There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Rapid repetitive movements of the thumb (1 min duration) produce a reversible decrease
in the activated primary motor cortex (MI) excitability to transcranial magnetic stimulation
(TMS) with recovery within 35-40 min. In the present study we investigated (1) the
role of peripheral sensory feedback in inducing such decrease and (2) possible effects
of exercise on the non-activated MI. Stimulation of peripheral Ia afferent fibres,
induced by 1 min vibration of thenar muscles and 2 Hz electrical stimulation of the
median nerve at the wrist, have no effect on motor evoked potential (MEP) amplitude
to TMS suggesting no role for sensory feedback to produce MI excitability modulation.
Exercise produces a significant (P < 0.01) decrease of MEPs for homologous non-exercised
muscles with concomitant contraction of corresponding motor cortical output maps,
suggesting that changes in MI excitability also occur in the nonactivated hemisphere.
This 'crossed' effect might relate to an interhemispheric transfer of information,
via homotopic connections of the corpus callosum.