Postural support requirements preferentially modulate late components of the gastrocnemius response to transcranial magnetic stimulation

Cassandra Russell, Nathan Difford, Alexander Stamenkovic, Paul Stapley, Darryl McAndrew, Caitlin Arpel, Colum MacKinnon, Jonathan Shemmell

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Mounting evidence suggests that motor evoked potentials (MEPs) recorded in upper limb muscles with postural support roles following transcranial magnetic stimulation receive contributions from both corticospinal and non-corticospinal descending pathways. We tested the hypothesis that neural structures responsible for regulating upright balance are involved in transmitting late portions of TMS-induced MEPs in a lower limb muscle. MEPs were recorded in the medial gastrocnemius muscles of each leg, while participants supported their upright posture in five postural conditions that required different levels of support from the target muscles. We observed that early and late portions of the MEP were modulated independently, with early MEP amplitude being reduced when high levels of postural support were required from a target muscle. Independent modulation of early and late MEPs by altered postural demand suggests largely separable transmission of each part of the MEP. The early component of the MEP is likely generated by fast-conducting corticospinal pathways, whereas the later component may be primarily transmitted along a polysynaptic cortico-reticulospinal pathway.

Original languageEnglish (US)
Pages (from-to)2647-2657
Number of pages11
JournalExperimental Brain Research
Volume240
Issue number10
DOIs
StatePublished - Oct 2022

Bibliographical note

Publisher Copyright:
© 2022, The Author(s).

Keywords

  • Balance control
  • Brainstem
  • Cortico-reticulospinal
  • Corticospinal
  • Posture
  • Reticular formation
  • Triceps surae
  • Humans
  • Evoked Potentials, Motor/physiology
  • Pyramidal Tracts/physiology
  • Transcranial Magnetic Stimulation
  • Upper Extremity
  • Electromyography
  • Muscle, Skeletal/physiology

PubMed: MeSH publication types

  • Journal Article

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