ORCID Profile
0000-0002-3863-6675
Current Organisation
Macquarie University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Cognitive Science | Neurocognitive Patterns and Neural Networks | Biological psychology | Sensory systems | Sensory Systems | Neurosciences | Artificial Intelligence and Image Processing | Cognitive neuroscience | Central Nervous System | Cognitive Science not elsewhere classified | Pattern Recognition and Data Mining | Database Management | Linguistic Processes (incl. Speech Production and Comprehension) | Biomedical imaging
ANZSRC Socio-Economic Objective (SEO)
Hearing, Vision, Speech and Their Disorders | Information Processing Services (incl. Data Entry and Capture) | Nervous System and Disorders | Expanding Knowledge in the Information and Computing Sciences | Expanding Knowledge in Psychology and Cognitive Sciences | Expanding Knowledge in Technology |
Related Links
Publications
Stop signals delay synchrony more for finger tapping than vocalization: a dual modality study of rhythmic synchronization in the stop signal task
Publisher: PeerJ
Date: 12-07-2018
DOI: 10.7717/PEERJ.5242
Abstract: A robust feature of sensorimotor synchronization (SMS) performance in finger tapping to an auditory pacing signal is the negative asynchrony of the tap with respect to the pacing signal. The Paillard–Fraisse hypothesis suggests that negative asynchrony is a result of inter-modal integration, in which the brain compares sensory information across two modalities (auditory and tactile). The current study compared the asynchronies of vocalizations and finger tapping in time to an auditory pacing signal. Our first hypothesis was that vocalizations have less negative asynchrony compared to finger tapping due to the requirement for sensory integration within only a single (auditory) modality (intra-modal integration). However, due to the different measurements for vocalizations and finger responses, interpreting the comparison between these two response modalities is problematic. To address this problem, we included stop signals in the synchronization task. The rationale for this manipulation was that stop signals would perturb synchronization more in the inter-modal compared to the intra-modal task. We hypothesized that the inclusion of stop signals induce proactive inhibition, which reduces negative asynchrony. We further hypothesized that any reduction in negative asynchrony occurs to a lesser degree for vocalization than for finger tapping. A total of 30 participants took part in this study. We compared SMS in a single sensory modality (vocalizations (or auditory) to auditory pacing signal) to a dual sensory modality (fingers (or tactile) to auditory pacing signal). The task was combined with a stop signal task in which stop signals were relevant in some blocks and irrelevant in others. Response-to-pacing signal asynchronies and stop signal reaction times were compared across modalities and across the two types of stop signal blocks. In the blocks where stopping was irrelevant, we found that vocalization (−61.47 ms) was more synchronous with the auditory pacing signal compared to finger tapping (−128.29 ms). In the blocks where stopping was relevant, stop signals induced proactive inhibition, shifting the response times later. However, proactive inhibition (26.11 ms) was less evident for vocalizations compared to finger tapping (58.06 ms). These results support the interpretation that relatively large negative asynchrony in finger tapping is a consequence of inter-modal integration, whereas smaller asynchrony is associated with intra-modal integration. This study also supports the interpretation that intra-modal integration is more sensitive to synchronization discrepancies compared to inter-modal integration.
Investigating predictive coding in younger and older children using MEG and a multi-feature auditory oddball paradigm
Publisher: Oxford University Press (OUP)
Date: 16-03-2023
Abstract: There is mounting evidence for predictive coding theory from computational, neuroimaging, and psychological research. However, there remains a lack of research exploring how predictive brain function develops across childhood. To address this gap, we used pediatric magnetoencephalography to record the evoked magnetic fields of 18 younger children (M = 4.1 years) and 19 older children (M = 6.2 years) as they listened to a 12-min auditory oddball paradigm. For each child, we computed a mismatch field “MMF”: an electrophysiological component that is widely interpreted as a neural signature of predictive coding. At the sensor level, the older children showed significantly larger MMF litudes relative to the younger children. At the source level, the older children showed a significantly larger MMF litude in the right inferior frontal gyrus relative to the younger children, P & 0.05. No differences were found in 2 other key regions (right primary auditory cortex and right superior temporal gyrus) thought to be involved in mismatch generation. These findings support the idea that predictive brain function develops during childhood, with increasing involvement of the frontal cortex in response to prediction errors. These findings contribute to a deeper understanding of the brain function underpinning child cognitive development.
Investigating Predictive Coding in Younger and Older Children Using MEG and a Multi-Feature Auditory Oddball Paradigm
Publisher: Cold Spring Harbor Laboratory
Date: 28-07-2022
DOI: 10.1101/2022.07.26.501632
Abstract: There is mounting evidence for predictive coding theory from computational, neuroimaging, and psychological research. However there remains a lack of research exploring how predictive brain function develops across childhood. To address this gap, we used paediatric magnetoencephalography (MEG) to record the evoked magnetic fields of 18 younger children ( M = 4.1 years) and 19 older children ( M = 6.2 years) as they listened to a 12-minute auditory oddball paradigm. For each child, we computed a mismatch field ‘MMF’: an electrophysiological component that is widely interpreted as a neural signature of predictive coding. Consistent with our hypotheses, the older children showed significantly larger MMF litudes relative to the younger children. Furthermore, the older children showed a significantly larger MMF litude in the right inferior frontal gyrus (IFG 0.312 to 0.33 s) relative to the younger children, p .05. These findings support the idea that predictive brain function develops during childhood, with increasing involvement of the frontal cortex in response to prediction errors. These findings contribute to a deeper understanding of the brain function underpinning child cognitive development. This is the first paediatric MEG study to examine the sources underlying the MMF. Older children showed larger MMF litudes in the right inferior frontal gyrus. Results support the idea that predictive brain function develops during childhood.
Lateralization of brain activation in fluent and non-fluent preschool children
Publisher: Frontiers Media SA
Date: 28-05-2014
Event-related fields evoked by vocal response inhibition
Publisher: Springer Science and Business Media LLC
Date: 28-01-2016
DOI: 10.1007/S00221-016-4555-2
Abstract: The current study examined event-related fields (ERFs) evoked by vocal response inhibition in a stimulus-selective stop-signal task. We compared inhibition-related ERFs across a younger and an older group of adults. Behavioural results revealed that stop-signal reaction times (RTs), go-RTs, ignore-stop RTs and failed stop RTs were longer in the older, relative to the younger group by 38, 123, 149 and 116 ms, respectively. The litude of the ERF M2 peak (approximately 200 ms after the stop signal) evoked on successful stop trials was larger compared to that evoked on both failed stop and ignore-stop trials. The M4 peak (approximately 450 ms after stop signal) was of larger litude in both successful and failed stops compared to ignore-stop trials. In the older group, the M2, M3 and M4 peaks were smaller in litude and peaked later in time (by 24, 50 and 76 ms, respectively). We demonstrate that vocal response inhibition-related ERFs exhibit a similar temporal evolution to those previously described for manual response inhibition: an early peak at 200 ms (i.e. M2) that differentiates successful from failed stopping, and a later peak (i.e. M4) that is consistent with a neural marker of response checking and error processing. Across groups, our data support a more general decline of stimulus processing speed with age.
Associative learning of response inhibition affects perceived duration in a subsequent temporal bisection task
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.ACTPSY.2019.102952
Abstract: Interval timing, the ability to discern the duration of an event, is integral to appropriately navigating the world, from crossing the road to catching a ball. Several features of an event can affect its perceived duration, for ex le it has previously been shown that a large stimulus is perceived to last longer than a small stimulus. In the current article, participants performed either a Go/No-Go or variable foreperiod task prior to performing a temporal bisection task. In both the Go/No-Go and variable foreperiod tasks, participants learned an association between a particular response and a particular stimulus. Subsequently, the perceived duration of these stimuli was tested in a temporal bisection task. Our findings indicated that associating a stimulus with response inhibition (i.e. a No-Go stimulus) decreased perceived duration compared to a stimulus associated with a response (a Go stimulus). Associating a stimulus with either a short or long foreperiod, on the other hand, did not affect perceived duration. We relate this finding back to the coding efficiency theory and the processing principle. A No-Go stimulus requires more cognitive processing than a Go stimulus and would thus be predicted to increase, rather than decrease, perceived duration in both these time perception theories. Finally, we suggest how our findings might be used in future investigations of interval timing.
Diffuse noxious inhibitory control evoked by tonic craniofacial pain in humans
Publisher: Wiley
Date: 02-2011
DOI: 10.1016/J.EJPAIN.2010.06.009
Abstract: Tonic pain in one body segment can inhibit the perception of pain in another body segment. This phenomenon is mediated by diffuse noxious inhibitory controls (DNIC), and its efficacy in craniofacial regions is investigated in this study. A compressive device that evoked a tonic, moderate/severe, headache-like, conditioning pain (∼8/10 on a visual analogue scale) was applied for 15min. Eleven males participated in the study. Pressure pain threshold (PPT) and pressure pain tolerance (PPTol) at multiple heterosegmental body sites (right masseter, splenius capitis, second intermediate phalange, brachioradialis and tibialis anterior) were measured before, during and at multiple time points (5, 20 and 35min) after the termination of the conditioning pain. PPTs and PPTols were compared within participants across two experimental sessions one that included painful conditioning stimulation, and a separate control session on a different day. Painful conditioning increased PPT significantly during pain over the masseter (p<0.05) and over the tibialis anterior (p<0.01). PPTol was unchanged. In the period after the painful conditioning stimulation PPT was depressed compared to control. This study shows that pain evoked from the craniofacial region evokes DNIC-like mechanisms on segmental as well as heterosegmental sites.
Interlimb generalization of learned bayesian visuomotor prior occurs in extrinsic coordinates
Publisher: Society for Neuroscience
Date: 07-2018
DOI: 10.1523/ENEURO.0183-18.2018
Abstract: Recent work suggests that the brain represents probability distributions and performs Bayesian integration during sensorimotor learning. However, our understanding of the neural representation of this learning remains limited. To begin to address this, we performed two experiments. In the first experiment, we replicated the key behavioral findings of Körding and Wolpert (2004), demonstrating that humans can perform in a Bayes-optimal manner by combining information about their own sensory uncertainty and a statistical distribution of lateral shifts encountered in a visuomotor adaptation task. In the second experiment, we extended these findings by testing whether visuomotor learning occurring during the same task generalizes from one limb to the other, and relatedly, whether this learning is represented in an extrinsic or intrinsic reference frame. We found that the learned mean of the distribution of visuomotor shifts generalizes to the opposite limb only when the perturbation is congruent in extrinsic coordinates, indicating that the underlying representation of learning acquired during training is available to the untrained limb and is coded in an extrinsic reference frame.
Reduced activation of left orbitofrontal cortex precedes blocked vocalization
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.JFLUDIS.2012.05.001
Abstract: While stuttering is known to be characterized by anomalous brain activations during speech, very little data is available describing brain activations during stuttering. To our knowledge there are no reports describing brain activations that precede blocking. In this case report we present magnetoencephalographic data from a person who stutters who had significant instances of blocking whilst performing a vowel production task. This unique data set has allowed us to compare the brain activations leading up to a block with those leading up to successful production. Surprisingly, the results are very consistent with data comparing fluent production in stutterers to controls. We show here that preceding a block there is significantly less activation of the left orbitofrontal and inferiorfrontal cortices. Furthermore, there is significant extra activation in the right orbitofrontal and inferiorfrontal cortices, and the sensorimotor and auditory areas bilaterally. This data adds weight to the argument forwarded by Kell et al. (2009) that the best functional sign of optimal repair in stutterering is activation of the left BA 47/12 in the orbitofrontal cortex. At the end of this activity the reader will be able to (a) identify brain regions associated with blocked vocalization, (b) discuss the functions of the orbitofrontal and inferior frontal cortices in regard to speech production and (c) describe the usefulness and limitations of magnetoencephalography (MEG) in stuttering research.
