 Participants also undergo transcranial magnetic stimulation TMS. For this procedure, an insulated wire coil is held over the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that travels through the scalp and skull and causes small electrical currents in the brain cortex outer part of the brain. The stimulation may cause twitching in the muscles of the face, arm, or leg. The electrical activity of the muscles is recorded with a computer or other recording device, using electrodes attached to the skin with tape. 