Diminished Social Memory and Hippocampal Correlates of Social Interactions in Chronic Social Defeat Stress Susceptibility

BACKGROUND: Susceptibility to chronic stress has been associated with depression, a mood disorder that highly implicates the hippocampus. Hippocampal contribution to stress susceptibility has been supported by findings in mice following chronic social defeat stress (CSDS). However, little is known about the role of hippocampal activity in determining the development of stress susceptibility.<br /> METHODS: We used the UCLA Miniscope to longitudinally measure the activity of dorsal CA1 hippocampal neurons during CSDS. In addition to examining the representation of social information by these neurons, we compared social memory in mice that were either susceptible or resilient to CSDS.<br /> RESULTS: We observed more stable dorsal CA1 correlates of social interaction and social memory in CSDS-resilient mice. Such changes were absent in CSDS-susceptible mice and accompanied by greater social memory impairments.<br /> CONCLUSIONS: CSDS susceptibility may be supported by hippocampal social cognitive processes, as reflected in diminished hippocampal representations of social information and greater impairment in social memory in suspectible compared with resilient mice.