ORCID Profile
0000-0002-1435-2993
Current Organisation
Deakin University
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Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.BBR.2013.04.027
Abstract: Research indicates that mirror neurons are important for social cognition, including emotion processing. Emerging evidence, however, also reveals that emotional stimuli might be capable of modulating human mirror neuron system (MNS) activity. The current study used transcranial magnetic stimulation (TMS) to assess putative mirror neuron function following emotionally evocative images in twenty healthy adults. Participants observed videos of either a transitive hand action or a static hand while undergoing TMS of the primary motor cortex. In order to examine the effect of emotion on the MNS, each video was preceded by an image of either a positive, negative or neutral valence. MNS activity was found to be augmented by both the positive and negative (relative to neutral) stimuli, thus providing empirical support for a bi-directional link between emotion and the MNS, whereby both positively and negatively valenced stimuli are capable of facilitating mirror neuron activity. The potential adaptive significance of this finding is discussed.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.NEUBIOREV.2016.01.008
Abstract: Noninvasive brain stimulation has been demonstrated to modulate cortical activity in humans. In particular, theta burst stimulation (TBS) has gained notable attention due to its ability to induce lasting physiological changes after short stimulation durations. The present study aimed to provide a comprehensive meta-analytic review of the efficacy of two TBS paradigms intermittent (iTBS) and continuous (cTBS), on corticospinal excitability in healthy in iduals. Literature searches yielded a total of 87 studies adhering to the inclusion criteria. iTBS yielded moderately large MEP increases lasting up to 30 min with a pooled SMD of 0.71 (p<0.00001). cTBS produced a reduction in MEP litudes lasting up to 60 min, with the largest effect size seen at 5 min post stimulation (SMD=-0.9, P<0.00001). The collected studies were of heterogeneous nature, and a series of tests conducted indicated a degree of publication bias. No significant change in SICI and ICF was observed, with exception to decrease in SICI with cTBS at the early time point (SMD=0.42, P=0.00036). The results also highlight several factors contributing to TBS efficacy, including the number of pulses, frequency of stimulation and BDNF polymorphisms. Further research investigating optimal TBS stimulation parameters, particularly for iTBS, is needed in order for these paradigms to be successfully translated into clinical settings.
Publisher: MDPI AG
Date: 03-02-2023
DOI: 10.3390/BIOS13020220
Abstract: The cortical response to transcranial magnetic stimulation (TMS) has notable inter-trial variability. One source of this variability can be the influence of the phase and power of pre-stimulus neuronal oscillations on single-trial TMS responses. Here, we investigate the effect of brain oscillatory activity on TMS response in 49 distinct healthy participants (64 datasets) who had received single-pulse TMS over the left dorsolateral prefrontal cortex. Across all frequency bands of theta (4–7 Hz), alpha (8–13 Hz), and beta (14–30 Hz), there was no significant effect of pre-TMS phase on single-trial cortical evoked activity. After high-powered oscillations, whether followed by a TMS pulse or not, the subsequent activity was larger than after low-powered oscillations. We further defined a measure, corrected_effect, to enable us to investigate brain responses to the TMS pulse disentangled from the power of ongoing (spontaneous) oscillations. The corrected_effect was significantly different from zero (meaningful added effect of TMS) only in theta and beta bands. Our results suggest that brain state prior to stimulation might play some role in shaping the subsequent TMS-EEG response. Specifically, our findings indicate that the power of ongoing oscillatory activity, but not phase, can influence brain responses to TMS. Aligning the TMS pulse with specific power thresholds of an EEG signal might therefore reduce variability in neurophysiological measurements and also has the potential to facilitate more robust therapeutic effects of stimulation.
