Behavioral and neurophysiological changes associated with a single session of bimanual task practice after stroke

Objective Stroke survivors often show slower, uncoordinated bimanual performance. This study examined the effects of a single session of bimanual task practice on performance, coordination, motor corticospinal excitability (CSE), and transcallosal inhibition in stroke survivors compared to age-matched controls. Methods Eleven individuals with chronic stroke and ten neurotypical controls practiced a naturalistic bimanual task for 400 trials. Movement time, errors and bimanual coordination ability were assessed before and after practice. Transcranial magnetic stimulation was used to examine CSE of the ipsilesional and contralesional motor cortices (M1), and ipsilateral silent period duration and inhibition in the two M1s at pre- and post-test. Results Both groups significantly reduced movement time without increasing errors. Controls improved bimanual coordination, but stroke survivors did not. Controls showed significant increases in bilateral CSE, while stroke survivors showed increase only in contralesional CSE. Ipsilateral silent period duration and inhibition remained unchanged in both groups. Conclusions A single session of bimanual task practice improves speed, but not bimanual coordination in stroke survivors. Novel to this study, contralesional, but not ipsilesional CSE is modulated following a single bimanual task practice session. Significance Findings highlight potential clinical relevance for neurorehabilitation strategies targeting bimanual coordination for improved arm function.