG research, and in choosing baseline conditions for different paradigms.
Publisher: Springer Science and Business Media LLC
Date: 06-1977
DOI: 10.3758/BF03335318
Publisher: Wiley
Date: 07-2006
DOI: 10.1111/J.1460-9568.2006.04879.X
Abstract: Evidence suggests that the component frequencies of the electroencephalogram (EEG) are dynamically adjusted to provide particular brain states at stimulus occurrence, and that these facilitate cortical processing of the stimulus. We examined relationships between stimulus intensity, the phase of narrow-band EEG activity at stimulus onset, and the resultant event-related potentials (ERPs) in a passive auditory oddball task, using a novel conceptualization of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). EEG responses to the standard stimuli (50 vs. 80 dB, varied between subjects) were analysed. Prestimulus narrow-band EEG activity (in 1-Hz bands from 1 to 13 Hz) at Cz was assessed for each trial by digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz and Pz. Preferred brain states at various frequencies were indicated by 16-34% differential occurrence within the orthogonal phase dimensions explored. The preferred states were associated with smaller N1, N2 and N3, larger P2 and P3, shorter N1, P2, N2 and P3 latencies, and some intensity effects. These effects reflected the operation of three separate phase-influenced mechanisms, involving anticipatory potentials and prestimulus oststimulus litudes in various EEG frequencies. Results indicate that, even in paradigms with a slightly varying interstimulus interval, brain dynamics provide preferred brain states at the moment of stimulus presentation, which differentially affect the EEG correlates of stimulus processing.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.IJPSYCHO.2008.09.003
Abstract: This study investigated EEG coherence differences between two groups of children with attention-deficit/hyperactivity disorder Combined type (AD/HD), with or without comorbid Reading Disabilities (RD), and normal control subjects. Each group consisted of 20 children between the ages of 8 and 12 years, and groups were matched on age and gender. EEG was recorded during an eyes-closed resting condition from 21 monopolar derivations. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. In the intrahemispheric comparisons, the AD/HD groups compared to controls showed across-hemisphere reductions in coherences in the delta band at longer inter-electrode distances. Interhemispheric coherences in the frontal areas were elevated in theta and reduced in alpha in the temporal area, coherences were reduced in alpha. Compared with children with AD/HD without comorbid RD, intrahemispheric coherences at shorter inter-electrode distances in children with comorbid RD were reduced in the left hemisphere for slow wave activity, particularly delta. Across hemispheres, the comorbid group also showed a reduced level of intrahemispheric coherence at longer inter-electrode distances in alpha. There were no interhemispheric differences associated with RD. The present results indicate that children with AD/HD and comorbid RD show deficits additional to those found in AD/HD patients without comorbid RD. These involve reduced lateralisation and impaired coupling of frontal and occipital brain regions in children with comorbid RD. Results confirm and clarify the additivity of brain dysfunctions in children with comorbid AD/HD and RD, previously reported by EEG power studies. Findings suggest that optimal treatment of these children should recognise the need to specifically address the RD, in addition to employing a medication regime focussed on the AD/HD symptoms.
Publisher: Springer Science and Business Media LLC
Date: 03-1984
DOI: 10.3758/BF03332162
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.IJPSYCHO.2007.04.002
Abstract: Previous research examining auditory target ERPs in an inter-modal oddball task has shown that early components are affected by intra-modal processes, whilst components in the later part of the ERP, around 200-400 ms, are affected by both inter-modal and intra-modal processes. These findings led to the conclusion that there are separate stages of auditory target processing--an early modality-specific stage and a later context-dependent stage. The present study investigated this further by simultaneously presenting a visual standard stimulus with an auditory standard stimulus in an oddball task. The aim was to determine whether the inclusion of the visual standard stimulus in this task affected the ERP to targets. The auditory-visual oddball task consisted of a regularly presented combined auditory and visual standard stimulus (80%) and an infrequent auditory target (20%). The ERPs to targets in the auditory-visual oddball task were compared to those in an auditory oddball task, which had identical auditory stimuli and no visual standards. The results showed that the early components N100, P200 and N200 did not differ between tasks. This was in line with earlier results, and confirmed that activity up to 200 ms is unaffected by visual standard stimuli. The later components P250, P300 and P350 were larger and showed topographic differences in the auditory-visual oddball task. This was interpreted as reflecting separate inter-modal and intra-modal processes at later stages. In particular, the P300 and P350 components were argued to represent separate inter-modal and intra-modal components. Overall, this study provides further evidence of auditory processing occurring in two stages, an early modality-dependent stage and a later context-dependent stage.
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.IJPSYCHO.2004.09.001
Abstract: Electroencephalographic (EEG) coherence between two points is strongly related to the distance between them, being inflated by volume conduction effects at short distances and reduced by signal phase differences at larger distances. This precludes simple comparison of coherence estimates involving different inter-electrode distances. We investigated adjusting coherence measures to remove such distance effects. After subtracting the estimated effects of random coherence due to volume conduction, exponential regression of the reduced coherence values against measured inter-electrode distance was used to estimate the remaining effects of inter-electrode distance. Residuals from this procedure were taken as coherences corrected for the systematic distance effects. These were adjusted to the mean reduced coherence level to avoid complexities in conceptualising negative residual coherences. It was found that systematic inter-electrode distance effects accounted for more than 50% of the variance remaining after removal of random coherence estimates. After these were also removed, substantial effects of EEG frequency band, different regions of the brain, and interhemispheric versus intrahemispheric values, as well as laterality effects within the latter, were obtained. Regional and frequency differences in adjusted coherence appear to reflect patterns expected from normal cortical development, but detailed understanding of more complex interactive effects is limited by the lack of relevant developmental data. Adjusting coherence values to remove systematic variability due to inter-electrode distances better represents cortico-cortical coupling and allows more efficient statistical analysis. This may contribute towards a better integration of coherence data in the EEG exploration of both normal and atypical brain functioning.
Publisher: Springer Science and Business Media LLC
Date: 09-1979
DOI: 10.1007/BF01531738
Publisher: Springer Science and Business Media LLC
Date: 03-1975
DOI: 10.3758/BF03326832
Publisher: Wiley
Date: 15-11-2013
DOI: 10.1111/J.1469-8986.2012.01491.X
Abstract: This study examined temporal determinants of the P300 component of the ERP in a three-stimulus visual oddball task. Frequent standards, with equiprobable targets and infrequent nontargets, were utilized. We tested whether the infrequent nontarget-to-nontarget interval (infrequent NNI) influences P300 litudes and latencies analogously to the target-to-target interval (TTI). EEG was recorded from 27 participants, and response time and P300 effects of TTIs and infrequent NNIs were assessed. Increases in TTI augmented target P300 litudes and decreased latencies and response times. However, this modulation of P300 litude was weak for manipulations of infrequent NNI. P300 latencies increased initially before decreasing across infrequent NNI levels. Together, these findings support the notion that the P300 has an underlying temporal mechanism that is modulated by motivationally significant events. Theoretical implications are discussed.
Publisher: Elsevier BV
Date: 1993
DOI: 10.1016/0301-0511(93)90092-M
Abstract: Two apparently new effects in human cardiac responding, "primary bradycardia" and "vagal inhibition", were first described by the Laceys. These effects have been considered by some researchers to reflect differential cardiac innervation, analogous to similar effects observed in animal preparations with direct vagal stimulation. However, it has been argued that such effects arise merely from the data-analytic techniques introduced by the Laceys, and hence are not genuine cardiac cycle effects. Jennings, van der Molen, Somsen and Ridderinkhoff (Psychophysiology, 28 (1991) 596-606) recently proposed a plotting technique and statistical procedure in an attempt to resolve this issue. The present paper demonstrates that the plotting technique fails to achieve their stated aim, since it identifies data from identical cardiac responses as showing cardiac-cycle effects. In addition, the statistical procedure is shown to be reducible to a trivial test of response occurrence. The implication of these demonstrations, in the context of other work, is that this area of investigation has reached a dead end.
Publisher: Elsevier BV
Date: 06-1988
DOI: 10.1016/0167-8760(88)90045-1
Abstract: Phasic changes in respiratory period, electrodermal activity, and the vasoconstrictive peripheral pulse litude response, were examined in matched groups of autistic, retarded, and normal children using repeated presentation of simple visual and auditory stimuli of differing magnitudes. Analysis of response magnitudes as a function of group membership, trials, stimulus magnitude, and age, indicated both similarities and differences between the autistic and control groups. The autistic group differed from the control groups in its failure to show response habituation to repeatedly presented stimuli. However, data indicated that autistic children coded stimulus magnitude similarly to controls, suggesting that the failure to adequately process stimulus novelty does not reflect a general processing failure. Autistic children also exhibited relative hyperreactivity in all measures. Age effects showed this to be interpretable as reflecting developmental delay. These two differences support a recent two-factor theory of autism.
Publisher: Elsevier BV
Date: 1987
DOI: 10.1016/0167-8760(87)90042-0
Abstract: Time-dependent bradycardia, a term introduced by the Laceys (Lacey and Lacey, 1980), refers to the fact that the duration of a cardiac cycle is related to when in that cycle, or the just preceding cycle, certain stimuli occur. Since stimulus effects on heart activity with very short latencies have been known for a long time, the question arises whether the effect is one in its own right, or whether it is simply a result of the new way of data reduction introduced by the Laceys. Theoretically, the effect can be explained without assuming anything beyond the well-known short latency bradycardia often observed upon stimulation. Derivation of the effect from an empirical curve of cardiac activity not related to cycle phase shows that we are not dealing with a new effect.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.IJPSYCHO.2015.05.010
Abstract: A recent series of studies of the auditory equiprobable Go/NoGo task, using fixed interstimulus intervals (ISIs), proposed a processing schema relating observed event-related potential (ERP) components to sequential processing stages. However, it has been demonstrated that attention and ERP components can be affected by the predictable rhythmic timing of fixed ISIs. Hence the aim of the current study was to test the robustness of that processing schema with an unpredictable arrhythmic variable ISI. EEG was recorded from 30 university students at 30 scalp sites in an unwarned auditory equiprobable Go/NoGo task using a variable ISI. Following our previous studies, Go and NoGo ERP components were derived using temporal principal components analysis (PCA). Of the unrestricted Varimax-rotated factors, seven were identifiable as components based on their topography, polarity, and latency: two subcomponents of the N1 (N1-1, and processing negativity, PN), P2/N2b, N2c/P3a, P3b, and two subcomponents of the slow wave (SW-1 and SW-2). These components showed Go/NoGo effects comparable to those previously noted with fixed ISI, supporting the proposed processing schema. The Late Positivity (LP) component, previously speculated to mark cortical deactivation after processing the NoGo stimulus, was not present in the sequence of components. In its absence, activity underlying the observed sustained P300/late positive complex may be involved in processing temporally-uncertain stimuli.
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.IJPSYCHO.2022.05.011
Abstract: Our previous studies of the equiprobable auditory Go/NoGo task have been used to substantiate a perceptual/cognitive Processing Schema in young and older adults, and in children. The processes in the Schema are linked to PCA components derived separately from Go and NoGo ERPs. Here we investigated sex differences in the child Schema. Two groups of fourteen children (aged 8 to 13 years) were in idually matched on age and presented with four stimulus blocks of the equiprobable Go/NoGo task, each containing 75 NoGo and 75 Go tones in random order. Separate NoGo and Go ERPs were obtained from each child and submitted to temporal Principal Components Analyses (PCAs). Each ERP was analysed in two epochs (-100-400 ms and 300-800 ms) to improve the cases:variables ratio. Four pairs of temporal PCAs, each with unrestricted VARIMAX rotation, separately quantified the NoGo and Go ERPs of each epoch in each group. After these pairs were combined in temporal order, four sets of similar components were extracted. Many identified components were differentially enhanced to either NoGo or Go, as in previous work with children. The Female group had NoGo component latencies that were systematically some 3.5% greater than in Males, but there were no sex differences in Go latencies. Females also displayed fewer NoGo commission and Go omission errors, and faster Go RT than Males. Females had larger NoGo N2b, and larger Go components from N2b through to the late positivity. These results, including their ERP component/behaviour correlations, can be integrated as a task-specific behavioural and ERP processing enhancement in girls that suggests their developmental advantage over boys in this age range.
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S1388-2457(02)00115-3
Abstract: This study investigated the presence of electroencephalographic (EEG) clusters within a s le of children with the inattentive type of attention-deficit/hyperactivity disorder (ADHD). Subjects consisted of 100 boys with ADHD and 40 age-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and relative power in the delta, theta, alpha and beta bands. Factor analysis was used to group sites into 3 regions frontal, central and posterior. These data were subjected to cluster analysis. Two distinct EEG clusters of children with the inattentive type of ADHD were found. These were characterised by (a) increased high- litude theta with deficiencies of delta and beta activities, and (b) increased slow wave and deficiencies of fast wave activity. These two subtypes are independent of current diagnostic categories, and consist of a cortically hypoaroused group and a group typified by a maturational lag in central nervous system (CNS) development. These results support a re-conceptualisation of ADHD based on the CNS abnormality underlying the disorder rather than the behavioural profile of the child. This has the potential to add a level of predictive validity, which is currently lacking in the present diagnostic systems.
Publisher: International Society for Neurofeedback Research (ISNR)
Date: 07-2011
Publisher: Wiley
Date: 03-03-2014
DOI: 10.1111/PSYP.12198
Abstract: Physiological arousal is purportedly a key determinant in the development and maintenance of gambling behaviors, with problem gambling conceptualized in terms of abnormal autonomic responses. Theoretical conceptualizations of problem gambling are discordant regarding the nature of deficit in this disorder some accounts posit that problem gamblers are hypersensitive to reward, and others that they are hyposensitive to reward and/or punishment. Previous research examining phasic electrodermal responses in gamblers has been limited to laboratory settings, and reactions to real gaming situations need to be examined. Skin conductance responses (SCRs) to losses, wins, and losses disguised as wins (LDWs) were recorded from 15 problem gamblers (PGs) and 15 nonproblem gamblers (NPGs) while they wagered their own money during electronic gaming machine play. PGs demonstrated significantly reduced SCRs to reward. SCRs to losses and LDWs did not differ for either PGs or NPGs. This hyposensitivity to wins may reflect abnormalities in incentive processing, and may represent a potential biological marker for problem gambling.
Publisher: Springer Science and Business Media LLC
Date: 03-1977
DOI: 10.3758/BF03335305
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.IJPSYCHO.2009.08.010
Abstract: Previous research has shown that auditory targets in inter-modal oddball conditions are processed in two stages, an early modality-specific and a later context-dependent stage. The aim of this study was to investigate how the processing of auditory target stimuli is affected by the inclusion of an additional infrequent auditory non-target stimulus in inter-modal oddball conditions. 17 subjects received 300 stimuli in each of a two- and a three-stimulus version of the inter-modal oddball task. Both tasks included 240 (80%) presentations of a counter-phasing checkerboard randomly interspersed with 60 presentations of an auditory stimulus. In the two-stimulus condition subjects received 60 (20%) target stimuli. In the three-stimulus condition subjects received 30 (10%) target and 30 (10%) non-target stimuli. ERPs to the two target stimuli and ERPs to targets and auditory non-targets in the three-stimulus condition were investigated. Early components N100 and P200 were larger to non-targets than targets. N140, an additional frontal negativity in inter-modal oddball conditions, was larger in the three-stimulus compared with the two-stimulus condition. Targets produced two late positive components (P250/P3a and P300). In the three-stimulus task the P250/P3a was enhanced frontally and P300 was enhanced in right parietal regions. Non-target auditory stimuli produced a broad negativity (N285) at this latency. All stimuli produced a late positivity (P350) that demonstrated task-related topographic differences. The results are interpreted with respect to previous inter-modal oddball findings and research into auditory processing.
Publisher: Elsevier BV
Date: 07-1992
DOI: 10.1016/0167-8760(92)90014-3
Abstract: This study examined the N100 component of the event related potential in a habituation paradigm with short interstimulus intervals. The paradigm was designed to be relatively brief in duration (approx. 4 min for each of two conditions), so that it could be used for clinical populations with cognitive dysfunction, in which compliance may be a problem with long paradigms. Two conditions - Ignore and Attend - were employed with normal subjects. In each condition, 15 stimulus trains, each consisting of 10 innocuous tones, were presented. The eighth tone was a change stimulus. There was a fixed interstimulus interval of 1.1 s and an inter-train interval of 5 s. From the perspective of traditional Orienting Response theory, evidence was sought for within-train habituation in terms of diminished N100 litude to repeated stimuli, response recovery to the change stimulus, and dishabituation of the response to the following standard stimuli. Habituation was suggested by significant decreases of approx. 50% with stimulus repetition, and response recovery to the change stimulus in both conditions. However, there was no evidence of dishabituation following the change stimulus. These results confirm that N100 fails to meet the formal requirements of response habituation, suggesting instead that it may index an earlier process than the Orienting Response.
Publisher: Wiley
Date: 1976
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.IJPSYCHO.2011.10.007
Abstract: We aimed to clarify the event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Participants were presented with 16 innocuous tones, alternating in intensity, at long variable inter-stimulus intervals, with no task. This allowed us to examine stimulus novelty and intensity effects in the absence of stimulus-related task demands. Single-trial ERPs were extracted to obtain estimates of the early N1 and the late positive complex (LPC) to each stimulus. Electrodermal responses showed substantial main effects of trials and intensity, supporting their functionality as an OR index. Cardiac deceleration showed no systematic change with intensity or trials, suggesting that it marks the transient onset of each stimulus, early in the stimulus-processing sequence. Respiratory pause showed a substantial main effect of trials but no intensity effect, suggesting that it reflects an intermediate processing stage. A main effect of intensity, but no simple trial effect, was apparent in the N1, suggesting that it reflects a different intermediate processing stage. The subsequent LPC showed only a topographic interaction with trials and intensity, failing to support any substantive role in OR processing. These different stimulus-response profiles are discussed in the context of a sequential processing model of the OR.
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.IJPSYCHO.2014.03.007
Abstract: Single-trial data from autonomic and ERP measures were used to capture the rapidly decreasing initial responses characteristic of the orienting reflex (OR) to repeated stimuli. Stimulus-response patterns were compared to determine central analogues of autonomic indices of processes leading to the OR, and the OR itself. Participants were presented with 12 indifferent tones in an auditory dishabituation paradigm. Temporal principal component analysis (PCA) decomposed EOG-corrected ERP data for 16 subjects. Response patterns of ERPs, cardiac, and respiratory responses were compared to the phasic skin conductance response (SCR). SCR decremented over trials, recovered on the change trial, and dishabituated to the representation of the standard, meeting the formal definition of habituation required of the OR. The evoked cardiac response showed no trial effects. Respiratory pause (RP) decreased linearly over trials, recovering marginally on the change trial. Nine identifiable ERP components were extracted: P1, N1-3, N1-1, processing negativity (PN), P2, P3a, P3b, a novelty-sensitive P3 component (labelled HabP3), and the slow wave (SW). P3b and SW showed decrement over trials, but with no recovery, HabP3 showed decrement and increased response on the change trial, while the P1, N1 subcomponents, P2 and P3a were insensitive to novelty. Stimulus-response patterns of the RP and HabP3 suggest sensitivity to novelty processing, while the P1, N1-3, N-1, PN, P2, P3a and cardiac deceleration appear to mark processing prior to novelty, such as stimulus transient detection (cardiac deceleration) and/or intensity processing. This study supports predictions of preliminary process theory, demonstrating fractionation of 3 autonomic and 9 ERP components to novelty, and disconfirming the unitary nature of the OR.
Publisher: Elsevier BV
Date: 2005
DOI: 10.1016/J.IJPSYCHO.2004.06.003
Abstract: The post-stimulus primary bradycardia--sometimes labelled as the first evoked cardiac response, ECR1--is regarded as a response which is independent of the stimulus novelty factor. Despite this however, in our previous research we have observed a noticeable variation of this response, which made us suspect that there could be some additional factor influencing it. To test this, we designed a habituation procedure to measure susceptibility of the ECR1 to stimulus repetition. In our experimental design, we also included a measure of the level of activation (arousal) as a possible additional factor influencing the time-course of the cardiac response. The level of arousal over the study was measured by the Activation-Deactivation Adjective Check List (AD ACL). Our results show that mere stimulus repetition does not influence the time-course of ECR1. However, another pattern of results appeared when one of the dimensions of AD ACL, namely Tense Arousal, was taken into account. We observed different ECR time-courses during the initial stimulus presentations for subjects with high and low levels of Tense Arousal. These results are interpreted within the framework of Preliminary Process Theory in terms of the different attentional patterns in subjects with high and low levels of Tense Arousal.
Publisher: Springer Science and Business Media LLC
Date: 19-07-2006
DOI: 10.1007/S00221-006-0590-8
Abstract: In the Go/NoGo task, the P3 component of the event-related potential elicited by NoGo stimuli is topographically anterior to that from Go stimuli. This anteriorisation has been linked to the response inhibition thought to be required when NoGo stimuli are presented, and suggested as an index of inhibition. We report a preliminary investigation of this question from an orienting reflex (OR) perspective, in which the autonomic skin conductance response (SCR) was used as an OR "yardstick". We presented subjects with a random mix of 15 target and 15 non-target auditory stimuli with a short inter-stimulus interval, and explored the sources of the resultant P3s using low-resolution electromagnetic tomography (LORETA). Across-subject mean SCRs showed exponential decrement over trials and a larger response to targets, as expected from the OR perspective. LORETA analysis of the across-subject mean initial P3s showed exponential response decrement of their common sources, suggestive of the Novelty P3. Grand mean P3s to targets and non-targets appeared to correspond to the P3b and P3a, respectively. These results suggest that anteriorisation of the P3 to NoGo stimuli may reflect processing related to the basic involuntary OR to indifferent (non-significant) stimuli rather than an active inhibitory process.
Publisher: Springer Science and Business Media LLC
Date: 12-1980
DOI: 10.1007/BF00287235
Publisher: Frontiers Media SA
Date: 2012
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.IJPSYCHO.2014.03.010
Abstract: Increases in the target-to-target interval (TTI) systematically enhance the litude of the target P300 ERP component. Research examining changes in nontarget P300 related to nontarget-to-nontarget interval (NNI) or sequential probability manipulations has produced inconsistent results, with some studies reporting no enhancement in nontarget P300 and others finding response profiles analogous to TTI effects. Our aim was to clarify these differences. All participants completed a specially designed auditory equiprobable Go/NoGo task with manipulations of TTI and NNI while their EEG activity was recorded. P300 litudes were extracted using temporal PCA with Varimax rotation. P3b to targets and nontargets increased systematically as respective TTIs/NNIs increased, but this change did not differ between stimulus types. The Slow Wave did not show any effect of interval, but was more positive to targets than nontargets when interval was collapsed. P3b findings show that matching-stimulus interval effects are not restricted to targets, but discrepancies relative to previous research suggest that NNI effects in P3b may depend on additional processing of nontarget stimuli.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.CLINPH.2007.08.023
Abstract: Previous research has shown that caffeine produces a general increase in arousal. The present study examined caffeine-induced arousal effects on performance and auditory ERPs. We sought components showing litude changes without topography changes, as would be expected of a pure arousal lification of source activity. The effects of a single oral dose of caffeine (250 mg) were examined in a randomised double-blind placebo-controlled repeated-measures cross-over study. Subjects abstained from caffeine for 4h before the testing sessions, which were conducted, in the afternoon, one week apart. A simple auditory Go/NoGo task was used, with a random mix of 75 tones at 1000 Hz and 75 at 1500 Hz. All tones were 60 dB SPL, 50 ms duration (rise/fall time 5 ms), with SOA 1100 ms. There was a reduction in RT, but no effects on omission or commission errors. The major ERP effects of caffeine were focal rather than global increases in P1, P2 and P3b litudes to Go stimuli, with no changes in latency. There were no effects on N1 or N2 to Go stimuli, and no effects on any components in response to NoGo stimuli. The results suggest that caffeine differentially improves aspects of the processing related to response production and task performance, contrary to the widespread lification of ERP component litudes, and latency reductions, expected of an increase in general arousal. These results add auditory ERP data to the list of complex effects of caffeine on brain function and behaviour. They appear to rule out a simple arousal interpretation, and suggest directions for future research.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.CLINPH.2007.08.020
Abstract: Stimulant medications are the most commonly used treatments for Attention-Deficit/Hyperactivity Disorder (AD/HD) in North America and Australia, although it is still not entirely known how these medications work. This study investigated the effects of stimulant medications on the EEG of girls with AD/HD. An initial EEG was recorded during an eyes-closed resting condition. Data from 19 electrode sites were Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. The data were then averaged into 9 regions and an analysis of both global and regional differences was performed. Subjects were placed on a six-month trial of a stimulant and a second EEG was recorded at the end of the trial. The unmedicated girls had significantly greater total power, absolute delta and theta, more relative theta especially in the frontal regions, and reduced frontal relative delta and beta activity compared with controls. Medication resulted in normalisation of theta power, but after medication, increased relative beta was also apparent in the AD/HD group. These results indicate that stimulant medications result in a normalisation of slow wave activity in the EEG. In line with published research on the effects of arousal on the EEG, these results suggest that stimulant medications may have their therapeutic effect by improving the EEG substrate of processing deficits in these children. However, this requires further testing during active processing tasks. This is the first study to investigate the effect of stimulant medications on the EEG of girls with AD/HD.