Topological segregation of functional networks increases in developing brains
Publisher: Cold Spring Harbor Laboratory
Date: 27-07-2018
DOI: 10.1101/378562
Abstract: A growing literature conceptualises human brain development from a network perspective, but it remains unknown how functional brain networks are refined during the preschool years. The extant literature erges in its characterisation of functional network development, with little agreement between haemodynamic- and electrophysiology-based measures. In children aged from 4 to 12 years, as well as adults, age appropriate magnetoencephalography was used to estimate unbiased network topology, using minimum spanning tree (MST) constructed from phase synchrony between beamformer-reconstructed time-series. During childhood, network topology becomes increasingly segregated, while cortical regions decrease in centrality. We propose a heuristic MST model, in which a clear developmental trajectory for the emergence of complex brain networks is delineated. Our results resolve topological reorganisation of functional networks across temporal and special scales in youth and fill a gap in the literature regarding neurophysiological mechanisms of functional brain maturation during the preschool years.
A Guided Tutorial on Modelling Human Event-Related Potentials with Recurrent Neural Networks
Publisher: MDPI AG
Date: 28-11-2022
DOI: 10.3390/S22239243
Abstract: In cognitive neuroscience research, computational models of event-related potentials (ERP) can provide a means of developing explanatory hypotheses for the observed waveforms. However, researchers trained in cognitive neurosciences may face technical challenges in implementing these models. This paper provides a tutorial on developing recurrent neural network (RNN) models of ERP waveforms in order to facilitate broader use of computational models in ERP research. To exemplify the RNN model usage, the P3 component evoked by target and non-target visual events, measured at channel Pz, is examined. Input representations of experimental events and corresponding ERP labels are used to optimize the RNN in a supervised learning paradigm. Linking one input representation with multiple ERP waveform labels, then optimizing the RNN to minimize mean-squared-error loss, causes the RNN output to approximate the grand-average ERP waveform. Behavior of the RNN can then be evaluated as a model of the computational principles underlying ERP generation. Aside from fitting such a model, the current tutorial will also demonstrate how to classify hidden units of the RNN by their temporal responses and characterize them using principal component analysis. Statistical hypothesis testing can also be applied to these data. This paper focuses on presenting the modelling approach and subsequent analysis of model outputs in a how-to format, using publicly available data and shared code. While relatively less emphasis is placed on specific interpretations of P3 response generation, the results initiate some interesting discussion points.
Investigation of an unusual, high-frequency jaw tremor with coherence analysis
Publisher: Wiley
Date: 07-12-2008
DOI: 10.1002/MDS.21863
Abstract: Normal physiological tremor of the jaw has a frequency of 6 to 8 Hz. A patient is described with jaw tremor at frequencies of 12 Hz during jaw movement and 15 Hz when the jaw was relaxed. The 15 Hz tremor was driven by synchronous, bilateral bursts of activity in the temporalis and masseter muscles, which alternated with digastric bursts. Coherence analysis indicated the tremor was highly correlated with both opening and closing muscle activity, and that the opening and closing muscles were about 180 degrees out of phase. The existence of two tremors with different, nonphysiological peak frequencies and the influence of attention, relaxation, and movement in switching from one tremor frequency to the other, suggest that more than one generator may be operating.
A systematic literature review of neuroimaging research on developmental stuttering between 1995 and 2016
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.JFLUDIS.2017.03.007
Abstract: Stuttering is a disorder that affects millions of people all over the world. Over the past two decades, there has been a great deal of interest in investigating the neural basis of the disorder. This systematic literature review is intended to provide a comprehensive summary of the neuroimaging literature on developmental stuttering. It is a resource for researchers to quickly and easily identify relevant studies for their areas of interest and enable them to determine the most appropriate methodology to utilize in their work. The review also highlights gaps in the literature in terms of methodology and areas of research. We conducted a systematic literature review on neuroimaging studies on developmental stuttering according to the PRISMA guidelines. We searched for articles in the pubmed database containing "stuttering" OR "stammering" AND either "MRI", "PET", "EEG", "MEG", "TMS"or "brain" that were published between 1995/01/01 and 2016/01/01. The search returned a total of 359 items with an additional 26 identified from a manual search. Of these, there were a total of 111 full text articles that met criteria for inclusion in the systematic literature review. We also discuss neuroimaging studies on developmental stuttering published throughout 2016. The discussion of the results is organized first by methodology and second by population (i.e., adults or children) and includes tables that contain all items returned by the search. There are widespread abnormalities in the structural architecture and functional organization of the brains of adults and children who stutter. These are evident not only in speech tasks, but also non-speech tasks. Future research should make greater use of functional neuroimaging and noninvasive brain stimulation, and employ structural methodologies that have greater sensitivity. Newly planned studies should also investigate sex differences, focus on augmenting treatment, examine moments of dysfluency and longitudinally or cross-sectionally investigate developmental trajectories in stuttering.
Performance of bimanual finger coordination tasks in speakers who stutter
Publisher: Frontiers Media SA
Date: 23-09-2021
DOI: 10.3389/FPSYG.2021.679607
Abstract: Stuttering is a neurodevelopmental speech disorder characterized by the symptoms of speech repetition, prolongation, and blocking. Stuttering-related dysfluency can be transiently alleviated by providing an external timing signal such as a metronome or the voice of another person. Therefore, the existence of a core motor timing deficit in stuttering has been speculated. If this is the case, then motoric behaviors other than speech should be disrupted in stuttering. This study examined motoric performance on four complex bimanual tasks in 37 adults who stutter and 31 fluent controls. Two tasks utilized bimanual rotation to examine motor dexterity, and two tasks used the bimanual mirror and parallel tapping movements to examine timing control ability. Video-based analyses were conducted to determine performance accuracy and speed. The results showed that in iduals who stutter performed worse than fluent speakers on tapping tasks but not on bimanual rotation tasks. These results suggest stuttering is associated with timing control for general motor behavior.
Association between magnetoencephalographic interictal epileptiform discharge and cognitive function in young children with typical development and with autism spectrum disorders
Publisher: Frontiers Media SA
Date: 19-11-2018
Co-Increasing Neuronal Noise and Beta Power in the Developing Brain
Publisher: Cold Spring Harbor Laboratory
Date: 12-11-2019
DOI: 10.1101/839258
Abstract: Accumulating evidence across species indicates that brain oscillations are superimposed upon an aperiodic 1/ f - like power spectrum. Maturational changes in neuronal oscillations have not been assessed in tandem with this underlying aperiodic spectrum. The current study uncovers co-maturation of the aperiodic component alongside the periodic components (oscillations) in spontaneous magnetoencephalography (MEG) data. Beamformer-reconstructed MEG time-series allowed a direct comparison of power in the source domain between 24 children (8.0 ± 2.5 years, 17 males) and 24 adults (40.6 ± 17.4 years, 16 males). Our results suggest that the redistribution of oscillatory power from lower to higher frequencies that is observed in childhood does not hold once the age-related changes in the aperiodic signal are controlled for. When estimating both the periodic and aperiodic components, we found that power increases with age in the beta band only, and that the 1/ f signal is flattened in adults compared to children. These results suggest a pattern of co-maturing beta oscillatory power with the aperiodic 1/ f signal in typical childhood development.
Beta oscillations, timing, and stuttering
Publisher: Frontiers Media SA
Date: 05-01-2015
Rates of false positive outcomes on the A-WPTAS picture items in a sample of non-concussed athletes
Publisher: Informa UK Limited
Date: 10-05-2021
Reduced Auditory Steady State Responses in Autism Spectrum Disorder
Publisher: Cold Spring Harbor Laboratory
Date: 11-11-2019
DOI: 10.1101/837633
Abstract: Auditory steady state responses (ASSRs) are elicited by clicktrains or litude-modulated tones, which entrain auditory cortex at their specific modulation rate. Previous research has reported reductions in ASSRs at 40Hz for autism spectrum disorder (ASD) participants and first-degree relatives of people diagnosed with ASD [1,2]. Using a 1.5s-long auditory clicktrain stimulus, designed to elicit an ASSR at 40Hz, this study attempted to replicate and extend these findings. Magnetencephalography (MEG) data were collected from 18 adolescent ASD participants and 18 typically developing controls. The ASSR localised to bilateral primary auditory regions. Regions of interest were thus defined in left and right primary auditory cortex (A1). While the transient gamma-band response (tGBR) from 0-0.1s following presentation of the clicktrain stimulus was not different between groups, for either left or right A1, the ASD group had reduced oscillatory power at 40Hz from 0.5 to 1.5s post-stimulus onset, for both left and right A1. Additionally, the ASD group had reduced inter-trial coherence (phase consistency over trials) at 40Hz from 0.64-0.82s for right A1 and 1.04-1.22s for left A1. In this study, we did not conduct a clinical autism assessment (e.g. the ADOS), and therefore it remains unclear whether ASSR power and/or ITC are associated with the clinical symptoms of ASD. Overall, our results support a specific reduction in ASSR oscillatory power and inter-trial coherence in ASD, rather than a generalised deficit in gamma-band responses. We argue that this could reflect a developmentally relevant reduction in non-linear neural processing.
Periodontal anaesthetisation decreases rhythmic synchrony between masseteric motor units at the frequency of jaw tremor
Publisher: Springer Science and Business Media LLC
Date: 07-190728635
DOI: 10.1007/S00221-006-0824-9
Abstract: This study links the reduction in jaw physiological tremor around 8 Hz following periodontal mechanoreceptor (PMR) anaesthetisation to changes in coherence between masseteric motor unit discharges. We have recorded single motor unit activity from two separate sites in the right masseter muscle during a low level tonic contraction, both prior to and during anaesthetisation of the peri-incisal PMRs. Anaesthetisation of PMRs decreased coherent activity between motor units circa 8 Hz, and decreased synchrony between the same motor unit pairs. It is proposed that tremor-generating inputs that cause rhythmic synchronisation of masseteric motor units arise from, or are lified by the PMRs.
Neural correlates of encoding in novel word learning
Publisher: Center for Open Science
Date: 26-04-2022
Abstract: A central observation in the recognition memory literature is that neural processes occurring during encoding of stimuli are predictive of their later recognition. Compared to items that are later forgotten, encoding of correctly recognised items has been associated with greater litude between 400 ms and 800 ms post stimulus onset across centro-parietal sites (the difference-due-to-memory ERP effect), increased EEG power in the theta and gamma frequency bands and decreased EEG power in the alpha and beta bands, and increased theta-gamma phase- litude coupling. Importantly, theories of encoding based on these findings imply that these effects should be domain-general. In this pre-registered study, we tested this assumption by exploring neural correlates of successful encoding in learning of novel names for novel concepts. Following the previous studies, we used three different measures of neural activity, ERPs, time-frequency representations of power, and phase- litude coupling however, for either of these measures, we could not reject the null hypothesis of no difference between the novel names that were later recalled and those that were not. We provide three possible interpretations of our findings, and our main conclusion is that the existing theories of encoding may be underspecified and that properly-powered pre-registered studies are needed to further constrain these theories.
