In this study, the investigators will be examining the effects of repetitive transcranial magnetic stimulation (rTMS) on executive function deficits in individuals with autism spectrum disorder. Half of the participants will be chosen by chance to receive active rTMS stimulation while half will be chosen by chance to receive sham rTMS. Sham rTMS will feel the same as active rTMS only there will be no direct brain stimulation. This is necessary to ensure that active rTMS is efficacious in the enhancement of executive function in individuals with autism spectrum disorder. Based on results from a recently published pilot study, the investigators propose that active rTMS treatment will result in a significant improvement in working memory performance compared to sham rTMS treatment.

This study is a randomized, double blind, sham controlled study to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) as a treatment for executive function deficits in individuals with autism spectrum disorder between 16 and 25 years of age. The study duration is approximately 3 months, with the rTMS sessions lasting for 4 weeks, 5 times a week, for about 1 hour each. Several scales will be used to assess for symptom severity and adaptive functioning. Cognition will be assessed using a validated battery.

This study also involves a type of brain imaging known as magnetic resonance imaging (MRI) at the beginning and at the end of the 4 weeks of daily rTMS to better understand the effects of rTMS on brain structure and function. Investigators will measure the size and connections of different parts of the brain to assess brain structure and blood flow while participants are completing some basic tasks to asses brain function.

Inclusion Criteria Autism Spectrum Disorder (ASD):

• Are fluent in the English language
• Have a diagnosis of high functioning ASD (HF-ASD) (i.e., are verbal with an Intelligence Quotient (IQ) ≥ 70)
• Are competent to consent based on the subjects' ability to provide a spontaneous narrative description of the key elements of the study
• Are clinically stable as determined by their treating physician, with no medication changes over the past 4 weeks

Exclusion Criteria (ASD):

• Have a history of substance abuse or dependence in the last 6 months or have a positive urine toxicology screen
• Have a concomitant major medical or neurologic illness
• Have had a seizure in the past, or have a first-degree relative with epilepsy
• Have an abnormal clinical EEG
• Are pregnant or likely to get pregnant during the next 4 weeks
• Are clinically unstable
• Are on benzodiazepines or anticonvulsant medication
• Have a history of rTMS treatment.

Inclusion Criteria (Healthy Controls):

• Are fluent in the English language
• Competent to consent

Exclusion Criteria (Healthy Controls):

• Have a history of substance abuse or dependence in the last 6 months or have a positive urine toxicology screen
• Have a major medical or neurologic illness
• Have a diagnosed learning disorder or impaired academic or adaptive functioning on history
• Are pregnant
• Have an IQ < 80
• Have a psychiatric diagnosis on diagnostic interview assessments.