Project Summary Social attachment is fundamental to our daily lives and is disrupted in various psychiatric disorders. However, development of new therapeutic options for enhancing social attachment has been hampered by our imprecise understanding of the underlying cellular and circuit mechanisms. At the heart of neural circuits underlying social attachment is the nucleus accumbens (NAc), and recent work by my thesis lab, investigating pair bonding in monogamous prairie voles, suggests that individual neurons of the NAc encode for partner- associated social interaction. In a series of new analyses focused on how populations of neurons encode for pair bonding, I found that neurons exhibited synchronous activity as a function of pair bond formation. Further analyses suggest that inhibitory interneurons, which provide a powerful source of inhibition within the NAc, may coordinate this synchrony between neurons. Thus, the goal of this proposal is to examine precisely how NAc interneurons encode pair bonds, and to test whether NAc interneurons are necessary for bond-induced neuronal synchrony and for pair bond formation. This project will leverage cutting-edge methods for both observing and manipulating NAc interneurons and would provide the first interneuron-specific insights into how the prairie vole NAc facilitates pair bonding. Together, the experiments in this proposal will expand our fundamental understanding of how social attachment is supported at the cellular level within the nucleus accumbens. This work will also provide the applicant with invaluable training for his future career as a pediatric neurologist focused on translating foundational knowledge from cellular and circuits neuroscience into novel, highly precise therapies for social dysfunction.