Self-initiation and temporal cueing of monaural tones reduce the auditory N1 and P2
Publisher: Springer Science and Business Media LLC
Date: 11-08-2012
DOI: 10.1007/S00221-012-3204-7
Abstract: Event-related potentials (ERPs) to tones that are self-initiated are reduced in their magnitude in comparison with ERPs to tones that are externally generated. This phenomenon has been taken as evidence for an efference copy of the motor command acting to suppress the sensory response. However, self-initiation provides a strong temporal cue for the stimulus which might also contribute to the ERP suppression for self-initiated tones. The current experiment sought to investigate the suppression of monaural tones by temporal cueing and also whether the addition of self-initiation enhanced this suppression. Lastly, the experiment sought to investigate the lateralisation of the ERP suppression via presenting these monaural tones to each ear respectively. We examined source waveforms extracted from the lateralised auditory cortices and measured the modulation of the N1 and P2 components by cueing and self-initiation. Self-initiation significantly reduced the litude of the N1 component. Temporal cueing without self-initiation significantly reduced the P2 component. There were no significant differences in the litude of either the N1 or the P2 between self-initiation and temporal cuing. There was a significant lateralisation effect on the N1—it being significantly larger contralateral to the ear of stimulation. There was no interaction between lateralisation and side of the temporal cue or side of self-initiation suggesting that the effects of self-initiation and temporal cuing are equal bilaterally. We conclude that a significant proportion of ERP suppression by self-initiation is a result of inherent temporal cueing.
Behavioral and multimodal neuroimaging evidence for a deficit in brain timing networks in stuttering: a hypothesis and theory
Publisher: Frontiers Media SA
Date: 25-06-2014
Reduced auditory steady state responses in autism spectrum disorder
Publisher: Springer Science and Business Media LLC
Date: 07-2020
DOI: 10.1186/S13229-020-00357-Y
Abstract: Auditory steady state responses (ASSRs) are elicited by clicktrains or litude-modulated tones, which entrain auditory cortex at their specific modulation rate. Previous research has reported reductions in ASSRs at 40 Hz for autism spectrum disorder (ASD) participants and first-degree relatives of people diagnosed with ASD (Mol Autism. 2011 :11, Biol Psychiatry. 2007 :192–197). Using a 1.5 s-long auditory clicktrain stimulus, designed to elicit an ASSR at 40 Hz, this study attempted to replicate and extend these findings. Magnetencephalography (MEG) data were collected from 18 adolescent ASD participants and 18 typically developing controls. The ASSR localised to bilateral primary auditory regions. Regions of interest were thus defined in left and right primary auditory cortex (A1). While the transient gamma-band response (tGBR) from 0-0.1 s following presentation of the clicktrain stimulus was not different between groups, for either left or right A1, the ASD group had reduced oscillatory power at 40 Hz from 0.5 to 1.5 s post-stimulus onset, for both left and right A1. Additionally, the ASD group had reduced inter-trial coherence (phase consistency over trials) at 40 Hz from 0.64-0.82 s for right A1 and 1.04-1.22 s for left A1. In this study, we did not conduct a clinical autism assessment (e.g. the ADOS), and therefore, it remains unclear whether ASSR power and/or ITC are associated with the clinical symptoms of ASD. Overall, our results support a specific reduction in ASSR oscillatory power and inter-trial coherence in ASD, rather than a generalised deficit in gamma-band responses. We argue that this could reflect a developmentally relevant reduction in non-linear neural processing.
Modulation of human exteroceptive jaw reflexes during simulated mastication
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.CLINPH.2008.11.016
Abstract: To investigate changes in synaptic input from lower lip afferents to human jaw muscle motoneurons during simulated mastication. The lower lip of 14 subjects was stimulated electrically under static and dynamic conditions. In the static condition, subjects bit at mid-open position and received stimuli while keeping the masseteric excitation level at 20%, 40%, 60%, 80%, or 100% of the maximum EMG (generated during simulated chewing). In the dynamic condition, the subjects 'masticated' at their habitual chewing pace, and stimuli were delivered whenever the jaw crossed a predetermined gape. In both conditions, mildly (scores of 2-3 on a 0-10 rating scale) and moderately (scores of 5-6) painful stimulus intensities were used. Under static conditions, there was no modulation of the inhibitory masseteric reflexes with the level of the background level of excitation used in these experiments. However, under dynamic conditions there were significant strength modulations with gape that differed between mildly and moderately painful stimuli. Reflexes in response to mildly painful stimuli were 'gated' during simulated mastication: as the teeth moved closer toward occlusion, the inhibitory response was progressively reduced. Conversely, responses to moderately painful stimuli became stronger as the teeth moved closer toward occlusion. The modulation described allows smooth mastication to occur as it gates out mildly painful signals while responding strongly when the signal indicates potential or actual damage closer to occlusion.
Comprehensive behavioural intervention for tics
Publisher: IMR Press
Date: 10-05-2022
Mandibular physiological tremor is reduced by increasing-force ramp contractions and periodontal anaesthesia
Publisher: Springer Science and Business Media LLC
Date: 08-08-2007
DOI: 10.1007/S00221-007-1083-0
Abstract: We have previously shown that the application of anaesthesia to periodontal mechanoreceptors (PMRs) dramatically reduces the 6-12 Hz physiological tremor (PT) in the human mandible during constant isometric contractions where visual feedback is provided. This current study shows that during a r contraction where force is slowly increased, the litude of mandibular PT is almost five times smaller on average than when the same force r is performed in reverse, i.e. force is slowly decreased. This smaller tremor is associated with a higher mean firing rate of motor units (MUs) as measured by the sub-30 Hz peak in the multi-unit power spectrum. The decrease in the litude of PT following PMR anaesthetisation is associated in some instances with a similar increase in the overall firing rate however this change does not match the diminution of tremor. The authors postulate that the decrease in mandibular PT during increasing force r s may be due to a change in the mean firing rate of the MUs. The change in tremor seen during PMR anaesthetisation may in part be due to a similar mechanism however other factors must also contribute to this.
Grey matter volume differences in the left caudate nucleus of people who stutter
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.BANDL.2016.08.009
Abstract: The cause of stuttering has many theoretical explanations. A number of research groups have suggested changes in the volume and/or function of the striatum as a causal agent. Two recent studies in children and one in adults who stutter (AWS) report differences in striatal volume compared that seen in controls however, the laterality and nature of this anatomical volume difference is not consistent across studies. The current study investigated whether a reduction in striatal grey matter volume, comparable to that seen in children who stutter (CWS), would be found in AWS. Such a finding would support claims that an anatomical striatal anomaly plays a causal role in stuttering. We used voxel-based morphometry to examine the structure of the striatum in a group of AWS and compared it to that in a group of matched adult control subjects. Results showed a statistically significant group difference for the left caudate nucleus, with smaller mean volume in the group of AWS. The caudate nucleus, one of three main structures within the striatum, is thought to be critical for the planning and modulation of movement sequencing. The difference in striatal volume found here aligns with theoretical accounts of stuttering, which suggest it is a motor control disorder that arises from deficient articulatory movement selection and sequencing. Whilst the current study provides further evidence of a striatal volume difference in stuttering at the group level compared to controls, the significant overlap between AWS and controls suggests this difference is unlikely to be diagnostic of stuttering.
Relationship between epileptiform discharges and social reciprocity or cognitive function in children with and without autism spectrum disorders: An MEG study
Publisher: Wiley
Date: 19-07-2020
DOI: 10.1111/PCN.13093
The Role of Transcranial Direct Current Stimulation (tDCS) in Tourette Syndrome: A Review and Preliminary Findings
Publisher: MDPI AG
Date: 08-12-2017
Asymmetric activation of motor cortex controlling human anterior digastric muscles during speech and target-directed jaw movements
Publisher: American Physiological Society
Date: 07-2009
Abstract: Like most of the cranial muscles involved in speech, the trigeminally innervated anterior digastric muscles are controlled by descending corticobulbar projections from the primary motor cortex (M1) of each hemisphere. We hypothesized that changes in corticobulbar M1 excitability during speech production would show a hemispheric asymmetry favoring the left side, which is the dominant hemisphere for language processing in most strongly right handed subjects. Fifteen volunteers aged 24.5 ± 5.3 (SD) yr participated. All subjects were strongly right handed as reported by questionnaire. A surface electromyograph (EMG) was recorded bilaterally from digastrics and jaw movement detected by an accelerometer attached to a lower incisor. Focal transcranial magnetic stimulation (TMS) was used to assess corticomotor excitability of the digastric representation in M1 of both hemispheres during four tasks: 1) static isometric contraction of digastrics 2) speaking a single word 3) visually guided, nonspeech jaw movement that matched the jaw kinematics recorded during task 2 and 4) reciting a sentence. Background EMG was well matched in all tasks and jaw kinematics were similar around the time of the TMS pulse for tasks 2–4. TMS resting thresholds and digastric muscle-evoked potential (MEP) size during isometric contraction did not differ for TMS over left versus right M1. MEPs elicited by TMS over left, but not right M1 increased in size during speech and nonspeech jaw movement compared with isometric contraction. We conclude that left corticobulbar M1 is preferentially engaged for descending control of digastric muscles during speech and the performance of a rapid jaw movement to match a target kinematic profile.
Adaptive Motor Imagery
Publisher: Oxford University Press (OUP)
Date: 04-12-2016
Abstract: The consequences of losing the ability to move a limb are traumatic. One approach that examines the impact of pathological limb nonuse on the brain involves temporary immobilization of a healthy limb. Here, we investigated immobilization-induced plasticity in the motor imagery (MI) circuitry during hand immobilization. We assessed these changes with a multimodal paradigm, using functional magnetic resonance imaging (fMRI) to measure neural activation, magnetoencephalography (MEG) to track neuronal oscillatory dynamics, and transcranial magnetic stimulation (TMS) to assess corticospinal excitability. fMRI results show a significant decrease in neural activation for MI of the constrained hand, localized to sensorimotor areas contralateral to the immobilized hand. MEG results show a significant decrease in beta desynchronization and faster resynchronization in sensorimotor areas contralateral to the immobilized hand. TMS results show a significant increase in resting motor threshold in motor cortex contralateral to the constrained hand, suggesting a decrease in corticospinal excitability in the projections to the constrained hand. These results demonstrate a direct and rapid effect of immobilization on MI processes of the constrained hand, suggesting that limb nonuse may not only affect motor execution, as evidenced by previous studies, but also MI. These findings have important implications for the effectiveness of therapeutic approaches that use MI as a rehabilitation tool to ameliorate the negative effects of limb nonuse.
Neuromagnetic brain activity associated with anticipatory postural adjustments for bimanual load lifting
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.NEUROIMAGE.2012.10.042
Abstract: During bimanual load lifting, the brain must anticipate the effects of unloading upon the load-bearing arm. Little is currently known about the neural networks that coordinate these anticipatory postural adjustments. We measured neuromagnetic brain activity with whole-head magnetoencephalography while participants performed a bimanual load-lifting task. Anticipatory adjustments were associated with reduction in biceps brachii muscle activity of the load-bearing arm and pre-movement desynchronization of the cortical beta rhythm. Beamforming analyses localized anticipatory brain activity to the precentral gyrus, basal ganglia, supplementary motor area, and thalamus, contralateral to the load-bearing arm. To our knowledge this is the first human neuroimaging study to directly investigate anticipatory postural adjustments and to explicitly partition the anticipatory and volitional aspects of brain activity in bimanual load lifting. These data contribute to our understanding of the neural systems supporting anticipatory postural adjustments in healthy adults.
