For transcranial magnetic stimulation, a wire coil is held on the subject's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. The subject hears a click and feels a pulling sensation on the skin under the coil. There may also be a twitch in the muscles of the arm or leg. During the TMS, subjects are asked to name pictures of common everyday objects that appear on a computer screen. They are asked to name them as fast and as accurately as possible. Their voice is recorded to determine the accuracy of their answers and the time it takes to answer. Subjects may also be asked to tense certain muscles slightly or perform other simple actions during the TMS to position the coil properly.