Publisher: Springer Science and Business Media LLC
Date: 13-10-2020
DOI: 10.1038/S41598-020-74103-Y
Abstract: Electroconvulsive therapy (ECT) is a highly effective neuromodulatory intervention for treatment-resistant major depressive disorder (MDD). Presently, however, understanding of its neurophysiological effects remains incomplete. In the present study, we utilised resting-state electroencephalography (RS-EEG) to explore changes in functional connectivity, network topology, and spectral power elicited by an acute open-label course of ECT in a cohort of 23 patients with treatment-resistant MDD. RS-EEG was recorded prior to commencement of ECT and again within 48 h following each patient’s final treatment session. Our results show that ECT was able to enhance connectivity within lower (delta and theta) frequency bands across subnetworks largely confined to fronto-central channels, while, conversely, more widespread subnetworks of reduced connectivity emerged within faster (alpha and beta) bands following treatment. Graph-based topological analyses revealed changes in measures of functional segregation (clustering coefficient), integration (characteristic path length), and small-world architecture following ECT. Finally, post-treatment enhancement of delta and theta spectral power was observed, which showed a positive association with the number of ECT sessions received. Overall, our findings indicate that RS-EEG can provide a sensitive measure of dynamic neural activity following ECT and highlight network-based analyses as a promising avenue for furthering mechanistic understanding of the effects of convulsive therapies.
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 05-2023
Publisher: Hindawi Limited
Date: 31-08-2023
DOI: 10.1155/2023/9958884
Publisher: Cold Spring Harbor Laboratory
Date: 08-01-2021
DOI: 10.1101/2021.01.06.425653
Abstract: There is evidence to suggest a disruption of gamma-aminobutyric acid (GABA) in autism spectrum disorder (ASD), but findings are mixed. Concurrent electroencephalography and transcranial magnetic stimulation (TMS-EEG) provides a novel method by which to probe GABA-mediated cortical inhibition. With a particular focus on GABAB-ergic mechanisms, we investigated the N100 peak of the TMS evoked potential (TEP), as well as long interval cortical inhibition (LICI EEG ) in adults with ASD (n = 23 12 female) without intellectual disability, and a neurotypical comparison group (n =22 12 female) matched for age, sex, and IQ. Seventy-five single-(spTMS) and 75 paired-(ppTMS 100 ms inter-stimulus-interval) pulses were applied to the right primary motor cortex (M1), right temporoparietal junction (TPJ), and right dorsolateral prefrontal cortex (DLPFC) while EEG was recorded from 20 scalp electrodes. Additionally, electromyography (EMG) was used to investigate corticospinal inhibition following ppTMS to M1 (LICI EMG ). There were no group differences in the N100 litude or latency following spTMS. LICI outcomes following ppTMS, as measured by either EEG or EMG, also did not differ between groups. These findings were further supported by Bayesian analyses, which provided weak-moderate support for the null hypothesis. Data presented here reflect adults without intellectual disability, and the generalisability of these results is therefore limited. The findings of this study argue against GABAB-ergic impairment in adults with ASD without intellectual disability, at least at the cortical regions examined. Further research investigating these mechanisms in ASD at various ages, with varying degrees of symptomatology, and at different brain sites is an important factor in understating the role of GABA in the neuropathophysiology of ASD.
Publisher: Wiley
Date: 20-06-2022
DOI: 10.1111/PSYP.14121
Abstract: Understanding built environment exposure as a component of environmental enrichment has significant implications for mental health, but little is known about the effects design characteristics have on our emotions and associated neurophysiology. Using a Cave Automatic Virtual Environment while monitoring indoor environmental quality (IEQ), 18 participants were exposed to a resting state (black), and two room scenes, control (white) and condition (blue), to understand if the color of the virtual walls affected self‐report, autonomic nervous system, and central nervous system correlates of emotion. Our findings showed that exposure to the chromatic color condition (blue) compared to the achromatic control (white) and resting‐state (black, no built environment) significantly increased the range in respiration and skin conductance response. We also detected a significant increase in alpha frontal midline power and frontal hemispheric lateralization relative to blue condition, and increased power spectral density across all electrodes in the blue condition for theta, alpha, and beta bandwidths. The ability for built environment design to modulate emotional response has the potential to deliver significant public health, economic, and social benefits to the entire community. The findings show that blue coloring of the built environment increases autonomic range and is associated with modulations of brain activity linked to emotional processing.