The Magnetic Acoustic Change Complex and Mismatch Field: A Comparison of Neurophysiological Measures of Auditory Discrimination
Publisher: American Institute of Mathematical Sciences (AIMS)
Date: 2017
Premovement brain activity in a bimanual load-lifting task
Publisher: Springer Science and Business Media LLC
Date: 13-11-2010
DOI: 10.1007/S00221-010-2470-5
Abstract: Even the simplest volitional movements must be precisely coordinated with anticipatory postural adjustments. Little is currently known about the neural networks that coordinate these adjustments in healthy adults. We measured brain activity prior to movement during a bimanual load-lifting task, designed to elicit anticipatory adjustments in a restricted and well-defined set of musculature in the arm. Electroencephalography and magnetoencephalography brain measurements were obtained from eleven participants while they performed a bimanual load-lifting task that required precise inter-limb coordination. Anticipatory biceps brachii inhibition in the loaded arm was associated with a robust desynchronization of the beta rhythm. Beamforming analyses localized beta band responses to the parietal lobules, pre- and post-central gyri, middle and medial frontal gyri, basal ganglia and thalamus. The current study shows that premovement brain activity in a bimanual load-lifting task can be imaged with magnetoencephalography. Future experiments will partition out brain activity associated with anticipatory postural adjustments and volitional movements. The experimental paradigm will also be useful in the study of motor function in patients with developmental or degenerative disorders.
Decisional carryover effects in interval timing
Publisher: Springer Science and Business Media LLC
Date: 02-01-2020
DOI: 10.3758/S13414-019-01922-1
Abstract: Decisional carryover refers to the tendency to report a current stimulus as being similar to a prior stimulus. In this article, we assess decisional carryover in the context of temporal judgments. Participants performed a temporal bisection task wherein a probe between a long and short reference duration (Experiment 1) was presented on every trial. In Experiment 2, every other trial presented a duration the same as the short or long reference duration. In Experiment 3, we concurrently varied both the size and duration of stimuli. Experiment 1 demonstrated the typical decisional carryover effect in which the current response was assimilated towards the prior response. In Experiment 2, this was not the case. Conversely, in Experiment 2, we demonstrated decisional carryover from the prior probe decision to the reference duration trials, a judgment which should have been relatively easy. In Experiment 3, we found carryover in the judgment of both size and duration, and a tendency towards decisional carryover having a larger effect size when participants were making size judgments. Together, our findings indicate that decisional carryover in duration judgments occur given relatively response-certain trials and that this effect appears to be similar in both size and duration judgments. This suggest that decisional carryover is indeed decisional in nature, rather than due to assimilative effects in perception, and that the difficulty of judging the previous test stimuli may play a role in whether assimilation occurs in the following trial when judging duration.
Automatic morpheme identification across development: Magnetoencephalography (MEG) evidence from fast periodic visual stimulation
Publisher: Frontiers Media SA
Date: 07-09-2022
DOI: 10.3389/FPSYG.2022.932952
Abstract: The present study combined magnetoencephalography (MEG) recordings with fast periodic visual stimulation (FPVS) to investigate automatic neural responses to morphemes in developing and skilled readers. Native English-speaking children ( N = 17, grade 5–6) and adults ( N = 28) were presented with rapid streams of base stimuli (6 Hz) interleaved periodically with oddballs (i.e., every fifth item, oddball stimulation frequency: 1.2 Hz). In a manipulation-check condition, tapping into word recognition, oddballs featured familiar words (e.g., roll ) embedded in a stream of consonant strings (e.g., ktlq ). In the experimental conditions, the contrast between oddball and base stimuli was manipulated in order to probe selective stem and suffix identification in morphologically structured pseudowords (e.g., stem + suffix pseudowords such as softity embedded in nonstem + suffix pseudowords such as trumess ). Neural responses at the oddball frequency and harmonics were analyzed at the sensor level using non-parametric cluster-based permutation tests. As expected, results in the manipulation-check condition revealed a word-selective response reflected by a predominantly left-lateralized cluster that emerged over temporal, parietal, and occipital sensors in both children and adults. However, across the experimental conditions, results yielded a differential pattern of oddball responses in developing and skilled readers. Children displayed a significant response that emerged in a mostly central occipital cluster for the condition tracking stem identification in the presence of suffixes (e.g., softity vs. trumess ). In contrast, adult participants showed a significant response that emerged in a cluster located in central and left occipital sensors for the condition tracking suffix identification in the presence of stems (e.g., softity vs. stopust ). The present results suggest that while the morpheme identification system in Grade 5–6 children is not yet adult-like, it is sufficiently mature to automatically analyze the morphemic structure of novel letter strings. These findings are discussed in the context of theoretical accounts of morphological processing across reading development.
A Conceptual Lemon: Theta Burst Stimulation to the Left Anterior Temporal Lobe Untangles Object Representation and Its Canonical Color
Publisher: MIT Press - Journals
Date: 05-2014
DOI: 10.1162/JOCN_A_00536
Abstract: Object recognition benefits greatly from our knowledge of typical color (e.g., a lemon is usually yellow). Most research on object color knowledge focuses on whether both knowledge and perception of object color recruit the well-established neural substrates of color vision (the V4 complex). Compared with the intensive investigation of the V4 complex, we know little about where and how neural mechanisms beyond V4 contribute to color knowledge. The anterior temporal lobe (ATL) is thought to act as a “hub” that supports semantic memory by integrating different modality-specific contents into a meaningful entity at a supramodal conceptual level, making it a good candidate zone for mediating the mappings between object attributes. Here, we explore whether the ATL is critical for integrating typical color with other object attributes (object shape and name), akin to its role in combining nonperceptual semantic representations. In separate experimental sessions, we applied TMS to disrupt neural processing in the left ATL and a control site (the occipital pole). Participants performed an object naming task that probes color knowledge and elicits a reliable color congruency effect as well as a control quantity naming task that also elicits a cognitive congruency effect but involves no conceptual integration. Critically, ATL stimulation eliminated the otherwise robust color congruency effect but had no impact on the numerical congruency effect, indicating a selective disruption of object color knowledge. Neither color nor numerical congruency effects were affected by stimulation at the control occipital site, ruling out nonspecific effects of cortical stimulation. Our findings suggest that the ATL is involved in the representation of object concepts that include their canonical colors.
Localized estimation of electromagnetic sources underlying event-related fields using recurrent neural networks
Publisher: Cold Spring Harbor Laboratory
Date: 24-04-2023
DOI: 10.1101/2023.04.23.537963
Abstract: To use a recurrent neural network (RNN) to reconstruct neural activity responsible for generating noninvasively measured electromagnetic signals. Output weights of an RNN were fixed as the lead field matrix from volumetric source space computed using the boundary element method with co-registered structural magnetic resonance images and magnetoencephalography (MEG). Initially, the network was trained to minimize mean-squared-error loss between its outputs and MEG signals, causing activations in the penultimate layer to converge towards putative neural source activations. Subsequently, L1 regularization was applied to the final hidden layer, and the model was fine-tuned, causing it to favour more focused activations. Estimated source signals were then obtained from the outputs of the last hidden layer. We developed and validated this approach with simulations before applying it to real MEG data, comparing performance with three existing methods: beamformers, minimum-norm estimate, and dynamical statistical parametric mapping. The proposed method had higher output signal-to-noise ratios than the others and comparable correlation and error between estimated and simulated sources. Reconstructed MEG signals were also equal or superior to the other methods in terms of their similarity to ground-truth. When applied to MEG data recorded during an auditory roving oddball experiment, source signals estimated with the RNN were generally consistent with expectations from the literature and qualitatively smoother and more reasonable-looking than estimates from the other methods. This work builds on recent developments of RNNs for modelling event-related neural responses by incorporating biophysical constraints from the forward model, thus taking a significant step towards greater biological realism and introducing the possibility of exploring how input manipulations may influence localized neural activity.
Distinct spatial scale sensitivities for early categorization of faces and places: neuromagnetic and behavioral findings
Publisher: Frontiers Media SA
Date: 2013
High gamma oscillations in medial temporal lobe during overt production of speech and gestures
Publisher: Public Library of Science (PLoS)
Date: 23-10-2014
Studying Brain Function in Children Using Magnetoencephalography
Publisher: MyJove Corporation
Date: 08-02-2019
DOI: 10.3791/58909
Abstract: Magnetoencephalography (MEG) is a non-invasive neuroimaging technique which directly measures magnetic fields produced by the electrical activity of the human brain. MEG is quiet and less likely to induce claustrophobia compared with magnetic resonance imaging (MRI). It is therefore a promising tool for investigating brain function in young children. However, analysis of MEG data from pediatric populations is often complicated by head movement artefacts which arise as a consequence of the requirement for a spatially-fixed sensor array that is not affixed to the child's head. Minimizing head movements during MEG sessions can be particularly challenging as young children are often unable to remain still during experimental tasks. The protocol presented here aims to reduce head movement artefacts during pediatric MEG scanning. Prior to visiting the MEG laboratory, families are provided with resources that explain the MEG system and the experimental procedures in simple, accessible language. An MEG familiarization session is conducted during which children are acquainted with both the researchers and the MEG procedures. They are then trained to keep their head still whilst lying inside an MEG simulator. To help children feel at ease in the novel MEG environment, all of the procedures are explained through the narrative of a space mission. To minimize head movement due to restlessness, children are trained and assessed using fun and engaging experimental paradigms. In addition, children's residual head movement artefacts are compensated for during the data acquisition session using a real-time head movement tracking system. Implementing these child-friendly procedures is important for improving data quality, minimizing participant attrition rates in longitudinal studies, and ensuring that families have a positive research experience.
Neural correlates of face perception modeled with a convolutional recurrent neural network
Publisher: IOP Publishing
Date: 04-2023
Abstract: Objective. Event-related potential (ERP) sensitivity to faces is predominantly characterized by an N170 peak that has greater litude and shorter latency when elicited by human faces than images of other objects. We aimed to develop a computational model of visual ERP generation to study this phenomenon which consisted of a three-dimensional convolutional neural network (CNN) connected to a recurrent neural network (RNN). Approach. The CNN provided image representation learning, complimenting sequence learning of the RNN for modeling visually-evoked potentials. We used open-access data from ERP Compendium of Open Resources and Experiments (40 subjects) to develop the model, generated synthetic images for simulating experiments with a generative adversarial network, then collected additional data (16 subjects) to validate predictions of these simulations. For modeling, visual stimuli presented during ERP experiments were represented as sequences of images (time x pixels). These were provided as inputs to the model. By filtering and pooling over spatial dimensions, the CNN transformed these inputs into sequences of vectors that were passed to the RNN. The ERP waveforms evoked by visual stimuli were provided to the RNN as labels for supervised learning. The whole model was trained end-to-end using data from the open-access dataset to reproduce ERP waveforms evoked by visual events. Main results. Cross-validation model outputs strongly correlated with open-access ( r = 0.98) and validation study data ( r = 0.78). Open-access and validation study data correlated similarly ( r = 0.81). Some aspects of model behavior were consistent with neural recordings while others were not, suggesting promising albeit limited capacity for modeling the neurophysiology of face-sensitive ERP generation. Significance. The approach developed in this work is potentially of significant value for visual neuroscience research, where it may be adapted for multiple contexts to study computational relationships between visual stimuli and evoked neural activity.
Neural Correlates of Encoding in Novel Word Learning
Publisher: University of California Press
Date: 2023
Abstract: A central observation in the recognition memory literature is that neural processes occurring during encoding of stimuli are predictive of their later recognition and recall. Compared to items that are later forgotten, encoding of correctly recognised items has been associated with greater litude between 400 ms and 800 ms post stimulus onset across centro-parietal sites (the difference-due-to-memory ERP effect), increased EEG power in the theta and gamma frequency bands and decreased EEG power in the alpha and beta bands, and increased theta-gamma phase- litude coupling. Importantly, theories of encoding based on these findings imply that these effects should be domain-general. In this pre-registered study, we tested this assumption by exploring neural correlates of successful encoding in learning of novel names for novel concepts. Following the previous studies, we used three different measures of neural activity, ERPs, time-frequency representations of power, and phase- litude coupling however, for either of these measures, we could not reject the null hypothesis of no difference between the novel names that were later recalled and those that were not. We provide three possible interpretations of our findings, and our main conclusion is that the existing theories of encoding may be underspecified and that properly-powered pre-registered studies are needed to further constrain these theories.
