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Past, Current and Future Clinical Applications of MEG [chapter]

Garreth Prendergast, Mark Hymers
2011 Magnetoencephalography  
In many ways, the use of MEG in the epilepsy population represents a bench-mark for what may be possible in other clinical populations.  ...  Beamformers typically focus on the total power of a response (Hymers et al., 2010) , however in recent years there has been an increase in the number of variations of specific filter implementations.  ... 
doi:10.5772/28783 fatcat:wzr4wfu3bjgx5a5obn6mmjuoh4

Delineating single subject oscillatory brain networks with Spatio-Spectral Eigenmodes [article]

Andrew J Quinn, Gary GR Green, Mark Hymers
2020 bioRxiv   pre-print
The spatial and spectral structure of oscillatory networks in the brain provide a readout of the underlying neuronal function. Within and between subject variability in these networks can be highly informative but also poses a considerable analytic challenge. Here, we describe a method that simultaneously estimate spectral and spatial network structure without assumptions about either feature distorting estimation of the other. This enables analyses exploring how variability in the frequency
more » ... spatial structure of oscillatory networks might vary both across the brain and across individuals. The method performs a modal decomposition of an autoregressive model to describe the oscillatory signals present within a time-series based on their peak frequency and damping time. Moreover, an alternate mathematical formulation for the system transfer function can be written in terms of these oscillatory modes; describing the spatial topography and network structure of each component. We define a set of Spatio-Spectral Eigenmodes (SSEs) from these parameters to provide a parsimonious description of oscillatory networks. Crucially, the SSEs preserve the rich between-subject variability and are constructed without pre-averaging within specified frequency bands or limiting analyses to single channels or regions. After validating the method on simulated data, we explore the structure of whole brain oscillatory networks in eyes-open resting state MEG data from the Human Connectome Project. We are able to show a wide variability in peak frequency and network structure of alpha oscillations and reveal a distinction between occipital high-frequency alpha and parietal low-frequency alpha. The frequency difference between occipital and parietal alpha components is present within individual participants but is partially masked by larger between subject variability; a 10Hz oscillation may represent the high-frequency occipital component in one participant and the low-frequency parietal component in another. This rich characterisation of individual neural phenotypes has the potential to enhance analyses into the relationship between neural dynamics and a person's behavioural, cognitive or clinical state
doi:10.1101/2020.06.21.157412 fatcat:62e2qapq6ngqvp6x4rkad7d6ga

SAILS: Spectral Analysis In Linear Systems

Andrew Quinn, Mark Hymers
2020 Journal of Open Source Software  
Autoregressive modelling provides a powerful and flexible parametric approach to modelling uni-or multi-variate time-series data. AR models have mathematical links to linear timeinvariant systems, digital filters and Fourier based frequency analyses. As such, a wide range of time-domain and frequency-domain metrics can be readily derived from the fitted autoregressive parameters. These approaches are fundamental in a wide range of science and engineering fields and still undergoing active
more » ... pment. SAILS (Spectral Analysis in Linear Systems) is a python package which implements such methods and provides a basis for both the straightforward fitting of AR models as well as exploration and development of newer methods, such as the decomposition of autoregressive parameters into eigenmodes.
doi:10.21105/joss.01982 fatcat:xzy7s6nfb5denfyyh5dn55mvqu

Delineating between-subject heterogeneity in alpha networks with Spatio-Spectral Eigenmodes

Andrew J. Quinn, Gary G.R. Green, Mark Hymers
2021 NeuroImage  
Software All simulation, MVAR modelling and model decomposition steps are computed in Python 3.7.3 the Spectral Analysis In Linear Sys-tems toolbox ( Quinn and Hymers, 2020 ) ,  ... 
doi:10.1016/j.neuroimage.2021.118330 pmid:34237443 pmcid:PMC8456753 fatcat:es67dy44czejjfj2nyv65saxwy

Examining the Effects of One- and Three-Dimensional Spatial Filtering Analyses in Magnetoencephalography

