Individual differences in prosocial learning are represented in the hippocampal dorsal CA1

Animals can learn about danger by observing conspecifics, but whether and how they acquire behaviors through positive affective states of others is not understood. Here we show that by observing a demonstrator, mice learn to take actions that benefit others and that are goal-directed and flexible. Chemogenetic silencing experiments showed that activity in hippocampal dorsal CA1 (dCA1) was required for observers to learn action-outcome associations in a social context. Fiber photometry recordings revealed inter-individual differences in dCA1 activity patterns during observation that tracked the observer's subsequent prosocial or selfish behavioral propensities. Optogenetic manipulations demonstrated that the dCA1 is key during observation and can orient a mouse's actions toward prosocial or selfish choices in future interactions. Our study provides a mouse model of social transmission of knowledge that guides prosocial behavior and that may be relevant for studying disorders in which the ability to learn from others' actions is compromised.