PROJECT SUMMARY Unlike adult alcohol exposure, the cellular and behavioral effects of adolescent binge drinking do not recover following periods of abstinence, suggesting that alcohol exposure across adolescence has the potential to permanently disrupt the brain’s developmental trajectory. However, while prior research has focused on the underlying mechanisms driving this loss and restoration of newborn hippocampal neurons, no research has investigated how adolescent intermittent ethanol (AIE) impacts the ability of surviving hippocampal neuroprogenitor cells (NPCs) to appropriately integrate into adult hippocampal circuitry. In order to test the impact of adolescent alcohol on network integration of developing neurons, we will use a reporter mouse line (DCX-CreERT2/tdtomato) which was developed to specifically tag and then fate-map NPCs across their lifespan. This technique will allow us to track how alcohol impacts the ability of adolescent maturing neurons to effectively integrate into mature dentate circuitry. We will test whether AIE impairs proper formation of dendritic arborization in adolescent-maturing NPCs (AIM 1/K99). We will then test whether adolescent alcohol further impairs the electrophysiological properties of these NPCs in adulthood (AIM 2/K99). As it remains unclear whether maturational changes in neurons mediate loss of behavioral flexibility, we will test whether adolescent ethanol impairs neuronal activation in response to behavioral flexibility tasks (AIM 3/K99). However, due to the additional burdens of childcare following the birth of my firstborn son, Leonardo Preston (4/18/2023), I am requesting this supplement to support hiring a research technician in order to expedite the immunohistochemical components of the parent grant. The aims of this project will remain unchanged with this supplement request, and the technical training aspects of this grant (ex vivo electrophysiology, Aim 2) will continued to be performed by myself. Collectively, these experiments will provide critical insight into the impact of adolescent alcohol on the resulting phenotypic fate and circuit regulation of surviving NPCs in both sexes.