 - Paired-pulse transcranial magnetic stimulation TMS: A wire coil is held to the subjects scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. The effect of paired-pulse TMS on the muscles is detected with electrodes taped to the skin on the arms or legs. 