Sam Johnson, Garreth Prendergast, Mark Hymers, Gary Green, Yong He
2011 PLoS ONE  
This is performed using a Lagrange multiplier, the exact form of which marks the difference between the Van Veen and the Huang Type I beamformer.  ...  The first was a somatosensory experiment, full details of which can be found in Hymers et al [9] . A plastic diaphragm was used to stimulate the right index finger.  ... 
doi:10.1371/journal.pone.0022251 pmid:21857916 pmcid:PMC3152290 fatcat:3umgwnqdzred5bgz37f6igdwh4

Scaffolding imagination: A role for medial frontal cortex in the expression of off-task thought [article]

Mladen Sormaz, Hao-Ting Wang, Theodoros Karapanagiotidis, Charlotte Murphy, Mark Hymers, Daniel Margulies, Elizabeth Jefferies, Jonathan Smallwood
2017 bioRxiv   pre-print
We often think about people, places and events that are outside of our immediate environment. Although prior studies have explored how we can reduce the occurrence of these experiences, the neurocognitive process through which they are produced are less understood. The current study builds on developmental and evolutionary evidence that language helps organise and express our thoughts. Behaviorally, we found the occurrence of task unrelated thought (TUT) in easy situations was associated with
more » ... inking in words. Using experience sampling data, in combination with online measures of neural function, we established that activity in a region of anterior cingulate cortex/medial-prefrontal cortex (mPFC) tracked with changes in the expression of TUT. This region is at the intersection of two mPFC clusters identified through their association with variation in aspects of spontaneous thought: thinking in words (dorsal) and mental time travel (ventral). Finally, using meta-analytic decoding we confirmed the dorsal/ventral distinction within mPFC corresponding to a functional difference between domains linked to language and meaning and those linked to memory and scene construction. This evidence suggests a role for mPFC in the expression of TUT that may emerge from interactions with distributed neural signals reflecting processes such as language and memory.
doi:10.1101/153973 fatcat:on74dilrffeujelhqzrg4bz5gm

Charting the effects of TMS with fMRI: Modulation of cortical recruitment within the distributed network supporting semantic control

Glyn P. Hallam, Carin Whitney, Mark Hymers, Andre D. Gouws, Elizabeth Jefferies
2016 Neuropsychologia  
The target areas were marked on a tight-fitting elastic cap worn by the participant throughout stimulation.  ...  Each individual anatomical image was overlaid on the MNI template and the subject-specific stimulation site was marked.  ... 
doi:10.1016/j.neuropsychologia.2016.09.012 pmid:27650816 pmcid:PMC5155664 fatcat:azhyl7xv2vd45iqbq5lxqvldvq

Anterior paracingulate and cingulate cortex mediates the effects of cognitive load on speech sound discrimination

Silvia P. Gennari, Rebecca E. Millman, Mark Hymers, Sven L. Mattys
2018 NeuroImage  
Details of the approach to ISSS data acquisition and data analysis are described in Hymers et al. (2015) .  ...  Linear and quadratic trends were removed per-voxel using an in-house tool, which took into account the times at which data were acquired (Hymers et al., 2015) .  ... 
doi:10.1016/j.neuroimage.2018.06.035 pmid:29902588 fatcat:jniqth23k5hxjm5rufawatiyb4

The neural correlates of semantic richness: Evidence from an fMRI study of word learning

Roberto A. Ferreira, Silke M. Göbel, Mark Hymers, Andrew W. Ellis
2015 Brain and Language  
., Göbel, Silke M., Hymers, Mark et al. (1 more author) (2015) The neural correlates of semantic richness : Evidence from an fMRI study of word learning.  ... 
doi:10.1016/j.bandl.2015.02.005 pmid:25797097 fatcat:at3cr5bt2reargsxs2ivarxg5e

Conceptual control across modalities: graded specialisation for pictures and words in inferior frontal and posterior temporal cortex

Katya Krieger-Redwood, Catarina Teige, James Davey, Mark Hymers, Elizabeth Jefferies
2015 Neuropsychologia  
Words in quotation marks were presented as auditory probes and did not appear on the screen.  ...  with the findings of fMRI studies that have used multi-voxel pattern analysis to investigate brain areas representing specific semantic features and concepts: several studies using simple tasks without marked  ... 
doi:10.1016/j.neuropsychologia.2015.02.030 pmid:25726898 pmcid:PMC4582805 fatcat:er7waczy5jfnpijfrv24wesqfu

