Postural challenge affects motor cortical activity in young and old adults

Selma Papegaaij*, Wolfgang Taube, Helco G. van Keeken, Egbert Otten, Stephane Baudry, Tibor Hortobagyi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Scopus)

Abstract

When humans voluntarily activate a muscle, intracortical inhibition decreases. Such a decrease also occurs in the presence of a postural challenge and more so with increasing age. Here, we examined age-related changes in motor cortical activity during postural and non-postural contractions with varying levels of postural challenge. Fourteen young (age 22) and twelve old adults (age 70) performed three conditions: (1) voluntary contraction of the soleus muscle in sitting and (2) leaning forward while standing with and (3) without being supported. Subthreshold transcranial magnetic stimulation was applied to the soleus motor area suppressing ongoing EMG, as an index of motor cortical activity. The area of EMG suppression was similar to 60% smaller (p <0.05) in unsupported vs. supported leaning and sitting, with no difference between these latter two conditions (p > 0.05). Even though in absolute terms young compared with old adults leaned farther (p = 0.018), there was no age effect or an age by condition interaction in EMG suppression. Leaning closer to the maximum without support correlated with less EMG suppression (rho = -0.44, p = 0.034). We conclude that the critical factor inmodulating motor cortical activity was postural challenge and not contraction aim or posture. Age did not affect the motor control strategy as quantified by the modulation of motor cortical activity, but the modulation appeared at a lower task difficulty with increasing age. (C) 2015 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)78-85
Number of pages8
JournalExperimental Gerontology
Volume73
DOIs
Publication statusPublished - Jan-2016

Keywords

  • Balance
  • Aging
  • Postural activation
  • Voluntary activation
  • Transcranial magnetic stimulation
  • Intracortical inhibition
  • TRANSCRANIAL MAGNETIC STIMULATION
  • INTRACORTICAL INHIBITION
  • SOLEUS MUSCLE
  • CORTICOSPINAL PATHWAYS
  • SHOULDER POSITIONS
  • HAND MUSCLES
  • EXCITABILITY
  • CONTRACTION
  • PERFORMANCE
  • RESPONSES

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