Plastic changes in interhemispheric inhibition with practice of a two-hand force production task: a transcranial magnetic stimulation study.

We studied the effects of practice of an unusual two-hand finger force production task on electromyographic and force responses to transcranial magnetic stimulation (TMS). Prior to practice, force production by a hand resulted in decreased TMS-induced responses in the other hand. After practice, fingers that were explicitly required to produce force during practice showed a significant drop in these inhibitory effects, while other fingers did not. We conclude that interhemispheric inhibitory projections can show plastic changes that favor the execution of a practiced task.