Crossed corticospinal facilitation between arm and trunk muscles in humans
File(s)
Accepted version
Author(s)
Chiou, Shin-Yi
Strutton, Paul H
Perez, Monica A
Type
Journal Article
Abstract
A voluntary contraction of muscles with one arm increases corticospinal excitability of projections to the contralateral resting arm, a phenomenon known as crossed facilitation. Although many motor tasks engage simultaneous activation of the arm and trunk, interactions between corticospinal projections targeting these segments remain largely unknown. Using transcranial magnetic stimulation over the trunk representation of the primary motor cortex we examined motor evoked potentials (MEPs) in the resting erector spinae (ES) muscle when the contralateral arm remained at rest or performed 20% of isometric maximal voluntary contraction (MVC) into index finger abduction, thumb abduction, elbow flexion and elbow extension. We found that MEP size in the ES increased during all voluntary contractions, with greater facilitation occurring during elbow flexion and index finger abduction. To further examine the origin of changes in MEP size we measured short-interval intracortical inhibition (SICI) and cervicomedullary MEPs (CMEPs) in the ES muscle during elbow flexion and index finger abduction and when the arm remained at rest. Notably, SICI decreased and CMEPs remained unchanged in the ES during both voluntary contractions compared with rest, suggesting a cortical origin for the effects. Our findings reveal crossed facilitatory interactions between trunk extensor and proximal and distal arm muscles, particularly for elbow flexor and index finger muscles, likely involving cortical mechanisms. These interactions might reflect the different role of these muscles during functionally relevant arm and trunk movements.
Date Issued
2018-11
Date Acceptance
2018-05-30
Citation
Journal of Neurophysiology, 2018, 120 (5), pp.2595-2602
ISSN
0022-3077
Publisher
American Physiological Society
Start Page
2595
End Page
2602
Journal / Book Title
Journal of Neurophysiology
Volume
120
Issue
5
Copyright Statement
© 2018 the American Physiological Society
Sponsor
Wellcome Trust
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/29847230
Grant Number
097816/Z/11/B
Subjects
Corticospinal pathway
erector spinae
intracortical inhibition
motor evoked potentials
subcortical pathways
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2018-05-30