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.IJPSYCHO.2008.09.009
Abstract: This study investigated whether ERPs from an inter-modal oddball task could distinguish between adults with Attention-Deficit/Hyperactivity Disorder (AD/HD) and controls. Two age-matched groups of young adult males (18 AD/HD, 18 controls) were presented with an inter-modal oddball task in which a counter-phasing checkerboard was the non-target visual stimulus (randomly presented on 80% of trials), and a 2000 Hz tone was the auditory target (20% of trials). Stimuli were presented at a fixed rate (stimulus-onset asynchrony 1.03 s) and participants were required to silently count all targets. The AD/HD group showed globally enhanced P2 and reduced N2 litudes to auditory targets, with no differences in target P3, together with topographic differences in N1 to auditory targets, and P1, N1, P2, N2 and P3 to visual non-targets, compared with controls. These results were interpreted in terms of early sensory-processing impairments in adults with AD/HD, which may be partially overcome through effortful processing, as reflected in the later endogenous ERP components.
Publisher: Elsevier BV
Date: 07-1978
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.IJPSYCHO.2009.08.003
Abstract: The stimulus-response pattern of the skin conductance response (SCR) was used as a model of the Orienting Reflex (OR) to assess the P1, N1, P2, N2 and late positive complex (LPC/P300) components of the ERP in a simple habituation paradigm, in which a single series of 12 innocuous tones were presented at a very long interstimulus interval (2 min). To maintain their waking state during this boring task, participants were instructed to alternately close or open their eyes to each stimulus. None of the baseline-to-peak ERP measures showed trials effects comparable with the marked habituation over trials shown by the SCRs. Principal Components Analysis was used to decompose the ERP, yielding factors identified as the N1, N2, P3a, P3b and Novelty P3 components. An additional factor represented later eye-movement activity. No trial effects were apparent for the N1, N2, P3a or P3b components. The Novelty P3 showed marked response decrement over trials. These results are discussed in relation to current conceptualisations of the OR.
Publisher: Springer Science and Business Media LLC
Date: 09-1981
DOI: 10.1007/BF01531510
Abstract: The shikimate pathway, a metabolic pathway absent in humans, is responsible for the production of chorismate, a branch point metabolite. In the malaria parasite, chorismate is postulated to be a direct precursor in the synthesis of p-aminobenzoic acid (folate biosynthesis), p-hydroxybenzoic acid (ubiquinone biosynthesis), menaquinone, and aromatic amino acids. While the potential value of the shikimate pathway as a drug target is debatable, the metabolic dependency of chorismate in P. falciparum remains unclear. Current evidence suggests that the main role of chorismate is folate biosynthesis despite ubiquinone biosynthesis being active and essential in the malaria parasite. Our goal in the present work was to expand our knowledge of the ubiquinone head group biosynthesis and its potential metabolic dependency on chorismate in P. falciparum. We systematically assessed the development of both asexual and sexual stages of P. falciparum in a defined medium in the absence of an exogenous supply of chorismate end-products and present biochemical evidence suggesting that the benzoquinone ring of ubiquinones in this parasite may be synthesized through a yet unidentified route.
Publisher: Elsevier BV
Date: 05-1993
DOI: 10.1016/0167-8760(93)90039-R
Abstract: For many years, it has been well-accepted that the litude of the phasic orienting response is directly dependent on both stimulus intensity and novelty, at least within innocuous intensity ranges. Surprisingly, the joint contribution of these stimulus parameters has not been convincingly specified in the literature. A two-step analytical procedure, which is logically necessary to provide a valid solution to the problem, is outlined. Data are then presented which demonstrate that there is a multiplicative relationship between the two parameters in their joint determination of response litude. That is, stimulus intensity and novelty interact in the production of the phasic electrodermal orienting response to innocuous stimuli.
Publisher: Elsevier BV
Date: 11-1988
DOI: 10.1016/0167-8760(88)90023-2
Abstract: Bernstein et al. (1985) presented the results of an extensive study of the effects of stimulus significance upon electrodermal and heart rate responses. This report examines some of these data from the perspective of preliminary process theory (Barry, 1984b). The categorisation of significance manipulations into prestimulus vigilance and poststimulus signal value outcomes is supported by differential responding in the electrodermal and cardiac measures, as predicted by preliminary process theory.
Publisher: Wiley
Date: 31-01-2018
DOI: 10.1111/PSYP.13065
Abstract: Previous research suggests that young adults do not need active and effortful inhibition to successfully complete the auditory equiprobable go/no-go task, a view that was incorporated into Barry and De Blasio's sequential processing schema for this task. However, recent evidence in children suggests that view could be incorrect. The present research aims to clarify the functionality of the N2 and P3 subcomponents within the proposed schema, assessing the role of inhibition in this task. To optimize the quantification of the N2 and P3 subcomponents, separate temporal PCAs were applied to the go/no-go ERP data from 40 young adults. Correlations were then used to link subcomponent litudes with performance outcomes, informing a functional interpretation of each subcomponent. Larger N2b and P3a litudes were each linked to fewer commission errors. N2c litude also increased with intrain idual reaction time variability, but no performance outcomes were associated with P3b. These findings link the young adult N2b and P3a with inhibition in the auditory equiprobable task, confirming the importance of control for successful nontarget processing in that paradigm. The functionality of N2c and P3b remain unclear from our results. However, these outcomes improve our understanding of cognitive processing in equiprobable tasks, and contribute to an improved conceptualization of the sequential processing schema.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.IJPSYCHO.2013.01.016
Abstract: This study examined autonomic measures and event-related potentials (ERPs) associated with elicitation and habituation of the basic Orienting Reflex (OR). Subjects received 16 innocuous tones with intensity alternating between 60 and 80 dB, at long inter-stimulus intervals. There was no stimulus-related task, so we could examine the effects of stimulus novelty and intensity in the absence of task demands. Cardiac, respiratory, peripheral vasoconstriction, and electrodermal measures were recorded, as well as continuous EEG. Single-trial ERPs were obtained, and components extracted by Principal Components Analysis were examined for potential response fractionation in the central indices of stimulus processing. The predicted fractionation of autonomic measures was obtained: cardiac deceleration showed no systematic change with intensity or trials, respiratory pause showed a substantial main effect of trials but no intensity effects, peripheral vasoconstriction showed intensity but no trials effects, and electrodermal responses showed substantial main effects of trials and intensity. A range of intensity and novelty effects were obtained in components identified as the N1, P3a, P3b, Novelty P3, and the classic Slow Wave. The different stimulus-response profiles of the ERP components are discussed in relation to the autonomic response profiles within the context of a sequential processing theory of OR elicitation.
Publisher: Elsevier BV
Date: 08-2001
DOI: 10.1016/S0167-8760(01)00135-0
Abstract: The effect of age on the topographic distribution of auditory event-related potentials (ERPs) recorded during a two-tone discrimination, or oddball, task was examined in two subtypes of attention deficit/hyperactivity disorder (AD/HD) as defined by the most recent diagnostic manual, DSM-IV. EEG was recorded at 17 sites from AD/HD predominantly inattentive type (n=50) and AD/HD combined type (n=50) subjects aged from 8 to 17 years 11 months. ERP components were quantified at each site. Results revealed topographic differences from controls (n=50) that were common to both subtypes (e.g. target and standard P2 litude, and standard P2 latency) or unique to a particular subtype of AD/HD (Inattentive type: target N1, N2, P3b and standard N2 litude, target P2 latency Combined type: target N1, P2, N2 and P3b litude, target N2 and standard N1 latency). These group differences showed different age effects. The across-region results revealed differing patterns of abnormal component development for each subtype, indicating a qualitative difference in information processing stage deficits in each of these AD/HD subtypes.
Publisher: Authorea, Inc.
Date: 31-08-2023
DOI: 10.22541/AU.169352107.71903657/V1
Abstract: The aim of this study was to explore the mechanism of the age-related P3 ‘anterior’ shift using high-precision temporal principal components analysis (tPCA). Continuous EEG was recorded from younger and older adults while completing a two-stimulus visual oddball task. We narrowed our tPCA input to the P3 range to enhance precision and reveal potentially overlapping temporal components. eLORETA was used to model group and condition-related differences in component sources to further understanding of the functional relevance and neurobiology of the P3 anterior shift. The target P3a and P3b and the nontarget P3/l-P3 (late P3) evidenced the expected anterior shift. There was a general reduction in P3 component litudes in older compared to younger adults across both stimulus types, consistent with the P3 ‘ageing effect’. For all P3 components, eLORETA modelled changes in activation of multiple and diffuse sources with age, suggesting that neural processing is extending beyond frontal regions and that crosstalk between different neural networks is likely. Findings are aligned with the dedifferentiation hypothesis, as reduced P3 target litudes reflect attenuated responding to a preferred stimulus, and the anterior shift to nontargets is a form of neural broadening, or decreased selectivity of processing and increased responding to a non-preferred stimulus.
Publisher: Springer Science and Business Media LLC
Date: 06-1982
DOI: 10.3758/BF03332938
Publisher: Frontiers Media SA
Date: 2013
Publisher: Frontiers Media SA
Date: 2014
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.CLINPH.2006.10.002
Abstract: This study is the first to investigate EEG coherence differences between two groups of children with attention-deficit/hyperactivity disorder combined type (AD/HD), with or without comorbid oppositional defiant disorder (ODD), and normal control subjects. Each group consisted of 20 males. All subjects were between the ages of 8 and 12 years, and groups were matched on age. EEG was recorded during an eyes-closed resting condition from 21 monopolar derivations. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha, and beta bands. Children with comorbid AD/HD and ODD had intrahemispheric coherences at shorter inter-electrode distances significantly reduced from those apparent in children with AD/HD without comorbid ODD. Such reduced coherences in the comorbid group appeared to wash out coherence elevations previously noted in AD/HD studies. The present results suggest that, rather than suffering an additional deficit, children with AD/HD and comorbid ODD show significantly less CNS impairment than AD/HD patients without comorbid ODD. These results have treatment implications, suggesting that behavioural training, perhaps using family-based cognitive behavioural therapy, could be useful for those children with AD/HD and comorbid ODD. This should focus on the ODD symptoms, in association with a medication regime focussed on the AD/HD symptoms.
Publisher: Elsevier BV
Date: 09-1993
DOI: 10.1016/0167-8760(93)90068-Z
Abstract: Freude and Ullsperger (1989) reported that positive potentials occurred on some trials in a single trial analysis of the Readiness Potential (RP). The present study investigated the effect of split attention on the occurrence of RPs of different polarities as well as comparing the post-movement potential and auditory-evoked potential after RPs of different polarities. In part 1 of the study, subjects (n = 16) pressed a key in a self-paced manner, concentrating on the movement. In part 2 they were asked to discriminate between two randomly-ordered tones, triggered by the key press (with a delay of 560 ms), and to announce the result to the experimenter verbally. The results of part 1 matched previous findings, in that in 41% of all trials RP was positive. In part 2 there was a significant increase in the relative frequency of positive RPs to 54%. This resulted in the magnitude of the averaged RP decreasing from part 1 to part 2. The early component of the averaged RP, which had begun about 1300 ms before the movement in part 1 of the study, disappeared in part 2, where the averaged RP began only 350 ms before the movement. The post-movement potential was significantly larger when the preceding RP was negative. In part 2 of the study we found an N100 in response to the tone this was larger after positive RPs, but the difference was not significant. The implications of these novel findings for interpretation of the averaged RP are discussed.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.IJPSYCHO.2008.01.007
Abstract: Although stimulant medications are the most commonly-used treatments for Attention-Deficit/Hyperactivity Disorder (AD/HD), as many as 20% of treated children do not respond clinically to stimulants. One non-stimulant medication that has been widely used when the stimulants fail is a tricyclic antidepressant, imipramine hydrochloride. This study investigated the effects of imipramine on the EEG of children with AD/HD who were poor responders to dex hetamine and ritalin, but who showed clinical improvement on a six month trial of imipramine. An initial pre-medication EEG was recorded during an eyes-closed resting condition, with data Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. A second EEG was recorded at the end of the imipramine trial. Compared to controls, the unmedicated AD/HD children had significant global increases in absolute and relative theta, with decreased global absolute and relative alpha, increased posterior relative delta, and decreased posterior absolute beta. No change in the EEG was found as a result of administering the medication. These results suggest that good responders to imipramine have an underlying EEG abnormality different from that in children who respond to the stimulants, and that an initial pre-treatment EEG may be useful in selecting a trial medication. However, as no change in the EEG was found with imipramine, it is unlikely that the EEG will be useful in evaluating responsivity to this medication.
Publisher: Elsevier BV
Date: 04-2000
DOI: 10.1016/S0167-8760(00)00083-0
Abstract: Twenty-four undergraduate university students with no known neurological disorders completed the Recognition Memory Test (Warrington, A., 1984. Recognition Memory Test manual. Windsor, Berkshire: NFER-Nelson.) while event-related potentials (ERPs) were recorded. Twelve subjects were instructed to feign a recognition memory deficit (malingering group), while the remainder served as controls. The malingerers performed poorly on the test compared to the control group. The 'old/new effect', an ERP measure thought to reflect recognition memory processes, did not differ between the groups, indicating recognition of previously learned material in the malingering group despite poor test performance. The study also revealed a second, early, old/new effect, maximal at left frontal sites in the malingering relative to the control group, suggesting task-related processing differences between the two groups. These effects appear to be of potential value in the detection of malingering of cognitive impairment in the clinical situation.
Publisher: Elsevier BV
Date: 11-1989
DOI: 10.1016/0167-8760(89)90009-3
Abstract: Most patients contact their general practitioner (GP) following presentation to an Emergency Department (ED) after a self-harm incident, and strategies to help GPs manage these patients include efficient communication between services. The aim of this study was to assess the standard of documentation and communication to primary care from secondary care as recommended by the National Institute of Clinical Excellence (NICE) guidelines on the short-term management of people who self-harm. An audit of medical records (ED and Psychiatric) on people aged 16 years and over who had presented to the ED following self-harm, benchmarked according to government guidelines, was performed. Data were collected over a 4-week period at a general teaching hospital. We collected data on 93 consecutive episodes of self-harm 62% of episodes were communicated to primary care, 58% of these communications were within 24 h and most within 3 days. Patient identifying details and follow-up arrangements were specified in most cases. Communication via psychiatric staff was most detailed. ED clinicians provided few communications and were of limited content. Communication with the patient's GP was not made in half of those cases seen by a mental health specialist. Government guidelines are only partially being met. Reliance on communication by ED staff would leave a substantial proportion of patients discharged from the ED with no or minimal communication to primary care. Psychiatric services need to improve the rate of communication to the patient's GP following assessment A national s le of National Health Service (NHS) trusts would establish if this is a problem elsewhere.
Publisher: Elsevier BV
Date: 11-1979
DOI: 10.1016/0301-0511(79)90043-7
Abstract: Omenn syndrome is a severe primary immunodeficiency with putative autoimmune manifestations of the skin and gastrointestinal tract. The disease is caused by hypomorphic mutations in recombination-activating genes that impair but do not abolish the process of VDJ recombination, leading to the generation of autoreactive T cells with a highly restricted receptor repertoire. Loss of central tolerance in genetically determined autoimmune diseases, e.g., autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, is associated with defective expression by medullary thymic epithelial cells of AIRE, the transcription activator that induces thymic expression of tissue-specific antigens. Analysis of AIRE expression in the thymi of 2 Omenn syndrome patients and 1 SCID patient, by real-time RT-PCR and immunohistochemistry, demonstrated a profound reduction in the levels of AIRE mRNA and protein in patients as compared with a normal control subject. Lack of AIRE was associated with normal or even increased levels of keratin and lymphotoxin-beta receptor mRNAs, while mRNAs of the self-antigens insulin, cytochrome P450 1a2, and fatty acid-binding protein were undetectable in thymi from immunodeficiency patients. These results demonstrate that deficiency of AIRE expression is observed in severe immunodeficiencies characterized by abnormal T cell development and suggest that in Omenn syndrome, the few residual T cell clones that develop may escape negative selection and thereafter expand in the periphery, causing massive autoimmune reactions.
Publisher: Elsevier BV
Date: 09-2013
Publisher: BMJ
Date: 08-2006
DOI: 10.1136/EBMH.9.3.68
Publisher: Elsevier BV
Date: 12-2006
DOI: 10.1016/J.IJPSYCHO.2006.01.004
Abstract: We commonly teach beginning science students that theory generates hypotheses which direct our research, framing our experimental observations and that in turn, these supply the data which support or contradict theory, allowing its self-correction and further development. These propositions are explored here in the context of psychophysiology, concentrating on ex les in relation to the Orienting Reflex (OR). It is demonstrated that the realist approach generally portrayed in our teaching about theory and theory testing is not the dominant ethos in this field. Indeed, we pay little more than lip-service to the ideal we teach about. One outcome described here is that the promise offered us by the OR in the 1960s has not been realised. It is argued that this failure may be symptomatic of much of science, suggesting that we need to consciously work to raise the perceived value of theory. The ideation element of theoretical activity can be fostered, and it is argued that we need to do so explicitly at a number of levels in the education of our students, beginning in the early coursework stages and continuing in their research training and development.
Publisher: Elsevier BV
Date: 08-2002
DOI: 10.1016/S1388-2457(02)00147-5
Abstract: This study investigated electroencephalographic (EEG) differences between good and poor responders to methylphenidate in boys with the Inattentive type of Attention-Deficit/Hyperactivity Disorder (ADHD). Twenty good and 15 poor responders to methylphenidate, based on the results of a continuous performance task, and 35 age- and sex-matched control subjects, participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. EEG differences were found between the ADHD children and controls which were compatible with previous literature on the Inattentive type. Differences were also found between the good and poor responders to methylphenidate. Good responders had EEG profiles that suggested that they were more cortically hypoaroused than poor responders.
Publisher: Informa UK Limited
Date: 12-2013
Publisher: Elsevier BV
Date: 06-2004
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.IJPSYCHO.2015.08.002
Abstract: The phasic orienting reflex (OR) was investigated using single-trial data collected concurrently from 4 autonomic measures and event-related potentials (ERPs). In an auditory dishabituation paradigm, twelve indifferent tones of two intensities (60 or 80 dB, intensity change on trial 11, counterbalanced between subjects) were presented at very long interstimulus intervals (ISIs). Novelty and intensity based stimulus-response patterns were examined seeking ERP analogues of autonomic measures representing pre-OR and OR processing. Skin conductance response (SCR) represented the phasic OR index. EOG-corrected ERP data for 16 subjects were decomposed by a temporal Principal Components Analysis (PCA). SCR diminished over 10 standard trials, recovered on change trial 11, dishabituated to the re-presentation of the standard tone on trial 12, and showed intensity effects at the change - formal requirements for an OR index. The evoked cardiac response (HR) showed no trial or intensity effects. Respiratory pause (RP) decreased linearly over trials and showed recovery but no dishabituation or intensity effect. Peripheral vasoconstriction (PVC) failed to decrement but exhibited an intensity effect. Ten identifiable ERP components were extracted: Na, P1, N1-1, PN, P2, P3a, P3b, a novelty-sensitive HabP3, an intensity-sensitive IntP3, and the Slow Wave (SW). Pattern 1 showed no trial or intensity effects (HR, P1, PN, P2) Pattern 2 showed no trial effect but an intensity effect (PVC, Na, N1-1, P3a) and Pattern 3 demonstrated habituation and an intensity effect (SCR, RP, P3b, HabP3, IntP3, SW). The observed fractionation of autonomic and central measures is consistent with Preliminary Process Theory (PPT) rather than the notion of a unitary OR.
Publisher: Frontiers Media SA
Date: 27-02-2015
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.JNEUMETH.2019.04.001
Abstract: The majority of electroencephalographic (EEG) investigations in normal ageing have determined EEG spectra from epochs recorded in the eyes-closed (EC) and/or eyes-open (EO) resting states, and summed litudes or power estimates within somewhat-arbitrary and/or inconsistently defined traditional frequency band limits. Natural frequency components were sought using a data-driven frequency Principal Components Analysis (f-PCA) approach, optimised to reduce between-condition and between-group misallocation of variance. Frequency component correspondence was screened using the Congruence Coefficient and topographic correlations for potential matches on Condition and/or Group. The litudes of corresponding natural components were then explored as a function of these independent variables. Separate f-PCAs with Young and Older adults' EC and EO data each yielded between six and nine components that peaked across the traditional delta to beta band ranges. Across these, two components were matched on Group and Condition, while a further six were matched on Condition (within-groups), and four on Group (within-conditions). Multiple frequency components were found within the traditional bands, and provided a wider perspective in terms of additional natural component details. In addition to novel insights, the well-documented age-related spectral reductions were seen in the common delta component, and in one EC (but no EO) alpha component. This combination of optimised f-PCA approach and component screening procedure has wide potential in the EEG field beyond the ageing topic explored here, being applicable across an extensive range of studies using EEG oscillations to explore aspects of cognitive processing and in idual differences.
Publisher: Springer Science and Business Media LLC
Date: 12-1984
DOI: 10.3758/BF03327206
Publisher: Springer Science and Business Media LLC
Date: 11-2002
DOI: 10.1007/S00213-002-1205-0
Abstract: Stimulant medications are the most commonly used treatments for attention deficit/hyperactivity disorder (ADHD) in North America and Australia, although it is still not entirely known how these medications work. This study aimed to investigate the effects of stimulant medications on the EEG of children with the Combined subtype of ADHD. An initial EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. Theta/alpha and theta/beta ratios were also calculated. Subjects were placed on a 6-month trial of a stimulant and a second EEG was recorded at the end of the trial. The ADHD group had significantly greater absolute delta and theta, less posterior absolute beta, more relative theta, and less relative alpha than the control group, which is typical of EEG studies of children with ADHD. The use of stimulant medications resulted in normalisation of the EEG, primarily evident in changes in the theta and beta bands. These results suggest that stimulants act to increase cortical arousal in children with ADHD, normalising their brain activity.
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.CLINPH.2005.09.026
Abstract: This study investigated intrahemispheric and interhemispheric EEG coherences as a function of age in girls with different DSM-IV subtypes of Attention-Deficit/Hyperactivity Disorder (AD/HD). It completes a series of 3 studies aimed at clarifying developmental and gender impacts on the coupling between brain regions in this disorder. Three groups of 40 children (AD/HD combined type, AD/HD inattentive type, and normal controls) participated. Each group contained 8 females in each of 5, 1-year age bands from 8 to 12 years. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. Developmental effects in intrahemispheric coherences at shorter and longer inter-electrode distances were not as predicted by Thatcher's two-compartment model, contrary to previous findings in boys. Females with AD/HD showed evidence of developmental delay and widespread anomalous elevations in coherence. Girls with AD/HD of the combined type showed similar but greater anomalies than girls with AD/HD of the inattentive type. Girls with AD/HD show coherence anomalies relative to age- and gender-matched controls, which differ substantially from those shown by boys with AD/HD. These coherence anomalies did not differ in nature between girls with different DSM-IV subtypes of AD/HD, suggesting that subtype differences in girls reflect only symptom severity. The data reported here indicate qualitative differences in EEG coherences in girls with AD/HD compared with controls, and quantitative differences between girls with different subtypes of AD/HD. Both sets of effects differ in nature from those previously found in boys with AD/HD, showing the need to carefully consider gender in future studies of AD/HD.
Publisher: Elsevier BV
Date: 11-1999
DOI: 10.1016/S0167-8760(99)00068-9
Abstract: Adolescent unmedicated ADHD males and age- and sex-matched normal control subjects were examined simultaneously using EEG and EDA measures in a resting eyes-open condition. ADHD adolescents showed increased absolute and relative Theta and Alpha1 activity, reduced relative Beta activity, reduced skin conductance level (SCL) and a reduced number of non-specific skin conductance responses (NS.SCRs) compared with the control subjects. Our findings indicate the continuation of increased slow wave activity in ADHD adolescents and the presence of a state of autonomic hypoarousal in this clinical group.
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.NLM.2008.07.007
Abstract: The orienting reflex (OR), elicited by an innocuous stimulus, can be regarded as a model of the organism's interaction with its environment, and has been described as the unit of attentional processing. A major determinant of the OR is the novelty of the eliciting stimulus, generally operationalized in terms of its reduction with stimulus repetition, the effects of which are commonly described in habituation terms. This paper provides an overview of a research programme, spanning more than 30 years, investigating psychophysiological aspects of the OR in humans. The major complication in this research is that the numerous physiological measures used as dependent variables in the OR context fail to jointly covary with stimulus parameters. This has led to the development of the Preliminary Process Theory (PPT) of the OR to accommodate the complexity of the observed stimulus-response patterns. PPT is largely grounded in autonomic measures, and current work is attempting to integrate electroencephalographic measures, particularly components in the event-related brain potentials reflecting aspects of stimulus processing. The emphasis in the current presentation is on the use of the defining criteria of the habituation phenomenon, and Groves and Thompson's Dual-process Theory, in the development of PPT.
Publisher: Hogrefe Publishing Group
Date: 2005
DOI: 10.1027/0269-8803.19.1.24
Abstract: Abstract. In an S1-S2 Go/NoGo task the impact of slow potentials following S1, particularly the late component of the contingent negative variation (CNV), on the following cognitive-processing waveforms to S2 (e.g., N2 and P3) remains unclear. A common method to correct for these confounding slow waves has used a forced baseline shortly before S2. The impact of this on ERP measures relating to S2 is unclear. An earlier method of CNV correction, devised to remove its effect on P3 measures by using different baselines for each condition, appears questionable. This study explored the removal of the CNV from both Go and NoGo waveforms to clarify the sensory and cognitive components elicited by S2. Principal Component Analysis (PCA) was performed on the ERP means, and a component relating to the CNV was subtracted from each subject's raw data for each site and condition. Results showed that this effectively removed the CNV without distortion of the S2 ERP morphology. This technique may prove useful in the analysis of the N2 and P3 as indicators of processes involved in response inhibition.
