Project Summary The hippocampus plays a critical role in the formation of episodic memories by generating distinct, conjunctive representations of (spatial and social) experiences and transferring these representations to prefrontal cortical sites for memory storage or consolidation. Age-related cognitive decline and mild-cognitive impairment (MCI) are characterized by increased memory interference, decreased stability of memory representations and inefficient memory consolidation. Evidence from humans, non-human primates and rodents demonstrate reduced hippocampal neurogenesis, hippocampal hyperactivity and inflexible remapping during age- related cognitive decline and MCI. Parvalbumin inhibitory interneurons (PV INs) play a pivotal role in memory discrimination and consolidation by regulating neuronal excitability and synchronizing neuronal firing underlying neuronal ensembles and sharp-wave ripples (SWRs). Thus, reduced PV IN recruitment in hippocampal CA2, a hub for social memory processing, may contribute to age-associated social memory impairments. Here, we propose a role for neurogenesis-inhibition coupling in the dentate gyrus-CA2 as a candidate circuit mechanism by which adult-born neurons promote social memory consolidation in adulthood and aging. In response to the FOA, we will develop and validate an in vivo gain-of-function platform for iterative testing of pro-cognitive potential of novel candidate regulators of neurogenesis-inhibition coupling during aging. Towards this goal, we will build on extensive preliminary and published data and integrate a genetic approach to enhance neurogenesis, input-specific manipulation of PV INs, activity-dependent molecular profiling of PV INs, PV IN targeted viral expression, optogenetics, ex vivo and in vivo local field potential recordings and an aging-sensitive social memory behavioral paradigm. Together, these Aims will establish proof-of-concept for a novel platform for targeting a neurogenesis-inhibition coupling mechanism to improve social memory in aging and MCI.