Role of the Intact Hemisphere in Recovery of Motor Function After Stroke

INCLUSION CRITERIA: Patients with single ischemic hemispheric lesions at least 12 months after the stroke who had a severe paresis (below MRC grade 2) of the affected arm initially. An anatomical MRI scan will be acquired at the NIH if a recent one (within 6 months) is not available. Normal volunteers who are willing and able to perform the tasks will be included in the study. Healthy normal volunteers recruited for the study will receive neurological and physical exams to ensure their healthy conditions. EXCLUSION CRITERIA: Patients with more than one stroke. Patients with bilateral motor impairment. Patients with cerebellar or brainstem lesions. Patients or subjects unable to perform the task (wrist or elbow flexion at least MRC grade 2). Patients or subjects with history of severe alcohol or drug abuse, psychiatric illness like severe depression, poor motivational capacity, or severe language disturbances, particularly of receptive nature or with serious cognitive deficits (defined as equivalent to a mini-mental state exam score of 20 or less). Patients or subjects with severe uncontrolled medical problems (e.g. cardiovascular disease, severe rheumatoid arthritis, active joint deformity of arthritic origin, active cancer or renal disease, any kind of end-stage pulmonary or cardiovascular disease, or a deteriorated condition due to age, uncontrolled epilepsy or others). Patients or subjects with metal in the cranium except mouth. Patients or subjects with dental braces, metal fragments from occupational exposure or surgical clips in or near the brain. Patients or subjects with eye, blood vessel, cochlear or eye implants. Patients or subjects with increased intracranial pressure as evaluated by clinical means. Patients with cardiac or neural pacemakers, intracardiac lines and/or implanted medication pumps. Patients or subjects with history of loss of consciousness or epilepsy. Patients or subjects with unstable cardiac dysrhythmia. Patients or subjects with h/o hyperthyroidism or individuals receiving drugs acting primarily on the central nervous system.