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.IJPSYCHO.2008.11.007
Abstract: Children with Attention-deficit Hyperactivity Disorder (AD/HD) show deficits in executive inhibitory functions such as behavioral inhibition and interference control, but investigations of both of these domains in the same groups of children is scarce, especially with concurrent consideration of ERP indices of inhibitory processes. Twenty children with AD/HD and 20 matched controls aged between 8 and 14 years performed visual Go-Nogo (30% Nogo) and Flanker tasks while EEG was recorded. Results indicated that children with AD/HD traded off speed for accuracy in the Go-Nogo task, resulting in similar levels of response inhibition accuracy in the Flanker task response speed and errors were at control levels, while misses were increased and showed an enhanced interference effect. In the Go-Nogo task, the AD/HD group showed reduced Go/Nogo P2, a reduced central N2 Nogo>Go effect, and a more anterior Go/Nogo P3 compared to controls. For the Flanker task, the AD/HD group showed delayed N1 and P2, dramatically reduced N2 to Incongruent stimuli, enhanced N2 to Neutral stimuli, as well as increased P3 to Incongruent stimuli, compared to controls. These results indicate that Go-Nogo behavioral inhibition and Flanker interference control were not equally impaired in children with AD/HD, and that factors such as effort, arousal and motivation require further investigation.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.IJPSYCHO.2013.05.015
Abstract: Evidence for the nature and extent of the prestimulus EEG contributions to ERP determination has been mounting, and we have recently mapped these within an equiprobable auditory Go/NoGo task. Here we examined if the pattern of relationships in the Go/NoGo would generalise to an auditory habituation paradigm. Count and No-task conditions were assessed, and we predicted broadly corresponding effects between Go and Count, and NoGo and No-task conditions. Single-trial data were obtained at the midline sites (Fz, Cz, Pz). Prestimulus EEG in each of the traditional bands was quantified using a sliding FFT window, and five ERP components were manually identified. The corresponding EEG and ERP data were then correlated across subjects, sites, and trials, separately for each ERP component measure ( litude, latency), task condition (Count, No-task), and EEG band (delta, theta, alpha, beta). Despite the substantial paradigm and methodological differences, 10 of the 17 expected prestimulus EEG-ERP directional relationships (i.e., direct or inverse effects) were confirmed across the traditional bands and ERP components, and only one was in the opposite direction. Importantly, 18 additional relationships reached significance here these occurred across the EEG bands, and ERP components. Together these findings confirm the significant contributions of prestimulus EEG to subsequent ERP responses. These appear to be at least partially independent of the paradigm and EEG methodology employed, suggesting that there is merit in mapping these contributions further. Our findings also indicate the improved sensitivity of the statistical approach used here in detecting such EEG-ERP relationships.
Publisher: Elsevier BV
Date: 02-2002
DOI: 10.1016/S1388-2457(01)00736-2
Abstract: This series of studies investigated (1) electroencephalographic (EEG) differences between good and poor responders to methylphenidate, (2) EEG differences between good and poor responders to dex hetamine, and (3) differences in the EEGs of good responders to methylphenidate versus dex hetamine, within s les of children with the combined type of attention-deficit/hyperactivity disorder (ADHD). Twenty good and 20 poor responders to each of methylphenidate and dex hetamine, based on the results of a continuous performance task, and 20 age-matched control subjects, participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. EEG differences were found between the good and poor responders to each medication. Good responders to methylphenidate had EEG profiles that suggested that they were more cortically hypoaroused than poor responders. In contrast, the good responders to dex hetamine appeared to be more maturationally lagged than the poor responders. The two good-responder groups had EEG profiles which suggested that there were two different underlying central nervous system (CNS) dysfunctions. Children with the combined type of ADHD do not constitute a homogeneous clinical group, as different types of CNS dysfunction are present within this population. These results also indicate the need for medication testing to be undertaken before a child is prescribed stimulant medication for ADHD.
Publisher: Elsevier
Date: 2013
DOI: 10.1016/B978-0-7020-5307-8.00003-X
Abstract: Current views of the genesis of the event-related potential (ERP) emphasize the contribution of ongoing oscillations - the ongoing electroencephalogram (EEG) is recognized as much more than "background noise" to be removed by response averaging to find the ERP. Early work from Başar's group noted that repetitive stimuli led to selective phase re-ordering of activity in the delta and alpha bands, such that enhanced brain negativity occurred at the time of the regular stimulus. Other work related negativity in alpha activity at stimulus onset to improved reaction times and ERP enhancements. These findings led us to begin a program of brain dynamics studies exploring pre-stimulus EEG phase states, their preferential occurrence in paradigms with regularly presented stimuli, and their relation to ERP outcomes. In particular, with very narrow EEG bands, we have repeatedly found that certain phase states preferentially occur at stimulus onset, implying ongoing phase re-ordering driven by stimulus occurrence. Effects are weakened with slightly varying inter-stimulus intervals, but still occur reliably. Further, these preferential phase states are functionally effective in relation to the ERP correlates of efficient stimulus processing. Preferential phase occurrence and their effects were originally reported in auditory oddball tasks, using narrow EEG bands derived by digital filtering. A recent study is presented illustrating generalization of the phenomenon in the auditory Go/NoGo task, using narrow bands derived by FFT techniques. Our current work is extending this research in normal children (to provide a comparative context for research in children with AD/HD), and well-functioning elderly (to provide a context for future work in relation to Alzheimer's disease).
Publisher: Wiley
Date: 17-08-2011
DOI: 10.1111/J.1469-8986.2011.01271.X
Abstract: This study examined skin conductance responses, the late positive complex of the event-related potential, and pupillary dilation responses as autonomic and central correlates of the orienting reflex (OR) in the context of indifferent and significant stimuli. In particular, we aimed to clarify the inconsistencies surrounding the pupillary dilation response as an OR index. An auditory dishabituation paradigm was employed, and physiological measures were recorded from 24 participants. Response decrement to a repeated stimulus, response recovery to a change stimulus, and subsequent dishabituation were assessed. Findings confirmed expectations that the skin conductance response and the late positive complex are indices of the OR. The pupillary dilation response, however, demonstrated an unexpected sensitivity to stimulus novelty only, while the prestimulus measure of tonic pupil diameter showed the significance effect that was expected of the phasic measure. Together, these findings argue against the suggestion that the pupillary dilation response is an OR index. The erse results obtained from this experiment contribute to our understanding of the OR, and provide impetus for further research with a variety of paradigm manipulations.
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 07-1993
DOI: 10.1016/0167-8760(93)90093-5
Abstract: This study examined phasic and tonic measures of electrodermal activity in a simple habituation paradigm with innocuous visual stimuli. Prestimulus skin conductance levels were taken as measures of the arousal level existing at each stimulus presentation, and the subsequent electrodermal responses were taken as indices of the phasic orienting reflex (OR) elicited by each stimulus. The arousal level was considered as a tonic OR measure. Both the tonic and phasic ORs showed effects of trials. Arousal levels also showed an initial sensitization, as suggested by dual-process theory. After within-subject effects of arousal changes over trials were removed by simple regression analyses, novelty still remained as the major determinant of phasic OR magnitude. This finding is discussed in relation to the OR mechanism.
Publisher: Oxford University Press (OUP)
Date: 22-12-2005
Abstract: In a dichotic paradigm, duration-deviant mismatch negativity (MMN) largely reflects standard stimuli presented to the same ear as the deviant, suggesting an independent representation for each ear. We sought to assess this representation independence. Twenty-two participants, presented left (all 2000 Hz, 70-dB sound pressure level [SPL]) and right (all 800 Hz, 85-dB SPL) ear sounds, attended to 1 ear per block. A series of successive trains of 6-30 sounds were presented to each ear. Although 1 ear received short (40 ms) standard sounds, the other received an equal number of long (120 ms) standards. In the next train, the standard durations were switched between the ears. Stimulus onset asynchrony ranged from 120 to 440 ms. Duration deviants (240 ms) replaced the final standards of some trains. MMN latency simultaneously moved earlier for the ear changing from long to short standards and later for the ear changing from short to long standards. Based on a simple linear model, more than 80% of the memory trace reflected within-channel standards. We conclude that independently changeable memory traces underlie dichotic presentation. Separation of the representation for the attended subset of stimuli is proposed as core to the mechanism of sustained attention.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.PHYSBEH.2011.09.018
Abstract: The current study reports on a number of heart rate responses observed in rats subjected to a discriminatory Pavlovian fear conditioning procedure. Rats learned that a series of six auditory pips was followed by a footshock when presented alone, but not when the pip series was preceded by a visual safety signal. Each auditory pip in the series evoked a fast transient (<1s) cardiac deceleration. This was the case on both trials followed by shock and on trials not followed by shock. The onset of the safety light evoked a similar fast deceleration. We propose that these transient decelerations are similar to the human Evoked Cardiac Response 1 (ECR1), a brief modest deceleration evoked by simple sensory stimuli that is thought to reflect an early process of stimulus registration. Immediately following these pip-evoked decelerations, modest fast accelerations were observed. These accelerations were larger when the pip series was followed by shock than when it was not followed by shock. We propose a potential linkage between these accelerations and the human acceleratory ECR2 component, which is associated with more elaborate processing following stimulus registration something likely to take place when the pip series predicts an aversive event. Both the ECR1- and ECR2-like responses were embedded within a slow, gradual heart rate increase across the entire pip series. This tonic increase was significantly larger on trials with footshock and is therefore probably associated with anticipatory fear of the upcoming shock. An additional special type of cardiac response was found to the first pip in the series not preceded by the safety signal here, a much larger and more sustained deceleration was apparent. This response appears relatable to the prolonged deceleration reported in humans in response to aversive picture content. We discuss the cardiac responses found in rats in the current study in the context of heart rate responses known in the human literature.
Publisher: Elsevier BV
Date: 06-2002
DOI: 10.1016/S0167-8760(01)00201-X
Abstract: An important method for removing the effect of ocular artefact from the EEG is 'EOG correction'. This method estimates the proportion of ocular artefact that is in the EEG, and removes it by subtraction. To date, EOG correction research has focused on problems relating to the estimation of the correction coefficients. Using both mathematical rationale and empirical data, this paper addresses issues relating to the subtraction phase, such as the magnitude of error that can be expected due to EOG correction. Using ERP methodology, principal component and regression analyses, it is shown that the N1P2 complex propagates forward to the horizontal and radial (but not vertical) electrooculograms (EOG), and it is shown mathematically that this will result in EOG-correction error. Assuming an accurate estimate of ocular contamination of the EEG, maximal subtraction-phase error of the N1P2 complex was found to be a prefrontal attenuation of 15-22%, decreasing to central and occipital enhancements of 3-4% and 13-14%, respectively. The magnitude of this subtraction-phase error is compared to between-subject ERP variability and to error associated with EOG rejection (omitting data contaminated by ocular artefact). It is argued that such EOG correction error is small relative to both artefact rejection procedures and to normal variability found in ERP studies, and that it is less pernicious than artefact rejection procedures.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.CLINPH.2007.07.028
Abstract: Recent work has attempted to clarify the energetics of physiological responding and behaviour by refining and separating the operational definitions of "arousal" and "activation", which have different effects on physiological responding and behaviour. At the EEG level, we relate the former to widespread activity, and the latter to task-specific topographically-focussed activity reflecting regional processing. This study aimed to investigate this further in terms of differences in EEG activity between eyes-closed and eyes-open resting conditions. EEG activity was recorded from 28 university students during both eyes-closed and eyes-open resting conditions, Fourier transformed to provide estimates for absolute power in the delta, theta, alpha and beta bands, and analysed in 9 regions across the scalp. Skin conductance level was also measured as an indicator of arousal level. Across the eyes-closed conditions, skin conductance levels were negatively correlated with mean alpha levels. Skin conductance levels increased significantly from eyes-closed to eyes-open conditions. Reductions were found in across-scalp mean absolute delta, theta, alpha and beta from the eyes-closed to eyes-open condition. Topographic changes were also evident in all bands except for alpha, with reduced lateral frontal delta and posterior theta, and decreased posterior/increased frontal beta in the eyes-open condition. In particular, the topographic beta effects indicate that the across-scalp reduction arose from focal reductions rather than global changes. The obtained results confirm the use of mean alpha level as a measure of resting-state arousal under eyes-closed and eyes-open conditions. The focal nature of EEG effects in the other bands suggests that these reflect cortical processing of visual input, producing differences in activation between eyes-closed and eyes-open resting conditions, rather than just the simple increase in arousal level shown in alpha. This study demonstrates that the eyes-closed and eyes-open conditions provide EEG measures differing in topography as well as power levels. These differences should be recognised when evaluating EEG research, and considered when choosing eyes-open or eyes-closed baseline conditions for different paradigms.
Publisher: Elsevier BV
Date: 12-1998
DOI: 10.1016/S0013-4694(98)00087-X
Abstract: In the field of EOG correction, discrepancies have been found between the propagation rates for different types and frequencies of eye movement. However, Croft and Barry demonstrated that these differences can be explained by the affect of EOG magnitude on the correction procedure (Croft, R.J. and Barry, R.J. EOG correction: a new perspective. Electroenceph. clin. Neurophysiol., 1998, 107: 387-394). This study utilized a new 'aligned-artifact average' technique (AAA) to examine whether propagation is constant across eye movement types and frequencies, and tested the AAA as an EOG correction tool. Two experiments manipulated interference levels in real data sets to determine if interference affected propagation coefficients (Bs). The third tested real data for the effect of forward propagation of eye movement related neural potentials on Bs, and the fourth utilized computer simulations to assess the effectiveness of the new AAA correction procedure. Interference was found to inflate B at low EOG litude, and its removal removed B variation and inflation. The forward propagation of eye movement related neural potentials had very little effect on B. The AAA procedure produced near perfect corrections of the simulated data, superior to a comparison method. EOG propagation is constant across eye movement types and frequencies, and thus only one correction coefficient should be calculated and applied to data. The AAA method provides a more accurate correction and makes possible, for the first time, the adequate correction of posterior sites.
Publisher: Hogrefe Publishing Group
Date: 2005
DOI: 10.1027/0269-8803.19.1.11
Abstract: Abstract. The aim of the present study was to investigate behavioral and electrophysiological indices of developing response activation and inhibition processes in child, young-adult, and adult groups. Sixty subjects, with 20 in each of the child (mean age 10.8 years), young-adult (mean age 20.7 years), and older adult (mean age 36.4 years) groups, performed an auditory Go/NoGo task while task performance variables and EEG were recorded. ERPs were derived to Go (response activation) and NoGo (response inhibition) stimuli, with the litude and latency of the N1, P2, N2, and P3 ERP components analyzed as a function of age. Results indicate improved task performance, and a reduction in the latency of each component and the litude of the N2 and P3 components, with increasing age. Analyses of Go versus NoGo effects indicated differential utilization of inhibition-related processing stages in children compared to adults, with some minor differences between the two adult groups. Go/NoGo effects were evident during early stages of processing, such as those indexed by the N1 and N2 components in children, but only in later stages, as indexed by P3, in adult subjects. This study provides much-needed data on the normative development of response activation and inhibition, as operationalized by the auditory Go/NoGo task, in children and two groups of younger/older adult subjects.
Publisher: Elsevier BV
Date: 05-2005
DOI: 10.1016/J.CLINPH.2004.12.007
Abstract: This study investigated the diagnostic utility of EEG power during eyes-closed resting conditions for children with attention-deficit/hyperactivity disorder (AD/HD). Subjects consisted of 253 boys with AD/HD combined type and 67 age-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and was Fourier transformed to provide estimates for total power and absolute and relative power in delta, theta, alpha and beta bands. Factor analysis was used to group sites into frontal, central and posterior regions, with these data subjected to cluster analysis. Logistic regression was performed on the entire AD/HD s le versus control, for AD/HD clusters versus control, and then for each AD/HD cluster independently versus control, using total, absolute and relative power measures. Logistic regression performed on the clusters independently produced the best classification results, with a sensitivity of 89.0% and a specificity of 79.6%, with an overall classification accuracy of 87.0%. The obtained classification results are supportive of an independent diagnostic test for AD/HD based on EEG power at rest. This is the first study to investigate sensitivity and specificity of EEG power for AD/HD in a resting condition.
Publisher: Elsevier BV
Date: 10-1999
DOI: 10.1016/S0006-3223(99)00038-4
Abstract: Impaired processing of faces in patients with schizophrenia may underlie aspects of disturbance in their social interaction. This study examined patterns of eye fixation in subjects with schizophrenia and non-psychiatric controls, while processing a high resolution picture of a neutral face and a nonbiological complex geometric stimulus. Ten-second sequences of eye movement were recorded video-oculographically (50 s les/sec) while subjects were "free-viewing" the stimuli. An essential element of the study was customized software that ensured stimulus presentation on a video display only after subjects were fixated upon a centre-screen cue, so that all subjects began stimulus processing from the same point. Compared with the control group, subjects with schizophrenia exhibited reduced scanpath lengths and a tendency toward fewer fixations for the face stimulus. They also showed an initial relative right spatial hemineglect (for the first voluntary fixation) when viewing the Rey figure, but not when viewing the face stimulus. Overall, there were no significant differences between the schizophrenia and control groups in the lateral distribution of subsequent fixations for either stimulus. Disturbed spatial and temporal patterns of eye movement in some people with schizophrenia may reflect sub-optimal processing of face stimuli, that may predispose these in iduals to dysfunctional interpretation of facial communication cues.
Publisher: Elsevier BV
Date: 02-2003
DOI: 10.1016/S0167-8760(02)00119-8
Abstract: Stimulant medications are the most commonly-used treatments for Attention-Deficit/Hyperactivity Disorder (ADHD) in North America and Australia, although it is still not entirely known how these medications work. This study investigated the effects of stimulant medications on the EEG of children with the Inattentive type of ADHD. An initial EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. Theta/alpha and theta/beta ratios were also calculated. Subjects were placed on a 6-month trial of a stimulant and a second EEG was recorded at the end of the trial. Subjects were included in this study only if they showed a good clinical response during the trial. The unmedicated ADHD group had significantly greater absolute and relative theta, less relative alpha, and higher theta/alpha and theta/beta ratios than the control group. The stimulant medications resulted in a normalisation of the EEG, with changes in the theta, alpha and beta bands being most evident. These results suggest that stimulants act to increase cortical arousal in children with ADHD, normalising their EEG.
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.CLINPH.2004.06.004
Abstract: We aimed to examine the relation between the phase of electroencephalogram (EEG) alpha activity at stimulus onset and event-related potentials (ERPs) in a fixed-inter-stimulus interval auditory 'oddball' task, using a novel conceptualisation of orthogonal phase effects (cortical negativity versus positivity, negative driving versus positive driving, waxing versus waning). EEG responses to button-press targets, from 14 subjects presented with 4 blocks of 150 stimuli (50% target probability), were examined. Pre-stimulus alpha activity (8-13 Hz) at Pz was assessed for each trial by digital filtering of the EEG. The alpha cycle at Pz, starting from a negative-going zero crossing, was used to sort trials into 4 phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz, and Pz. Preferred brain states in this paradigm were indicated by an 8% greater occurrence of negative driving than positive driving, and a 33% greater occurrence of waxing than waning phases. Negative driving phases were associated with increased N1 latencies and decreased N2 litudes. Latencies of N1 and P2 were reduced in waxing phases. These reflected systematic changes in alpha frequency and litude at stimulus onset. In a fixed-inter-stimulus interval paradigm, component frequencies of the EEG are dynamically adjusted in order to provide brain states at the moment of stimulus presentation which differentially affect the EEG correlates of stimulus processing. The results add to our understanding of the genesis of the ERP, indicating the importance of the dynamic interplay between instantaneous EEG activity and stimulus processing reflected in the ERP.
Publisher: Wiley
Date: 10-05-2015
DOI: 10.1111/PSYP.12447
Abstract: The equiprobable go/no-go task lacks the dominant go imperative found in the usual go/no-go task, and hence we previously regarded it as involving little inhibition. However, children have relative difficulty with this task, and demonstrate large frontal no-go N2s. We investigated whether this child N2 plays an inhibitory role, using performance measures to illuminate the link between N2 and inhibition. Forty children aged 8 to 13 were presented with four stimulus blocks each containing 75 go and 75 no-go tone stimuli in random order. A temporal PCA with unrestricted varimax rotation quantified the mean go and no-go ERP component litudes. Most identified components were differentially enhanced to go or no-go as in adults, supporting a previously proposed differential processing schema. Between subjects, larger frontocentral no-go N2bs were associated with fewer commission errors. Hence, the no-go N2b in this paradigm can be interpreted as an in idual marker of inhibition in children.
Publisher: Frontiers Media SA
Date: 16-06-2016
Publisher: Wiley
Date: 03-02-2020
DOI: 10.1111/PSYP.13538
Publisher: Wiley
Date: 05-0007
Abstract: The P3(00) is an electrophysiological index of neural processing that varies with such stimulus parameters as interstimulus interval (ISI) and target probability, with a common view being that it reflects an endogenous form of memory update. Building on previous research, we argue that relations between P3 litude and both ISI and probability may be attributable to the target-to-target interval (TTI). Employing between-subject (Experiment 1 N = 24) and within-subject (Experiment 2 N = 10) designs, the present paper addresses this by testing subjects on a standard two-tone auditory oddball task as well as a one-tone task. In both studies, P3 litude increased and latency decreased linearly with TTI, and these relations were relatively unaffected by ISI or probability. This suggests that ISI and probability per se do not independently affect P3 litude, and that TTI offers a strong explanation of the reported relations between P3 litude and both ISI and probability.
Publisher: Springer Science and Business Media LLC
Date: 14-09-2005
DOI: 10.1007/S00213-005-0144-Y
Abstract: Previous research investigating the effects of stimulants, such as methylphenidate (MPH), on children with attention deficit/hyperactivity disorder (AD/HD) has rarely included autonomic measures of arousal. Our aim was to clarify the effects of MPH on central and autonomic measures in AD/HD children during a continuous performance task (CPT) using a naturalistic open-label study. Thirty-six boys (18 AD/HD and 18 control) participated in a CPT over two trial periods, allowing a more valid estimate of the effects of medication, rather than assuming that retesting per se has no substantial impact. MPH was administered to the AD/HD group 1 h prior to the second trial. Errors and reaction time (RT) were recorded as measures of performance, electrodermal activity as an autonomic nervous system measure and event-related potentials (ERPs) as an index of central nervous system activity. AD/HD children made more errors than controls in the first session, but no group differences were found after medication. No significant differences were observed for RT. Skin conductance level was found to be lower in AD/HD children than controls, but this difference was also ameliorated after medication. Conversely, mean skin conductance response to target stimuli was found not to differ between groups during the initial test phase but became significantly different in phase 2. ERP data showed topographic differences between groups in N1, P2, N2 and P3 at the initial test phase, which were reduced at the second test. Stimulant medication ameliorated some of the dysfunctions in AD/HD children, which are reflected in behavioural and ERP measures. These results, in combination with general differences in electrodermal activity, support a hypo-arousal model of AD/HD, which can explain the action of MPH in these children.
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.PHYSBEH.2009.06.007
Abstract: Previous studies from this laboratory have explored the relationships between physiological response magnitudes, behavioural performance measures, current arousal level, and activation (defined as task-related change in arousal) during a continuous performance task. We have reported larger physiological responses with increased arousal, and performance improvement with higher levels of activation. Performance results have been consistent at the level of averaged data, whether obtained from between-participant studies using across-trials averaging (yielding one data point per person), or using across-subject within-trials averaging (yielding 1 data point per trial). The present study was designed to explore this relationship at the in idual level. A repeated continuous performance task (CPT) was used with normal adults. Reaction time performance at each target in the first block was considered relative to the corresponding target in the second block. Skin conductance level (SCL) was recorded during the task as an index of arousal at each target. Activation at each target in the first block was calculated by subtracting the level of arousal at the corresponding target in the second block. The relationship between first-block performance enhancement and activation in different participants followed different trends. Some participants showed the traditional inverted-U relationship, and some showed the opposite trend. In line with our previous studies, the average linear relationship over all participants was positive. The importance of these findings is discussed in relation to sport performance enhancement.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.BIOPSYCHO.2007.11.002
Abstract: The timing of caffeine effects on arousal levels was examined. From previous work in our laboratory, an increase in skin conductance level (SCL) was used as the marker of arousal increase, and we sought to identify the timing of this and related effects following caffeine ingestion. A single oral dose of caffeine (250 mg) was used in a randomised double-blind placebo-controlled repeated-measures cross-over study. Eyes-closed resting electroencephalogram (EEG) and autonomic data (SCL, heart rate, respiration rate, and systolic and diastolic blood pressure) during 2 min epochs that commenced every 4 min after ingestion, were analysed. The SCL placebo data were used to identify potential arousal measures prior to examining caffeine effects. Caffeine was associated with increased SCL, increased respiratory rate and a global reduction in alpha power. There were no significant cardiovascular effects of caffeine-induced arousal. These caffeine results are consistent with our recent electrodermal and EEG studies of arousal, and confirm the potential use of caffeine as a simple means of experimentally modifying arousal levels without task-related confounds.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.IJPSYCHO.2010.10.008
Abstract: A group of methods that are employed for removing ocular artifact from the electroencephalogram (EEG) is referred to as electrooculogram (EOG) correction methods. These use least-square linear regression, and the relative success of these is yet to be established. Improving on previous EOG correction validation studies, we present a new validation technique (with greater face validity) and use it to compare four commonly employed EOG correction methods. Data consisted of ERP traces to auditory stimuli that were embedded in up, down, left and right eye movements (EMs), recorded from 24 subjects. A 'Peak Difference' validation measure was employed, which determined the magnitude of the difference of two auditory N100 peaks (those associated with EMs with opposing polarities). All correction methods produced data that was better than not correcting at all. EOG correction methods that accounted for vertical EM, horizontal EM and blink artifact separately using separate EOG channels, produced the best corrections, with some further advantage in methods that enhanced signal (EOG) to noise (EEG) ratios when calculating correction coefficients.
Publisher: Wiley
Date: 19-11-2019
DOI: 10.1111/PSYP.13300
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.NLM.2011.02.007
Abstract: In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2-4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5-7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.
