There is sufficient evidence to suggest that behavioral abnormalities observed in autism may be, in part, the result of dysregulation of glutamate neurotransmission in the brain. One method of measuring glutamate in the brain in a non-invasive measure is termed Magnetic Resonance Spectroscopy (MRS). This technique is based on the same principles as MRI but, instead of images, it provides information about the biochemical composition of the brain. In this study, the investigators will study glutamate concentrations in the brain of older children and adolescents with normal intelligence and autism. In addition, secondary analyses of MRS analysis will measure concentrations of other brain chemicals such as choline, creatine and NAA and exploring possible correlations between abnormalities in such chemicals and the symptoms of autism. Significance: Several currently used pharmacological treatments of autism spectrum disorder symptoms include targeting receptors for this neurotransmitter, and a better understanding of the role of glutamate transmission on symptoms of autism will lead to better targeted intervention strategies in the future.