 At Boston Childrens Hospital, each subjects participation in the study will consist of four visits: two screening visits, and two TMS sessions. At Beth Israel Deaconess Medical Center, each subjects participation will consist of three visits: one screening visit, and two TMS sessions. Each screening visit is expected to last between 2-3 hours, during which participants will first provide informed consent. Participants will then receive a thorough medical examination by a neurologist, and a neuropsychological evaluation including IQ measures and ASD specific evaluations. If eligible to continue, participants will then come back for two identical TMS visits, that are spaced 1-5 weeks apart. These visits are expected to last between 3-4 hours, and include the TMS measures of brain plasticity. 