Publisher: Elsevier BV
Date: 02-1996
DOI: 10.1016/0167-8760(95)00049-6
Abstract: Electroencephalographic measures (EEG) and skin conductance level (SCL) respectively reflect cerebral cortical activity and sympathetic autonomic activity. Such central and autonomic activities associated with arousal generally have been studied separately, despite their potential to reflect complementary dimensions of reticular-thalamo-hypothalamo-cortical activating networks. In this study, we examined the relationship between cortical (19 EEG sites) and autonomic (SCL) activities recorded simultaneously in 10 normal adults. Two second pre-stimulus EEGs and SCLs were assessed from an habituation paradigm which presented 22 trains of 7 tones in an 'ignore' condition. The mean SCLs of the epochs across subjects showed an initial rise (sensitization) followed by an exponential decline (habituation). Although EEG associated with the tones did not demonstrate such a distinct profile, EEG total power and band powers (beta, alpha and theta) associated with the trains showed a systematic increasing response profile. In the group data the mean SCLs within trains showed a significant correlation with alpha and beta band powers. Finer EEG band analyses indicated that beta 3 at Fz and alpha 2 at Cz showed the strongest separate linear correlations with SCL. beta 3 and alpha 1 at Fz were found to jointly covary with SCL. The findings indicate a substantive relationship between measures of cerebral function and autonomic arousal.
Publisher: Elsevier BV
Date: 12-1998
DOI: 10.1016/S0013-4694(98)00086-8
Abstract: In the field of EOG correction, discrepancies have been found between the propagation rates for different types and frequencies of eye movement. This study attempted to determine whether these differences could be explained by the affect of EOG magnitude on the correction procedure. Experiment 1 utilized simulated data to determine whether the combination of EOG magnitude and other forms of interference distorted the estimation of the propagation coefficients (Bs). Experiment 2 used real data to determine if the patterns obtained in Expt. 1 were apparent in real data. Matched t tests found that simulated low power EOG produced inflated Bs as a function of interference in Expt. 1. Experiment 2 found the same relationship between B and EOG magnitude as with the simulations. The findings are consistent with the thesis that eye movement related fields propagate similarly for a range of EOG types and frequencies, suggesting that the B differences reported in the literature are artifactual, and indicating the need for a new correction procedure.
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.CLINPH.2009.07.045
Abstract: This paper describes recommended methods for the use of event-related brain potentials (ERPs) in clinical research and reviews applications to a variety of psychiatric and neurological disorders. Techniques are presented for eliciting, recording, and quantifying three major cognitive components with confirmed clinical utility: mismatch negativity (MMN), P300, and N400. Also highlighted are applications of each of the components as methods of investigating central nervous system pathology. The guidelines are intended to assist investigators who use ERPs in clinical research, in an effort to provide clear and concise recommendations and thereby to standardize methodology and facilitate comparability of data across laboratories.
Publisher: Elsevier BV
Date: 09-1995
DOI: 10.1016/0165-1781(95)02315-N
Abstract: This event-related potential study systematically varied the number of nontargets (1, 3, 5, 7, 9) preceding the target tone in an oddball experiment and examined the effect of this on N2, P3, and reaction time measures in schizophrenic patients and normal volunteers. Schizophrenic patients were found to have reduced P3 litudes, but this reduction was restricted to series when the targets followed an intermediate number (3-7) of nontargets, and not when targets followed a short (1) or long series (9) of nontargets. Although other interpretations of this finding are possible, the pattern of results could be explained by the hypothesis that the refractory period governing the generation of the P3 component was prolonged in schizophrenia.
Publisher: Elsevier BV
Date: 02-2003
DOI: 10.1016/S1388-2457(02)00363-2
Abstract: This article reviews the event-related potential (ERP) literature in relation to attention-deficit/hyperactivity disorder (AD/HD). ERP studies exploring various aspects of brain functioning in AD/HD are reviewed, ranging from early preparatory processes to a focus on the auditory and visual attention systems, and the frontal inhibition system. Implications of these data for future research and development in AD/HD are considered. A complex range of ERP deficits has been associated with the disorder. Differences have been reported in preparatory responses, such as the contingent negative variation. In the auditory modality, AD/HD-related differences are apparent in all components from the auditory brain-stem response to the late slow wave. The most robust of these is the reduced posterior P3 in the auditory oddball task. There are fewer studies of the visual attention system, but similar differences are reported in a range of components. Results suggesting an inhibitory processing deficit have been reported, with recent studies of the frontal inhibitory system indicating problems of inhibitory regulation. The research to date has identified a substantial number of ERP correlates of AD/HD. Together with the robust AD/HD differences apparent in the EEG literature, these data offer potential to improve our understanding of the specific brain dysfunction(s) which result in the disorder. Increased focus on the temporal locus of the information processing deficit(s) underlying the observed range of ERP differences is recommended. Further work in this field may benefit from a broader conceptual approach, integrating EEG and ERP measures of brain function.
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.IJPSYCHO.2007.10.001
Abstract: Attention-Deficit/Hyperactivity Disorder (AD/HD) is the most common psychiatric disorder of childhood, but it is becoming increasingly more apparent that more than half the childhood sufferers will continue to manifest symptoms of the disorder as adults. While EEG coherence in children with AD/HD has been examined extensively, no studies have investigated coherence in adults with the disorder. This study investigated EEG coherence in adults with AD/HD. EEG was recorded from 18 adult males with AD/HD, and an age- and gender-matched control group, during an eyes-closed resting condition. Waveshape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. A laterality effect was found for intrahemispheric coherence at long inter-electrode distances, with the AD/HD group showing reduced hemispheric differences in the delta band compared to the control group. In the alpha band, at short-medium inter-electrode distances, the AD/HD group also had lower coherences than the control group. The results suggest that theta coherence differences reported in children with AD/HD may be associated with hyperactivity, which is reduced in adults with AD/HD, while reduced alpha coherence could be associated with inattention, which remains in adult with AD/HD. Reduced delta coherence also appears to be an aspect of the disorder which may develop from later childhood into adolescence and adulthood.
Publisher: Elsevier BV
Date: 12-1995
DOI: 10.1016/0167-8760(95)00036-4
Abstract: A core feature of post-traumatic stress disorder (PTSD) is hypervigilence to threatening material. This study measured processing of threat material in PTSD with simultaneously acquired initial eye movements and electrodermal activity, following presentation of threatening and neutral words. Ten PTSD subjects and 10 controls were presented with 4 words in parafoveal range. On trials in which a threat word was present, PTSD subjects demonstrated initial eye fixations on the threat word more than controls. PTSD subjects also demonstrated more orienting responses on all trials than controls. These results suggest that processing of threat information in PTSD can be usefully investigated with convergent psychophysiological methodologies.
Publisher: Hogrefe Publishing Group
Date: 2007
DOI: 10.1027/0269-8803.21.2.109
Abstract: Abstract. The present study examined the development of response inhibition in the stop-signal task across child (8-13 years), young-adult (18-22 years), and middle-aged adult (29-47 years) groups through a dissociation of low- and higher-frequency ERP activity. Fifty-one subjects (n = 17 in each group) performed the stop-signal task, which consisted of a visual choice reaction time (RT) task and auditory stop-signals, while EEG was recorded. The original EEG data (0.01-30 Hz) was subsequently filtered to separate slow-wave (0.01-2 Hz) and residual (2-30 Hz) activity. Performance findings revealed that stop-signal reaction time (SSRT) decreased from the child to young-adult group and then showed a small increase in the middle-aged adult group. Original ERPs revealed decreasing N1 and N2 litudes and increasing P2 and P3 litudes across the scalp with increasing age for successful-stop trials. These developmental effects did not occur in the residual waveforms after removal of slow-wave activity. For failed-stop trials, a response-locked negative component, identified as the error-negativity (Ne), showed an age-related decrease in litude across the scalp in the residual, but not the original, waveform. The error-positivity (Pe) increased in litude with age in the original data, but this was accounted for by a positive slow-wave (PSW). Together, the findings suggest that underlying slow-wave activity accounts for a large number of developmental effects in the traditionally quantified ERP components, but may also obscure effects occurring in residual activity. These findings highlight the importance of dissociating low- and higher-frequency ERP activity in developmental research.
Publisher: Wiley
Date: 07-02-2007
DOI: 10.1111/J.1469-8986.2007.00495.X
Abstract: Target-to-target interval (TTI) is a primary determinant of P300 litude, such that longer TTIs yield larger components than shorter intervals. Systematic manipulations of TTI affect component litude, latency, and associated response time in a fashion that suggests that the template update hypothesis can account for these outcomes. The present study examines whether manipulations of TTI (from 1 to 16 s) and stimulus intensity (soft and loud tones) produce outcomes consistent with this hypothesis. A single-stimulus task was employed in which only target stimuli were presented. P300 litude increased, peak latency decreased, and response time increased as TTI became longer, with less effect for soft compared to loud stimulus conditions on P300 litude at Pz. TTI increases also augmented N100 litude, with consistently smaller litudes obtained for soft relative to loud stimuli. Overall, P300 measures are sensitive to both temporal and physical stimulus factors. Theoretical implications are discussed.
Publisher: Springer Science and Business Media LLC
Date: 04-2003
DOI: 10.1007/S00787-003-0315-5
Abstract: This study investigated EEG differences between children with Hyperkinetic Disorder (HKD), HKD sub-threshold attention deficit (HKDsub), and control children, in order to determine from an EEG perspective whether children with HKDsub represent a valid clinical disorder. Twenty-four boys were included in each of the three age-matched groups. The HKD group had greater total power and absolute delta and theta, more relative theta, and less relative alpha and beta than the control group. The HKDsub group had EEG profiles which were different from both control children and children with HKD, with the HKDsub group having EEG results generally between the HKD and control group. Additionally, a number of topographic differences were found in the frontal regions which suggest that the two HKD groups have independent EEG components. These results support the inclusion of a diagnostic category of attention deficit in future editions of the ICD.
Publisher: Wiley
Date: 04-01-2019
DOI: 10.1111/PSYP.13327
Publisher: Elsevier BV
Date: 02-2000
Publisher: Elsevier BV
Date: 1981
DOI: 10.1016/0031-9384(81)90080-9
Abstract: Coxsackievirus B (CVB) is a common human enterovirus that causes systemic infection but specifically replicates to high titers in the pancreas. It was reported that certain viruses induce mitochondrial fission to support infection. We documented that CVB triggers mitochondrial fission and blocking mitochondrial fission limits infection. The transient receptor potential channels have been implicated in regulating mitochondrial dynamics namely, the heat and capsaicin receptor transient receptor potential cation channel subfamily V member 1 (TRPV1) contributes to mitochondrial depolarization and fission. When we transiently warmed HeLa cells to 39 °C prior to CVB exposure, infection was heightened, whereas cooling cells to 25 °C reduced infection. Inducing "cold" by stimulating transient receptor potential cation channel subfamily M member 8 (TRPM8) with menthol led to reduced infection and also resulted in lower levels of mitochondrial fission during infection. Additionally, menthol stabilized levels of mitochondrial antiviral signaling (MAVS) which is known to be tied to mitochondrial dynamics. Taken together, this highlights a novel pathway wherein CVB relies on TRPV1 to initiate proviral mitochondrial fission, which may contribute to the disruption of antiviral immunity. TRPM8 has been shown to antagonize TRPV1, and thus we hypothesize that stimulating TRPM8 blocks TRPV1-mediated mitochondrial fragmentation following CVB exposure and attenuates infection.
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.CLINPH.2016.02.008
Abstract: This study investigated differences in EEG coherence measures between two groups of children with Attention-Deficit/Hyperactivity Disorder (AD/HD) - one with the more common EEG profile (increased theta), and a group with excess alpha activity as the dominant EEG abnormality. 26 children (aged 9-13years) with AD/HD were included in each of the excess-theta and excess-alpha groups, and were age- and sex-matched with 26 control subjects. EEG was recorded from 19 electrode sites during an eyes-closed resting condition. Wave-shape coherence was calculated for eight intrahemispheric and eight interhemispheric electrode pairs, for the delta, theta, alpha and beta bands. In comparison with the controls, the excess-theta AD/HD group had increased theta intrahemispheric coherences at short-medium inter-electrode distances. Frontally, the excess-theta AD/HD group had increased interhemispheric theta and reduced beta coherences. The excess-alpha group primarily showed increased slow wave (delta and theta) intrahemispheric coherence at short-medium inter-electrode distances, and reduced alpha coherence at longer inter-electrode distances, compared with controls. An increase in frontal interhemispheric theta coherence was also found. These results suggest that AD/HD children with excess alpha power have an underlying connectivity dysfunction in the frontal lobes, which is found in common with other subjects with the excess-theta EEG profile. However, a number of qualitative differences exist that could be associated with other aspects of the AD/HD diagnosis. The excess-alpha group appeared to have fewer frontal-lobe abnormalities than the excess-theta AD/HD group. This is the first study to investigate coherence in AD/HD children who have the atypical profile of increased alpha power in their EEG.
Publisher: Elsevier BV
Date: 09-2001
DOI: 10.1016/S0165-1781(01)00277-3
Abstract: Studies of children with attention deficit/hyperactivity disorder (ADHD) have typically found elevated levels of slow wave activity in their EEGs, but in two of our previous studies, a small subset of ADHD children with excess beta activity in the EEG was identified. The aim of this study was to determine whether children with excess beta activity represent a distinct electrophysiological subtype of ADHD, to quantify the differences in their EEGs, and to determine if this group of children with ADHD have behavioural profiles different from other children with ADHD. Results indicated that children with excess beta represent a small independent subset of children diagnosed with ADHD, which primarily consists of children with a diagnosis of ADHD combined type. Behaviourally, this group was similar to other children with ADHD, although the excess-beta group were more prone to temper tantrums and to be moody. The excess in beta activity was found primarily in the frontal regions and may be associated with frontal lobe self-regulation and inhibition control.
Publisher: Wiley
Date: 18-01-2019
DOI: 10.1111/PSYP.13330
Abstract: Caffeine's stimulant properties were used to test a proposed processing schema for children's processing stages in the equiprobable auditory go/no-go task. Active control-related ERP components were hypothesized to be differentially enhanced by caffeine. Caffeine (80 mg) was administered in a counterbalanced, randomized, double-blind, placebo-controlled, cross-over study of 24 children, aged 8-12 years. Four blocks of an equiprobable auditory go/no-go task were completed on each of two occasions, while on or off caffeine. ERP data sets from each condition (caffeine/go, placebo/go, caffeine/no-go, placebo/no-go) were subjected to separate temporal PCAs with extraction and varimax rotation of all components. Caffeine significantly reduced reaction time and go omission errors, and enhanced go PN, N2c, and P3b, and no-go N1-1 and N2b. This selective enhancement of different go/no-go components by caffeine matched the predicted lification of biomarkers of children's active control processing in this task. Some unexpected findings also support further refinements in the child processing schema.
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.IJPSYCHO.2018.05.005
Abstract: Ongoing EEG activity contributes to ERP outcomes of stimulus processing, and each of these measures is known to undergo (sometimes significant) age-related change. Variation in their relationship across the life-span may thus elucidate mechanisms of normal and pathological ageing. This study assessed the relationships between low-frequency EEG prestimulus brain states, the ERP, and behavioural outcomes in a simple equiprobable auditory Go/NoGo paradigm, comparing these for 20 young (M
Publisher: Springer Science and Business Media LLC
Date: 06-1976
DOI: 10.3758/BF03326573
Publisher: Elsevier BV
Date: 04-1995
DOI: 10.1016/0165-1781(95)02556-C
Abstract: The averaging of in idual late component event related potential (ERP) responses, particularly P300, has revealed significant differences between schizophrenic patients and normal subjects. However, the averaging process removes the variability of the in idual epochs that constitute that average. The response-variance-curve (RVC) method quantifies the variability of the in idual epochs and allows examinations of windows of maximum variance. In this study, we examine the complementary nature of the RVC method to the traditional averaging approach. The averaged N200 and P300 ERP components differed significantly between the schizophrenic and normal groups, but not between the unmedicated and medicated schizophrenic patients. The RVC measure, on the other hand, revealed systematic differences in variability, maximal between 190 and 240 ms, between the unmedicated and medicated schizophrenic patients. The RVC measure therefore provides a focused time frame in which to examine dysfunctions in information processing and macroscopic scale changes in brain function due to medication.
Publisher: IOP Publishing
Date: 16-03-2021
Abstract: Objective. The power spectrum of the human electroencephalogram (EEG) as a function of frequency is a mix of brain oscillations (Osc) (e.g. alpha activity around 10 Hz) and non-Osc or noise of uncertain origin. ‘White noise’ is uniformly distributed over frequency, while ‘pink noise’ has an inverse power-frequency relation (power ∝ 1/ f ). Interest in EEG pink noise has been growing, but previous human estimates appear methodologically flawed. We propose a new approach to extract separate valid estimates of pink and white noise from an EEG power spectrum. Approach. We use simulated data to demonstrate its effectiveness compared with established procedures, and provide an illustrative ex le from a new resting eyes-open (EO) and eyes-closed (EC) dataset. The topographic characteristics of the obtained pink and white noise estimates are examined, as is the alpha power in this s le. Main results. Valid pink and white noise estimates were successfully obtained for each of our 5400 in idual spectra (60 participants × 30 electrodes × 3 conditions/blocks [EO 1 , EC, EO 2 ]). The 1/ f noise had a distinct central scalp topography, and white noise was occipital in distribution, both differing from the parietal topography of the alpha Osc. These differences point to their separate neural origins. EC pink and white noise powers were globally greater than in EO. Significance . This valid estimation of pink and white noise in the human EEG holds promise for more accurate assessment of oscillatory neural activity in both typical and clinical groups, such as those with attention deficits. Further, outside the human EEG, the new methodology can be generalized to remove noise from spectra in many fields of science and technology.
Publisher: Elsevier BV
Date: 12-1999
DOI: 10.1016/S0006-3223(99)00042-6
Abstract: Attention-deficit/hyperactivity disorder (ADHD) in children and adolescents is characterized by excessive restlessness and an extremely poor concentration span, resulting in impulsive and disruptive behavior. Clinical observation of ADHD in adults suggests that the hyperactivity component is diminished although the impulsive type behaviors remain apparent. EEG studies of children and adolescents with ADHD have reported significantly higher levels of low frequency activity (predominantly theta) and lower levels of beta activity than normal controls. We examined the relationship between the age-related changes reported in clinical observation and changes in EEG activity occurring in a group of ADHD patients ranging in age from 6 to 42 years. Quantitative EEGs were obtained from the midline sites of 25 children, 25 adolescents and 25 adults diagnosed with ADHD, and compared with those of age matched normal controls. Theta activity was elevated in the ADHD groups across all age groups compared with the normal controls. The extent of the reduction in relative beta activity in the ADHD groups compared to normal controls decreased with increasing age. Given that the hyperactivity component in ADHD reduces with age while the impulsivity component remains, these data, in ADHD, suggest that decreased beta activity may be linked to hyperactivity and increased theta activity to impulsivity.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CLINPH.2008.01.013
Abstract: Autistic spectrum disorder (ASD) has been defined as a neurodevelopmental disorder with associated deficits in executive function, language, emotional, and social function. ASD has been associated with pathophysiology in cerebral organization. The current study investigated quantitative EEG findings in twenty children diagnosed with autistic disorders as compared to 20 controls matched for gender, age and IQ. The EEG was recorded during an eyes-closed resting condition and topographical differences in cerebral functioning were examined using estimates of absolute, relative, and total power, as well as intrahemispheric and interhemispheric coherences. There were group differences in power, intrahemispheric and interhemispheric coherences. Findings included excessive theta, primarily in right posterior regions, in autistics. There was also a pattern of deficient delta over the frontal cortex and excessive midline beta. More significantly, there was a pattern of underconnectivity in autistics compared to controls. This included decreased intrahemispheric delta and theta coherences across short to medium and long inter-electrode distances. Interhemispherically, delta and theta coherences were low across the frontal region. Delta, theta and alpha hypocoherence was also evident over the temporal regions. Lastly, there were low delta, theta and beta coherence measurements across posterior regions. These results suggest dysfunctional integration of frontal and posterior brain regions in autistics along with a pattern of neural underconnectivity. This is consistent with other EEG, MRI and fMRI research suggesting that neural connectivity anomalies are a major deficit leading to autistic symptomatology. This paper reports the largest integrated study of EEG power and coherence during a resting state in children suffering autism spectrum disorder.
Publisher: Elsevier BV
Date: 11-1979
DOI: 10.1016/0301-0511(79)90041-3
Abstract: The detection and description of the evoked cardiac response (ECR) has received much attention in recent literature, with an increasing concentration upon the 'noise' problem of sinus arrhythmia (SA). A departure from extrapolated pre-stimulus activity, obtained by employing procedures of various complexities, has been proposed as an SA-free measure of the ECR. The use of such procedures without consideration of respiratory changes appears questionable. Simulation of HR protocols across a change in respiratory period indicates that spurious ECRs, similar in form to those in the published literature, may be produced by such techniques. A simple method of correcting the problem is outlined.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.IJPSYCHO.2013.07.011
Abstract: It has been suggested that the P300 component of the ERP is an electrophysiological index of memory-updating processes associated with task-relevant stimuli. Component magnitude varies with the time separating target stimuli (target-to-target interval: TTI), with longer TTIs eliciting larger P300 litudes. According to the template-update perspective, TTI effects observable in the P300 reflect the updating of stimulus-templates in working memory (WM). The current study explored whether young adults' memory-task ability could predict TTI effects in P300. EEG activity was recorded from 50 university students (aged 18-25 years) while they completed an auditory equiprobable Go/NoGo task with manipulations of TTIs. Participants also completed a CogState® battery and were sorted according to their WM score. ERPs were analysed using a temporal PCA. Two P300 components, P3b and the Slow Wave, were found to linearly increase in litude to longer TTIs. This TTI effect differed between groups only for the P3b component: The high WM group showed a steeper increase in P3b litude with TTI than the low WM group. These results suggest that TTI effects in P300 are directly related to WM processes.
Publisher: International Society for Neurofeedback Research (ISNR)
Date: 12-05-2005
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.1016/J.BANDC.2006.03.011
Abstract: The N2 and P3 components have been separately associated with response inhibition in the stop-signal task, and more recently, the N2 has been implicated in the detection of response-conflict. To isolate response inhibition activity from early sensory processing, the present study compared processing of the stop-signal with that of a task-irrelevant tone, which subjects were instructed to ignore. Stop-signals elicited a larger N2 on failed-stop trials and a larger P3 on successful-stop trials, relative to ignore-signal trials, likely reflecting activity related to failed and successful stopping, respectively. ERPs between fast and slow reaction-time (RT) groups were also examined as it was hypothesised that greater inhibitory activation to stop faster responses would manifest in the component reflecting this process. Successful-stop P3 showed the anticipated effect (globally larger litude in the fast than slow RT group), supporting its association with the stopping of an ongoing response. In contrast, N2 was larger in the slow than fast RT group, and in contrast to the predictions of the response-conflict hypothesis, successful-stop N2 and the response-locked error-negativity (Ne) differed in scalp distribution. These findings indicate that the successful-stop N2 may be better explained as a deliberate form of response control or selection, which the slow RT group employed as a means of increasing the likelihood of a successful-stop. Finally, a comparison of stimulus and response-locked ERPs revealed that the failed-stop N2 and P3 appeared to reflect error-related activity, best observed in the response-locked Ne and error-positivity (Pe). Together these findings indicate that the successful-stop N2 and P3 reflect functionally distinct aspects of response control that are dependent upon performance strategies, while failed-stop N2 and P3 reflect error-related activity.
Publisher: Elsevier BV
Date: 06-1989
DOI: 10.1016/0301-0511(89)90006-9
Abstract: Barry and O'Gorman (1987) employed a response-averaging technique to investigate the electrodermal orienting response (OR) to stimulus omission. We obtained reliable evidence of increased response latency to stimulus omission, supporting an explanation of the missing-stimulus effect in terms of Maltzman's voluntary OR. Wilson's (1989) commentary on our article addresses both methodological and theoretical aspects. This response first examines his methodological difficulties, and provides simulation exercises which serve as a validation of our procedure. We then examine Wilson's theoretical points. His alternative theoretical explanation of the missing-stimulus effect, in terms of a systematic bias in the time-keeper of the stimulus-comparator process, is shown to be untenable. His remaining problem, concerning what he terms "assessment of stimulus significance", appears to have arisen through misinterpretation of our theory. A clarification of our theoretical position indicates the internal consistency of our use of "significance" and "voluntary OR".
Publisher: Elsevier BV
Date: 10-2002
DOI: 10.1016/S0167-8760(02)00037-5
Abstract: Twenty undergraduate students participated in an elaborative learning test to evaluate the relationship between electrical brain activity and subsequently recalled and not-recalled words. Data collected from the midline (Fz, Cz, Pz) and lateral scalp sites (F3, F4, C3, C4, P3, P4) were analysed. The difference between event-related potentials (ERPs) elicited by subsequently recalled and not-recalled words, the ERP memory effect, was evaluated for each portion (primacy, plateau and recency) of the serial-position curve (SPC). We compared peak litudes for the P1, N1, P2, N400, P3 and frontal positive slow wave (FPSW) components. The electrophysiological data support the hypothesis that different mechanisms underlie primacy and recency effects during free recall paradigms. There was no support for the hypothesis that an association arises between memory and the FPSW when subjects utilise elaborative learning strategies. The P2 component predicted subsequent recall at the primacy portion of the SPC, and P1 predicted recall at the primacy and plateau portions of the curve. The findings suggest that the early positive components of the ERP (i.e. P1 and P2) are useful indices of the differential stimulus processing during elaborative learning which predicts later recall.