The expected oddball
Publisher: Springer Science and Business Media LLC
Date: 12-09-2020
DOI: 10.1007/S00426-018-1093-5
Abstract: The oddball duration effect describes how a rare stimulus amongst a string of standard stimuli is perceived to have a longer duration than the standards, even if they are of the same objective duration. Several theories have been proposed to explain this phenomenon. In order to adjudicate between opposing explanations, we have borrowed three extensively studied paradigms from the variable foreperiod literature: the sequential foreperiod, temporal cueing and a skewed foreperiod distribution. This approach allowed us to examine the effects of positional expectation on perceived oddball duration, while avoiding confounds from first-order positioning of the oddball in a sequence of standards. Through these three experiments, we demonstrate a clear role of positional expectation in the lengthening of the perceived duration of an oddball. We show that this expectation effect is separable from other drivers of the oddball duration illusion.
Modulation of Masseteric Reflexes by Simulated Mastication
Publisher: SAGE Publications
Date: 04-12-2009
Abstract: It is well-known that limb muscle reflexes are modulated during human movements. However, little is known about the existence of equivalent masticatory muscle reflex modulation. We hypothesized that masticatory reflexes would be modulated during chewing so that smooth masticatory movements occur. To examine this hypothesis, we studied the modulation of inhibitory reflexes evoked by periodontal mechanoreceptor activation and of excitatory reflexes evoked by muscle spindle activation during simulated mastication. In 28 participants, 1- and 2-N mechanical taps were delivered to the incisor. Reflex responses to these taps were examined in the average masseteric electromyogram. To differentiate between periodontal mechanoreceptor- and muscle-spindle-mediated reflex components, we performed experiments prior to, and in the presence of, periodontal anesthesia. Both periodontal mechanoreceptor and muscle spindle reflexes were reduced during simulated masticatory movements.
Motor neuroplasticity
Publisher: Elsevier BV
Date: 09-2020
Transcranial magnetic stimulation reduces masseter motoneuron pool excitability throughout the cortical silent period
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CLINPH.2007.12.019
Abstract: To evaluate the time-course of changes in masseter motoneuron pool excitability following transcranial magnetic stimulation of motor cortex, and relate this to the duration of the masseter cortical silent period (CSP). Surface EMG was recorded bilaterally from masseter and digastric muscles in 13 subjects. Focal TMS was applied at 1.3x active motor threshold (AMT) to motor cortex of one hemisphere to elicit a muscle evoked potential (MEP) and silent period bilaterally in masseter as subjects maintained an isometric bite at approximately 10% maximum. With jaw muscles relaxed, a servo-controlled stretcher evoked a stretch reflex in masseter which was conditioned by TMS (1.3x AMT) at 14 different conditioning-testing intervals. There were 20 trials at each interval, in random order. TMS evoked no MEP in resting masseter, but often produced a small MEP in digastric. Mean (+/-SE) masseter CSP was 67+/-3ms. The masseter stretch reflex was facilitated when stretch preceded TMS by 8 and 10ms, which we attribute to spatial summation of corticobulbar and Ia-afferent excitatory inputs to masseter. Masseter stretch reflex litude was reduced when TMS was given up to 75ms before stretch, and for up to 2ms afterwards. We conclude that descending corticobulbar activity evoked by TMS acts bilaterally on brainstem interneurons that either inhibit masseter motoneurons or increase pre-synaptic inhibition of Ia-afferent terminals for up to 75ms after TMS. The reduction of masseter motoneuron pool excitability following TMS has a similar time-course to the CSP. In contrast to the situation for spinal and facial (CN VII) muscles, the masseter CSP appears to have no component that can be attributed exclusively to cortical mechanisms. Abnormalities in the masseter cortical silent period observed in neurological conditions may be due to pathophysiological changes at cortical and/or sub-cortical levels.
Masseter length determines muscle spindle reflex excitability during jaw-closing movements
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.AJODO.2009.12.033
Abstract: The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns. Twenty-eight adult volunteers (16 women ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif and Mona Lisa, Canberra, Australia). Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008). These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses.
Cortical activity differs between position- and force-control knee extension tasks
Publisher: Springer Science and Business Media LLC
Date: 21-08-2015
DOI: 10.1007/S00221-015-4404-8
Abstract: Neural control differs between position- and force-control tasks as evident from ergent effects of fatigue and pain. Unlike force-control tasks, position-control tasks focus on a postural goal to maintain a joint angle. Cortical involvement is suggested to be less during postural control, but whether this differs between position- and force-control paradigms remains unclear. Coherence estimates the functional communication between spatially distinct active regions within the cortex (cortico-cortical coherence CCC) and between the cortex and muscles (corticomuscular coherence CMC). We investigated whether cortical involvement differed between force-control and more posturally focused, position-control tasks. Seventeen adults performed position- and force-control knee extensor efforts at a submaximal load (10 % maximum voluntary contraction). Surface electromyography was recorded from the right knee extensor and flexor muscles and brain activity using electroencephalography (EEG). CCC and CMC in the beta (13-30 Hz) and gamma (30-45 Hz) frequency bands were calculated between combinations of intra- and inter-hemispheric pairs of electrodes, and between four EEG electrodes that approximated the left motor cortical area, and right knee extensor EMG, respectively. Differences in EEG power and muscle activity were also calculated. CCC was greater across distributed regions in the force-control task. Beta EEG power in the left hemisphere was higher for the position-control task. Although averaged CMC data differed between tasks, there was no task difference for in idual CMC data. Muscle activity and force did not differ between tasks. The results demonstrate differential cortical contributions to control force- versus position-control tasks. This might contribute to differences in performance outcomes of these tasks that have been shown previously.
Head and Neck Characteristics as Risk Factors For and Protective Factors Against Mild Traumatic Brain Injury in Military and Sporting Populations: A Systematic Review
Publisher: Springer Science and Business Media LLC
Date: 06-05-2022
DOI: 10.1007/S40279-022-01683-2
Abstract: Investigators have proposed that various physical head and neck characteristics, such as neck strength and head and neck size, are associated with protection from mild traumatic brain injury (mTBI/concussion). To systematically review the literature and investigate potential relationships between physical head and neck characteristics and mTBI risk in athletic and military populations. A comprehensive search of seven databases was conducted: MEDLINE, EMBASE, CINAHL, Scopus, SPORTDiscus, Cochrane Library, and Web of Science. Potential studies were systematically screened and reviewed. Studies on military and athletic cohorts were included if they assessed the relationship between physical head-neck characteristics and mTBI risk or proxy risk measures such as head impact kinematics. The systematic search yielded a total of 11,723 original records. From these, 22 studies met our inclusion criteria (10 longitudinal, 12 cross-sectional). Relevant to our PECO (Population, Exposure, Comparator, and Outcomes) question, exposures included mTBI incidence and head impact kinematics (acceleration, velocity, displacement) for impacts during sport play and training and in controlled laboratory conditions. Outcome characteristics included head and neck size (circumference, mass, length, ratios between these measures), neck strength and endurance, and rate of force development of neck muscles. We found mixed evidence for head and neck characteristics acting as risk factors for and protective factors against mTBI and increased susceptibility to head impacts. Head-neck strength and size variables were at times associated with protection against mTBI incidence and reduced impact kinematics (14/22 studies found one or more head-neck variable to be associated with protection) however, some studies did not find these relationships (8/22 studies found no significant associations or relationships). Interestingly, two studies found stronger and larger athletes were more at risk of sustaining high impacts during sport. Strength and size metrics may have some predictive power, but impact mitigation seems to be influenced by many other variables, such as behaviour, sex, and impact anticipation. A meta-analysis could not be performed due to heterogeneity in study design and reporting. There is mixed evidence in the literature for the protective capacity of head and neck characteristics. We suggest field-based mTBI research in the future should include more dynamic anthropometric metrics, such as neck stiffness and response to perturbation. In addition, laboratory-based mTBI studies should aim to standardise design and reporting to help further uncover these complicated relationships.
Methods of time and frequency domain examination of physiological tremor in the human jaw
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.HUMOV.2005.09.003
Abstract: This paper discusses, using the human jaw as a model, some of the commonly used techniques for examining physiological tremor. The EMG component driving mandibular physiological tremor approximately 7Hz can be revealed in the time domain manifestation of EMG by demodulation. The co-occurrence of approximately 7Hz physiological tremor (PT) in force and EMG can also be seen in the frequency domain representations of these signals and coherence analysis provides a method by which the degree of co-occurrence can be statistically investigated. Additionally, estimation of time lags between the signals by phase and cumulant density analysis provides evidence of the direction of dependence. Data presented herein using these techniques illustrates that for the human jaw, PT arises from a rhythmic component of EMG. This component is frequency and litude invariant across a range of bite forces indicating that it is not due to interaction between the stretch reflex and the mechanical resonance of the system.
A study on synaptic coupling between single orofacial mechanoreceptors and human masseter muscle
Publisher: Springer Science and Business Media LLC
Date: 23-11-2005
DOI: 10.1007/S00221-005-0231-7
Abstract: The connection between in idual orofacial mechanoreceptive afferents and the motoneurones that innervate jaw muscles is not well established. For ex le, although electrical and mechanical stimulation of orofacial afferents in bulk evokes responses in the jaw closers, whether similar responses can be evoked in the jaw muscles from the discharge of type identified single orofacial mechanoreceptive afferents is not known. Using tungsten microelectrodes, we have recorded from 28 afferents in the inferior alveolar nerve and 21 afferents in the lingual nerve of human volunteers. We have used discharges of single orofacial afferents as the triggers and the electromyogram (EMG) of the masseter as the source to generate spike-triggered averaged records to illustrate time-based EMG modulation by the nerve discharge. We have then used cross correlation analysis to quantify the coupling. Furthermore, we have also used coherence analysis to study frequency-based relationship between the nerve spike trains and the EMG. The discharge patterns of the skin and mucosa receptors around the lip and the gingiva generated significant modulation in EMGs with a success rate of 40% for both cross correlation and coherence analyses. The discharge patterns of the periodontal mechanoreceptors (PMRs) generated more coupling with a success rate of 70% for cross correlation and about 35% for coherence analyses. Finally, the discharges of the tongue receptors displayed significant coupling with the jaw muscle motoneurones with a success rate of about 40% for both analyses. Significant modulation of the jaw muscles by single orofacial receptors suggests that they play important roles in controlling the jaw muscle activity so that mastication and speech functions are executed successfully.
Whole-language and item-specific inhibition in bilingual language switching
Publisher: MDPI AG
Date: 05-08-2020
Abstract: A prominent theory of bilingual speech production holds that appropriate language selection is achieved via inhibitory control. Such inhibition may operate on the whole-language and/or item-specific level. In this study, we examined these two levels of control in parallel, by introducing a novel element into the traditional cued language switching paradigm: half of the stimuli were univalent (each required naming in the same language every time it appeared), and the other half were bivalent (each required naming in different languages on different trials). Contrasting switch and stay trials provided an index for whole-language inhibition, while contrasting bivalent and univalent stimuli provided an index for item-specific inhibition. We then investigated the involvement of domain-general brain mechanisms in these two levels of language control. Neuroimaging studies report activation of the pre-supplementary motor area (pre-SMA), a key region in the executive control brain network, during language switching tasks. However, it is unclear whether or not the pre-SMA plays a causal role in language control, and at which level it exerts control. Using repetitive transcranial magnetic stimulation (TMS) to transiently disrupt the pre-SMA, we observed an essential role of this brain region in general speech execution, while evidence for its specific involvement in each level of inhibition remains inconclusive.
