Project Summary Autism spectrum disorder (ASD) is a cluster of related neurodevelopmental disorders that collectively impact 1 in 54 children in the United States. Shank3 is an ASD-associated gene because of evidence linking human Shank3 dysfunction to ASD and due to ASD-related behaviors caused by Shank3 mutations in two mouse lines. Shank3 mutant mice have multiple neuronal deficiencies in the striatum (altered synaptic structure and function, dendritic spine hypertrophy, corticostriatal hyperconnectivity, and enlarged striatal volume) and transcriptome in the striatum suggests additional dysregulation in glutamate-related and kinase-related genes. Research on how the Shank3 mutation affects ASD or social behavior more broadly is currently limited by the focus on a single inbred mouse species. The recent availability of a Shank3 mutant prairie vole represents a critical advance because, unlike mice, prairie voles are genetically diverse, share complex social behaviors with humans (monogamous pair bonding, bi-parental care, social loss-induced depression, and empathy- based consoling), and the full spectrum of social behaviors can be quantified in free-living prairie voles under natural conditions. The objective of this proposal is to determine the effects of Shank3 mutation in prairie voles on complex social behaviors in the field and laboratory, and the underlying biological mechanisms in the brain. Our central hypothesis is that Shank3 mutation in prairie voles alters striatal transcription regulating social behavior, which interacts with genotype to change both naturally observed and laboratory-induced species- specific complex social behaviors that are relevant to autism. Specific Aim 1 will determine the changes in natural social behaviors caused by Shank3 mutation. We will track social and reproductive behavior of free- living Shank3 mutant and wild-type prairie voles in semi-natural field enclosures over 3.5 months using an automated behavioral monitoring system, video cameras, and social network analyses. Specific Aim 2 will determine and integrate the transcriptome, genome and behavior of Shank3 mutant voles. We will test laboratory voles on a behavioral battery of their unique species-specific social behaviors, and then sequence the transcriptome and genome from dissected striatum. We will combine the three data sets using multi-omic integration. Together, this will provide critical information regarding the molecular and cellular alterations caused by Shank3 mutation, which will be directly relevant to potential clinical treatments and therapies. The proposed research will also validate the most recent innovation in transgenic prairie voles as a model for Shank3-related autism research.