Neural mechanisms underlying song and speech perception can be differentiated using an illusory percept

Mark Hymers, Garreth Prendergast, Can Liu, Anja Schulze, Michellie L. Young, Stephen J. Wastling, Gareth J. Barker, Rebecca E. Millman
2015 NeuroImage  
The issue of whether human perception of speech and song recruits integrated or dissociated neural systems is contentious. This issue is difficult to address directly since these stimulus classes differ in their physical attributes. We therefore used a compelling illusion (Deutsch et al. 2011) in which acoustically identical auditory stimuli are perceived as either speech or song. Deutsch's illusion was used in a functional MRI experiment to provide a direct, within-subject investigation of the
more » ... brain regions involved in the perceptual transformation from speech into song, independent of the physical characteristics of the presented stimuli. An overall differential effect resulting from the perception of song compared with that of speech was revealed in right midposterior superior temporal sulcus/right middle temporal gyrus. A left frontotemporal network, previously implicated in higher-level cognitive analyses of music and speech, was found to co-vary with a behavioural measure of the subjective vividness of the illusion, and this effect was driven by the illusory transformation. These findings provide evidence that illusory song perception is instantiated by a network of brain regions that are predominantly shared with the speech perception network.
doi:10.1016/j.neuroimage.2014.12.010 pmid:25512041 fatcat:36mtc6dzsvdn5hnd5dlm3rw64a

Patterns of neural response in scene-selective regions of the human brain are affected by low-level manipulations of spatial frequency

David M. Watson, Mark Hymers, Tom Hartley, Timothy J. Andrews
2016 NeuroImage  
We found that image filter had a marked effect on the patterns of response in scene-selective regions.  ...  These manipulations had a marked effect on the low level image properties.  ... 
doi:10.1016/j.neuroimage.2015.08.058 pmid:26341028 fatcat:mko434cwjrfyhjz4nhbnxzdmtm

Task-based and resting-state fMRI reveal compensatory network changes following damage to left inferior frontal gyrus

Glyn P. Hallam, Hannah E. Thompson, Mark Hymers, Rebecca E. Millman, Jennifer M. Rodd, Matthew A. Lambon Ralph, Jonathan Smallwood, Elizabeth Jefferies
2018 Cortex  
The design matrix was conducted in a similar fashion to that described in Hymers et al. (2015) .  ...  This method involved enantiomorphic normalization, which uses information from the contralateral intact hemisphere to fill in the area marked by the lesion mask Nachev et al., 2008) .  ... 
doi:10.1016/j.cortex.2017.10.004 pmid:29223933 fatcat:dqbufg3qt5enjnchrqygbf4zui

Responses in the right posterior superior temporal sulcus show a feature-based response to facial expression

Tessa R. Flack, Timothy J. Andrews, Mark Hymers, Mohammed Al-Mosaiwi, Samuel P. Marsden, James W.A. Strachan, Chayanit Trakulpipat, Liang Wang, Tian Wu, Andrew W. Young
2015 Cortex  
2015) 'Responses in the right posterior superior temporal sulcus show a feature-based response to facial expression.', Cortex., 69 . pp. 14-23. Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata
more » ... in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. This is a repository copy of Responses in the right posterior superior temporal sulcus show a feature-based response to facial expression.
doi:10.1016/j.cortex.2015.03.002 pmid:25967084 fatcat:d2g4fmd7v5f4xbmykxpig3mdou

Default mode network can support the level of detail in experience during active task states

Mladen Sormaz, Charlotte Murphy, Hao-ting Wang, Mark Hymers, Theodoros Karapanagiotidis, Giulia Poerio, Daniel S. Margulies, Elizabeth Jefferies, Jonathan Smallwood
2018 Proceedings of the National Academy of Sciences of the United States of America  
Whether experience was based on verbal or visual codes was associated with neural patterns at around the 70th percentile of the principal gradient, marked in orange in Fig. 5 .  ... 
doi:10.1073/pnas.1721259115 pmid:30150393 fatcat:zmcxwlmlm5hjtj2dgylbgnikiu
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