Abstract
OBJECTIVES: To assess the effect of unilateral and bilateral hand movements on interhemispheric inhibition (IHI), which was assessed with transcranial magnetic stimulation and compared between healthy volunteers and patients with stroke. METHODS: Eleven patients with chronic hemiparetic stroke performed paretic and bilateral hand tasks, and six healthy volunteers performed right-hand and bilateral hand tasks. IHI between the hemispheres was assessed using transcranial magnetic stimulation before and 0, 10, and 30 min after both tasks. RESULTS: IHI from contralesional to ipsilesional motor cortex (M1) after the bilateral hand task was disinhibited more strongly and for a longer time than that after the paretic hand task in stroke patients. IHI from ipsilesional to contralesional M1 in stroke patients was significantly disinhibited with the bilateral hand task and inhibited with the paretic hand task 10 min after the tasks. Task and time had no significant effects on IHI in both tasks in healthy volunteers. CONCLUSIONS: Inter-hemispheric inhibitory interneurons were modified differently by unilateral and bilateral hand movements. Bilateral hand movement might have a stronger effect on IHI than paretic hand movement.