Does TMS disruption of the left primary motor cortex affect verb retrieval following exposure to pantomimed gestures?
Publisher: Frontiers Media SA
Date: 12-12-2018
An investigation of compensation and adaptation to auditory perturbations in individuals with acquired apraxia of speech
Publisher: Frontiers Media SA
Date: 19-12-2018
Is the human masticatory system devoid of recurrent inhibition?
Publisher: Springer Science and Business Media LLC
Date: 30-11-2006
DOI: 10.1007/S00221-006-0774-2
Abstract: The aim of the present study was to investigate the existence or otherwise of a functional recurrent inhibitory system (Renshaw cell system) in the motoneurons that innervate human masticatory muscles. In a previous study, L: -acetylcarnitine (L: -Ac), a substance known to potentiate recurrent inhibition in humans was found to alter, in a specific way, the discharge variability, and the synchronous activity of motor units depending on the presence or absence of recurrent inhibition in the corresponding motoneuron pool. Using a similar paradigm, we have recorded the tonic discharge activity of motor unit pairs from the masseter muscle during voluntary isometric contraction while subjects were undergoing continuous intravenous saline (SAL, NaCl 0.9%) perfusion. Following a brief baseline-recording period, the subjects were given a test injection of either L: -Ac or isotonic saline (SAL) in a double blind manner. The variability, synchronization, and coherence between the motor unit discharges were analysed during three successive periods: pre-injection, during injection, and post-injection, each lasting 2-3 min. Neither L: -Ac nor SAL injection induced a significant change in the inter-spike interval (ISI) or the coefficient of variation of the ISIs in the motor units tested. There were also no significant changes in the pattern of synchronous activity or in the coherence, which reflects the common frequency content of the unit discharges. Reminiscent of what had been observed previously with motoneurons without recurrent inhibition in the Abductor Digitorum Minimi muscle, the lack of effects of L: -Ac injection on the firing behaviour of masseter motoneurons may suggest that classical Renshaw cell inhibition is lacking in this motoneuron pool.
Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS
Publisher: Frontiers Media SA
Date: 03-06-2014
Neuro-dynamics of executive control in bilingual language switching: An MEG study
Publisher: Elsevier BV
Date: 06-2020
Augmenting melodic intonation therapy with non-invasive brain stimulation to treat impaired left-hemisphere function: two case studies
Publisher: Frontiers Media SA
Date: 2014
Oddball onset timing
Publisher: Springer Science and Business Media LLC
Date: 15-03-2021
Neural correlates of face perception modeled with a convolutional recurrent neural network
Publisher: Cold Spring Harbor Laboratory
Date: 03-01-2023
DOI: 10.1101/2023.01.02.522523
Abstract: Event-related potential (ERP) sensitivity to faces is predominantly characterized by an N170 peak that has greater litude and shorter latency when elicited by human faces than images of other objects. We developed a computational model of visual ERP generation to study this phenomenon which consisted of a convolutional neural network (CNN) connected to a recurrent neural network (RNN). We used open-access data to develop the model, generated synthetic images for simulating experiments, then collected additional data to validate predictions of these simulations. For modeling, visual stimuli presented during ERP experiments were represented as sequences of images (time x pixels). These were provided as inputs to the model. The CNN transformed these inputs into sequences of vectors that were passed to the RNN. The ERP waveforms evoked by visual stimuli were provided to the RNN as labels for supervised learning. The whole model was trained end-to-end using data from the open-access dataset to reproduce ERP waveforms evoked by visual events. Cross-validation model outputs strongly correlated with open-access (r = 0.98) and validation study data (r = 0.78). Open-access and validation study data correlated similarly (r = 0.81). Some aspects of model behavior were consistent with neural recordings while others were not, suggesting promising albeit limited capacity for modeling the neurophysiology of face-sensitive ERP generation.
Taking action in hand: effects of gesture observation on action verb naming
Publisher: Informa UK Limited
Date: 04-12-2019
Filling your time
Publisher: Elsevier BV
Date: 06-2023
Periodontal anaesthesia reduces common 8 Hz input to masseters during isometric biting
Publisher: Springer Science and Business Media LLC
Date: 18-11-2005
DOI: 10.1007/S00221-005-0144-5
Abstract: During isometric contractions of the jaw muscles, oscillations in the rectified masseteric EMG record that are coherent with the mandibular force output are evident at ~8 Hz. We have investigated the load dependence of these oscillations under both force and EMG feedback conditions and the extent to which these oscillations are coupled bilaterally in the jaw muscles. We further investigated the extent to which afferent information arising from the periodontium during biting influenced the extent of ~8 Hz EMG tremor and the bilateral coupling between masseters at this frequency. Using coherence analysis we have shown that a significant load-independent coupling of EMG between the closing muscles of the jaw occurs at ~8 Hz as a result of common ~8 Hz input to the masseters. This common input is significantly reduced when afferent information from the periodontium is blocked. These results suggest that afferent information arising from the periodontium enhances the expression of peripheral tremulous activity, which may be important for optimising the response of the jaw to changes in forces occurring between the teeth.
Increased segregation of functional networks in developing brains
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.NEUROIMAGE.2019.06.055
Abstract: A growing literature conceptualises typical brain development from a network perspective. However, largely due to technical and methodological challenges inherent in paediatric functional neuroimaging, there remains an important gap in our knowledge regarding the typical development of functional brain networks in "preschool" childhood (i.e., children younger than 6 years of age). In this study, we recorded brain oscillatory activity using age-appropriate magnetoencephalography in 24 children, including 14 preschool children aged from 4 to 6 years and 10 school children aged from 7 to 12 years. We compared the topology of the resting-state brain networks in these children, estimated using minimum spanning tree (MST) constructed from phase synchrony between beamformer-reconstructed time-series, with that of 24 adults. Our results show that during childhood the MST topology shifts from a star-like (centralised) toward a more line-like (de-centralised) configuration, indicating the functional brain networks become increasingly segregated. In addition, the increasing global network segregation is frequency-independent and accompanied by decreases in centrality (or connectedness) of cortical regions with age, especially in areas of the default mode network. We propose a heuristic MST model of "network space", which posits a clear developmental trajectory for the emergence of complex brain networks. Our results not only revealed topological reorganisation of functional networks across multiple temporal and spatial scales in childhood, but also fill a gap in the literature regarding neurophysiological mechanisms of functional brain maturation during the preschool years of childhood.
MEG for kids
Publisher: Frontiers Media SA
Date: 24-04-2014
Abstract: Your brain is made up of billions of neurons all chattering away to each other. MEG allows us to listen in on their conversations by measuring your brain’s magnetic field.
Is the human masticatory system devoid of recurrent inhibition?
Publisher: Springer Science and Business Media LLC
Date: 11-01-2007
Functional connectivity learning via Siamese-based SPD matrix representation of brain imaging data
Publisher: Elsevier BV
Date: 06-2023
Theta tACS impairs episodic memory more than tDCS
Publisher: Springer Science and Business Media LLC
Date: 13-01-2023
DOI: 10.1038/S41598-022-27190-Y
Abstract: Episodic memory deficits are a common consequence of aging and are associated with a number of neurodegenerative disorders (e.g., Alzheimer’s disease). Given the importance of episodic memory, a great deal of research has investigated how we can improve memory performance. Transcranial electrical stimulation (TES) represents a promising tool for memory enhancement but the optimal stimulation parameters that reliably boost memory are yet to be determined. In our double-blind, randomised, sham-controlled study, 42 healthy adults (36 females 23.3 ± 7.7 years of age) received anodal transcranial direct current stimulation (tDCS), theta transcranial alternating current stimulation (tACS) and sham stimulation during a list-learning task, over three separate sessions. Stimulation was applied over the left temporal lobe, as encoding and recall of information is typically associated with mesial temporal lobe structures (e.g., the hippoc us and entorhinal cortex). We measured word recall within each stimulation session, as well as the average number of intrusion and repetition errors. In terms of word recall, participants recalled fewer words during tDCS and tACS, compared to sham stimulation, and significantly fewer words recalled during tACS compared with tDCS. Significantly more memory errors were also made during tACS compared with sham stimulation. Overall, our findings suggest that TES has a deleterious effect on memory processes when applied to the left temporal lobe.
The effects of impulsivity and proactive inhibition on reactive inhibition and the go process: insights from vocal and manual stop signal tasks
Publisher: Frontiers Media SA
Date: 06-10-2015
Cortical Oscillatory Dysrhythmias in Visual Snow Syndrome: A MEG Study
Publisher: Cold Spring Harbor Laboratory
Date: 18-05-2021
DOI: 10.1101/2021.05.17.444460
Abstract: Visual Snow (VS) refers to the persistent visual experience of static in the whole visual field of both eyes. It is often reported by patients with migraine and co-occurs with conditions like tinnitus and tremor. The underlying pathophysiology of the condition is poorly understood. Previously we hypothesised, that VSS may be characterised by disruptions to rhythmical activity within the visual system 1 . To test this, data from 18 patients diagnosed with visual snow syndrome (VSS), and 16 matched controls, were acquired using Magnetoencephalography (MEG). Participants were presented with visual grating stimuli, known to elicit decreases in alpha-band (8-13Hz) power and increases in gamma-band power (40-70Hz). Data were mapped to source-space using a beamformer. Across both groups, decreased alpha power and increased gamma power localised to early visual cortex. Data from primary visual cortex (V1) were compared between groups. No differences were found in either alpha or gamma peak frequency or the magnitude of alpha power, p .05. However, compared with controls, our VSS cohort displayed significantly increased V1 gamma power, p=.035. This new electromagnetic finding concurs with previous fMRI and PET findings suggesting that in VSS, the visual cortex is hyper-excitable. The coupling of alpha-phase to gamma litude (i.e., phase- litude coupling, PAC) within V1 was also quantified. Compared with controls, the VSS group had significantly reduced alpha-gamma PAC, p .05, indicating a potential excitation-inhibition imbalance in VSS, as well as a potential disruption to top-down “noise-cancellation” mechanisms. Overall, these results suggest that rhythmical brain activity in primary visual cortex is both hyperexcitable and disorganised in VSS, consistent with visual snow being a condition of thalamocortical dysrhythmia.
Periodontal-Masseteric Reflexes Decrease with Tooth Pre-load
Publisher: SAGE Publications
Date: 02-2008
DOI: 10.1177/154405910808700213
Abstract: The responses of incisal periodontal mechanoreceptors to increasing mechanical stimulation are known to follow a hyperbolic-saturating course. The implications of these properties for the reflexive control of bite-force have not been examined directly. In line with the abovementioned receptor characteristics, we hypothesized that the periodontal-masseteric reflex will reduce as a function of increasing incisal pre-load. In 10 participants, a central incisor was repeatedly tapped (0.4 N). We measured the modulation by pre-load (0.2–2.0 N) of the reflex frequency-response at and between 3 and 20 Hz. The entrainment of the reflex increased with frequency up to 20 Hz and diminished with increasing pre-load. Importantly, the hyperbolic relationship shown here between the periodontal-masseteric reflex and tooth pre-load agreed with the load/response relationships predicted by single-receptor and tooth movement studies. This study demonstrated that periodontal mechano-receptors are able to contribute to the ongoing control of only small bite-forces.
