Although autism spectrum disorder (ASD) is one of the most heritable cognitive disorders, the genetic causes of ASDs remain uncertain. It is thought that ASDs are caused by aberrant connections between neurons in the brain. It is not understood how multiple diverse genetic factors cause the common symptoms of ASDs but because many genes are involved in controlling the development of the neural circuits affected in ASDs, mutations in any of multiple genes could lead to the disruption of these circuits. Thus, understanding how neural circuitries are altered in animal models of ASDs may provide insights into the etiology of this disorder. In the present study, Dr. Xiong will examine neural connectivity in a mouse model of autism. Using sophisticated imaging techniques, he will map short-range and long-range neural connections in the auditory cortex of mice lacking MeCP2, the gene mutated in Rett Syndrome, a genetic disorder which shares many common features with ASDs. Determining which neural pathways, when disrupted, produce the autistic-like behaviors seen in the MeCP2 mutant mouse should provide insight into the neural pathways disrupted in autism. This study may provide insights into the neurobiology of autism, as well as help to develop a general and efficient strategy for relating genes to neurological dysfunction in rodent models of autism.