Role of GABAergic Transmission in Auditory Processing in Autism Spectrum Disorder

Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome. Researchers think brain development may be controlled by gamma-aminobutyric acid (GABA). They want to learn how abnormalities in the GABA system may contribute to ASD. Objective: To see if repetitive transcranial magnetic stimulation (rTMS) creates short-term changes in how different parts of the brain communicate. Eligibility: Right-handed people ages 11-17 with ASD, and healthy volunteers ages 18-25. Design: Participants will be screened with: Medical history Physical exam Medicine review Neurological exam Psychological tests and rating scales Forms and surveys. Participants will have a hearing test and ear exam. Participants will have magnetic resonance imaging (MRI) of the brain. They will lie on a table that moves in and out of the MRI scanner. They may look at a screen while in the scanner. A coil will be placed over their head. Participants will have magnetic resonance spectroscopy. It takes pictures of chemicals in the brain using the MRI scanner. Participants will have magnetoencephalography. They will sit in a chair. A helmet with magnetic field sensors will be placed on their head. Participants will have TMS. A wire coil will be held on their scalp. A brief electrical current will pass through the coil. Participants will have electromyography. Sticky pad electrodes will be placed on the skin during TMS. The electrical activity of their muscles will be measured. Participants will have rTMS. It uses short bursts of magnetic pulses to affect brain activity. ASD participants may have visits scheduled as often as 1 time a week or as far apart as 2 months based on the participants or study team's availability. Healthy volunteers will have 3 visits over 3-4 weeks....