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.BRS.2015.10.006
Abstract: Several studies have trialled anodal transcranial direct current stimulation (a-tDCS) for the enhancement of working memory (WM) in both healthy and neuropsychiatric populations. However, the efficacy of this technique remains to be clearly established. This review provides a quantitative synthesis of the published literature investigating the effects of a-tDCS, compared to sham, on WM, as assessed using the n-back, Sternberg and digit-span tasks. We also separated results from tasks performed 'online' (during stimulation) and 'offline' (following stimulation). The secondary aim was to assess for any additional effects of current density and stimulation duration. Comprehensive literature searches were performed using MEDLINE, Embase, PsychINFO, CENTRAL and Scopus from July 1998 to June 2014. In healthy cohorts, a-tDCS produced a trend towards improvement for offline WM accuracy (p = 0.05) and a small, but significant improvement in reaction time (p = 0.04) however, no significant effects were observed for online tasks (accuracy [p = 0.29], reaction time [p = 0.42]). In the neuropsychiatric cohort, a-tDCS significantly improved accuracy for online (p = 0.003), but not offline (p = 0.87) tasks, and no effect was seen for either online (p = 0.20) or offline (p = 0.49) reaction times. Secondary analyses controlling for current density and stimulation duration provided limited support for the role of these factors in influencing a-tDCS efficacy. This review provides some evidence of a beneficial effect of a-tDCS on WM performance. However, the small effect sizes obtained, coupled with non-significant effects on several analyses require cautious interpretation and highlight the need for future research aimed at investigating more optimised stimulation approaches.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.BRAINRES.2019.146506
Abstract: Cognitive impairment is a prevalent non-motor feature of Parkinson's disease (PD) which can present even in early stages of the disease. Impairments in executive processing and working memory (WM) are common and have been attributed, in part, to abnormalities within the dorsolateral prefrontal cortex (DLPFC) and broader fronto-striatal circuitry. Previous studies in cognitively normal adults have suggested intermittent Theta Burst Stimulation (iTBS), an excitatory plasticity-inducing non-invasive brain stimulation technique, can enhance these cognitive functions. Fourteen participants with a diagnosis of idiopathic PD received either Active or Sham iTBS over the left DLPFC across two separate experimental sessions as part of a double-blind sham-controlled crossover experimental design. The Berg's Card Sorting Test (BCST) and N-Back tasks, which measure executive function and WM respectively, were administered prior to iTBS and again five- and 30-minutes following stimulation. Despite being well-tolerated, iTBS failed to modulate performance on any of the cognitive outcome measures. This finding was further supported by Bayes Factor analyses which indicated moderate levels of support for the null hypothesis overall. This initial pilot study therefore does not support single-session iTBS as an efficacious method for modulating either executive processes or WM in PD. We discuss potential reasons for this finding along with directions for future research.
Publisher: Springer Science and Business Media LLC
Date: 18-05-2020
Publisher: Cold Spring Harbor Laboratory
Date: 22-09-2023
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.NEUBIOREV.2016.03.006
Abstract: Transcranial electrical stimulation (tES) techniques are able to induce changes in cortical excitability and plasticity through the administration of weak currents to the brain and are currently being used to manipulate a vast array of cognitive processes. Despite the widespread use of tES technologies within both research and remedial settings, their precise neurophysiological mechanisms of action are not well established outside of the motor cortex. The expanding use of tES within non-motor brain regions highlights the growing need for a more comprehensive understanding of the effects of stimulation across a ersity of cortical locations. The combination of transcranial magnetic stimulation with electroencephalography (TMS-EEG) provides a method of directly probing both local and widespread changes in brain neurophysiology, through the recording of TMS-evoked potentials and cortical oscillations. In this review we explore TMS-EEG as a tool for examining the impact of tES on cortical function and argue that multimodal approaches which combine tES with TMS-EEG could lead to a deeper understanding of the mechanisms which underlie tES-induced cognitive modulation.
