rTMS to Improve Motor Function in Autism

Inclusion Criteria: ASD or control participants must meet all of the inclusion criteria to eligible for this study: 1. Aged between 18 and 40 years old. 40 years is chosen as the cut-off because of the report of high rates of Parkinsonism in autistic adults \> 39years; 2. Have IQ\>70; 3. Are able to read, write and communicate effectively in English; 4. Are able to provide informed consent. We will recruit only intellectually-able autistic adults. The intellectual ability will be determined using WASI-II. The ability to provide consent will be determined using clinical assessment. 5. Have no prior history of seizure; 6. Must sign and date the informed consent form; 7. Stated willingness to comply with all study procedures; 8. Agreement to adhere to Lifestyle Considerations, that is: refrain from consumption of alcohol, tobacco, marijuana, or caffeine on the day of study visits. All ASD participants: 1. Will have DSM-5 diagnosis of ASD without intellectual disability, confirmed by clinical assessment and the Autism Diagnostic Observation Schedule - 2 (ADOS-2); 2. Will have significant motor function difficulties defined as a standard composite score \<40 (i.e., \>1 standard deviation below the mean) on either fine or gross motor composite scores of the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition or BOT-2; 3. Are clinically stable as determined by clinical assessment, with no medication changes over the past 4 weeks. Given the high variability of handedness in ASD, we will include participants with left, right or mixed handedness. Exclusion Criteria: ASD or control participants will be excluded if they experience/have: 1. Current pregnancy; 2. Current or past history of co-morbid medical condition that may require urgent medical intervention; 3. DSM-5 substance use disorder (other than tobacco) within the past 6 months; however, all participants will be asked to refrain from smoking or taking caffeine four hours prior to the iTBS session; 4. Significant hearing or visual impairment interfering with the ability to read or hear instructions; 5. Significantly debilitating medical or neurologic illness (e.g., encephalitis, aneurysms, tumors, central nervous system infections), or acute or unstable medical illnesses as determined by project physician (e.g., uncontrolled diabetes); 6. Metal implants or a pace-maker; 7. Prior rTMS treatment; In addition, ASD participants will be excluded if they report taking benzodiazepines or anticonvulsants currently. NT controls will be excluded if they have: 1. Presence of psychopathology other than specific phobia, as screened by Personality Assessment Inventory and; 2. A known diagnosis of Pervasive Developmental Disorder or ASD among any biologically related family members.