. Prefrontal rTMS causes cutaneous discomfort and muscle twitching; therefore, an optimal control condition, ie, sham condition, would mimic the cutaneous sensation and muscular discomfort of rTMS without stimulating the brain. Ideally, the quality and intensity of the sham condition would feel identical to the quality and intensity of the rTMS condition, except that the sham would have no effect on cortical activity. We designed and built a focal electrical stimulation system as a sham rTMS condition