rTMS involves repeated magnetic pulses delivered in trains or short bursts of impulses. A brief electrical current is passed through a wire coil held on the scalp. The current creates a magnetic pulse that stimulates the brain. The subject hears a click and may feel a pulling sensation on the skin under the coil. There may be a twitch in muscles of the face, arm or leg. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The effect of TMS on the muscles is detected with small metal disk electrodes taped onto the skin of the right hand. Subjects receive four rTMS blocks per 10 minutes. Each block consists of a total of 375 pulses.