Publisher: Elsevier BV
Date: 03-2000
DOI: 10.1016/S1388-2457(99)00256-4
Abstract: A form of EOG correction called the 'aligned-artifact average' (AAA) method has been advanced by the authors. In contrast to many previous methods, this used a correction coefficient (B), based on an average of eye movements rather than raw data, to remove eye movement related contamination from the EEG. The first part of this study was aimed at determining whether a variation of this procedure that is more easily implemented would produce a similar correction. The second part was designed to determine the number of epochs needed in an average to correct adequately. Subjects performed a series of eye movement tasks whilst EEG and EOG data were recorded. Data were manipulated according to either the AAA or an alternate new ERP method (NERP) and the resultant Bs were compared in part A. In part B, averages were created from varying numbers of epochs, and the resultant r(2)-values were compared. The AAA and NERP methods produced the same Bs, and averages with at least 40 epochs were required for adequate B estimation for both VEOG and HEOG. There is no difference between the AAA and NERP methods and thus it is acceptable to use the more easily implemented NERP method for EOG correction. It is recommended that when applying this procedure, at least 40 epochs should be used to make up the averages from which to calculate correction coefficients.
Publisher: Elsevier BV
Date: 2011
DOI: 10.1016/J.PSYCHRES.2009.09.004
Abstract: Attention-deficit/hyperactivity disorder (AD/HD) is the most common psychiatric disorder of childhood, although AD/HD is rarely the only diagnosis given to these children. Within the literature there is some debate as to whether it is valid to diagnose AD/HD with autism as a comorbid disorder, since the present diagnostic systems exclude the diagnosis of both disorders in the same child. The aim of this study was to determine whether electroencephalography (EEG) differences exist between two groups of children diagnosed with AD/HD, one scoring high (AD/HD+) and one scoring low (AD/HD-) on a measure of autism. The EEG was recorded during an eyes-closed resting condition from 19 electrodes, and Fourier transformed to provide absolute and relative power estimates in delta, theta, alpha and beta bands. Compared to age- and sex-matched controls, the AD/HD- group had increased absolute power in all frequency bands, somewhat higher relative theta activity and decreased relative delta. In comparison to the AD/HD- group, patients with autistic features (AD/HD+) had a number of qualitative differences in the beta and theta bands. These results indicate the presence of two comorbid conditions in the AD/HD+ group, which suggests that AD/HD and autism can occur in the same in idual.
Publisher: Elsevier BV
Date: 12-1998
DOI: 10.1016/S0167-8760(98)00040-3
Abstract: We examined whether the litude decrement traditionally found for the N1 peak of the event-related potential (ERP) with repetition of auditory stimuli results from the process of habituation or from the refractory period of the neural elements underlying the N1 response. These competing accounts of the process underlying the N1 decrement with repetition differ in terms of the predicted effects of variations in stimulus repetition and interstimulus interval (ISI). These predictions were examined using a short-term habituation design with a factorial combination of stimulus repetition and ISI. Forty-five subjects received 21 stimulus trains, each consisting of seven innocuous tones, all at 1 kHz except the sixth, which was a 1.5-kHz tone. Each subject was assigned to one of three ISI conditions (either 1, 3 or 10 s). The results provide little support for the view that N1 response decrement with stimulus repetition reflects a process of habituation. The present results provide greater support for the view that this decrement is based on the separate refractory periods or recovery cycle processes of at least two neural generators contributing to activity in the N1 peak latency range.
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.PSYCHRES.2005.09.002
Abstract: Attention-deficit/hyperactivity disorder (AD/HD) is recognized as a disorder affecting children and adolescents and has more recently been documented to continue into adulthood in a proportion of patients. One of the common treatments for AD/HD is the use of stimulant medications. Numerous studies have examined the therapeutic effects of stimulant medications in children, adolescents and adults with the disorder, reporting improvements in attention, concentration, and hyperactive and impulsive behaviours. Several studies have also examined the effects of stimulants on the electroencephalograph (EEG) of children and adolescents with the disorder, but to date, there have been no studies examining the effects of stimulant medication on the EEG of adults with AD/HD. In the present study, we aimed to replicate previous EEG findings in adults with AD/HD relative to controls and to examine whether there was any change in this profile following treatment with dex hetamine. The EEG was recorded at rest in an eyes-open condition from 50 adults diagnosed with AD/HD and assessed as good responders to treatment, both before and after treatment with dex hetamine, and 50 control subjects. The pre-medication results are similar to those found in previous research that compared the EEGs of adults with AD/HD and control subjects. Following medication, there was a significant reduction in slow wave activity in the AD/HD group to levels similar to those in the control group. These results suggest that changes in brain function of good responders to dex hetamine, as reflected in the EEG, may underlie the behavioural improvements observed in the clinical setting.
Publisher: Elsevier BV
Date: 12-2000
DOI: 10.1016/S0167-8760(00)00114-8
Abstract: Peak-to-peak litudes of the N1P2 and N2P3 components in the target ERPs from a fixed interstimulus interval auditory oddball paradigm were investigated as a function of within-subject pre-stimulus levels of alpha activity. Fourteen subjects were each presented with 600 auditory stimuli in a two-tone auditory oddball paradigm which required a button-press to targets, presented with 50% probability. Pre-stimulus alpha activity at Pz was assessed for each trial by digital filtering from 8 to 13 Hz, and alpha RMS litude was used to sort the ERPs at Pz and Cz. A direct relationship was obtained between component litudes at both Pz and Cz and pre-stimulus alpha level at Pz. Component latencies were strongly related to post-stimulus alpha peaks and troughs. These data confirm the intimate relationship between central nervous system activation, as evidenced by spontaneous EEG in the pre-stimulus period, and the ERP resulting from stimulus presentation.
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.CLINPH.2005.06.008
Abstract: A substantial body of evidence shows that several separate components underlie the late positive complex (LPC) of the ERP. Each of these has been proposed as a possible neural index of the orienting reflex (OR), but none has clearly met the criteria required for identification as an OR. The skin conductance response (SCR) is the most extensively examined index of the OR, and was used here as an OR 'yard-stick'. The primary aim of this study was to determine if any of the components of the LPC show stimulus-response relationships analogous to those of the SCR. ERPs and SCRs were simultaneously recorded from 72 subjects during an ERP dishabituation paradigm, in which a habituation stimulus (S1) was presented for a series of trials, during which a different stimulus (S2) was interpolated. This sequence was presented in a series of trains, allowing across-train LPC and SCR exploration as a function of trial. The sensitivity of these components to stimulus intensity and significance, other stimulus dimensions important in defining the OR, was also examined. We utilised a PCA with varimax rotation to separate the ERP components underlying the LPC. Four factors extracted appeared to correspond to the classic Slow Wave, the P3b, the Novelty P3 and the P3a. While the LPC exhibited a stimulus-response relationship analogous to the SCR, each of the separate components was differentially sensitive to aspects of the stimulus manipulations examined here. This study has demonstrated that the LPC is an adequate EEG index of the OR. However, the underlying components of the LPC examined here--which we consider to be the classic slow wave, P3b, Novelty P3 and P3a--cannot be used interchangeably as OR indices. This study clarifies links between the autonomic OR and its CNS correlates.
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.CLINPH.2016.02.010
Abstract: We recently proposed a sequential processing schema for the equiprobable auditory Go/NoGo task, based on a principal components analysis (PCA) of event-related potentials (ERPs) from a university student s le. Here we sought to replicate the schema, and use it to explore processing in well-functioning older adults. We compared behavioural responding and ERPs of 20 independent-living older adults (Mage=68.2years) to data from a sex- and handedness-matched group of university students (Mage=20.4years). ERPs had substantial latency differences between the groups, and hence were subjected to separate group temporal PCAs. Component latencies were systematically increased in the older group by some 26%, with no significant increase in RT or error rates. Despite some differences in their identified components, each group displayed differential component responsivity to Go versus NoGo this was reduced in the older participants. The results support our processing schema, and provide insight into the processing stages in well-functioning older adults. Understanding the perceptual and cognitive processing stages in normal ageing is a pre-requisite for research on mild cognitive impairment and dementia. This study may also provide a simple paradigm and schema suitable for further exploration of functionality in ageing.
Publisher: Informa UK Limited
Date: 21-07-2009
Publisher: Elsevier BV
Date: 04-2002
DOI: 10.1016/S1388-2457(02)00036-6
Abstract: This study investigated differences in intrahemispheric and interhemispheric electroencephalographic (EEG) coherences between attention-deficit/hyperactivity disorder (ADHD) and control children, and between children with the Combined (ADHDcom) and Inattentive (ADHDin) types of ADHD. Three age- and sex-matched groups of 40 children, aged 8-12 years, diagnosed with ADHDcom, ADHDin, and normal control children, participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed. Wave-shape coherence was calculated for 8 intrahemispheric electrode pairs (4 in each hemisphere), and 8 interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. At shorter inter-electrode distances, ADHD children had elevated intrahemispheric coherences in the theta band and reduced lateral differences in the theta and alpha bands. At longer inter-electrode distances, ADHD children had lower intrahemispheric alpha coherences than controls. Frontally, ADHD children had interhemispheric coherences elevated in the delta and theta bands, and reduced in the alpha band. An alpha coherence reduction in temporal regions, and a theta coherence enhancement in central arietal/occipital regions, were also apparent. ADHDcom had greater intrahemispheric theta and beta coherences than ADHDin. Frontally, ADHDcom had higher levels of interhemispheric coherences than ADHDin for the delta and theta bands. In central arietal/occipital regions, beta coherences were elevated in ADHDcom. EEG coherences suggest reduced cortical differentiation and specialisation in ADHD, particularly in cortico-cortical circuits involving theta activity. Generally, ADHDcom children displayed greater anomalies than ADHDin children.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.BIOPSYCHO.2007.03.003
Abstract: We examined putative central nervous system (CNS) indices of tonic and phasic aspects of the orienting reflex (OR) in a passive event-related potential (ERP) dishabituation paradigm. Pre-stimulus skin conductance level (SCL) and the subsequent skin conductance response (SCR) were used as tonic and phasic OR "yard-sticks", respectively. Their stimulus-response patterns were used to assess two ERP components: the tonic pre-stimulus contingent negative variation (CNV) and the subsequent phasic late positive complex (LPC). SCLs and SCRs derived from each trial of the first train presented were compatible with traditional OR studies. Across-train means were also derived for each of the four measures examined. Arousal changes, as indexed by the SCL, were weak in the CNV which showed an additional expectancy effect. The LPC showed a stimulus-response pattern across trials identical to that of the SCR. This study clarifies links between the traditional autonomic measures of the indifferent OR and its CNS correlates, and encourages an OR perspective and/or interpretation of ERP effects.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.CLINPH.2014.02.018
Abstract: To compare sequential processing in the unwarned auditory equiprobable Go/NoGo task in children and adults, in the context of a recently developed adult schema. Adult and child s les completed an equiprobable auditory Go/NoGo task while EEG was recorded from 19 channels. Go and NoGo ERPs were decomposed using unrestricted Varimax-rotated PCAs for the groups separately, and in combination. The separate adult and child components were compared using the Congruence Coefficient. Brain sources of each assessed component were examined using eLORETA. Corresponding adult/child components were tentatively identified: two N1 subcomponents (N1-1, PN) and P2, followed by N2, P3 (separate P3a/P3b in children), the classic Slow Wave (SW), and a diffuse Late Positivity (LP). While early and late components showed similarities, the intermediate P2 and N2 differed substantially in their stimulus effects. Aspects of "Go" vs. "NoGo" categorisation differ between adults and children, but subsequent processing reflected in the different Go/NoGo P3 components, and their sequellae, are similar. This is the first detailed examination of child responses in this paradigm. The tested schema appears relatively robust in adults, and the child results may aid our understanding of developmental aspects of cognitive processing in normal and atypical in iduals.
Publisher: Elsevier BV
Date: 11-2002
DOI: 10.1016/S0167-8760(02)00090-9
Abstract: Twenty-two undergraduate students completed a recognition memory test while event-related potentials (ERPs) were recorded. During the testing phase, subjects distinguished old from new words in a forced-choice format. There were two counterbalanced within-subject conditions, one in which subjects performed to the best of their abilities, and another with instructions to feign memory impairment. Test scores and response latencies differed significantly between the two conditions. Analysis of PCA-defined epochs revealed that old words were more positive than new in the control condition, with this difference confined to frontal regions and interpreted as reflecting familiarity-based recognition judgements. In the malingering task, this old/new word difference emerged earlier and was broadly distributed across the scalp. A discriminant function analysis using reaction time and ERP measures resulted in 82% correct classification of honest and simulated performance, with 79% correct on cross-validation.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.IJPSYCHO.2009.02.002
Abstract: The aim of this study was to investigate links between the N2 and P3 NoGo ERP components in a visual Go/NoGo paradigm and inhibition in social drinkers. Forty participants were ided into three groups on the basis of their level of alcohol consumption, with two extreme groups, Light and Heavy, each with 13 subjects, selected for investigation. While impaired control over drinking was found in the Heavy group, there were no group differences in anxiety, depression, or locus of control. The Go N2 was slightly smaller centrally and in the midline for the Heavy compared to the Light group, but the Go P3 showed no group differences. The NoGo N2 was slightly smaller centrally, and the NoGo P3 was globally much smaller, in the Heavy group. Only the NoGo P3 reduction was correlated with alcohol consumption. That is, the NoGo P3 was the ERP component reflecting heavy social drinking. However, this could not be considered a marker of inhibition deficit, as the groups had similar performance levels in the task. Further consideration of the literature indicated that this is generally compatible with performance results in other studies that have attributed NoGo P3 differences to inhibition deficits, casting doubt on that interpretation. An alternative interpretation in terms of the orienting reflex (OR) is offered. This suggests that in iduals with impairments in basic aspects of reflexive OR functioning may be prone to risk-taking behaviours, such as those associated with alcohol/drug abuse.
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.IJPSYCHO.2010.06.027
Abstract: The phasic evoked cardiac response (ECR) produced by innocuous stimuli requiring cognitive processing may be described as the sum of two independent response components. An initial heart rate (HR) deceleration (ECR1), and a slightly later HR acceleration (ECR2), have been hypothesised to reflect stimulus registration and cognitive processing load, respectively. This study investigated the effects of processing load in the ECR and the event-related potential, in an attempt to find similarities between measures found important in the autonomic orienting reflex context and ERP literature. We examined the effects of cognitive load within-subjects, using a long inter-stimulus interval (ISI) ANS-style paradigm. Subjects (N=40) were presented with 30-35 80dB, 1000Hz tones with a variable long ISI (7-9s), and required to silently count, or allowed to ignore, the tone in two counterbalanced stimulus blocks. The ECR showed a significant effect of counting, allowing separation of the two ECR components by subtracting the NoCount from the Count condition. The auditory ERP showed the expected obligatory processing effects in the N1, and substantial effects of cognitive load in the late positive complex (LPC). These data offer support for ANS-CNS connections worth pursuing further in future work.
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.IJPSYCHO.2006.07.001
Abstract: The present study examined the development of response inhibition during the Stop-signal and Go/Nogo tasks in children using performance and ERP measures. Twenty-four children aged 7 to 12 years completed both tasks, each with an auditory Nogo/Stop-signal presented on 30% of trials. On average, response inhibition was more difficult in the Stop-signal than Go/Nogo task. Response inhibition performance did not develop significantly across the age range, while response execution varied significantly in a task dependent manner (Go/Nogo: increasing accuracy and reducing response variability with age Stop-signal: reducing Go mean reaction time and response variability with age). The N1, P2, N2 and P3 components showed different scalp distributions, with N1 and P2 peaking earlier, and P3 later, in Nogo compared to Stop stimuli. N2 and P3 litude were positively correlated with successful inhibition probability in the Go/Nogo task only. N2 litude and latency to both Nogo and successful Stop stimuli decreased linearly with age, but not in the frontal regions. N1 and P3 litude in the parietal region increased with age for Stop-signals. An age-related reduction in P3 latency to Nogo stimuli correlated significantly with reduced RT and variability in Go responding, indicating a relationship between efficient Nogo and Go processing. Together the behavioural and ERP results suggest little development of the response inhibition process as measured via the Stop-signal and Go/Nogo tasks across the 7 to 12 year age range, while response execution processes develop substantially.
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.IJPSYCHO.2013.04.018
Abstract: The nature of the relationships between the level of immediately-prestimulus EEG activity and auditory ERP components remains unclear. Particularly, both inverse and direct relationships have been reported for the alpha band. Here we aim to clarify the pattern of prestimulus EEG contributions in alpha (8-13 Hz), and investigate those in beta (14-24 Hz), for five ERP components (P1, N1, P2, N2, P3) in an auditory equiprobable Go/NoGo paradigm. Separate FFTs were applied to the prestimulus Cz data of each accepted trial. The alpha and beta bands were independently assessed. The mean prestimulus spectral band litude was computed and used to sort the trials at nine central sites, and the upper and lower sorted trial thirds were averaged to form ERPs for Go and NoGo responses. Prestimulus EEG level effects (High vs. Low) were examined in each component's latency and litude, and Go reaction time was also assessed. Prestimulus alpha directly modulated the litude of the positive components (P1, P2, P3), while prestimulus beta directly modulated the positivity of the exogenous component litudes (P1, N1, P2) each litude effect occurred independently of the Go/NoGo stimulus conditions. Prestimulus beta also inversely modulated Go N1 latency no reaction time effects were found for either band. The pattern of findings is intriguing and the various modulations are discussed in relation to attention and arousal. Together, these results confirm the importance of the EEG brain state immediately prestimulus, and indicate the considerable influence that these states have on event-related response processing.
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.IJPSYCHO.2012.09.016
Abstract: Ongoing low-frequency EEG activity has long been associated with ERP components and their cognitive processing interpretations, yet few studies have directly investigated the prestimulus low-frequency EEG-ERP relationships, particularly within the auditory domain. The present study assessed the delta (1-3 Hz) and theta (4-7 Hz) bands in idually, and their prestimulus influence on five subsequent components (P1, N1, P2, N2, and P3) within an equiprobable auditory Go/NoGo paradigm. At the nine central sites, accepted trials were sorted according to their ascending vertex prestimulus spectral band litude, and ERPs were derived from the upper and lower sorted thirds. The within-subjects analyses included litudes and latencies for both Go and NoGo responses, and Go response speed. Only component litudes showed effects of high/low prestimulus EEG level. Delta globally modulated the five components - all litudes were more positive with high prestimulus delta, regardless of stimulus condition. Theta did not influence P1, but inversely modulated P2 and P3 regionally, and produced stimulus-specific effects in N1, N2, and P3. Low prestimulus theta produced greater NoGo N2 and Go P3, and reduced NoGo P3 responses, each of these suggesting appropriately enhanced cognitive processing. Taken together, these effect patterns differentially implicate prestimulus delta and theta band activity in the determination of ERP component litudes and the cognitive processing associated with them.
Publisher: Elsevier BV
Date: 06-1980
DOI: 10.1016/0301-0511(80)90038-1
Abstract: The relationship between personality level of affect and habituation of electrodermal and respiratory measures was examined in two groups of normal subjects designated Low P (LP) and High P (HP) according to the P scale of the Eysenck Personality Questionnaire. Experiment 1 examined changes as a function of repeated presentation of simple visual stimuli. Group HP displayed reduced habituation rates for both respiratory pause and skin resistance response (SSR), although initial reactivity levels were similar for both groups. This effect was confirmed more strongly in Experiment 2, which utilized a simple counting task and groups separated more widely on P. The implications of these group differences were discussed in relation to the psychophysiological functioning of autistic children.
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.IJPSYCHO.2008.07.001
Abstract: Attention-Deficit/Hyperactivity Disorder (AD/HD) is the most common psychiatric disorder of childhood, but it is becoming increasingly apparent that more than half the childhood sufferers will continue to manifest symptoms of the disorder as adults. While the EEG of children with AD/HD has been extensively examined, comparatively little research has been conducted into the EEG of adults with the disorder. This study thus investigated the EEG of 20 adult males with AD/HD, and an age- and gender-matched control group, during an eyes-closed resting condition. The EEG was Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. The AD/HD group had significantly less absolute delta and more relative theta, across the entire scalp, than the control group. In absolute beta, the AD/HD group had less power at the midline, and an enhancement in power in the right posterior region. These results are similar to those found in children with AD/HD, and may suggest the presence of a processing deficit. A right posterior elevation in beta activity was also found, which could be related to the ongoing presence of reading disabilities in these subjects.
Publisher: Elsevier BV
Date: 05-2001
DOI: 10.1016/S0167-8760(00)00175-6
Abstract: This study examined patterns of physiological activity in elite pistol shooters and compared them with novice shooters. Heart rate and electrodermal activity were recorded for three 150-s epochs. Participants performed part of the Standard Pistol Shooting Protocol, firing five rounds at a target 25 m distant within the first 150 s epoch. In the second epoch, baseline data were recorded with the participant standing at rest. The third epoch was a repetition of the first epoch. For each shot, values of heart rate and skin conductance were calculated at half-second intervals from 20 s before to 10 s after the shot. In experts there was a slow reduction in skin conductance and heart rate levels prior to the shot, and a 'rebound' increase immediately following the shot, which were not apparent in the novice shooters. Pre-shot electrodermal levels for the expert shooters were lower for the best compared with the worst shots, and the duration of the pre-shot cardiac deceleration was longer and more systematic for best than for worst shots. The physiological profiles supported interpretation in terms of two separate state processes, arousal and vigilance, rather than a single construct. These physiological differences are discussed in terms of differential engagement with the task and its associated attentional narrowing in expert pistol shooters.
Publisher: Elsevier BV
Date: 02-2004
DOI: 10.1016/S1388-2457(03)00343-2
Abstract: This study aimed to explore the basis of a theoretical position which has major impact in the current literature on attention-deficit/hyperactivity disorder (AD/HD) - that the ratio of theta to beta power in the EEG (the theta/beta ratio) represents central nervous system (CNS) arousal. Resting state topographic EEG activity was investigated as a function of CNS arousal in normal right-handed boys. Arousal was defined in terms of electrodermal activity, which has a long history in Psychology as a measure of CNS arousal. Relative delta, theta, and beta power, and the theta/beta ratio, failed to differ significantly between age-matched groups which differed markedly in skin conductance level and non-specific electrodermal fluctuations. The high-arousal group showed significantly lower levels of relative alpha power, particularly in posterior and hemispheric regions, with higher alpha frequencies in these areas. These data fail to support the theoretical linkage between the theta/beta ratio and CNS arousal. Further work is needed to disentangle the different correlates of arousal and task-related activation, particularly in cognitive and attentional-processing terms. The outcomes of this study, in addition to clarifying the nature of EEG markers of CNS arousal, have important implications for our understanding of AD/HD, as they require re-evaluation of current models of the disorder.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.IJPSYCHO.2010.09.010
Abstract: We aimed to clarify the event-related potentials (ERPs) involved in elicitation and habituation of the orienting reflex (OR), seeking parallels with two autonomic measures reflecting different stages in OR-related processing. Participants were presented with 8 unexpected innocuous novel tones to one ear at long variable inter-stimulus intervals, and horizontal eye movement in the direction of the ear of stimulation was taken as a behavioural measure of the OR. Skin conductance, heart rate, and 19 EEG channels were also recorded. Single-trial ERPs were decomposed using principal components analysis for intervals covering the early N1 complex and the late positive complex (LPC). Eye movements at trial 1 showed significant directional differences with ear of stimulation, and this difference reduced over trials, providing behavioural evidence of OR elicitation and habituation. Electrodermal responses, Processing Negativity, and the Novelty P3 showed substantial main effects of trials, suggesting their close links to the OR. Cardiac deceleration and Component 1 of the N1 complex showed no change over trials, suggesting their association in marking the transient onset of each stimulus. Component 3 of the N1 complex, P3a, P3b, and early and late Slow Waves showed only topographic changes over trials, and their dominant continuation over the stimulus sequence rules them out as OR markers. Theory development is required to clarify the non-OR role of the LPC. These results point to the usefulness of a sequential-processing approach to the OR in accommodating the range of subcomponents in the ERP. These data also illustrate the value of single-trial ERP analysis in simple paradigms with very long inter-stimulus intervals.
Publisher: Elsevier BV
Date: 05-2001
DOI: 10.1016/S1388-2457(01)00488-6
Abstract: This study investigated age-related changes and sex differences in the EEGs of normal children. Forty boys and 40 girls, between the ages of 8 and 12 years, participated in this study. The EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, absolute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios. Absolute delta activity decreased with age. Relative delta and theta decreased and alpha and beta increased with increasing age. The theta/alpha and theta/beta ratios decreased with increasing age. All of these indicated a developmental reduction in slow wave activity. Maturational differences were found in the rates of change between the midline and the two hemispheres. In the absolute delta and the theta/beta ratio, the midline and the two hemispheres became more equipotential with age. In the beta band, power increased at a greater rate than in the two hemispheres. Sex differences were found, with males having less theta and more alpha than females. These results indicated that maturation occurs earlier at the midline than in the two hemispheres. Females were also found to have a developmental lag in the EEG compared with males.
Publisher: Elsevier BV
Date: 09-2003
DOI: 10.1016/S1388-2457(03)00112-3
Abstract: This study investigated the effects of stimulant medications on the Electroencephalography (EEG) of children with the combined type of attention-deficit/hyperactivity disorder (ADHD) together with excessive beta activity in their EEG. Twenty ADHD and 20 control subjects participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. Subjects were placed on a 6-month trial of a stimulant medication and a second EEG was recorded at the end of the trial. The unmedicated ADHD group had greater absolute and relative beta, less absolute and relative alpha, a higher theta/alpha and a lower theta/beta ratio than the control group. In the frontal regions the ADHD group had an increase in total power, absolute theta, absolute and relative beta and the theta/beta ratio, with greater relative delta, relative theta, and absolute and relative alpha in posterior regions. With medication use, absolute beta activity and frontal total power decreased, although these changes represented a reduction in power, not a normalisation. These results indicate that ADHD children with excessive beta activity in their EEG are probably not hypoaroused as previously suggested, and that beta activity in these children is probably only associated with the impulsivity and/or hyperactivity aspects of the disorder, but may not necessarily be associated with inattention. This study is the first to investigate effects of stimulant medications on the EEG of ADHD children with excessive beta activity in their EEG.
