Brain Use of Sensory Information to Generate Movement

This study will use transcranial magnetic stimulation (TMS) to investigate functions of brain regions that may use information from sensory organs, such as the eyes or ears, to generate movements. For TMS, a wire coil is held over the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. This may cause a pulling sensation on the skin under the coil and twitching in muscles of the face, arm, or leg. During the stimulation, the participant may be asked to tense certain muscles slightly or perform other simple actions. Healthy normal volunteers 18 years of age and older may be eligible for this study. Individuals with a history of neuropsychiatric disorders, brain lesions such as tumors, stroke, or trauma, or a history of significant medical disorders, such as cancer, may not participate. Candidates will be screened with a medical history, brief physical examination, and questionnaire. Participants will be presented a sequence of shapes (circles, rectangles, and triangle) and will count the number of a specified shape. Each number is assigned to a corresponding response button. The subject will push the appropriate button with the corresponding finger. During these experiments, the scalp will be stimulated by TMS. Each set of TMS measurements will take up to 3-1/2 hours.