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Past, Current and Future Clinical Applications of MEG
[chapter]
2011
Magnetoencephalography
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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]
2020
bioRxiv
pre-print
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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
doi:10.1101/2020.06.21.157412
fatcat:62e2qapq6ngqvp6x4rkad7d6ga
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... 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
SAILS: Spectral Analysis In Linear Systems
2020
Journal of Open Source Software
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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
doi:10.21105/joss.01982
fatcat:xzy7s6nfb5denfyyh5dn55mvqu
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... 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.
Delineating between-subject heterogeneity in alpha networks with Spatio-Spectral Eigenmodes
2021
NeuroImage
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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 ) , https://vcs.ynic.york.ac.uk ...
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
2011
PLoS ONE
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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]
2017
bioRxiv
pre-print
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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
doi:10.1101/153973
fatcat:on74dilrffeujelhqzrg4bz5gm
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... 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.
Charting the effects of TMS with fMRI: Modulation of cortical recruitment within the distributed network supporting semantic control
2016
Neuropsychologia
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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
2018
NeuroImage
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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
2015
Brain and Language
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., Göbel, Silke M. orcid.org/0000-0001-8845-6026, 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
2015
Neuropsychologia
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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
2015
NeuroImage
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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
doi:10.1016/j.neuroimage.2014.12.010
pmid:25512041
fatcat:36mtc6dzsvdn5hnd5dlm3rw64a
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... 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.
Patterns of neural response in scene-selective regions of the human brain are affected by low-level manipulations of spatial frequency
2016
NeuroImage
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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
2018
Cortex
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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
2015
Cortex
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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
doi:10.1016/j.cortex.2015.03.002
pmid:25967084
fatcat:d2g4fmd7v5f4xbmykxpig3mdou
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... 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.
Default mode network can support the level of detail in experience during active task states
2018
Proceedings of the National Academy of Sciences of the United States of America
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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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