Neurophysiology of Surround Inhibition in the Human Motor Cortex

Background: Movement disorders have many different causes and symptoms. Researchers still do not fully understand which parts of the brain are involved in fine movement. They want to learn about which brain regions could be abnormal in people with movement disorders. Objective: To better understand how the brain controls movement. Eligibility: Healthy, right-handed adults age 18-70 years old. Design: Participants will be screened with a physical exam and questions about their handedness. They may have a urine test. Participants will have 1 or 2 clinic visits. The first visit will last about 1.5 hours. The second will last about 3 hours. Participants will have structural magnetic resonance imaging (MRI). A strong magnetic field and radio waves take pictures of the brain. Participants will lie on a table that slides in and out of a metal cylinder. Participants may have transcranial magnetic stimulation. A wire coil is held on the scalp. A brief electrical current is passed through the coil and creates a magnetic pulse that stimulates the brain. Participants will wear a pair of glasses or a headband with small sensors so researchers can track head position. Participants will perform a simple index finger movement task. Participants may have surface electromyography from at least two hand muscles. Small metal disk or adhesive pad electrodes will be taped to the skin. Participants will be seated in a comfortable chair with their hands placed on a pillow. Participants may have an electroencephalography. A cap with small disc electrodes will be placed on the scalp.