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Cortical contributions to anticipatory postural adjustments in the trunk.

Authors
  • Chiou, Shin-Yi1
  • Hurry, Madeleine1
  • Reed, Thomas1
  • Quek, Jing Xiao1
  • Strutton, Paul H1
  • 1 The Nick Davey Laboratory, Division of Surgery, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, UK.
Type
Published Article
Journal
The Journal of Physiology
Publisher
Wiley (Blackwell Publishing)
Publication Date
Apr 01, 2018
Volume
596
Issue
7
Pages
1295–1306
Identifiers
DOI: 10.1113/JP275312
PMID: 29368403
Source
Medline
Keywords
License
Unknown

Abstract

Voluntary limb movements are associated with increases in trunk muscle activity, some of which occur within a time window considered too fast to be induced by sensory feedback; these increases are termed anticipatory postural adjustments (APAs). Although it is known that the function of APAs is to maintain postural stability in response to perturbations, excitability of the corticospinal projections to the trunk muscles during the APAs remains unclear. Thirty-four healthy subjects performed rapid shoulder flexion in response to a visual cue in standing and lying positions. Transcranial magnetic stimulation (TMS) was delivered over the trunk motor cortex to examine motor evoked potentials (MEPs) in erector spinae (ES) and in rectus abdominis (RA) muscles at several time points prior to the rise in electromyographic activity (EMG) of anterior deltoid (AD) muscle. TMS was also used to assess short-interval intracortical inhibition (SICI) and cervicomedullary MEPs (CMEPs) in ES in the standing position. MEPs in ES were larger at time points closer to the rise in AD EMG in both standing and lying positions, whereas MEPs in RA did not differ over the time course examined. Notably, SICI was reduced at time points closer to the rise in AD EMG, with no change in CMEPs. Our results demonstrate that increasing excitability of corticospinal projections to the trunk muscles prior to a voluntary limb movement is likely to be cortical in origin and is muscle specific.

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