Publisher: Springer Science and Business Media LLC
Date: 17-12-2020
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.NEUROIMAGE.2017.03.001
Abstract: Transcranial direct current stimulation (tDCS) is a well-recognised neuromodulatory technology which has been shown to induce short-lasting changes in motor-cortical excitability. The recent and rapid expansion of tDCS into the cognitive domain, however, necessitates deeper mechanistic understanding of its neurophysiological effects over non-motor brain regions. The present study utilised transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) to probe the immediate and longer-term effects of both a bipolar (BP-tDCS) and more focal 4×1 High-Definition tDCS (HD-tDCS) montage applied over the left DLPFC on TMS-evoked potentials (TEPs) and oscillations in 19 healthy adult participants. 2-back working memory (WM) performance was also assessed as a marker of cognitive function. Region of interest (ROI) analyses taken from the F1 electrode directly adjacent to the stimulation site revealed increased P60 TEP litudes at this location 5min following BP-tDCS and 30min following HD-tDCS. Further global cluster based analyses of all scalp electrodes revealed widespread neuromodulatory changes following HD-tDCS, but not BP-tDCS, both five and 30min after stimulation, with reductions also detected in both beta and gamma oscillatory power over parieto-occipital channels 30min after stimulation. No significant changes in WM performance were observed following either HD-tDCS or BP-tDCS. This study highlights the capacity for single-session prefrontal anodal tDCS montages to modulate neurophysiological processes, as assessed with TMS-EEG.
Publisher: Cold Spring Harbor Laboratory
Date: 20-10-2021
DOI: 10.1101/2021.10.19.464887
Abstract: The neurodevelopmental period spanning early-to-middle childhood represents a time of significant growth and reorganisation throughout the cortex. Such changes are critical for the emergence and maturation of a range of social and cognitive processes. Here, we utilised both eyes open and eyes closed resting-state electroencephalography (EEG) to examine maturational changes in both oscillatory (i.e., periodic) and non-oscillatory (aperiodic, ‘1/ f -like’) activity in a large cohort of participants ranging from 4-to-12 years of age (N=139, average age=9.41 years, SD=1.95). The EEG signal was parameterised into aperiodic and periodic components, and linear regression models were used to evaluate if chronological age could predict aperiodic exponent and offset, as well as well as peak frequency and power within the alpha and beta ranges. Exponent and offset were found to both decrease with age, while aperiodic-adjusted alpha peak frequency increased with age however, there was no association between age and peak frequency for the beta band. Age was also unrelated to aperiodic-adjusted spectral power within either the alpha or beta bands, despite both frequency ranges being correlated with the aperiodic signal. Overall, these results highlight the capacity for both periodic and aperiodic features of the EEG to elucidate age-related functional changes within the developing brain.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.JOCN.2014.11.025
Abstract: This article discusses three patients with likely Hirayama disease. They have no other significant past medical history and no personal or family history of other neurological disorders. Hirayama disease is a form of cervical myelopathy attributed to forward displacement of the posterior cervical dural sac on neck flexion with resultant cord compression and/or venous congestion. It is characterized by a pure motor focal amyotrophy in the distribution of C7, C8 and T1 spinal segmental-innervated muscles and differs from other motor neuron diseases by virtue of its ultimately non-progressive course.
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.CORTEX.2018.11.022
Abstract: Transcranial direct current stimulation (tDCS) provides a means of non-invasively inducing plasticity-related changes in neural circuits in vivo and is experiencing increasing use as a potential tool for modulating brain function. There is growing evidence that tDCS-related outcomes are likely to be influenced by an in idual's brain state at the time of stimulation, i.e., effects show a degree of 'state-dependency'. However, few studies have examined the behavioural and physiological impact of state-dependency within cognitively salient brain regions. Here, we applied High-Definition tDCS (HD-tDCS) over the left dorsolateral prefrontal cortex (DLPFC) in 20 healthy participants, whilst they either remained at rest, or performed a cognitive task engaging working memory (WM). In a third condition sham stimulation was administered during task performance. Neurophysiological changes were probed using TMS-evoked potentials (TEPs), event-related potentials (ERPs) recorded during n-back WM tasks, and via resting-state EEG (RS-EEG). From a physiological perspective, our results indicate a degree of neuromodulation following HD-tDCS, regardless of task engagement, as evidenced by changes in TEP litudes following both active stimulation conditions. Changes in ERP (P3) litudes were also observed for the 2-Back task following stimulation delivered during task performance only. However, no changes were seen on RS-EEG for any condition, nor were any group-level effects of either stimulation condition observed on n-back performance. As such, these findings paint a complex picture of neural and behavioural responses to prefrontal stimulation in healthy subjects and provide only limited support for state-dependent effects of HD-tDCS over the DLPFC overall.
