Interhemispheric plasticity in humans.

Med Sci Sports Exerc

Department of Exercise and Sport Science, East Carolina University, Greenville, NC 27858, USA.

Published: July 2011

Introduction: Chronic unimanual motor practice increases the motor output not only in the trained but also in the nonexercised homologous muscle in the opposite limb. We examined the hypothesis that adaptations in motor cortical excitability of the nontrained primary motor cortex (iM1) and in interhemispheric inhibition from the trained to the nontrained M1 mediate this interlimb cross education.

Methods: Healthy, young volunteers (n=12) performed 1000 submaximal voluntary contractions (MVC) of the right first dorsal interosseus (FDI) at 80% MVC during 20 sessions.

Results: Trained FDI's MVC increased 49.9%, and the untrained FDI's MVC increased 28.1%. Although corticospinal excitability in iM1, measured with transcranial magnetic stimulation (TMS) before and after every fifth session, increased 6% at rest, these changes, as those in intracortical inhibition and facilitation, did not correlate with cross education. When weak and strong TMS of iM1 were delivered on a background of a weak and strong muscle contraction, respectively, of the right FDI, excitability of iM1 increased dramatically after 20 sessions. Interhemispheric inhibition decreased 8.9% acutely within sessions and 30.9% chronically during 20 sessions and these chronic reductions progressively became more strongly associated with cross education. There were no changes in force or TMS measures in the trained group's left abductor minimi digiti and there were no changes in the nonexercising control group (n=8).

Conclusions: The findings provide the first evidence for plasticity of interhemispheric connections to mediate cross education produced by a simple motor task.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4137570PMC
http://dx.doi.org/10.1249/MSS.0b013e31820a94b8DOI Listing

Publication Analysis

Top Keywords

cross education
12
interhemispheric inhibition
8
fdi's mvc
8
mvc increased
8
excitability im1
8
weak strong
8
motor
5
interhemispheric
4
interhemispheric plasticity
4
plasticity humans
4

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!