Publisher: Hogrefe Publishing Group
Date: 2009
DOI: 10.1027/0269-8803.23.4.157
Abstract: Data are presented on EEG activity in typically developing controls, focusing on the traditional delta, theta, alpha, and beta bands through childhood, with some extensions into adolescence and adults. Both eyes-closed and eyes-open resting state data are discussed. These reflections of typical development provide a framework for illustrating EEG differences in people with attention deficit/hyperactivity disorder (AD/HD), and its main diagnostic types, from children to adults. Comorbidity effects in the EEG of children with AD/HD, particularly comorbid reading disabilities and conduct disorders, are also described. Some recent explorations of the links between arousal/activation and EEG activity may contribute to our understanding of the functional nature of brain oscillations in this context. Other aspects of oscillatory brain activity, coherence and event-related potentials, are also briefly discussed within this framework.
Publisher: Elsevier BV
Date: 08-2002
DOI: 10.1016/S0165-1781(02)00137-3
Abstract: This study investigated EEG differences between two groups of children with attention-deficit/hyperactivity disorder combined type (ADHD), with or without comorbid oppositional defiant disorder (ODD), and normal control subjects. Each group consisted of 20 males. All subjects were between the ages of 8 and 12 years, and groups were matched on age. EEG was recorded during an eyes-closed resting condition from 21 monopolar derivations, which were clustered into nine regions for analysis. The EEGs were Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. Values were also calculated for the theta/alpha and theta/beta ratios. The ADHD groups had more absolute and relative theta than the control group. Regionally, the ADHD groups had less relative alpha and more relative delta in posterior regions, and less relative beta in the frontal regions, than the control group. These differences were also apparent in both ratio measures. Only two significant topographic differences were found between the ADHD groups, with both of these being less deviant from normality in the ADHD+ODD group than the ADHD group. These results indicate that EEG correlates of ADHD are not clouded by the presence of comorbid ODD, which suggests possible applications in clinical practice.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.CLINPH.2007.11.042
Abstract: The contribution of movement-related potentials (MRPs) to the Go/NoGo N2 and P3 'inhibitory' effects is controversial. This study examined these components in overt and covert response inhibition tasks. Twenty adult participants counted or button-pressed in response to frequent (60%) and rare (20%) Go stimuli in a Go/NoGo task with equiprobable rare (20%) NoGo stimuli. The N2 NoGo effect did not differ between Count and Press responses, but the P3 NoGo effect was lified during the Press task. Additionally, subtraction of the ERP waveform for Count NoGo from Press NoGo trials revealed a positivity between 200 and 400ms, occurring maximally over the central region, contralateral to the responding hand. This difference wave became significant at 210-260ms, close to the estimated time taken to stop an overt response. The N2 NoGo effect may reflect a non-motoric stage of inhibition, or recognition of the need for inhibition, while the NoGo P3 may overlap with a positive MRP occurring specifically on trials where overt motor responses must be inhibited. The study confirms that the N2 and P3 NoGo effects are not solely due to movement-related potentials, and posits the NoGo P3 as a marker of motor inhibition.
Publisher: Springer Science and Business Media LLC
Date: 09-1978
DOI: 10.1007/BF01539634
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.BIOPSYCHO.2018.02.005
Abstract: Previous EEG-ERP dynamics studies found non-random "preferred" EEG phases at stimulus onset in a fixed interstimulus interval (ISI) equiprobable auditory Go/NoGo paradigm, with substantial effects on ERP components. Here we changed to a variable ISI task to prevent/reduce preferential phase occurrence. Discrete Fourier transforms decomposed prestimulus EEG at Cz for each trial to calculate the phase of different frequencies at stimulus onset we combined these into the delta, theta, alpha, and beta bands, and then sorted trials into phase quartiles for each. ERPs from the raw EEG, assessed using temporal Principal Components Analyses, were examined as a function of phase at stimulus onset. Preferential phase occurrence was reduced as predicted, but random phase substantially impacted component litudes. For ex le, negativity in delta enhanced Go and NoGo P3b and in theta reduced NoGo but not Go P3b. Overall, EEG phases at stimulus onset support differential cognitive processing in this two-choice task.
Publisher: Elsevier BV
Date: 03-2001
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.IJPSYCHO.2012.10.001
Abstract: Using a child s le, we examined the effects of the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset on the resultant event-related potentials (ERPs) in an equiprobable auditory Go/NoGo task with a fixed stimulus-onset asynchrony. We used FFT decomposition of the EEG at Cz to assess prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) for each trial. From the cycle at stimulus onset, trials were sorted into four phases for each of the 13 frequencies. ERPs were derived for each of these from the raw EEG activity at the midline sites. ERP responses were analysed in the context of a simple conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). At a number of frequencies, crossing the traditional frequency bands, the predicted non-random occurrence of phase-defined brain states was confirmed. The preferred states of negativity and negative driving were each associated with more efficient stimulus processing, as reflected in latency and litude differences of the N1 and P3 ERP components. The present results confirm the existence of preferred brain states and their impact on the efficiency of brain dynamics involved in perceptual and cognitive processing, and extend their occurrence from adults to children.
Publisher: Springer Science and Business Media LLC
Date: 04-03-2020
DOI: 10.1038/S41598-020-61060-9
Abstract: Past evidence of an early Processing Negativity in auditory Go/NoGo event-related potential (ERP) data suggests that young adults proactively process sensory information in two-choice tasks. This study aimed to clarify the occurrence of Go/NoGo Processing Negativity and investigate the ERP component series related to the first 250 ms of auditory processing in two Go/NoGo tasks differing in target probability. ERP data related to each task were acquired from 60 healthy young adults ( M = 20.4, SD = 3.1 years). Temporal principal components analyses were used to decompose ERP data in each task. Statistical analyses compared component litudes between stimulus type (Go vs. NoGo) and probability (High vs. Low). Neuronal source localisation was also conducted for each component. Processing Negativity was not evident however, P1, N1a, N1b, and N1c were identified in each task, with Go P2 and NoGo N2b. The absence of Processing Negativity in this study indicated that young adults do not proactively process targets to complete the Go/NoGo task and/or questioned Processing Negativity’s conceptualisation. Additional analyses revealed stimulus-specific processing as early as P1, and outlined a complex network of active neuronal sources underlying each component, providing useful insight into Go and NoGo information processing in young adults.
Publisher: Springer Science and Business Media LLC
Date: 05-1972
DOI: 10.3758/BF03328604
Publisher: Elsevier BV
Date: 11-1993
DOI: 10.1016/0167-8760(93)90008-D
Abstract: The present experiment was carried out to investigate elicitation and habituation of the electrodermal Orienting Response with stimulus trains utilising a short interstimulus interval (ISI) of 1.1 s. We sought evidence for within-train response decrement to repeated stimulus presentation, response recovery to a change stimulus and dishabituation following the change stimulus--the three properties necessary to unequivocally identify a decremental process as habituation. No autonomic study could be found using such a short ISI. Autonomic studies on this time scale are necessary if these measures are to be integrated with central event-related potential (ERP) measures of electrical brain function. Overcoming this paradigm gap required the development of novel measurement procedures to estimate the small electrodermal responses obtained, usually occurring on the recovery slope of the response to the previous stimulus in the train. With our novel measurement procedures, evidence was found indicating that electrodermal activity in such a paradigm exhibited the three classic criteria of habituation.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Springer Science and Business Media LLC
Date: 11-08-2016
DOI: 10.1038/SREP31200
Abstract: P300 (or P3) is a major positive complex in the human event-related potential, occurring some 300 ms after stimulus onset and long thought to be the cortical correlate of the Orienting Reflex, our automatic attention-grabbing response to a novel stimulus. The Novelty P3 was the third P3 subcomponent discovered (after P3a and P3b) and appeared promising in its sensitivity to stimulus novelty, the defining characteristic of the Orienting Reflex. But some 15 years later it was claimed to be indistinguishable from the previously-discovered P3a. This led to a decline in interest in the field and confused nomenclature, with some studies using “P3a” and “Novelty P3” interchangeably. However, recent similar studies have again reported three subcomponents of the P3. Further, using single-stimulus habituation paradigms, in addition to P3a and P3b, a later decrementing P3 subcomponent has been reported and recently labelled “HabP3” to avoid contention. We report three studies to resolve this chaotic situation, arguing for identification of the late subcomponent following the P3a and P3b as the Novelty P3. Reinstatement of the Novelty P3 as the central index of the Orienting Reflex will have widespread impact in a range of theoretical, practical and clinical areas involving novelty processing and attention.
Publisher: Elsevier BV
Date: 04-1995
DOI: 10.1016/0165-1781(95)02557-D
Abstract: The response-variance-curve (RVC) method quantifies the variability of the in idual epochs that constitute the average event related potential (ERP), providing complementary information to that offered by ERPs. Numerous studies have found that average ERP late components of an auditory "oddball" paradigm can differentiate schizophrenic patients from normal subjects. Our previous study of the RVC measure revealed significant differences between medicated and unmedicated schizophrenic patients in the maximum ERP variability from 190 to 240 ms. In the present study of unmedicated schizophrenic patients and normal control subjects, we examined the influence of intertarget intervals (generated by pseudorandom stimulus sequences in an auditory oddball paradigm) on the intratrial effects of ERP variability measured by the RVC. The ERPs of unmedicated schizophrenic patients were characterized by an instability in a latency window corresponding to the N200 component. The effect was particularly large at an intertarget interval of 7.8 s and was significantly reduced on either side of this intertarget interval.
Publisher: Wiley
Date: 1990
DOI: 10.1111/J.1469-8986.1990.TB02185.X
Abstract: Levinson and Edelberg's (1985) recent critique of scoring criteria for electrodermal studies pointed to the need to reduce the latency range used to define the electrodermal response. The present study examined the impact of such a narrowing of the latency window upon habituation and instructional effects in studies of the orienting response to low intensity innocuous stimuli. The first experiment found only a small effect of halving the latency window upon habituation to neutral stimuli, apparent as a strengthening of trends over trials. A second experiment showed somewhat larger effects with significant stimuli, apparent as slightly modified trial and group effects. These data support the view that nothing is to be lost by moving to a narrower latency range to define the electrodermal orienting response to stimulus presentation, and suggest that the advantages of such a change will become increasingly important as nonspecific electrodermal fluctuations increase with increasing electrodermal arousal. An analysis of habituation criteria within this context suggested that the choice of two rather than three no-response trials to define habituation adds to the benefits obtained by the selection of a narrow latency window to define the response.
Publisher: Elsevier BV
Date: 12-1987
DOI: 10.1016/0301-0511(87)90051-2
Abstract: Following response habituation to a regularly-presented innocuous stimulus, omission of that stimulus may elicit a response. The missing-stimulus effect has been of some importance in the development of Orienting Response (OR) theory, particularly Sokolov's neuronal model/stimulus comparator mechanism. Western work on this effect has been somewhat equivocal, with only some subjects emitting small responses at stimulus omission. Barry (1984b) proposed that the fragility of the data might reflect the elicitation of a voluntary OR (Maltzman, 1979) rather than the more robust (reflexive) involuntary OR commonly emphasised in OR work. A prediction generated from this hypothesis, that the OR to stimulus omission has a longer latency than that associated with physical stimuli, was tested here. The first experiment found such an effect in the electrodermal responses to simple visual stimuli and their omission. This was replicated in a second experiment with both significant and indifferent visual stimuli. These latency delays (group mean differences ranged from 1.15 to 1.65 s) imply an intervening process in the elicitation of the electrodermal response to stimulus omission, compatible with it being viewed as a voluntary OR. An implication of these results for the conceptualization of other ORs to stimulus change is discussed.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.CLINPH.2014.10.011
Abstract: To investigate whether the latent neural correlates of incentive processing differ between problem gamblers (PGs) and healthy controls (HCs). Event-related potential (ERP) data were derived while 16 PGs and 20 HCs played a computer electronic gaming machine (EGM) task. Psychophysiological responses to outcomes commonly encountered during EGM gambling, including Large wins, Small wins, Near-wins, and Losses, were examined using a spatiotemporal principal components analysis (PCA). Subjects also completed questionnaires that assessed their levels of impulsivity, attraction to appetitive stimuli, and avoidance of aversive stimuli. Losses elicited a feedback-related negativity (FRN), whereas wins elicited a feedback-related positivity (FRP) at the same latency and topography. PGs exhibited both attenuated FRN litudes following Losses and FRP litudes following Wins. Greater P3b litudes were found following Wins compared to Losses. FRN litudes following Near-wins were significantly reduced compared to Losses for both PGs and HCs. Trends for reduced P3b litudes following all outcome types, and for similar P3b litudes following Large and Small wins, were found for the PG group. We provide evidence that PGs are hyposensitive to both positive and negative outcomes. The finding that PGs are hyposensitive to reward and punishment provides valuable insight into the nature of deficit in this disorder, and provides a foundation for future research and clinical interventions.
Publisher: Elsevier BV
Date: 10-2004
Publisher: Elsevier
Date: 2013
DOI: 10.1016/B978-0-7020-5307-8.00017-X
Abstract: Our perspective on resting-state electroencephalogram (EEG) is that it provides a window into the substrate of cognitive and perceptual processing, reflecting the dynamic potential of the brain's current functional state. In an extended research program into the electrophysiology of attention deficit/hyperactivity disorder (AD/HD), we have examined resting-state EEG power and coherence, and event-related potentials (ERPs), in children, adolescents, and adults with the disorder. We sought initially to identify consistent AD/HD anomalies in these measures, relative to normal control subjects, and then to understand how these differences related to existing models of AD/HD. An emergent strand in this program has been to clarify the EEG correlates of "arousal" and to understand the role of arousal dysfunction as a core anomaly in AD/HD. To date, findings in this strand serve to rule out a commonly held dictum in the AD/HD field: that elevated theta/beta ratio is an indicator of hypo-arousal. In turn, this requires further work to elucidate the ratio's functional significance in the disorder. Our brain dynamics studies relating prestimulus EEG litude and phase states to ERP outcomes are expected to help in this regard, but we are still at a relatively early stage, currently examining these relationships in control children, in order to better understand normal aspects of brain dynamics before turning to children with AD/HD. This range of studies provides a framework for our recent work relating resting-state EEG anomalies, in in iduals with AD/HD, to their symptom profile. This has had promising results, indicating links between increased inattention scores and reduced resting EEG gamma power. With resting-state EEG coherence, reduced left lateralized coherences across several bands have correlated negatively with inattention scores, while reduced frontal interhemispheric coherence has been correlated negatively with hyperactivity/impulsivity scores. Such linkages appear to provide encouraging leads for future EEG research in AD/HD.
Publisher: Springer Science and Business Media LLC
Date: 03-1983
DOI: 10.1007/BF01531358
Publisher: Elsevier BV
Date: 02-1997
DOI: 10.1016/S0167-8760(96)00744-1
Abstract: The influence of two anxiolytics on basal heart rate and on the evoked cardiac response elicited by auditory stimuli, was studied in humans. Diazepam (Valium) (7.5 mg) and buspirone (Buspar) (7.5 mg), which differ in their psycho-pharmacological profiles, were used. Prestimulus vigilance and cognitive load were manipulated by instructions allowing the subjects to ignore the stimuli, or requiring them to count the tones. Drug effects were obtained in subjective alertness, basal heart rate level, and the evoked cardiac response. Diazepam reduced subjective alertness, while buspirone did not. Diazepam apparently increased heart rate levels relative to placebo, in contrast to buspirone, which produced an apparent decrease in heart rate. These drug-induced prestimulus heart rate level effects were associated with differential decelerations immediately following stimulus onset and appear to reflect differences in prestimulus vigilance. Opposite effects of the drugs were also observed in the second, acceleratory, component of the of the evoked cardiac response, and these were found to be independent of the prestimulus drug effects. Compared with placebo, buspirone appeared to enhance the acceleratory component in the count condition, while diazepam led to an apparent reduction of this component. Enhancement of this acceleration after buspirone may reflect an increase in cognitive effort directed to the performance of task-relevant behaviour, while the reduction of this component after diazepam can be regarded as a cognitive-motivational neutralisation of signal value. The differential effects of the two anxiolytics support the separation of the evoked cardiac response into different components and may also have implications for the clinical use of the drugs.
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.CLINPH.2006.09.027
Abstract: In the Go/NoGo task, the N2 and P3 components are often thought to index response inhibition, or conflict between competing responses. If so, they should be affected by response preparation when the prediction of an informative cue is incorrect. Twenty-six adult participants completed a cued-Go/NoGo task. Targets required a left or right button press, or no response, while cues predicted the probable identity of the target. Analyses examined (a) effects of cues on response preparation, and "inhibitory" components to NoGo targets, (b) typical Go/NoGo differences, and (c) the impact of cue (in)validity. A reaction time benefit was associated with valid cueing, and a cost with invalid cueing. Late CNV results indicated that participants used cue information to prepare responses, and the P3, but not the N2, showed an increase with prior preparation. Typical frontal N2 and P3 NoGo>Go effects were observed, and the P3 but not the N2 showed an Invalid>Valid effect. The P3, rather than the N2, reflects the inhibition of a planned response and/or the conflict between competing responses. The findings suggest the need for a major review of current interpretations of the N2 and P3 in inhibitory tasks.
Publisher: Springer Science and Business Media LLC
Date: 06-1983
DOI: 10.3758/BF03326784
Publisher: Elsevier BV
Date: 03-2003
DOI: 10.1016/S0167-8760(02)00151-4
Abstract: Previous work has indicated the importance of ongoing EEG activity in the elicitation of the event-related potential (ERP), supporting the conceptualisation of the ERP in terms of lification and attenuation of component frequencies in the EEG. We investigated the importance of the phase of narrow-band EEG activity in generating N1 and P2 components in the auditory ERP. An auditory oddball paradigm requiring a button-press response to targets, with fixed interstimulus interval (ISI) and 15% target probability, was utilised. The continuous EEG at Cz was recorded from 16 subjects as the raw data set. Offline digital filtering was used to separate the EEG into 13 narrow bands from 1 to 13 Hz. For each band, the phase at the onset of each non-target stimulus was determined. These were used to sub-average the unfiltered data stream at each of four phases for each of 13 frequencies for each subject. Phase effects were examined in terms of two orthogonal dimensions of electrical brain activity: Cortical negativity and negative driving. Stimulus onset varied as a function of these dimensions in a non-random fashion across frequency, indicating the preferential occurrence of particular phases, interpretable as preferred brain states. Large differential effects were also apparent in N1 and P2 litudes. These data indicate important aspects of brain dynamics, suggesting that in a fixed-ISI paradigm the component frequencies of the EEG are dynamically adjusted in order to provide particular brain states at stimulus occurrence to facilitate the brain's processing of the stimulus.
Publisher: Elsevier BV
Date: 08-2006
DOI: 10.1016/J.CLINPH.2006.04.015
Abstract: This study investigated EEG differences between children with attention-deficit/hyperactivity disorder (AD/HD) and matched control subjects, with either normal or low IQs. Twenty normal-IQ and 20 low-IQ children with AD/HD, and 40 age-, IQ- and sex-matched control subjects participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and absolute and relative power in the delta, theta, alpha and beta bands. Children with AD/HD had increased theta activity with decreased levels of alpha and beta activity compared to control subjects. IQ was not found to impact on the EEG. No significant differences were found between subjects with normal and low IQs, with the low- and high-IQ AD/HD groups having similar EEG profiles. Low-IQ children with AD/HD have similar EEG abnormalities to those with normal IQs, and IQ does not appear to impact on EEG power measures. This is the first study to investigate EEG differences in low-IQ children with and without AD/HD.
Publisher: Elsevier BV
Date: 03-1984
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.CLINPH.2012.09.006
Abstract: This article reviews the event-related potential (ERP) literature in relation to attention-deficit/hyperactivity disorder (AD/HD) over the years 2002-2012. ERP studies exploring various aspects of brain functioning in children and adolescents with AD/HD are reviewed, with a focus on group effects and interpretations in the domains of attention, inhibitory control, performance monitoring, non-pharmacological treatments, and ERP/energetics interactions. There has been a distinct shift in research intensity over the past 10 years, with a large increase in ERP studies conducted in the areas of inhibitory control and performance monitoring. Overall, the research has identified a substantial number of ERP correlates of AD/HD. Robust differences from healthy controls have been reported in early orienting, inhibitory control, and error-processing components. These data offer potential to improve our understanding of the specific brain dysfunction(s) which contribute to the disorder. The literature would benefit from a more rigorous approach to clinical group composition and consideration of age effects, as well as increased emphasis on replication and extension studies using exacting participant, task, and analysis parameters.
Publisher: Elsevier BV
Date: 11-1980
DOI: 10.1016/0301-0511(80)90052-6
Abstract: This study examined the use of the P scale of the Eysenck Personality Questionnaire as a pencil and paper estimate of level of affect lability. Groups of subjects differing on the P scale were presented with emotive and non-emotive words. High P (low affect) subjects appeared inhibited in their emotional rating of all words, and displayed a restricted range in their reporting of this rating. Further, the electrodermal activity elicited by these words differed between the groups, with high P subjects again appearing relatively inhibited. These results support the validity of the P scale as a measure of affect lability and have implications for a recent hypothesis of impaired functioning of the reticular activating system in early-onset psychosis. The results may also be interpreted to support the role of significance in elicitation of the orienting response.
Publisher: Wiley
Date: 29-10-2015
DOI: 10.1111/PSYP.12376
Abstract: We recently reported an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time-frequency (t-f) analysis of electrooculogram-corrected EEG was used to explore event-related synchronization (ERS)/desynchronization (ERD) in four EEG bands using arbitrarily selected time epochs and traditional frequency ranges. ERS in delta, theta, and alpha, and subsequent ERD in theta, alpha, and beta, showed substantial decrement over trials, yet effects of stimulus significance (count vs. no-task) were minimal. Here, we used principal components analysis (PCA) of the t-f data to investigate the natural frequency and time combinations involved in such stimulus processing. We identified four ERS and four ERD t-f components: six showed decrement over trials, four showed count > no-task effects, and six showed Significance × Trial interactions. This increased sensitivity argues for the wider use of our data-driven t-f PCA approach.
Publisher: Elsevier BV
Date: 02-2003
DOI: 10.1016/S1388-2457(02)00364-4
Abstract: This study investigated the EEG of girls with Attention-deficit/hyperactivity disorder (ADHD). Subjects consisted of 100 girls with ADHD between the ages of 8 and 12 years and 40 age- and gender-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and relative power in the delta, theta, alpha and beta bands. Factor analysis was used to group sites into 3 regions, covering frontal, central and posterior regions. The total ADHD group was compared to the control group as well as the data being subjected to cluster analysis. The ADHD subjects had greater total power, more relative theta, and less relative delta, alpha and beta than controls. Cluster analysis indicated the presence of two distinct EEG clusters of girls with ADHD. These were (a) a large subgroup characterized by increased total power, more relative theta, and less relative delta and beta than control subjects and (b) a small subgroup with a substantially-increased amount of high litude theta activity, with deficiencies in all other bands. These results indicate that girls with ADHD exhibit abnormalities in their EEGs, but there is far less variance in their EEG profiles than is found in boys with the disorder. The results also suggest that there may be distinct groups of girls with ADHD who are not being referred for clinical treatment. Recommendations are made for further research in this population. This study is significant in that it is the first major study to separately investigate the EEG of girls with ADHD.
Publisher: Frontiers Media SA
Date: 30-06-2016
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.IJPSYCHO.2007.05.011
Abstract: Previous research has shown that children with Attention-Deficit Hyperactivity Disorder of the Combined Type (AD/HDcom) have problems with response inhibition, with poorer task performance and atypical inhibition-related ERPs relative to control subjects, while little is known about response inhibition in children with Attention-deficit Hyperactivity Disorder of the Predominantly Inattentive Type (AD/HDin). In this study children with AD/HDin (N=12), AD/HDcom (N=13) and age-matched controls (N=13) aged between 8 and 14 years completed a Stop-signal task, with visual Go and auditory Stop-signal stimuli, while EEG was recorded. The results indicated that the groups did not differ on any inhibitory task performance measure, but the AD/HD groups showed more errors of omission to Go stimuli than controls. ERPs to the visual Go stimuli differed between children with AD/HDin and controls (increased central N1 and N2, decreased central P2 and increased parietal P3), while the AD/HDcom group showed only minor scalp distribution differences for N2 and P3. The AD/HDin group showed litude differences from controls to Stop signals (larger central N1 and parietal P3 reduced midline N2) and did not show a Successful vs. Failed inhibition effect for P3. The AD/HDcom group showed reduced parietal P3 to Stop signals, with the Trial Type effect present for N2 but not P3. These data suggest that the apparent atypical inhibitory processing at N2 and P3 may stem, at least in part, from atypical early sensory/alerting processing of all stimuli in children with AD/HDin.