Publisher: Wiley
Date: 02-09-2023
DOI: 10.1002/HBM.26061
Abstract: Understanding brain activity linked to built environment exposure is important, as it may affect underlying cognitive, perceptual, and emotional processes, which have a critical influence in our daily life. As our time spent inside buildings is rising, and mental health problems have become more prevalent, it is important we investigate how design characteristics of the built environment impact brain function. In this study, we utilized electroencephalography to understand whether the design elements of scale and color of interior built environments modulate functional brain connectivity (i.e., brain network communication). Using a Cave Automatic Virtual Environment, while controlling indoor environmental quality responsible for physiological comfort, healthy adult participants aged 18–55 years (66 for scale, subset of 18 for color), were exposed to context‐neutral indoor room scenes presented for two‐minutes each. Our results show that both enlarging and reducing scale enhanced theta connectivity across the left temporoparietal region and right frontal region. We also found when reducing the built environment scale, there was a network exhibiting greater high‐gamma connectivity, over the right frontoparietal region. For color, the condition (blue) contrasted to our achromatic control (white) increased theta connectivity in the frontal hemispheres. These findings identify a link between theta and gamma oscillations during exposure to the scale and color of the built environment, showing that design characteristics of the built environment could affect our cognitive processes and mental health. This suggests that, through the design of buildings, we may be able to mediate performance and health outcomes, which could lead to major health and economic benefits for society.
Publisher: SAGE Publications
Date: 26-09-2012
Abstract: To determine how accurately psychiatry and general medical doctors can differentiate epileptic and psychogenic non-epileptic seizures based on videotaped events (closest proxy to witnessed events). This study aims to establish how confidently this distinction can be made, the reasons why a particular diagnosis is reached, and inter-rater agreement. 18 videos of patients demonstrating a heterogeneous mixture of epileptic and psychogenic non-epileptic seizures were collected and ordered in a random mix. These videos were shown to groups of general physicians, medical registrars and residents ( n=19) as well as to psychiatrists and psychiatry registrars ( n=8) who were provided with a questionnaire. A total of 27 doctors participated in the study. The overall percentage of correct diagnoses was 55.4%. There were no significant differences in correct diagnosis rates between psychiatry and general medical doctors. There was poor inter-rater agreement (Kappa = 0.159). Neither group was particularly confident in reaching a diagnosis, and erse reasons underpinned the diagnoses given. Among the participants, merely observing an epileptic or non-epileptic event is insufficient to establish a definitive diagnosis. The results indicate poor diagnostic accuracy and agreement among psychiatry and general medical doctors. This may have important implications for both education and clinical practice.
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2022.108426
Abstract: We explored the utility of the Monetary Incentive Delay (MID) task with concurrent encephalography (EEG) as a marker of apathy in people with Huntington's disease (HD) as well as neurotypical controls. Specifically, we assessed between and within-group differences in the litude of the P300 and Contingent Negative Variation (CNV) event-related potentials as a function of motivational salience. In contrast to neurotypical controls, HD participants' ERP litudes were not differentially modulated by motivationally salient cues (i.e., signalling potential 'gain' or 'loss') compared to 'neutral' cues. Difference waves isolating litude specific to the motivationally salient cues were calculated for the P300 and CNV. Only the difference waves for ERPs elicited by 'gain' cues differentiated the groups. The CNV difference wave was also significantly correlated with clinical measures of apathy and processing speed in the HD group. These findings provide initial support for the use of the MID with EEG as a marker of apathy in HD, and its potential as a sensitive outcome measure for novel treatment development.