Belief, delusion, hypnosis, and the right dorsolateral prefrontal cortex: A transcranial magnetic stimulation study
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.CORTEX.2018.01.001
Abstract: According to the Two-Factor theory of delusional belief (see e.g. Coltheart at al., 2011), there exists a cognitive system dedicated to the generation, evaluation, and acceptance or rejection of beliefs. Studies of the neuropsychology of delusion provide evidence that this system is neurally realized in right dorsolateral prefrontal cortex (rDLPFC). Furthermore, we have shown that convincing analogues of many specific delusional beliefs can be created in nonclinical subjects by hypnotic suggestion and we think of hypnosis as having the effect of temporarily interfering with the operation of the belief system, which allows acceptance of the delusional suggestions. If the belief system does depend on rDLPFC, then disrupting the activity of that region of the brain by the application of repetitive transcranial magnetic stimulation (rTMS) will increase hypnotizability. Dienes and Hutton (2013) have reported such an experiment except that it was left DLPFC to which rTMS was applied. An effect on a subjective measure of hypnotizability was observed, but whether there was an effect on an objective measure could not be determined. We report two experiments. The first was an exact replication of the Dienes and Hutton experiment here we found no effect of rTMS to lDLPFC on any hypnotic measure. Our second experiment used rTMS applied to right rather then left DLPFC. This right-sided stimulation enhanced hypnotizability (when hypnotic response was measured objectively), as predicted by our hypothesis. These results imply a role for rDLPFC in the cognitive process of belief evaluation, as is proposed in our two-factor theory of delusion. They are also consistent with a conception of the acceptance of a hypnotic suggestion as involving suspension of disbelief.
Neuromagnetic imaging reveals timing of volitional and anticipatory motor control in bimanual load lifting
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.BBR.2013.03.020
Abstract: During bimanual load lifting, the brain not only contends with muscle activations in the load-lifting arm, but also has to pre-emptively modulate muscle activations in the load-bearing arm with temporal precision in order to minimize upward arm deflection. Premature or late inhibition in the load-bearing arm activity would result in augmented arm deflection. Little is currently known about the timing operation of motor systems subserving coordinated, bimanual actions. In this study, we measured neuromagnetic brain activity with whole-head magnetoencephalography while 15 participants performed a bimanual load-lifting task. To investigate neural processes prior to load lifting, a beamformer was applied to 6 contiguous 200 ms time epochs spanning the entire premovement phase of the motor task. The sequence of neural activations, following a signal to lift the weight, was chronologically ordered: firstly, the primary motor cortex contralateral to the load-lifting arm was activated, then the cerebellum, and lastly, the basal ganglia, thalamus and primary- re- motor areas contralateral to the load-bearing arm. The current data extend our understanding of the neural underpinnings of bimanual coordination. A model is proposed to account for the central organization of volitional and anticipatory motor control in bimanual load lifting.
Multimodal functional imaging of motor imagery using a novel paradigm
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.NEUROIMAGE.2013.01.001
Abstract: Neuroimaging studies have shown that the neural mechanisms of motor imagery (MI) overlap substantially with the mechanisms of motor execution (ME). Surprisingly, however, the role of several regions of the motor circuitry in MI remains controversial, a variability that may be due to differences in neuroimaging techniques, MI training, instruction types, or tasks used to evoke MI. The objectives of this study were twofold: (i) to design a novel task that reliably invokes MI, provides a reliable behavioral measure of MI performance, and is transferable across imaging modalities and (ii) to measure the common and differential activations for MI and ME with functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). We present a task in which it is difficult to give accurate responses without the use of either motor execution or motor imagery. The behavioral results demonstrate that participants performed similarly on the task when they imagined vs. executed movements and this performance did not change over time. The fMRI results show a spatial overlap of MI and ME in a number of motor and premotor areas, sensory cortices, cerebellum, inferior frontal gyrus, and ventrolateral thalamus. MI uniquely engaged bilateral occipital areas, left parahippoc us, and other temporal and frontal areas, whereas ME yielded unique activity in motor and sensory areas, cerebellum, precuneus, and putamen. The MEG results show a robust event-related beta band desynchronization in the proximity of primary motor and premotor cortices during both ME and MI. Together, these results further elucidate the neural circuitry of MI and show that our task robustly and reliably invokes motor imagery, and thus may prove useful for interrogating the functional status of the motor circuitry in patients with motor disorders.
Vocal response inhibition is enhanced by anodal tDCS over the right prefrontal cortex
Publisher: Springer Science and Business Media LLC
Date: 29-09-2016
DOI: 10.1007/S00221-015-4452-0
Abstract: Stopping outright (reactive inhibition) and slowing down (proactive inhibition) are types of response inhibition which have mainly been investigated in the manual effector system. This study compared reactive inhibition across manual and vocal effector systems, examined the effects of excitatory anodal transcranial direct current stimulation (anodal tDCS) over the right prefrontal cortex (right-PFC) and looked at the relationship between reactive and proactive inhibition. We hypothesised (1) that vocal reactive inhibition would be less effective than manual reactive inhibition as evidenced by longer stop signal reaction times (2) that anodal tDCS would enhance both vocal and manual reactive inhibitions and (3) that proactive and reactive inhibitions would be positively related. We tested 14 participants over two sessions (one session with anodal tDCS and one session with sham stimulation) and applied stimulation protocol in the middle of the session, i.e. only during the second of three phases. We used a stop signal task across two stop conditions: relevant and irrelevant stop conditions in which stopping was required or ignored, respectively. We found that reactive inhibition was faster during and immediately after anodal tDCS relative to sham. We also found that greater level of proactive inhibition enhanced reactive inhibition (indexed by shorter stop signal reaction times). These results support the hypothesis that the right-PFC is part of a core network for reactive inhibition and supports previous contention that proactive inhibition is possibly modulated via preactivating the reactive inhibition network.
Mandibular tremor during isometric contractions
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.ARCHORALBIO.2006.09.006
Abstract: The purpose of this short review is to consider the various hypotheses that are attributed to genesis of physiological tremor seen in the human jaw during isometric contractions.
Analysis methods for measuring fNIRS responses generated by a block-design paradigm
Publisher: Cold Spring Harbor Laboratory
Date: 22-12-2020
DOI: 10.1101/2020.12.22.423886
Abstract: fNIRS is an increasingly popular tool in auditory research, but the range of analysis procedures employed across studies complicates interpretation of data. To assess the impact of different analysis procedures on the morphology, detection, and lateralization of auditory responses in fNIRS. Specifically, whether averaging or GLM-based analyses generate different experimental conclusions, when applied to a block-protocol design. The impact of parameter selection of GLMs on detecting auditory-evoked responses was also quantified. 17 listeners were exposed to three commonly employed auditory stimuli: noise, speech, and silence. A block design was employed, comprising sounds of 5-s duration, and 10–20 s silent intervals. Both analysis procedures generated similar response morphologies and litude estimates, and both also indicated responses to speech to be significantly greater than to noise and silence. Neither approach indicated a significant effect of brain hemisphere on responses to speech. Methods to correct for systemic hemodynamic responses using short channels improved detection at the in idual level. Consistent with theoretical considerations, simulations, and other experimental domains, GLM and averaging analyses generate the same group-level experimental conclusions. We release this dataset publicly for use in future development and optimization of algorithms.
Time in the motor cortex
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.NEULET.2019.01.012
Abstract: Transcranial magnetic stimulation (TMS) allows for the monitoring of motor cortex dynamics in preparation for response. Using this method, it has previously been shown that motor evoked potentials (MEPs) are suppressed as a response approaches. In the current article, we applied TMS while participants either relaxed or contracted their first dorsal interosseous muscle. We varied the time at which TMS was applied, however, unlike previous studies, no participant response was required. Using this method, we provide evidence that MEPs systematically decrease with the duration of the trial, while inhibition is not similarly affected. Further, we found some evidence that MEPs are inversely proportional to the duration of the prior trial. These findings have ramifications for other research interested in the application of TMS, especially when used across multiple possible points in a trial. Further, this finding shows a role for the motor cortex in timing more broadly.
An EEG/MEG study of anticipatory postural adjustment in a bimanual load-lifting task
Publisher: Macquarie Centre for Cognitive Science
Date: 2010
DOI: 10.5096/ASCS200940
The role of periodontal mechanoreceptors in mastication
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.ARCHORALBIO.2006.11.014
Abstract: The aim of this review is to discuss what is known about the reflex control of the human masticatory system by the periodontal mechanoreceptors and to put forward a method for standardised investigation. To deliver mechanical stimulus in a reproducible way, the following precautions are suggested: the stimulus should be brought into secure contact with the area of stimulation, and slack between the probe and the area to be stimulated should be taken up by the application of a preload. It is also important to ensure that there is minimal simultaneous activation of receptor systems other than the periodontal mechanoreceptors. It is also necessary to standardise the method for recording and analysing the response.
Hearing the World Differently: Examining Predictive Coding Accounts of Autism Using MEG
Publisher: Cold Spring Harbor Laboratory
Date: 07-10-2022
DOI: 10.1101/2022.10.03.510718
Abstract: Predictive coding accounts of autism suggest that autistic perception is characterised by ergent precision weighting. The precise nature of this ergence, however, is debated. Here, we sought to disentangle competing predictive coding accounts of autism by testing them at a neural level. To this end, we used paediatric magnetoencephalography to record the auditory evoked fields of 10 young autistic children ( M = 6.2 years, range = 4.2– 8.6) and 63 neurotypical children ( M = 6.1 years, range = 3.0– 9.8) as they listened to a roving auditory oddball paradigm. For each participant, we subtracted the evoked responses to the ‘standard’ from the ‘deviant’ pure tones to calculate the mismatch field ‘MMF’: an electrophysiological component that is widely interpreted as a neural signature of predictive coding. We found no significant differences between the two groups’ MMF litudes, p .05. An exploratory analysis indicated larger MMF litudes in most of the autistic children compared to their average-age-matched neurotypical counterparts, p .05. We interpret these findings as preliminary evidence in support of the ‘inflexibly high prior and sensory precision’ account, and against the ‘inflexibly low prior-relative-to-sensory precision’ accounts of autistic perception. We used paediatric MEG to compare autistic and neurotypical MMFs litudes. Exploratory case-cohort analyses revealed mostly larger MMFs in autistic cases. Larger MMFs support the notion of precise, inflexible prediction errors in autism.
Evidence for a resting state network abnormality in adults who stutter
Publisher: Frontiers Media SA
Date: 27-04-2018
Analysis methods for measuring passive auditory fNIRS responses generated by a block-design paradigm
Publisher: SPIE-Intl Soc Optical Eng
Date: 22-05-2021
Deep factor learning for accurate brain neuroimaging data analysis on discrimination for structural MRI and functional MRI
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Atypical cortical connectivity in autism spectrum disorder (ASD) as measured by magnetoencephalography (MEG)
Publisher: Center for Open Science
Date: 15-05-2019
Abstract: Autism Spectrum Disorder (ASD) is a neurodevelopmental condition, characterised by impairments in social interaction and communication, the presence of repetitive behaviours, and multisensory hyper- and hypo-sensitives. This thesis utilised magnetoencephalography, in combination with robust analysis techniques, to investigate the neural basis of ASD. Based on previous research, it was hypothesised that cortical activity in ASD would be associated with disruptions to oscillatory synchronisation during sensory processing, as well as during high-level perspective-taking. More specifically, a novel framework was introduced, based on local gamma-band dysregulation, global hypoconnectivity and deficient predictive-coding. To test this framework, data were collected from adolescents diagnosed with ASD and age-matched controls.Using a visual grating stimulus, it was found that in primary visual cortex, ASD participants had reduced coupling between the phase of alpha oscillations and the litude of gamma oscillations (i.e. phase litude coupling), suggesting dysregulated visual gamma in ASD. These findings were based on a robust analysis pipeline outlined in Chapter 2. Next, directed connectivity in the visual system was quantified using Granger causality. Compared with controls, ASD participants showed reductions in feedback connectivity, mediated by alpha oscillations, but no differences in inter-regional feedforward connectivity, mediated by gamma oscillations. In the auditory domain, it was found that ASD participants had reduced steady-state responses at 40Hz, in terms of oscillatory power and inter-trial coherence, again suggesting dysregulated gamma. Investigating predictive-coding theories of ASD using an auditory oddball paradigm, it was found that evoked responses to the omission of an expected tone were reduced for ASD participants. Finally, we found reductions in theta-band oscillatory power and connectivity for ASD participants, during embodied perspective-taking. Overall, these findings fit the proposed framework, and demonstrate that cortical activity in ASD is characterised by disruptions to oscillatory synchronisation, at the local and global scales, during both sensory processing and higher-level perspective-taking.Keywords: Autism Spectrum Disorder Magnetoencephalography Oscillations Phase Amplitude Coupling Connectivity.