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.CLINPH.2015.05.015
Abstract: This study investigated differences in the EEG power and coherence of children with Asperger's Syndrome. Twenty boys with Asperger's Syndrome, aged 7-12 years, and an age and sex matched control group, participated in this study. The EEG was recorded during an eyes-closed resting condition from 19 electrode sites, which were clustered into nine regions prior to analysis. One minute of trace was analysed using Fourier transformations to obtain both absolute and relative power estimates in the delta, theta, alpha and beta frequency bands. Wave-shape coherence was calculated for 8 intrahemispheric and 8 interhemispheric electrode pairs. The Asperger's group had a global increase in absolute delta and an anterior increase in relative delta. Both absolute and relative theta were globally increased and relative alpha was globally decreased. Subjects with Asperger's Syndrome exhibited a broad pattern of reduced hemispheric asymmetry in intrahemispheric coherence. Reduced anterior interhemispheric coherence in the alpha and beta bands was also found in the Asperger's Syndrome group. These results suggest the existence of frontal lobe abnormalities in children with Asperger's Syndrome, and possible abnormalities in normal CNS maturational processes. This is the first major study to investigate EEG power and coherence anomalies in children with Asperger's Syndrome.
Publisher: Hogrefe Publishing Group
Date: 2005
DOI: 10.1027/0269-8803.19.2.91
Abstract: Abstract: The concepts of arousal and activation have had a confused history in Psychophysiology, and there is no widely accepted consensus on their usefulness in the field. This study aimed to explore whether these concepts could be separated in terms of their effects on the phasic Orienting Response (OR) and behavioral performance. We defined arousal at a particular time to be the energetic state at that time, reflected in electrodermal activity and measured by skin conductance level. Task-related activation was defined as the change in arousal from a resting baseline to the task situation. A continuous performance task was used with normal children. The magnitude of the mean phasic OR elicited by target stimuli was dependent on arousal, but not on task-related activation. Two performance measures (mean reaction time and number of errors) improved with increasing activation, but not with arousal. These data suggest the value of conceptualizing arousal and activation as separable aspects of the energetics of physiological and behavioral responding in future studies of attention, cognition, and emotion.
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.IJPSYCHO.2022.10.001
Abstract: The NoGo P3 event-related potential (ERP) component is often related to response inhibition, although its function in equiprobable Go/NoGo tasks is debated. Previous findings concerning the auditory equiprobable NoGo P3 (or P3a) could be distorted by averaging latency-variable ERP components. This study aimed to control NoGo P3 latency jitter to investigate the component's relationship with inhibitory demands and its neuronal sources across trials. P3 latency jitter was controlled using a novel procedure to enable single-trial P3 quantification across 126 healthy young adults (M
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.IJPSYCHO.2016.06.003
Abstract: We explored the separation of Go and NoGo effects in the ERP components elicited in an equiprobable Go/NoGo task, using different forms of temporal Principal Components Analysis (PCA). Following exploratory simulation studies assessing the PCA impact of latency jitter and between-condition latency differences in the P3 latency range, an empirical study compared results of a Combined PCA carried out using both Go and NoGo ERPs together as input, with those from two Separate PCAs carried out on the Go and NoGo ERPs separately. The simulation studies indicated that Separate PCAs provide adequate component recovery in the presence of P3 latency jitter, and that Combined PCAs provide good separation of components only when systematic condition-related latency differences are sufficiently large (here ~110ms). In the empirical data, broadly-similar components were obtained from the Combined and Separate PCAs, supporting previous findings from Combined PCA investigations, and the consequent interpretations of the sequential processing involved. However, the Separate PCAs generated latency differences for components in the Go and NoGo processing chains that better matched the late Go/NoGo ERP peaks, and produced better-defined and larger components that fitted the stages in a hypothetical processing schema developed for this paradigm. Overall, the Separate PCAs yielded a better partitioning of the ERP variance associated with the Go and NoGo conditions, and should be considered as the first choice in future investigations if systematic component or subcomponent latency differences are present or suspected.
Publisher: Elsevier BV
Date: 09-2004
Publisher: Elsevier BV
Date: 05-2001
DOI: 10.1016/S1388-2457(01)00487-4
Abstract: This study investigated age-related changes and sex differences in the EEGs of two groups of children with attention-deficit/hyperactivity disorder (ADHD) combined type and ADHD predominantly inattentive type, in comparison with a control group of normal children. Forty boys and forty girls were included in each group. The EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, absolute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios. Total power, relative alpha, and the theta/alpha and theta/beta ratios were differentiated between all 3 groups. Sex differences between the ADHD subjects and the control group were greater in males than females and matured faster in males. With increasing age, the EEG of the ADHD inattentive group was found to change at a similar rate to the changes found in the normal group, with the differences in power levels remaining constant. In the ADHD combined group, the power was found to change at a greater rate than in the ADHD inattentive group, with power levels of the two ADHD groups becoming similar with age. These results are supportive of a two-component model of ADHD, with the hyperactive/impulsive component maturing with age and the inattentive component remaining more stable.
Publisher: Elsevier BV
Date: 06-1995
DOI: 10.1016/0167-8760(95)00023-L
Abstract: The present study investigated whether the anticipatory heart rate (HR) deceleration response may reflect a pre-attentive process of stimulus registration and how reaction time (RT) and HR responses are influenced by the introduction of a psychological stressor. 60 subjects participated in a signalled RT task with a feedback stimulus containing information on their reaction time and accuracy. Changes in HR, skin conductance (SC) and respiration activity were monitored during performance in two conditions of a visual stimulus recognition task with a fixed foreperiod. In one condition subjects were informed that some electric shocks would be delivered to their right wrist (stress condition) in the other, subjects were simply engaged in the stimulus recognition without the stressor (no-stress condition). Stimuli consisted of geometrical figures and for each trial subjects were required to determine whether a probe stimulus was the same as or different from one of two memory items. Two reliable anticipatory HR decelerations, one preceding the imperative stimulus and the other preceding the feedback signal, were observed. Because the HR deceleration preceding the feedback signal (that did not require the inhibition of any specific motor response) was more pronounced than that obtained for the probe stimulus, it was concluded that HR deceleration response is an expression of stimulus processing rather than response preparation. Reaction times for 'same' stimuli were shorter than for 'different' stimuli. Averaged respiratory activity showed that with the onset of a warning signal subjects inspired and held their breath until they received the feedback signal. The averaged skin conductance data showed two main phasic increases, one after the probe stimulus onset and the other after the delivery of the feedback signal. This was taken to reflect the orienting response to the most significant stimuli.
Publisher: Elsevier BV
Date: 11-2001
DOI: 10.1016/S1388-2457(01)00668-X
Abstract: This study investigated the presence of EEG clusters within a s le of children with the combined type of attention-deficit/hyperactivity disorder (ADHD). Subjects consisted of 184 boys with ADHD and 40 age-matched controls. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, and relative power in the delta, theta, alpha and beta bands, and for the theta/beta ratio. Factor analysis was used to group sites into 3 regions, covering frontal, central and posterior regions. These data were subjected to cluster analysis. Three distinct EEG clusters of children with ADHD were found. These were characterized by (a) increased slow wave activity and deficiencies of fast wave, (b) increased high litude theta with deficiencies of beta activity, and (c) an excess beta group. These results indicate that children with ADHD do not constitute a homogenous group in EEG profile terms. This has important implications for studies of the utility of EEG in the diagnosis of ADHD. Efforts aimed at using EEG as a tool to discriminate ADHD children from normals must recognize the variability within the ADHD population if such a tool is to be valid and reliable in clinical practice.
Publisher: Elsevier BV
Date: 09-2001
DOI: 10.1016/S1389-9457(01)00121-6
Abstract: To examine the effect of nasal bilevel positive airway pressure (BiPAP) treatment for concurrent sleep-related breathing disorders (SRBDs) and attention-deficit hyperactivity disorder (ADHD) on electrophysiological measures of spontaneous brain activity and auditory stimulus processing. Nineteen children diagnosed with both SRBD and ADHD participated. Electroencephalogram (EEG) activity was recorded during a resting period and an auditory oddball task before beginning BiPAP treatment, after 6 months on treatment, and after a subsequent 1 week non-treatment period. Treatment effects on EEG and event-related potentials (ERPs) to target stimuli were examined via topographic analysis. Thirteen of the initial 19 children completed 6 months of BiPAP therapy, with six lost mainly due to compliance problems. Children on BiPAP therapy showed a significant decrease in slow-wave (delta and theta) and an increase in fast wave (beta) EEG activity. The P3 component of the ERP showed treatment effects in litude and latency. The electrophysiological data suggest that SRBDs may contribute to ADHD symptomatology. Treatment of SRBD with BiPAP therapy in children with concurrent ADHD can lead to significant changes, in the direction of normalization, of the typical electrophysiological features of ADHD.
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.BIOPSYCH.2009.04.027
Abstract: For nearly 20 years, the theta/beta power ratio in the electroencephalogram (EEG) has been used within the attention-deficit/hyperactivity disorder (ADHD) literature as a marker of central nervous system (CNS) arousal, underpinning current models of the disorder. However, this usage has not been validated. We aimed to directly test the theta/beta ratio as a marker of arousal within this population. Resting state EEG activity was investigated as a function of CNS arousal in two age-matched groups of boys (each n = 30), with and without ADHD. Arousal was defined in terms of skin conductance level (SCL), which has a long history as a measure of CNS arousal. Relative theta power and the theta/beta ratio were elevated, and SCL and relative alpha and beta power were reduced, in the ADHD group compared with control subjects. In both groups, mean alpha level correlated negatively with SCL. There was no significant correlation between the theta/beta ratio and SCL. These data contradict the supposed linkage between the theta/beta ratio and arousal in ADHD, confirming previous results from normal children. They suggest the need for reevaluation of current models of the disorder and reconceptualization of existing EEG data from both normal and atypical populations.
Publisher: Elsevier BV
Date: 08-1989
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.CLINPH.2011.02.036
Abstract: Studies indicate that the change from closed to open eyes in a resting condition results in an increase in skin conductance level (SCL) and a global decrease in EEG alpha activity, both indicative of increased arousal. Other studies show that ingestion of caffeine also produces SCL increase and alpha reduction. This study investigated the additivity of the effects of these two independent arousing variables. EEG activity and SCL were recorded from 22 university students during both eyes-closed and eyes-open resting conditions, under the action of both caffeine and placebo, in a counterbalanced randomised double-blind study. SCL increased significantly from eyes-closed to eyes-open conditions, and from placebo to caffeine, with no interaction. Global reductions in EEG alpha litude were apparent with opening of the eyes and caffeine ingestion again, there was no interaction. Caffeine had a larger effect than opening the eyes on SCL, but their relative effect sizes were reversed in alpha. The two dependent measures showed the predicted negative correlation in both eyes-closed placebo and eyes-open caffeine conditions, with the latter substantially reduced relative to the former. Caffeine and opening the eyes have additive effects on two measures of arousal, increasing SCL and reducing global EEG alpha. However, the independent variable effects are not equivalent, suggesting that one or both measures reflect additional non-arousal processes. As caffeine is widely used by both children and adults, knowledge of the additivity of arousal effects of caffeine and opening the eyes is important in controlling participant state in EEG studies. The current results confirm the use of mean global alpha litude as a measure of resting-state arousal, but also point to non-arousal effects of visual input.
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.IJPSYCHO.2005.03.012
Abstract: Research using resting EEG measures suggests that there is a large variability in EEG profiles within the common behaviourally defined DSM-IV subtypes of AD/HD. Within the predominantly inattentive type of AD/HD (AD/HDin), two distinct groups have been identified, based on underlying EEG activity that represents either cortical hypoarousal, or a maturational lag (with EEGs resembling those of younger children). This study investigated whether ERPs from an inter-modal oddball task could differentiate AD/HDin children from controls, and whether the ERPs of the two previously identified subgroups of AD/HDin children with different EEG profiles differ on this task. AD/HDin children (N=54), 27 identified as cortically hypoaroused and 27 as maturationally lagged, and 27 age-matched controls, were presented with an inter-modal oddball task in which the non-target stimulus was a counter-phasing checkerboard and the target was a 2000 Hz auditory tone. Stimuli (20% targets) were presented at a fixed ISI of 1.03 s and participants were required to count all targets. The task successfully differentiated the AD/HDin children from controls, with AD/HDin children having smaller N1, P2 and P3 litudes to both the auditory targets and the visual non-targets. These results were interpreted as indicating a generalised stimulus registration, facilitation and processing deficit in AD/HDin. The only difference between the EEG-defined subtypes was a relative increase in left-frontal N1 litude in the cortically hypoaroused group. This was interpreted as indicating reduced frontal lateralisation of N1 in the maturational lag group, supporting its labelling, and anomalous lateralisation in the cortical hypoarousal group.
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.IJPSYCHO.2010.06.357
Abstract: We examined relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in an equiprobable auditory Go/NoGo task with a fixed SOA, in the context of a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). ERP responses to each stimulus type were analysed. Prestimulus narrow-band EEG activity (in 1Hz bands from 1 to 13Hz) at Cz was assessed for each trial using FFT decomposition of the EEG data. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from the raw EEG activity at 9 central sites. The occurrence of preferred phase-defined brain states was confirmed at a number of frequencies, crossing the traditional frequency bands. As expected, these did not differ between Go and NoGo stimuli. These preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and litude of the N1 and P3 ERP components. The present results, although derived in a different paradigm by EEG decomposition methods different from those used previously, confirm the existence of preferred brain states and their impact on the efficiency of brain dynamics involved in perceptual and cognitive processing.
Publisher: Elsevier BV
Date: 03-2000
DOI: 10.1016/S1388-2457(99)00296-5
Abstract: The 'aligned-artefact average' (AAA) procedure was advanced by the authors as a technique suitable for removing eye movement-related artefacts from the EEG. It was proposed that this method would correct both blink and non-blink artefact from the EEG, using the same set of correction coefficients (Bs). However, recent evidence suggests that this simplification is not always accurate. Thus, we test here a revision of the AAA, including an appropriate allowance for the radial EOG (REOG) component, that does allow the use of the same Bs for the correction of blink and non-blink artefact. Blink (and saccade) ERP data from 15 subjects were corrected using the AAA method, with Bs calculated from the same blink (and saccade) data set (referent waveforms), or a different set of blink (and saccade) data, or using the new revised AAA procedure (RAAA). AAA Bs calculated from saccades corrected blinks poorly (and vice versa). However, the RAAA Bs corrected blink ERPs better than blink-derived Bs, and saccade ERPs better than saccade-derived Bs. It was also found that irrespective of correction type, inclusion of REOG improved correction. EOG correction is more accurate when the radial channel is included, but inclusion of REOG (and/or HEOG) is not sufficient to resolve the discrepancy between blink and saccade correction. Using the RAAA procedure, both blink and non-blink data can be corrected using the same set of Bs.
Publisher: Wiley
Date: 15-07-2014
DOI: 10.1111/PSYP.12286
Abstract: We aimed to clarify sequential processes for cue and imperative stimuli (targets/nontargets) in a continuous performance test (CPT), and how the preparatory contingent negative variation (CNV) affects physiological and behavioral responses. Single-trial event-related potentials (ERPs) obtained from 70 participants during a cued CPT were baselined to the cue (BtC) to include the CNV, or to the imperatives (BtI) to remove the CNV. Principal components analysis obtained cue and imperative ERP components, and congruence coefficients (rc ) evaluated similarities. The cue and imperative components were comparable, more so for the BtI- than BtC-imperative components (rc = .85). N1, PN, P2, N2c, and SW components were similar, but not the N2b and P3s. Imperative ERPs were largely unaffected by the resolving CNV. Similar cue and imperative components suggest similar sequential processes, while preparatory CNV activity enhanced physiological and behavioral responses.
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.CLINPH.2006.10.013
Abstract: This study investigated EEG abnormalities in adolescents with attention-deficit/hyperactivity disorder (AD/HD). Fifteen AD/HD subjects and 15 control subjects participated in this study. All subjects were between 14 and 17 years of age. The EEG was recorded from 19 electrode sites and was analysed to provide estimates of both absolute and relative power in the delta, theta, alpha and beta bands. Theta/alpha and theta/beta ratio coefficients were also calculated. Across the scalp, AD/HD subjects were characterised by greater absolute delta and theta activity, and an increased theta/beta ratio compared to controls. No group differences were found for either absolute or relative alpha, or absolute beta. However, AD/HD subjects demonstrated a reduction in relative beta activity in the posterior regions. The AD/HD group showed significant deviations from normal CNS development, in particular in posterior regions. This supports previous suggestions that in iduals with an EEG profile that is not indicative of a maturational lag are more likely to have AD/HD during adolescence. This is the first study to investigate EEG abnormalities in adolescents with AD/HD during an eyes-closed resting condition.
Publisher: Elsevier BV
Date: 04-1999
DOI: 10.1016/S0167-8760(98)00061-0
Abstract: Previous research has indicated that the auditory ERPs of children are dominated by a frontal negative slow-wave. This paper outlines a preliminary attempt to separate event-related low-frequency activity from traditional ERP components as found in older subjects. An active auditory oddball task was completed by 30 normal children aged from 8 to 18 years, and ERPs to target and standard stimuli were derived. The original ERP files were digitally filtered to calculate separate ERPs containing only 0.01-2 Hz activity (termed the SW-ERP) or 2-12 Hz activity (termed the RESIDUAL ERP) for each subject. The SW-ERP was maximally correlated with the slow-wave factor from a principal components analysis of the original target and standard waveforms. The SW-ERPs to target stimuli contained an early negative component which showed an age-related decrease, and a late positive component which did not. The SW-ERP was found to be partly responsible for the differences in component litude and morphology between sites observed in the raw ERPs.
Publisher: Wiley
Date: 28-03-2020
DOI: 10.1111/PSYP.13371
Publisher: Elsevier BV
Date: 03-2003
DOI: 10.1016/S1388-2457(02)00410-8
Abstract: Previous time-frequency studies have indicated that event-related low-frequency activity has important effects on component topography and developmental effects in auditory event-related potentials (ERPs) of children and adolescents. This study investigated the influence of event-related slow-wave (SW) (0.01-2 Hz) activity in the group differences seen between children with and without attention-deficit/hyperactivity disorder (AD/HD) of different subtypes. Time-frequency analysis techniques were applied to auditory ERP data derived from children with AD/HD predominantly inattentive type (n = 30), AD/HD combined type (n = 30) and age-matched control subjects (n = 30). Event-related early frontal negative and late posterior positive SW components were reduced in the AD/HD combined type group, but not AD/HD inattentive type group, relative to controls. The RESIDUAL ERPs, which represented event-related 2-12 Hz activity, showed clinical vs. control group differences in components that were similar in both AD/HD subtype groups. The time-frequency results showed that event-related SW (0.1-2 Hz) activity contributes importantly to group differences between AD/HD and control children, and the pattern of group differences from controls for each of the AD/HD subtype groups, which are evident in raw ERPs. These results emphasise both the clinical and developmental importance of this form of analysis. This novel approach revealed additional specific information about stimulus processing and regional inhibition/activation in two AD/HD subtypes, relative to control subjects.
Publisher: Elsevier BV
Date: 09-2005
Publisher: Elsevier BV
Date: 10-1996
DOI: 10.1016/S0165-1781(96)02893-4
Abstract: Auditory event-related potentials (ERPs) were recorded from 10 children diagnosed with attention deficit hyperactivity disorder (ADHD) and 10 age-, sex-, and IQ-matched control children. ERPs were recorded from 17 electrodes during an auditory two-tone discrimination ("oddball') paradigm. Subjects were instructed to press a hand-held response button to infrequently presented target tones. ERP components elicited to target and non-target stimuli were analyzed for between-group differences. Results indicated that for the children with ADHD relative to control children, an N2 component to non-target stimuli was larger in the posterior region and smaller in the frontal region. The P3b component to target stimuli was smaller in the posterior region and larger in the frontal region for the ADHD group compared with the control group. The between-group differences in P3b scalp distribution are indicative of a between-group difference in the neural generators of P3b. It is proposed that the ADHD group, relative to controls, utilizes an additional cognitive process when processing task-relevant stimuli. This process is more frontally distributed and may reflect an attentional compensation mechanism in the ADHD group.
Publisher: Elsevier BV
Date: 1984
DOI: 10.1016/0167-8760(84)90037-0
Abstract: Phasic changes in respiratory period, electrodermal activity (EDA), the evoked cardiac response (ECR), and the vasoconstrictive peripheral pulse litude response (PPAR), were examined in matched groups of autistic, retarded, and normal children, using repeated presentation of simple visual and auditory stimuli. Analysis as a function of group membership and age indicated that respiratory pause and EDA showed habituation in the retarded and normal groups, but not in the autistic group, with no age effects in any group. PPAR and ECR showed no habituation in any group, but within-group age differences, and a higher mean response level for the autistic subjects. The autistic children did not display the diminution of response level with increased age that was characteristic of both the control groups. These effects were obtained across both modalities. Results could not be attributed to between-group tonic cardiac arousal differences, and were interpreted as further indications of diminished sensitivity to reductions in stimulus novelty, as well as developmental delay, in early-onset psychosis.
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.IJPSYCHO.2013.06.012
Abstract: The unwarned auditory equiprobable Go/NoGo task provides a convenient means to assess differential processing, although our interpretations remain limited by the lack of research regarding the range of elicited components and their functional significance. We examined sequential processing in this paradigm, presenting 24 participants with a total of 300 trials in two blocks. EEG was recorded from 19 channels, and the Go and NoGo event-related potentials were decomposed using temporal Principal Components Analysis. Of the 218 unrestricted Varimax-rotated factors, seven were identifiable as components based on their latency, polarity, and topography: early N1, Processing Negativity (PN), and P2 components were followed by N2, P3, the classic Slow Wave (SW), and a diffuse Late Positivity (LP). N1 was enhanced to Go, as was the defining temporal topography of PN. NoGo produced increased centroparietal P2, frontocentral N2, and P3a, in comparison to Go, which produced a more parietal N2 and P3b, and an enhanced SW. The LP was larger in NoGo. These results suggest that N1 marks the beginning of Go and NoGo differentiation. Complete Go/NoGo categorisation is marked by N2 this is followed by different processing chains leading to the NoGo non-response (marked by P3a) and Go response (marked by P3b and SW). The larger LP in NoGo marks the cortical inactivation following the earlier cessation of processing in this condition.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.IJPSYCHO.2013.06.011
Abstract: Originally, the feedback related negativity (FRN) event-related potential (ERP) component was considered to be a robust neural correlate of non-reward unishment processing, with greater negative deflections observed following unfavourable outcomes. More recently, it has been suggested that this component is better conceptualised as a positive deflection following rewarding outcomes. The current study sought to elucidate the nature of the FRN, as well as another component associated with incentive-value processing, the P3b, through application of a spatiotemporal principal components analysis (PCA). Seventeen healthy controls played a computer electronic gaming machine (EGM) task and received feedback on credits won or lost on each trial, and ERPs were recorded. The distribution of reward/non-reward outcomes closely matched that of a real EGM, with frequent losses, and infrequent wins and near-wins. The PCA revealed that feedback elicited both a frontally maximal negative deflection to losses, and a positive deflection to wins (which was also sensitive to reward magnitude), implying that the neural generator/s of the FRN are differentially activated following these outcomes. As expected, greater P3b litudes were found for wins compared to losses. Interestingly, near-wins elicited significantly smaller FRN litudes than losses (with no differences in P3b litude), and may contribute to the maintenance of gambling behaviours on EGMs. The results of the current study are integrated into a response profile of healthy controls to outcomes of varying incentive value. This may provide a foundation for the future examination of in iduals who exhibit abnormalities in reward unishment processing, such as problem gamblers.
Publisher: Elsevier BV
Date: 12-2003
DOI: 10.1016/S0006-3223(03)00703-0
Abstract: The aim of the study was to investigate the inhibitory control of an ongoing motor response and to identify underlying neural deficiencies, manifested in event-related potentials, that cause poorer inhibitory performance in children with attention-deficit/hyperactivity disorder. A stop-signal paradigm with a primary visual task and auditory stop signal was used to compare performance in 13 children with attention-deficit/hyperactivity disorder and 13 control children, while event-related potentials were recorded simultaneously. Children with attention-deficit/hyperactivity disorder showed poorer inhibitory performance through a slower inhibitory process. Inhibitory processing of auditory stop signals was marked by a frontal N2 component that was reduced in the attention-deficit/hyperactivity disorder group relative to controls. A central positive component (P3) was associated with the success of inhibiting a response, but there were no group differences in its litude or latency. Findings support the hypothesis of deficient inhibitory control in children with attention-deficit/hyperactivity disorder. Slower inhibitory processing appears to be due to a specific neural deficiency that manifests in the processing of the stop signal as attenuated negativity in the N2 latency range.
Publisher: Elsevier BV
Date: 10-2005
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.IJPSYCHO.2005.03.004
Abstract: This study investigated the effects of methylphenidate on intrahemispheric and interhemispheric EEG coherence in children with Attention-Deficit/Hyperactivity Disorder (AD/HD). Twenty boys with AD/HD Combined type and 20 age- and sex-matched control subjects, aged 8 to 13 years, participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for eight intrahemispheric electrode pairs (four in each hemisphere), and eight interhemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. AD/HD children were tested both off and, 6 months later, on a therapeutic dose of methylphenidate. In intrahemispheric comparisons, AD/HD children had lower theta coherences at long inter-electrode distances, and reduced lateralisation at both long and short-medium inter-electrode distances than controls. For interhemispheric comparisons, AD/HD children showed increased coherences in the frontal regions for the low frequency bands (delta and theta), and reduced coherences in the alpha bands in all other regions. These EEG coherences suggest reduced cortical differentiation and specialisation in AD/HD, particularly in the frontal regions. Methylphenidate did not produce any changes in coherence values. The lack of sensitivity of coherence measures to methylphenidate in the present study suggests that eyes-closed resting EEG coherence measures are associated with structural connectivity of the underlying regions of the brain rather than the degree of functionality of these regions. These results suggest the existence of structural as well as functional brain dysfunction in AD/HD.