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.JOCN.2012.12.025
Abstract: Primary orthostatic tremor (POT) is a rapid 13-18 Hertz tremor that produces a subjective feeling of unsteadiness when standing, and is absent when seated or supine. It predominantly affects the legs during isometric contraction though a similar tremor can be seen in the arms and jaw. When present in the jaw this rapid tremor has been successfully treated with botulinum toxin. We sought to test whether symptoms of POT improved following injection of abobotulinumtoxinA to muscles in the legs. This randomised, double blind, placebo controlled cross-over design study enrolled eight patients with electrophysiologically confirmed POT. Each patient received injections of either 200 mU abobotulinumtoxinA or 0.9% saline in the tibialis anterior bilaterally, with cross-over after 20 weeks. Electrophysiological and clinical assessments were performed before and 6 weeks after each injection. Seven patients completed the study. No significant differences were seen in the primary outcome measures of time from standing to unsteadiness or symptom diary scores. Electrophysiological characteristics of POT remained remarkably constant throughout the study in all patients with variability of less than 1 Hertz in the frequency recorded. Falls were common, with one patient experiencing a fall with upper limb fracture whilst on the placebo. The frequency of falls correlated with both the severity of the self-rated symptoms and a shorter time to feeling unsteady with eyes closed. In conclusion, treatment with 200 mU of abobotulinumtoxinA in the tibialis anterior does not alter subjective experience of unsteadiness in POT. Postural instability and falls are common.
Publisher: Society for Neuroscience
Date: 26-08-2022
DOI: 10.1523/ENEURO.0104-22.2022
Abstract: There is currently no robust method to evaluate how built environment design affects our emotion. Understanding emotion is significant, as it influences cognitive processes, behavior, and wellbeing, and is linked to the functioning of physiological systems. As mental health problems are becoming more prevalent, and exposure to indoor environments is increasing, it is important we develop rigorous methods to understand whether design elements in our environment affect emotion. This study examines whether the scale of interior built environments modulate neural networks involved in emotion regulation. Using a Cave Automatic Virtual Environment (CAVE) and controlling for indoor environmental quality (IEQ), 66 adults (31 female, aged 18–55) were exposed to context-neutral enclosed indoor room scenes to understand whether built environment scale affected self-report, autonomic nervous system, and central nervous system correlates of emotion. Our results revealed enlarged scale increased electroencephalography (EEG) power in the β bandwidth. Frontal midline low-γ and high-γ power were also found to increase with enlarged scale, but contrary to our hypothesis, scale did not modulate frontal midline power or lateralization in the θ or α bandwidths. We did not detect an effect of scale on autonomic indicators or self-reported emotion. However, we did find increased range in skin conductance response (SCR) and heart rate variability (HRV) to the built environment conditions. This study provides a rigorous empirical framework for assessing the environmental impact of a design characteristic on human emotion and suggests that measures of high-frequency oscillations may provide a useful marker of the response to built environment.
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.BRS.2018.06.005
Abstract: Previous research has typically focussed on the neuromodulatory effects of direct currents applied over single regions of the cortex. However, complex processes such as working memory (WM) strongly rely on activations across a wider neural network and therefore might benefit from stimulation administered over multiple cortical targets. We examined the neurobiological and cognitive effects of High-Definition transcranial direct current stimulation (HD-tDCS) montages that either targeted the dorsolateral prefrontal cortex (DLPFC) alone, or simultaneously stimulated the DLPFC and parietal cortex (DLPFC + PC). In a within-subjects design, 16 healthy participants completed three experimental sessions in which they received HD-tDCS over either the DLPFC, the DLPFC + PC or sham stimulation. Changes in cortical reactivity were examined using transcranial magnetic stimulation combined with electroencephalography (TMS-EEG), while oscillatory power was measured via EEG recorded during n-back tasks. WM performance was also examined across several separate tasks. Stimulation using both the DLPFC or DLPFC + PC montages modulated cortical reactivity, as indexed by potentiation of the P60 TMS-evoked potential. However, only the dual-site DLPFC + PC stimulation produced a reduction in the litude of the N100 component, relative to baseline. Increases in theta and gamma power were also observed following this montage, when compared to baseline, but were not present following HD-tDCS over the DLPFC alone. Despite these neurophysiological changes, WM performance was not significantly modulated by HD-tDCS, regardless of stimulation montage. These results provide important initial insight into the behavioural and biological effects of stimulation over key cortical regions linked to WM and attest to the sensitivity of TMS-EEG and EEG in detecting subtle neurophysiological changes induced by HD-tDCS.
