Formation and consolidation of social memories in the ventral hippocampus

Animals exhibit a range of social interactions (dominance hierarchies, mating and parental behaviors) that rely on their ability to recognize conspecifics. It has been shown that the hippocampus is involved in the higher order representation of social signals in humans and monkeys. In rodents, however, the dorsal hippocampus was only weakly modulated by the presence of other rats. One hypothesis is that this lack of modulation in the dorsal hippocampus is related to the functional segregation of the hippocampus. Specifically, the anterior hippocampus of primates corresponding to the ventral hippocampus of rodents represents social information, and the dorsal hippocampus of rodents is mailnly concerned with spatial information. Our preliminary data suggest that social signals are represented in the rat ventral hippocampus. We will examine the formation and consolidation of social memories in the ventral hippocampus. The research plan is divided into four work packages: (WP1) refining our picture of socially evoked responses in the ventral hippocampus, (WP2) replay of socially evoked responses/social events in the ventral hipppocampus during sleep, (WP3) formation, artifical induction and consolidation of “rat-grandmother-cells”, (WP4) optogenetic manipulation of social memory consolidation during sleep. We will use a combination of low- and high-speed videography, ultrasound recordings, tetrode recording, in vivo whole-cell recordings and nanostimulation in socially interacting and sleeping animals. This work plans moves progressively from a description of the modulation of ventral hippocampus activity by social stimuli to an investigation of whether social information is replayed in the ventral hippocampus during sleep and finally to testing models of social memory formation and consolidation.