Associations between Hallucinogen Persisting Perception Disorder (HPPD) and non-visual perceptual disturbances
Publisher: Center for Open Science
Date: 21-03-2023
Abstract: Background:Hallucinogen Persistent Perception Disorder (HPPD) is a condition where the effects of hallucinogenic drugs reoccur long after the acute effects have stopped. No established risk factors or mechanisms for HPPD have been identified. However, reports have suggested a risk phenotype for HPPD due to associations with other perceptual disturbances. With the recent increase in therapeutic psychedelic drug use, it is essential to consider the existence of HPPD risk factors. Therefore, exploring potential links between HPPD and other perceptual disturbances, such as tinnitus and migraine with aura, is a necessary first step. This study aimed to investigate the association between HPPD and other perceptual disorders.Methods:One hundred thirty-eight in iduals with HPPD and 116 controls participated in a survey that assessed the prevalence of various perceptual disturbances, including photosensitivity, phonosensitivity, tinnitus, migraine with aura, vertigo, paraesthesia, and synaesthesia.Results:The survey results showed a significant association between HPPD and photosensitivity (OR=10.65), phonosensitivity (OR=8.00), and the number of perceptual disturbances (OR=1.59) in the HPPD group compared to the control group. The study also observed trends of dual prevalence between HPPD and tinnitus, migraine with aura, vertigo, paraesthesia, and synaesthesia. Participants with both HPPD and other perceptual disturbances were likelier to experience additional perceptual disturbances after the onset of HPPD.Conclusions:These findings suggest a common vulnerability or pathophysiological mechanism among these perceptual disturbances. Given the increasing therapeutic use of hallucinogens, the results of this study provide essential considerations for HPPD risk profiles. Moreover, they may guide future investigations into the pathophysiology and management options for HPPD.
Short-term effects on temporal judgement
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.ACTPSY.2018.01.009
Abstract: Our prior experiences provide the background with which we judge subsequent events. In the time perception literature one common finding is that providing participants with a higher percentage of a particular interval can skew judgment intervals will appear longer if the distribution of intervals contains more short experiences. However, changing the distribution of intervals that participants witness also changes the short-term, interval-to-interval, sequence that participants experience. In the experiment presented here, we kept the overall distribution of intervals constant while manipulating the immediately-prior experience of participants. In temporal bisection, this created a noted assimilation effect participants judged intervals as shorter given an immediately preceding short interval. In interval reproduction, there was no effect of the immediately prior interval length unless the prior interval had a linked motor command. We thus proposed that the immediately prior interval provided a context by which a subsequent interval is judged. However, in the case of reproduction, where a subsequent interval is reproduced, rather than seen, the effects of contextualization are attenuated.
Localized estimation of electromagnetic sources underlying event-related fields using recurrent neural networks
Publisher: IOP Publishing
Date: 08-2023
Abstract: Objective . To use a recurrent neural network (RNN) to reconstruct neural activity responsible for generating noninvasively measured electromagnetic signals. Approach . Output weights of an RNN were fixed as the lead field matrix from volumetric source space computed using the boundary element method with co-registered structural magnetic resonance images and magnetoencephalography (MEG). Initially, the network was trained to minimise mean-squared-error loss between its outputs and MEG signals, causing activations in the penultimate layer to converge towards putative neural source activations. Subsequently, L1 regularisation was applied to the final hidden layer, and the model was fine-tuned, causing it to favour more focused activations. Estimated source signals were then obtained from the outputs of the last hidden layer. We developed and validated this approach with simulations before applying it to real MEG data, comparing performance with beamformers, minimum-norm estimate, and mixed-norm estimate source reconstruction methods. Main results . The proposed RNN method had higher output signal-to-noise ratios and comparable correlation and error between estimated and simulated sources. Reconstructed MEG signals were also equal or superior to the other methods regarding their similarity to ground-truth. When applied to MEG data recorded during an auditory roving oddball experiment, source signals estimated with the RNN were generally biophysically plausible and consistent with expectations from the literature. Significance . This work builds on recent developments of RNNs for modelling event-related neural responses by incorporating biophysical constraints from the forward model, thus taking a significant step towards greater biological realism and introducing the possibility of exploring how input manipulations may influence localised neural activity.
The seven deadly sins of psychology
Publisher: Informa UK Limited
Date: 22-10-2021
Local context effects in the magnitude-duration illusion: Size but not numerical value sequentially alters perceived duration
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.ACTPSY.2020.103016
Abstract: Many aspects of an event can change perceived duration. A common ex le of this is the magnitude-duration illusion, in which a high magnitude (e.g. large or high value) stimulus will be perceived to last longer than a low magnitude stimulus. The effects of magnitude on perceived duration are normally considered in terms of global context effects what is large depends on the stimuli used throughout the experiment. In the current article, we examine local context effects in the magnitude-duration illusion, how trial-by-trial changes in magnitude affect the subjective duration of an event. We performed two experiments in which numerical magnitude and stimulus size were varied within either the ex le phase or reproduction phase of a temporal reproduction task. We showed that in the current trial the combined value-size magnitude presented in the ex le phase affected subsequent reproductions, while the magnitude presented in the reproduction phase did not. The size magnitude presented in the reproduction phase also affected the reproduction in the following trial, such that a larger stimulus in the current reproduction phase resulted in shorter reproductions in the next reproduction phase. This indicates that low level stimulus properties (i.e. size) can act to contextualize subsequent stimulus properties, which in turn affect perceived duration. The findings of our experiments add local, low-level, context effects to the known modifiers of perceived duration, as well as provide evidence with regards to the role of magnitude in interval timing.
“Shut up!” An electrophysiological study investigating the neural correlates of vocal inhibition
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2011.11.009
Abstract: A neural biomarker that can be applied to studies of oral communication disorders would provide a boon to researchers. While there has been much research conducted on manual response inhibition, very few studies have examined vocal response inhibition. To date, no study has examined the temporal aspects of vocal inhibition. Therefore, the present study attempted to identify the neural correlates of vocal response inhibition by recording electroencephalographic activity during a modified version of the stop signal task. We included an ignore signal condition matched for frequency and visual stimulation to the stop signal which importantly, was included in the same block of trials as the typical go and stop trials. Behavioural results showed that participants were able to inhibit a vocal response within approximately 324 ms. Statistical analysis of ERPs revealed that a positive component around 324 ms was significantly larger in litude during successfully stopped trials compared to in an ignore condition, particularly over a cluster of fronto-central electrodes. These results support the notion that the P3 component is a reliable index of vocal inhibition.
Development of effective connectivity in the core network for face perception
Publisher: Wiley
Date: 19-02-2015
DOI: 10.1002/HBM.22762
Speech-induced suppression for delayed auditory feedback in adults who do and do not stutter
Publisher: Frontiers Media SA
Date: 24-04-2020
Abnormal time course of low beta modulation in non-fluent preschool children: A magnetoencephalographic study of rhythm tracking
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.NEUROIMAGE.2015.10.086
Abstract: Stuttering is a disorder of speech affecting millions of people around the world. Whilst the exact aetiology of stuttering remains unknown, it has been hypothesised that it is a disorder of the neural mechanisms that support speech timing. In this article, we used magnetoencephalography (MEG) to examine activity from auditory regions of the brain in stuttering and non-stuttering children aged 3-9years. For typically developing children, we found that MEG oscillations in the beta band responded to rhythmic sounds with a peak near the time of stimulus onset. In contrast, stuttering children showed an opposite phase of beta band envelope, with a trough of activity at stimulus onset. These results suggest that stuttering may result from abnormalities in predictive brain responses which are reflected in abnormal entrainment of the beta band envelope to rhythmic sounds.
Threshold for Detection of Incisal Forces Is Increased by Jaw Movement
Publisher: SAGE Publications
Date: 03-03-2010
Abstract: Current knowledge regarding the sensitivity of the teeth to forces is based on psychophysical experiments that measured touch detection thresholds under static jaw conditions. It is not known whether jaw movements alter the perception of forces applied to the teeth, but, based on limb movement studies, it is hypothesized that the perception of mechanoreceptor outputs will be downwardly modulated by jaw movements. We predicted that, compared with static jaw conditions, rhythmic jaw movements would be associated with significantly higher psychophysical thresholds for the detection of incisally applied forces. In eight participants, mechanical pulses were delivered to an incisor during static jaw holding or during cyclic jaw opening and closing. Analogous to findings in human limbs, the psychophysical salience of periodontal mechanoreceptor feedback was downwardly modulated by physiologically relevant movements detection thresholds for mechanical pulses applied to a central incisor were significantly higher during jaw-closing movements than during static jaw positioning.
Natural vs forced language switching: Free selection and consistent language use eliminate significant performance costs and cognitive demands in the brain
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.NEUROIMAGE.2021.118797
Abstract: Bilinguals are known to switch language spontaneously in everyday conversations, even if there are no external requirements to do so. However, in the laboratory setting, language control is often investigated using forced switching tasks, which result in significant performance costs. The present study assessed whether switching would be less costly when performed in a more natural fashion, and what factors might account for this. Mandarin-English bilinguals engaged in language switching under three different contexts with varied task demands. We examined two factors which may be characteristic of natural switching: (i) freedom of language selection (ii) consistency of language used to name each item. Participants' brain activities were recorded using magnetoencephalography (MEG), along with behavioural measures of reaction speed and accuracy. The natural context (with both free selection and consistent language use for each item) produced better performance overall, showing reduced mixing cost and no significant switch cost. The neural effect of language mixing was also reversed in this context, suggesting that freely mixing two languages was easier than staying in a single language. Further, while switching in the forced context elicited increased brain activity in the right inferior frontal gyrus, this switch effect disappeared when the language used to name each item was consistent. Together, these findings demonstrate that the two factors above conjointly contribute to eliminating significant performance costs and cognitive demands associated with language switching and mixing. Such evidence aligns with lexical selection models which do not assume bilingual production to be inherently effortful.
Related Organisations
Related Funding Activities
Discovery Projects - Grant ID: DP180102524
Start Date: 05-2018
End Date: 06-2022
Amount: $453,869.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP170103148
Start Date: 2017
End Date: 12-2022
Amount: $367,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Early Career Researcher Award - Grant ID: DE130100868
Start Date: 04-2013
End Date: 06-2017
Amount: $336,284.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP210301259
Start Date: 05-2023
End Date: 05-2026
Amount: $351,667.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE230100150
Start Date: 2023
End Date: 12-2023
Amount: $930,213.00
Funder: Australian Research Council
View Funded Activity