Effect of Neural Constraints on Movement in Stroke

Inclusion Criteria: * History of unilateral supratentorial ischemic stroke that occurred at least six months prior to enrollment * Age between 18-80 * Paresis confined to one side, with substantial motor impairment of the upper limb and some residual voluntary movement (Upper Extremity Fugl-Meyer Assessment in the range of 10-50/66, Chedoke McMaster Stroke Assessment Hand section \<=4) * Ability to communicate, understand, and provide informed consent * Ability to elevate their limb against gravity up to at least 75 degrees of shoulder flexion and to generate active elbow extension * MRI compatible * Intact skin on the hemiparetic arm * Ability to sit for three hours. Exclusion Criteria: * Motor or sensory impairment in the non-affected limb (FMA\<66, filament \>3.6) * Any brainstem and/or cerebellar lesion * untreated cardiovascular disease * History of neurologic disorder other than stroke that affects the arms * Any acute or chronic painful condition in the upper extremities or spine, indicated by a score ≥5 on a 10-point visual analog scale * Current use of a pacemaker * History of seizure * Chemo denervation: botulinum toxin injection to any portion of the paretic upper extremity within the last 6 months, or phenol/alcohol injections \<12 months before participation * Flexion contractures larger than 30 degrees in the elbow, wrist, metacarpophalangeal joints (MCP) and interphalangeal joints (IP) after stretching for 15 minutes * Current participation in any experiment…