For TMS, an insulated wire coil is placed on the subject's scalp. A brief electrical current passes through the coil, creating a magnetic pulse that travels through the scalp and skull and causes small electrical currents in the cortex, or outer part of the brain. The stimulation may cause muscle, hand or arm twitching, or may cause twitches or temporary tingling in the forearm, head, or face muscles. During the stimulation, electrical activity of muscles is recorded with a computer or other recording device, using electrodes attached to the skin with tape. Some TMS sessions may be videotaped.