Publisher: Springer Science and Business Media LLC
Date: 2023
DOI: 10.1007/S12671-022-02052-W
Abstract: Mindfulness meditation is associated with better attention function. Performance monitoring and error-processing are important aspects of attention. We investigated whether experienced meditators showed different neural activity related to performance monitoring and error-processing. Previous research has produced inconsistent results. This study used more rigorous analyses and a larger s le to resolve the inconsistencies. We used electroencephalography (EEG) to measure the error-related negativity (ERN) and error positivity (Pe) following correct and incorrect responses to a Go/Nogo task from 27 experienced meditators and 27 non-meditators. No differences were found in the ERN (all p 0.05). Meditators showed larger global field potentials (GFP) in the Pe after correct responses and errors, indicating stronger neural responses ( p = 0.019, FDR-p = 0.152, np 2 = 0.095, BFincl = 2.691). This effect did not pass multiple comparison controls. However, single-electrode analysis of the Pe did pass multiple comparison controls ( p = 0.002, FDR-p = 0.016, np 2 = 0.133, BFincl = 220.659). Meditators also showed a significantly larger Pe GFP for errors, which would have passed multiple comparison controls, but was not a primary analysis ( p = 0.003, np 2 = 0.149, BF10 = 9.999). Meditation may strengthen neural responses related to performance monitoring. However, these strengthened neural responses were not specific to error monitoring (although the error-related Pe may be more sensitive to group differences than the correct response Pe). These conclusions remain tentative, because the single-electrode analysis passed multiple comparison controls, but the analysis including all electrodes did not. This study was not preregistered.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Cold Spring Harbor Laboratory
Date: 30-03-2022
DOI: 10.1101/2022.03.26.485953
Abstract: Growing evidence supports functional network alterations in autism spectrum disorder, however much less is known about the neural mechanisms underlying autistic traits in typically developing children. Using resting-state electroencephalographic (EEG) recordings, we examined whether functional connectivity could predict autistic trait expression in 127 children aged between 4-12 years. Regression models showed that right anterior theta connectivity was a significant predictor of autistic traits (p = 0.013), with increased connectivity in this region associated with greater autistic trait expression. These results corroborate similar recent findings in adults, extending this observation to a cohort of children spanning early-to-middle childhood. These findings further highlight EEG-derived functional connectivity as a sensitive physiological correlate of autistic trait expression in neurotypical children.
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 07-2023
Publisher: Wiley
Date: 10-09-2022
DOI: 10.1111/PSYP.14179
Abstract: Implicit sequence learning describes the acquisition of serially ordered movements and sequentially structured cognitive information, that occurs without awareness. Theta, alpha and beta cortical oscillations are present during implicit motor sequence learning, but their role in this process is unclear. The current study addressed this gap in the literature. A total of 50 healthy adults aged between 19 and 37 years participated in the study. Implicit motor sequence learning was examined using the Serial Reaction Time task where participants unknowingly repeat a sequence of finger movements in response to a visual stimulus. Sequence learning was examined by comparing reaction times and oscillatory power between sequence trials and a set of control trials comprising random stimulus presentations. Electroencephalography was recorded as participants completed the task. Analyses of the behavioral data revealed participants learnt the sequence. Analyses of oscillatory activity, using permutation testing, revealed sequence learning was associated with a decrease in theta band (4–7 Hz) power recorded over frontal and central electrode sites. Sequence learning effects were not observed in the alpha (7–12 Hz) or beta bands (12–20 Hz). Even though alpha and beta power modulations have long been associated with executing a motor response, it seems theta power is a correlate of sequence learning in the manual domain. Theta power modulations on the serial reaction time task may reflect disengagement of attentional resources, either promoting or occurring as a consequence of implicit motor sequence learning
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 08-2021
Publisher: Cold Spring Harbor Laboratory
Date: 12-01-2023
DOI: 10.1101/2023.01.11.23284450
Abstract: Major depressive disorder (MDD) is a leading cause of disability worldwide. One of the most efficacious treatments for treatment-resistant MDD is electroconvulsive therapy (ECT). Recently, magnetic seizure therapy (MST) was developed as an alternative to ECT due to its more favorable side effect profile. While these approaches have been very successful clinically, the neural mechanisms underlying their therapeutic effects are unknown. For ex le, clinical “slowing” of the electroencephalogram has been observed in both treatment modalities. A recent longitudinal study of a small cohort of ECT patients revealed that observed clinical slowing was better explained by increases in frontal aperiodic activity, an emerging EEG signal linked to neural inhibition. Here we investigate the role of aperiodic activity in a cohort of patients who received ECT and a cohort of patients who received MST treatment. We find that across treatments, frontal aperiodic activity better explains increases in delta band power associated with clinical slowing, compared to delta oscillations. Increased aperiodic activity is also linked to therapeutic efficacy, which is suggestive of a potential shared neural mechanism of action across ECT and MST: an increase in frontal inhibitory activity.
