Brain Inhibition of Muscle Movement in Normal Volunteers

Study Summary

This study will use transcranial magnetic stimulation, or TMS (described below), to examine how the brain controls muscle movement to prevent unwanted movements in surrounding muscles. For example, when a person moves a finger, a part of the brain called the cortex prevents unwanted movements in other fingers by a process called cortical inhibition. In people with the muscle disorder dystonia, cortical inhibition does not work properly and patients suffer from uncontrolled and sometimes painful movements. A better understanding of how this process works in normal people may shed light on what goes wrong in dystonia and how the condition can be treated. Healthy normal volunteers 19 years of age and older may be eligible for this study. Candidates will be screened with a medical history and physical and neurological examinations. People with a current medical or surgical condition or neurological or psychiatric illness may not participate, nor may individuals who are taking medication that may influence nervous system function. Participants will undergo TMS to record the electrical activity of muscles in the hand and arm that are activated by magnetic stimulation. For the procedure, subjects are seated in a chair with their hands placed on a pillow in their laps. A wire coil in placed on their scalps. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. Subjects will be asked to move their second finger in response to a loud beep or visual cue. In some trials, a brief, mild electrical shock will also be applied to the end of either the second or fifth finger. The shock is not painful. TMS may cause muscle, hand or arm twitching if the coil is near the part of the brain that controls movement, or it may induce twitches or temporary tingling in the forearm, head, or face muscles. The twitching may cause mild discomfort, but the procedure is rarely considered painful.

Conditions Studied

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