Structural and functional imaging studies have significantly improved the understanding of the neural basis of developmental and neurological disorders. However, despite recent advancements, anatomical imaging in autistic patients has generally revealed little evidence of pathology. In this proposal, high-resolution diffusion tensor imaging (DTI) of the mouse brain will be developed as a surrogate for better diagnosis of autism. The researchers will study the DTI properties of two mouse models that exhibit multiple behavioral and brain phenotypes relevant to autism, including reduced sociability and underdevelopment of the corpus callosum, which is the band of nerve fibers that join the two hemispheres of the brain. While DTI has been used extensively in human subjects, it would be useful to develop this methodology for rodents to assess the relationship between brain structure and social behavioral abnormalities in mouse models relevant to autism. Successful implementation of the proposed DTI techniques in these models will not only be helpful in understanding the biological and physiological basis of autism spectrum disorders, but will also benefit studies of other mouse models of developmental and psychiatric brain disorders.