Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS

The representation of upper limb muscles in the motor cortex is not clear-cut. The motor cortex contains areas that, when stimulated, may activate different muscles simultaneously, hence they seem to overlap. We expected the cortical representations of synergistic muscle pairs to overlap more than t...

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Main Authors: Fang Jin, Sjoerd M. Bruijn, Andreas Daffertshofer
Format: Article
Language:English
Published: Elsevier 2023-09-01
Series:NeuroImage: Reports
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666956023000284
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author Fang Jin
Sjoerd M. Bruijn
Andreas Daffertshofer
author_facet Fang Jin
Sjoerd M. Bruijn
Andreas Daffertshofer
author_sort Fang Jin
collection DOAJ
description The representation of upper limb muscles in the motor cortex is not clear-cut. The motor cortex contains areas that, when stimulated, may activate different muscles simultaneously, hence they seem to overlap. We expected the cortical representations of synergistic muscle pairs to overlap more than those of non-synergistic muscles. To test this, we used navigated transcranial magnetic stimulation to probe eight hand and forearm muscles of twenty healthy participants. We transformed the cortical representations of muscles to a template MRI to allow for group analysis. We found that the amount of overlap in cortical representations differed significantly between within-hand and within-forearm muscle combinations. Most synergistic muscle pairs, both within the hand, within the forearm and between them, had a larger overlap than non-synergistic muscle pairs. Our study demonstrates the largely overlapping nature of cortical representations of upper limb muscles. It is noteworthy that the overlap is elevated in muscles that usually act in a synergistic manner.
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spelling doaj-art-0cf22f3093574071b98b5d7e2ada336d2025-08-20T01:59:21ZengElsevierNeuroImage: Reports2666-95602023-09-013310018310.1016/j.ynirp.2023.100183Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMSFang Jin0Sjoerd M. Bruijn1Andreas Daffertshofer2Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands; Institute Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, NetherlandsDepartment of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands; Institute Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, NetherlandsDepartment of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands; Institute Brain and Behavior Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, Netherlands; Corresponding author. Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.The representation of upper limb muscles in the motor cortex is not clear-cut. The motor cortex contains areas that, when stimulated, may activate different muscles simultaneously, hence they seem to overlap. We expected the cortical representations of synergistic muscle pairs to overlap more than those of non-synergistic muscles. To test this, we used navigated transcranial magnetic stimulation to probe eight hand and forearm muscles of twenty healthy participants. We transformed the cortical representations of muscles to a template MRI to allow for group analysis. We found that the amount of overlap in cortical representations differed significantly between within-hand and within-forearm muscle combinations. Most synergistic muscle pairs, both within the hand, within the forearm and between them, had a larger overlap than non-synergistic muscle pairs. Our study demonstrates the largely overlapping nature of cortical representations of upper limb muscles. It is noteworthy that the overlap is elevated in muscles that usually act in a synergistic manner.http://www.sciencedirect.com/science/article/pii/S2666956023000284TMSNeuro-navigationMotor mappingCortical overlapMuscle synergies
spellingShingle Fang Jin
Sjoerd M. Bruijn
Andreas Daffertshofer
Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
NeuroImage: Reports
TMS
Neuro-navigation
Motor mapping
Cortical overlap
Muscle synergies
title Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
title_full Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
title_fullStr Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
title_full_unstemmed Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
title_short Overlap in the cortical representation of hand and forearm muscles as assessed by navigated TMS
title_sort overlap in the cortical representation of hand and forearm muscles as assessed by navigated tms
topic TMS
Neuro-navigation
Motor mapping
Cortical overlap
Muscle synergies
url http://www.sciencedirect.com/science/article/pii/S2666956023000284
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AT sjoerdmbruijn overlapinthecorticalrepresentationofhandandforearmmusclesasassessedbynavigatedtms
AT andreasdaffertshofer overlapinthecorticalrepresentationofhandandforearmmusclesasassessedbynavigatedtms