Publisher: Mary Ann Liebert Inc
Date: 08-2002
DOI: 10.1089/107555302760253621
Abstract: Exposure to active mobile phones (MP) has been shown to affect human neural function as shown by the electroencephalogram (EEG). Although it has not been determined whether such effects are harmful, a number of devices have been developed that attempt to minimize these MP-related effects. One such device, the Q Link Ally (QL Clarus Products, International, L.L.C., San Rafael, CA), is argued to affect the human organism in such a way as to attenuate the effect of MPs. The present pilot study was designed to determine whether there is any indication that QL does alter MP-related effects on the human EEG. Twenty-four (24) subjects participated in a single-blind, fully counterbalanced crossover design in which subjects' resting EEG and phase-locked neural responses to auditory stimuli were assessed under conditions of either active MP or active MP plus QL. The addition of QL to the MP condition increased resting EEG in the gamma range and did so as a function of exposure duration, and it attenuated MP-related effects in the delta and alpha range (at trend-level). The addition of the QL also affected phase-locked neural responses, with a laterality reversal in the alpha range and an alteration to changes over time in the delta range, a reduction of the MP-related beta decrease over time at fronto-posterior sites, and a global reduction in the gamma range that increased as a function of exposure duration. No unambiguous relations were found between these changes and either performance or psychologic state. This pilot study suggests that the addition of the QL to active MP-exposure does affect neural function in humans, altering both resting EEG patterns and the evoked neural response to auditory stimuli, and that there is a tendency for some MP-related changes to the EEG to be attenuated by the QL.
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.IJPSYCHO.2005.03.008
Abstract: Children with Attention Deficit/Hyperactivity Disorder (AD/HD) appear to be deficient in inhibitory processes, as reflected in behavioural and electrophysiological measures. This study examined the effect of methylphenidate (MPH) on response inhibition in children with AD/HD. Event-related potentials (ERPs) and skin conductance level (SCL) were recorded from 18 boys with AD/HD and 18 controls while they performed a cued Go/Nogo task with 70% Go probability. All participants performed the task twice, with an hour interval between test sessions. At the beginning of this interval children with AD/HD took their normal morning dose of MPH. The AD/HD group showed lower SCL than controls pre-medication, a difference not found subsequent to the administration of MPH. While the AD/HD group made more overall errors (omission+commission) pre-medication, and continued to make more omission errors than controls post-medication, the groups became comparable on the number of commission errors, suggesting MPH ameliorates deficits in response inhibition. Children with AD/HD displayed enhanced N1 and P2 litudes, and reduced N2 litudes relative to controls. These differences were not significant post-medication, at least partly attributable to the action of MPH. This study is unusual in the concurrent examination of electrodermal and electrophysiological measures of medication effects in children with AD/HD, with the retesting of both the AD/HD and control groups allowing a more valid estimate of the effects of medication, rather than assuming that retesting does not have a substantial impact.
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.IJPSYCHO.2005.03.005
Abstract: Cognition and behaviour depend on the integration of activity in different brain regions, and hence study of the coupling between regions is useful in understanding dysfunctional processes involved in disorders such as attention-deficit/hyperactivity disorder (AD/HD). Such coupling can be estimated by the electroencephalographic (EEG) coherence between scalp electrodes. However, EEG coherence between two points is strongly affected by the distance between them, being inflated by volume conduction effects at short distances and reduced by signal phase differences at larger distances. These distance effects preclude simple comparison of coherence estimates involving different inter-electrode distances. Our group recently introduced a procedure for adjusting coherence measures to remove such distance effects, and explored its potential using normal children. In this study we applied that coherence adjustment procedure to groups of children with AD/HD of the combined (AD/HDcom) and predominantly inattentive (AD/HDin) subtypes, and compared them with a control group. All groups were age- and gender-matched. AD/HD children were found to have a reciprocal pattern of coherence disturbance in the cortico-cortical circuits involved in slow and fast wave activity-elevated slow-wave coherences and reduced fast-wave coherences. This disturbance was larger for inter-hemispheric than intra-hemispheric coherences, and varied markedly with region, suggesting a complex pattern of coherence anomalies with a substantial frontal focus. This complex pattern differed little between subtypes, suggesting that it may constitute the fundamental dysfunction underlying the inattention common to both groups. In contrast, coherence was globally elevated in children with AD/HDcom compared with both AD/HDin and control children. This elevation in coherence may be directly related to the hyperactivity and impulsivity unique to that subtype. Further research using the coherence adjustment procedure appears useful in elucidating the electrophysiological anomalies underlying AD/HD and other disorders.
Publisher: SAGE Publications
Date: 09-1994
DOI: 10.3109/00048679409075872
Abstract: This study explores SPECT measured in schizophrenic patients at rest. Left temporal lobe activity was found to be decreased with increasing positive symptom's scores scores. Medicated patients showed a reversal of this pattern underlying this positive symptom effect. Patients with a recent history of auditory hallucinations showed an atypical right temporal lobe dominance, which occurred independently of medication status. These preliminary data are suggestive of the potential utility of SPECT to elucidate symptom/medication/brain activity interrelationships in schizophrenia.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.NEULET.2014.02.037
Abstract: Entrainment in physiological systems can be manifest in cases where phase-coupling (synchronization) between slow intrinsic oscillations and periodic motor responses, or vice versa, takes place. To test whether voluntary movement has something in common with entrainment of slow hemodynamic oscillations to motor responses, we studied blood pressure (BP), heart rate beat-to-beat intervals (RRI) and prefrontal (de)oxyhemoglobin (Hb/HbO2) during 5min of rest, 10min of self-paced, voluntary movements and 10min of stimulus-paced movements at 10s intervals in 9 subjects. Subjects were ided into 2 groups according to the timing of voluntary finger movements. It appeared that these movements occurred at relatively regular intervals of approximately 10s in 5 subjects (group A) while 4 subjects showed random or very short inter-movement intervals (group B). Two remarkable results were obtained: first, the phase coupling (COH(2)) between BP and RRI showed a significant (p=0.0061) interaction between activity (rest vs. movement) and group (A vs. B), with an increased (p=0.0003) coupling in group A. Second, the COH(2) between BP and Hb oscillations showed a significant (p=0.034) interaction between activity and group, with a decreased (p=0.079) coupling in group B. These results suggest that subjects able to initiate self-paced, voluntary movements at relatively regular intervals of ∼10s show an entrainment potential between physiological oscillations and motor responses. This also provides the first evidence that not only physiological oscillations can be entrained to motor responses, but also motor responses (voluntary movements) can be entrained to slow intrinsic oscillations.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2011
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BIOPSYCHO.2008.10.009
Abstract: Current views of the genesis of the event-related potential (ERP) contrast the phase-reset and evoked activity models. In the former, a portion of the ongoing electroencephalographic (EEG) activity becomes phase-locked at stimulus onset in the latter, processing in the brain contributes additional time-locked activity at each trial. This study aimed to explore these perspectives in an auditory Go/NoGo task. The interactions between these processes were examined using the litudes and topographies of pre- and post-stimulus EEGs in traditional bands, and the averaged ERPs, together with time-frequency analysis. Results indicate that both evoked activity and phase locking of ongoing EEG activity contribute substantially to the different Go and NoGo ERP components. Phase locking contributes most strongly to the early exogenous ERP components, with evoked brain activity related to cognitive processing contributing strongly to the endogenous ERP components. Evidence also suggests that extensive phase realignments may generate the power increases associated with early exogenous components. It is concluded that exogenous ERP components arise substantially from phase-resetting mechanisms involving ongoing EEG activity. In contrast, the endogenous components are substantially produced by evoked activity in various frequency bands, and their differences reflect differential cortical processing required for appropriate responding to the Go vs. NoGo stimuli.
Publisher: Elsevier BV
Date: 10-2002
DOI: 10.1016/S1388-2457(02)00215-8
Abstract: Mobile phones (MP) are used extensively and yet little is known about the effects they may have on human physiology. There have been conflicting reports regarding the relation between MP use and the electroencephalogram (EEG). The present study suggests that this conflict may be due to methodological differences such as exposure durations, and tests whether exposure to an active MP affects EEG as a function of time. Twenty-four subjects participated in a single-blind fully counterbalanced cross-over design, where both resting EEG and phase-locked neural responses to auditory stimuli were measured while a MP was either operating or turned off. MP exposure altered resting EEG, decreasing 1-4 Hz activity (right hemisphere sites), and increasing 8-12 Hz activity as a function of exposure duration (midline posterior sites). MP exposure also altered early phase-locked neural responses, attenuating the normal response decrement over time in the 4-8 Hz band, decreasing the response in the 1230 Hz band globally and as a function of time, and increasing midline frontal and lateral posterior responses in the 30-45 Hz band. Active MPs affect neural function in humans and do so as a function of exposure duration. The temporal nature of this effect may contribute to the lack of consistent results reported in the literature.
Publisher: Elsevier BV
Date: 02-2003
DOI: 10.1016/S1388-2457(02)00362-0
Abstract: This article reviews the electroencephalography (EEG) literature in relation to attention-deficit/hyperactivity disorder (AD/HD). The review briefly outlines the history of the disorder, focusing on the changing diagnostic systems which both reflect and constrain research into AD/HD. Both qualitative and quantitative EEG studies are examined, and their results are discussed in relation to various models of AD/HD. Implications of these data for future research and development in AD/HD are considered. In terms of resting EEG, elevated relative theta power, and reduced relative alpha and beta, together with elevated theta/alpha and theta/beta ratios, are most reliably associated with AD/HD. Theta/alpha and theta/beta ratios also discriminate diagnostic subgroups of AD/HD. Recent studies of EEG heterogeneity in this disorder indicate the existence of different profiles of cortical anomalies which may cut across diagnostic types. The research to date has identified a substantial number of EEG correlates of AD/HD which hold promise for improving our understanding of the brain dysfunction(s) underlying the disorder. Further work in this field may benefit from a broader conceptual approach, integrating EEG and other measures of brain function.
Publisher: Springer Science and Business Media LLC
Date: 12-1978
DOI: 10.3758/BF03326749
Publisher: Springer Science and Business Media LLC
Date: 09-1981
DOI: 10.3758/BF03326987
Publisher: Elsevier BV
Date: 12-1996
DOI: 10.1016/S0167-8760(96)00065-7
Abstract: Previous studies of auditory event-related potentials (ERPs) to an oddball task in children and adolescents focus on responses to target stimuli and provide little detail of age-related changes to standard stimuli. In this study, age-related changes in behavioural responding and ERP component morphology, litude and latency to standard and target stimuli were examined. Auditory ERPs to an oddball task were recorded from the midline sites (Fz, Cz and Pz) of 50 subjects aged 8 to 17 years 11 months. Behavioural results indicate a decrease in reaction time and errors of commission with age. To standard tones, N2 litude and N1 latency showed a linear decrease with age while an increase with age was found for P2 litude. For target tones, N1 and N2 litude and N1, N2 and P3 latency showed a linear decrease with age and P2 and P3 litude showed a linear increase with age. Age-related changes in the morphology of the ERP elicited by standard tones (especially the N2 and P2 components), as well as concurrent morphological changes in standard and target tones, are discussed.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.CLINPH.2007.04.006
Abstract: This study investigated differences in coherence measures between two groups of children with Attention-Deficit/Hyperactivity Disorder (ADHD) - with the typical EEG profile (increased theta and decreased beta activity), and with excess beta activity - and a normal control group. Thirty-four children with ADHD were included in each of the typical and excess beta groups, and were age and sex matched with 34 control subjects. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for eight intrahemispheric and eight interhemispheric electrode pairs, for the delta, theta, alpha and beta bands. In comparison to the controls, the typical ADHD group primarily had increased intrahemispheric theta and beta coherence at short-medium inter-electrode distances, and increased interhemispheric coherence for theta in the frontal and central arietal/occipital regions. Their laterality effect for interhemispheric short-medium inter-electrode distances was reduced in the theta band. Differences between the excess beta group and the control group were primarily found in laterality of the intrahemispheric theta coherence at short-medium electrode distances, and increased interhemispheric theta coherence in the frontal regions. Reduced delta coherence in the temporal regions was also found. These results suggest that ADHD children with excess beta power have an underlying brain dysfunction in the frontal lobes which is found in common with children with the typical EEG profile. However a number of qualitative differences exist which could be associated with other aspects of the ADHD diagnosis or another comorbid condition. This is the first study to investigate EEG coherence in ADHD children who have increased beta power.
Publisher: SAGE Publications
Date: 09-1981
DOI: 10.1177/016502548100400305
Abstract: The problems of establishing both quantitative and qualitative deficits in the behavioural profiles of various diagnostic subcategories of developmentally-disabled children are discussed in a developmental context. Ex les of clinical experimental studies from the literature concerned with the syndrome of early-onset psychosis are used to illustrate the importance of methodologically controlling for maturational variables. Methods of appropriate matching of control groups are suggested which should facilitate the delineation of specific and general deficits in subgroups of developmentally-delayed children.
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.IJPSYCHO.2009.05.003
Abstract: We examined relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in an auditory oddball task, varying both stimulus intensity and active vs. passive task requirements between groups. We used a novel conceptualisation of orthogonal phase effects (cortical negativity vs. positivity, negative driving vs. positive driving, waxing vs. waning). This study focused on the operation of three previously-reported phase-influenced mechanisms, involving prestimulus litudes, poststimulus litude changes, and the prestimulus contingent negative variation (CNV), in various EEG frequency bands. ERP responses to the standard stimuli were analysed. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz, and Pz. The occurrence of preferred phase-defined brain states was confirmed at a number of frequencies, crossing the traditional frequency bands. These preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and/or litude of all ERP components, and provided evidence of the operation of the three separate phase-influenced mechanisms. The preferred brain states occurred similarly across groups, suggesting that they reflect reflexive aspects of brain function associated with the timing of the stimuli, rather than voluntary attention. The impact on markers of cognitive function, such as the P3, suggests their important contributions to the efficiency of brain dynamics involved in perceptual and cognitive processing.
Publisher: Informa UK Limited
Date: 09-1977
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.CLINPH.2007.06.059
Abstract: We aimed to examine relationships between the phase of narrow-band electroencephalographic (EEG) activity at stimulus onset and the resultant event-related potentials (ERPs) in active vs. passive auditory oddball tasks, using a novel conceptualisation of orthogonal phase effects. This study focused on the operation of three recently-reported phase-influenced mechanisms, and ERP responses to the standard stimuli were analysed. Prestimulus narrow-band EEG activity (in 1 Hz bands from 1 to 13 Hz) at Cz was assessed for each trial using digital filtering. For each frequency, the cycle at stimulus onset was used to sort trials into four phases, for which ERPs were derived from both the filtered and unfiltered EEG activity at Fz, Cz and Pz. Preferred brain states at various frequencies were indicated by approximately 20% differential occurrence within the orthogonal phase dimensions explored. The preferred states were associated with more efficient processing of the stimulus, as reflected in differences in latency and/or litude of various ERP components, and provided evidence for the operation of the three separate phase-influenced mechanisms. Both the occurrence of preferred brain states, and the mechanisms linking them to ERP outcomes focused on here, appeared relatively invariant across tasks, suggesting that they largely reflect reflexive brain processes.
Publisher: Elsevier BV
Date: 05-1987
DOI: 10.1016/0167-8760(87)90074-2
Abstract: In recent years, psychophysiologists have increasingly used the peripheral pulse as a more convenient source of cardiac information than the electrocardiogram. We explored some of the measurement problems associated with this choice by comparing estimates, produced by both data sources, of the cardiac response evoked by innocuous visual stimuli. The most important difference is that pulse transit time results in the immediately-prestimulus beat of a significant proportion of pulse-derived responses being mislabelled as the following beat, shifting the entire apparent response by one beat. This reduces correlations between the data streams, and has implications for the adequate measurement of evoked cardiac responses.
Publisher: Informa UK Limited
Date: 03-2009
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.NEUROPHARM.2009.08.003
Abstract: Although stimulant medications are the most commonly-used treatments for Attention-Deficit/Hyperactivity Disorder (AD/HD), as many as 20% of treated children do not respond clinically to stimulants. This study investigated the effects of an acute dose of atomoxetine, a selective noradrenaline reuptake inhibitor (SNRI), on the electroencephalogram (EEG) and performance of children with AD/HD. An initial pre-medication EEG was recorded during an eyes-closed resting condition. Within two weeks, a second EEG was recorded 1 h after ingestion of 20 mg of atomoxetine. Data were Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha, beta and gamma bands. Compared to controls, the unmedicated AD/HD children had significantly elevated global absolute and relative delta, with reduced global relative alpha, and absolute and relative gamma, and many topographic differences. Atomoxetine produced significant global increases in absolute and relative beta, with several topographic changes in other bands, and a significant reduction in omission errors on a Continuous Performance Task. These results indicate that SNRIs can produce substantial normalisation of the AD/HD EEG profile, together with behavioural performance improvements. Although EEG changes induced by acute administration of psychostimulants (methylphenidate/dex hetamine) and atomoxetine are not identical, both classes of AD/HD drugs produce similar EEG band changes. Further analysis of EEG responses to SNRIs and psychostimulants could reveal common neurophysiological processes closely linked to clinical improvement of AD/HD symptoms in response to pharmacotherapy, providing translational markers for clinical efficacy studies and potential translational biomarkers for AD/HD drug discovery.
Publisher: Elsevier BV
Date: 08-2006
DOI: 10.1016/J.IJPSYCHO.2005.07.013
Abstract: The cued Go/NoGo task elicits response preparation during the foreperiod, and, depending on the S2 signal, either response execution or inhibition. This study aimed to determine how processes in the foreperiod might affect or predict post-S2 processing. Thirty-two adults participated in a cued Go/NoGo task (50% Go), with a median split of mean RT producing "Fast" and "Slow" groups. ERP measures were subjected to both ANOVA and regression techniques. There were no differences in the NoGo N2 effect related to response speed, nor was the effect related to pre-S2 processes. The anterior shift of the NoGo P3 was larger in the Fast group, and while the late CNV was associated with the absolute litude of both Go and NoGo P3, it was not related to the anterior-posterior Go/NoGo differences. Together, these data suggest that the inhibitory process may be reflected in the NoGo P3 effect, rather than the NoGo N2 effect.
Publisher: Elsevier BV
Date: 08-1991
DOI: 10.1016/0167-8760(91)90008-L
Abstract: A convenient portable recording device, HGM1, which allows digital field recording of skin conductance and heart rate data with laboratory levels of precision, is described. Ex les of in idual data are provided from a study of orienting response habituation, and from students participating in a study of examination anxiety, recorded while they sat scheduled class examinations. These illustrate the potential value of the device in field studies.
Publisher: Wiley
Date: 22-07-2014
DOI: 10.1111/PSYP.12292
Abstract: Temporal and thermal differences between the initiation of precursor, eccrine sweat and its surface discharge were investigated during passive heating. Sudomotor activity was evaluated using electrodermal (precursor) and ventilated sweat capsule measurements (dorsal fingers, dorsal hand, forehead, forearm). Passive heating significantly elevated auditory canal (0.5 degrees C) and mean body temperatures (0.9 degrees C). At each site, the precursor sudomotor thresholds occurred at a lower mean body temperature (P < .05), with an average elevation of 0.35 degrees C (SD 0.04). However, discharged thresholds were delayed until this temperature had risen 0.53 degrees C (SD 0.04), producing significant phase delays across sites (mean: 4.1 min [SD 0.5] P < .05). It is concluded that precise sudomotor threshold determinations require methods that respond to sweat accumulating within the secretory coil, and not discharged secretions, reinforcing the importance of electrodermal techniques.
Publisher: Informa UK Limited
Date: 05-1994
Publisher: Elsevier BV
Date: 04-2005
DOI: 10.1016/J.CLINPH.2004.10.002
Abstract: This study investigated intra-hemispheric and inter-hemispheric EEG coherences as a function of age in boys with different subtypes of Attention Deficit/Hyperactivity Disorder (AD/HD), in comparison with a control group of normal boys. Three groups of 40 children (AD/HD combined type, AD/HD inattentive type, and normal controls) participated. Each group contained 8 males in each 1 year band from 8 to 12 years. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intra-hemispheric electrode pairs (4 in each hemisphere), and 8 inter-hemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. Developmental effects in intra-hemispheric coherences at shorter and longer inter-electrode distances generally supported Thatcher's two-compartment model. Control boys showed evidence of development in longer-range inter-hemispheric coherences which was not apparent in AD/HD boys. Boys with AD/HD of the combined type showed qualitatively different anomalies than boys with AD/HD of the inattentive type. EEG coherences in normal boys of this age range develop systematically with age in a non-linear fashion. Boys with AD/HD do not show this development. They display coherence anomalies which differ in nature between DSM-IV subtypes, suggesting differences which are not relatable to simple symptom severity. The data reported here indicate differences in the development of EEG coherences in boys with AD/HD, and point to differences between the AD/HD subtypes which may help understanding of the disorder.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Wiley
Date: 2005
DOI: 10.1111/J.1468-8986.2005.00264.X
Abstract: EOG correction is a class of techniques that account for ocular artifact in the electroencephalogram (EEG) by subtracting electrooculographic data from the EEG. The purpose of this study was to evaluate four of these correction techniques (Verleger, Gasser, & Mocks, 1982 [VGM] Gratton, Coles, & Donchin, 1983 [GCD] Semlitsch, Presslich, Schuster, & Anderer, 1986 [SPSA] Croft & Barry, 2000 [CB]). Blinks, vertical eye movements (VEM), and horizontal eye movements (HEM) from 26 subjects were corrected using these techniques, and eye movement event-related potentials computed to aid validation. HEMs were corrected better by CB, VGM/GCD then SPSA, VEMs by CB, VGM/GCD then SPSA, and blinks by CB, SPSA, GCD and then VGM, with the advantage of CB substantial for blinks (eta2>.72), VEMs (eta2>.60), and HEMs (eta2>.27). It is argued that the CB procedure adequately accounts for ocular artifact in the EEG. Reasons for the limitations of the other procedures are discussed.
Publisher: Elsevier BV
Date: 03-1988
DOI: 10.1016/0167-8760(88)90029-3
Abstract: One problem in the optimization of athletic performance is that consistency in practice situations is not always carried over to competitive situations. There is an increase in irrelevant stimuli in competition which cannot always be gated out satisfactorily by the anxious athlete. We investigated the physiological responses to relevant and irrelevant stimuli of 48 elite female gymnasts differing in levels of anxiety and defensiveness. Cardiac responses were recorded to tone presentations and analyzed as a function of instructions, anxiety manipulation and group. The results suggest that phasic responses of high-anxious gymnasts were larger than those of low-anxious gymnasts. High-anxious gymnasts experience more difficulty in completely gating out the occurrence of irrelevant stimuli than do low-anxious gymnasts. Finally, under anxiety-producing conditions, high levels of defensiveness and anxiety in combination appear to have a debilitating effect on the gymnast's ability to discontinue processing of irrelevant stimuli, while truly low-anxious subjects appear distracted from processing relevant stimuli. Further investigation of the interactions between levels of trait anxiety and anxiety-producing situations in a sport-specific domain appear warranted. The role of defensiveness in these interactions should also be investigated.
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.IJPSYCHO.2009.05.012
Abstract: From previous work in our laboratory, increases in skin conductance level (SCL), together with global (across-scalp) decreases in electroencephalogram (EEG) alpha power and increases in alpha frequency, are useful indices of arousal increase, and here we sought to identify changes in these indices with caffeine ingestion in children. We explored the effects of a single oral dose of caffeine (80 mg) in a randomised double-blind placebo-controlled repeated-measures cross-over study. Thirty healthy children aged between 8 and 13 years (mean age 10.5 years 11 females) participated in two sessions, 1 week apart. EEG and SCL from a 3 min eyes-closed epoch, commencing approximately 30 min after ingestion of caffeine or placebo, were examined. Caffeine was associated with increased SCL, and a global reduction in EEG power in the theta and alpha bands, as well as topographically-focused reductions in delta and beta power, and a focal increase in alpha frequency. Only global alpha level demonstrated the expected inverse relationship with SCL in both placebo and caffeine conditions. These results are generally consistent with recent electrodermal and EEG studies of arousal. Together with our previous adult data, they indicate that caffeine can be used to increase arousal in both adults and children, without the potential confounds associated with varying task demands. Caffeine appears useful as a simple tool for manipulating arousal in studies exploring its role in physiological and behavioural functioning. This may be helpful in determining the role of hypothetical arousal anomalies in syndromes such as attention-deficit/hyperactivity disorder.
Publisher: Frontiers Media SA
Date: 10-08-2016
Publisher: Oxford University Press (OUP)
Date: 31-07-2019
Abstract: The COMT Val158Met polymorphism affects the availability of synaptic dopamine in the prefrontal cortex and has been widely studied as a genetic risk factor for psychosis. Schizotypy is associated with an increased risk of psychosis, with some studies implicating similar neurobiological mechanisms to schizophrenia. The present study sought to interrogate the link between the COMT Val158Met polymorphism and schizotypy using electroencephalogram (EEG) to identify neurophysiological mechanisms underpinning psychosis risk. Neurotypical (N = 91) adults were genotyped for the COMT Val158Met polymorphism, completed the Schizotypal Personality Questionnaire (SPQ), and had eyes open resting-state EEG recorded for 4 min. SPQ suspiciousness subscale scores were higher for in iduals homozygous for Val/Val and Met/Met versus Val/Met genotypes. Delta, theta, alpha-2, beta-1, and beta-2 litudes were lower for Val/Val than Met/Met in iduals. Lower theta litudes were correlated with higher total SPQ scores (P = 0.050), and multiple regression revealed that higher delta, and lower theta and beta-2 litudes (but not COMT genotype) best predicted total SPQ scores (P = 0.014). This study demonstrates the importance of COMT genotype in determining trait suspiciousness and EEG oscillatory activity. It also highlights relationships between dopaminergic alterations, EEG and schizotypy that are dissimilar to those observed in schizophrenia.
Publisher: Elsevier BV
Date: 09-2009
No related grants have been discovered for Robert J. Barry.