RT Journal Article SR Electronic T1 Adult-born neurons in the hippocampus are essential for social memory maintenance JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0182-20.2020 DO 10.1523/ENEURO.0182-20.2020 A1 Elise C Cope A1 Renée C Waters A1 Emma J Diethorn A1 Kristen A Pagliai A1 Carla G Dias A1 Mumeko Tsuda A1 Heather A Cameron A1 Elizabeth Gould YR 2020 UL http://www.eneuro.org/content/early/2020/10/15/ENEURO.0182-20.2020.abstract AB Throughout adulthood, the dentate gyrus continues to produce new granule cells, which integrate into the hippocampal circuitry. New neurons have been linked to several known functions of the hippocampus, including learning and memory, anxiety and stress regulation, and social behavior. We explored whether transgenic reduction of adult-born neurons in mice would impair social memory and the formation of social dominance hierarchies. We utilized a conditional transgenic mouse strain (TK mice) that selectively reduces adult neurogenesis by treatment with the antiviral drug valganciclovir (VGCV). TK mice treated with VGCV were unable to recognize conspecifics as familiar 24 hr after initial exposure. We then explored whether reducing new neurons completely impaired their ability to acquire or retrieve a social memory and found that TK mice treated with VGCV were able to perform at control levels when the time between exposure (acquisition) and re-exposure (retrieval) was brief. We then explored whether adult-born neurons are involved in dominance hierarchy formation by analyzing their home cage behavior as well as their performance in the tube test, a social hierarchy test, and did not find any consistent alterations in behavior between control and TK mice treated with VGCV. These data suggest that adult neurogenesis is essential for social memory maintenance, but not for acquisition nor retrieval over a short time frame, with no effect on social dominance hierarchy. Future work is needed to explore whether the influence of new neurons on social memory is mediated through connections with the CA2, an area involved in social recognition.Significance Statement Adult hippocampal neurogenesis has been implicated in behaviors linked to the hippocampus, including social behavior. We utilized a conditional transgenic mouse line to reduce adult-born neurons and explored social memory and social dominance hierarchy formation. We found that mice with reduced numbers of new neurons were unable to recognize conspecifics as familiar with a long delay after initial exposure but were able to recognize them as familiar with a short delay. We did not observe changes in social dominance as measured by home cage behavior or tube test performance in mice with reduced numbers of new neurons. These data confirm and extend previous reports to show that adult-born neurons are essential for maintenance but not for acquisition or short-term retrieval of social memories, nor for social dominance.