Bihemispheric Modulation of the Motor Cortex by Transcranial Direct Current Stimulation in Subacute Stroke Patients

We will consecutively enroll subacute (2-4 weeks after stroke onset) patients with first-time, unilateral, ischemic subcortical stroke in the middle cerebral artery territory with mild to moderate hand weakness. All subjects will be assessed for baseline upper extremity motor function (Fugl-Meyer test and Action Research Arm test), structural and functional magnetic resonance imaging (fMRI). A single session of bihemispheric tDCS (anodal tDCS to ipsilesional M1 and cathodal tDCS to contralesional M1 with 2 mA stimulation for 20 min) or sham tDCS (same but stimulation for only 2 min) with simultaneous physical/occupational therapy will be tested in each subject with a randomized sequence on different days (at least two days apart from each other). All stroke patients will receive standard medical and rehabilitation treatments during the study period. Changes in corticospinal excitability and transcallosal inhibition from the TMS study, as well as sensorimotor oscillations, MEG source projection, and functional connectivity from the task-related MEG will be assessed immediately before and after intervention.