Safety and Tolerability. An experienced data safety and monitoring board will be established. Primary adverse outcome for tDCS is any decrease in function of either upper extremity, screened for by both uni- and bi-manual measures. An established tDCS Safety and Tolerability evaluation (TST) will be performed on days 1, 5, and 10 on all subjects. Only trained personnel will administer treatments under the approval and certification from experienced brain stimulation team members. All tDCS interventions will occur within a hospital setting with immediate access to medical care in the unlikely event care is required. Any potential adverse events are immediately reported to the site and principal investigators, DSMB safety monitor, and ethics boards. For any potentially serious adverse events, treatments will be suspended pending decisions of the above.