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.BIOPSYCHO.2022.108448
Abstract: Growing evidence supports functional network alterations in autism spectrum disorder, however much less is known about the neural mechanisms underlying autistic traits in typically developing children. Using resting-state electroencephalographic (EEG) recordings, we examined whether functional connectivity could predict autistic trait expression in 127 children aged between 4 and 12 years. Regression models showed that right anterior theta connectivity was a significant predictor of autistic traits (p = 0.013), with increased connectivity in this region associated with greater autistic trait expression. These results corroborate similar recent findings in adults, extending this observation to a cohort of children spanning early-to-middle childhood. These findings further highlight EEG-derived functional connectivity as a sensitive physiological correlate of autistic trait expression in typically developing children.
Publisher: American Physiological Society
Date: 05-2021
Abstract: Combined single-pulse transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been used to probe the features of local networks in the cerebral cortex. Here, we investigated whether we can use this approach to explore long-range connections between the cerebellum and cerebral cortex. Ten healthy adults received single-pulse suprathreshold TMS to the cerebellum and an occipital arietal control site with double-cone and figure-of-eight coils while cerebral activity was recorded. A multisensory electrical control condition was used to simulate the sensation of the double-cone coil at the cerebellar site. Two cleaning pipelines were compared, and the spatiotemporal relationships of the EEG output between conditions were examined at sensor and source levels. Cerebellar stimulation with the double-cone coil resulted in large artifact in the EEG trace. The addition of SOUND filtering to the cleaning pipeline improved the signal such that further analyses could be undertaken. The cortical potentials evoked by the active TMS conditions showed strong relationships with the responses to the multisensory control condition after ∼50 ms. A distinct parietal component at ∼42 ms was found following cerebellar double-cone stimulation. Although evoked potentials differed across all conditions at early latencies, it is unclear as to whether these represented TMS-related network activation of the cerebellarthalamocortical tract, or whether components were dominated by sensory contamination and/or coil-driven artifact. This study highlights the need for caution when interpreting outcomes from cerebellar TMS-EEG studies.
Publisher: Elsevier BV
Date: 06-2021
DOI: 10.1016/J.PNPBP.2020.110082
Abstract: Magnetic seizure therapy (MST) is emerging as a safe and well-tolerated experimental intervention for major depressive disorder (MDD), with very minimal cognitive side-effects. However, the underlying mechanism of action of MST remains uncertain. Here, we used resting-state electroencephalography (RS-EEG) to characterise the physiological effects of MST for treatment resistant MDD. We recorded RS-EEG in 21 patients before and after an open label trial of MST applied over the prefrontal cortex using a bilateral twin coil. RS-EEG was analysed for changes in functional connectivity, network topology, and spectral power. We also ran further baseline comparisons between the MDD patients and a cohort of healthy controls (n = 22). Network-based connectivity analysis revealed a functional subnetwork of significantly increased theta connectivity spanning frontal and parieto-occipital channels following MST. The change in theta connectivity was further found to predict clinical response to treatment. An additional widespread subnetwork of reduced beta connectivity was also elucidated. Graph-based topological analyses showed an increase in functional network segregation and reduction in integration in the theta band, with a decline in segregation in the beta band. Finally, delta and theta power were significantly elevated following treatment, while gamma power declined. No baseline differences between MDD patients and healthy subjects were observed. These results highlight widespread changes in resting-state brain dynamics following a course of MST in MDD patients, with changes in theta connectivity providing a potential physiological marker of treatment response. Future prospective studies are required to confirm these initial findings.
Publisher: Mary Ann Liebert Inc
Date: 11-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2014
No related grants have been discovered for Aron Hill.