Oxytocin in periaqueductal gray plasticly regulates strain-dependent social recognition memory in mice, modeling social identity

Social identity differences are crucial for gregarious animals, impacting survival and social development. This is particularly evident in humans, where social stratification, cultural divides, and ethnic differences influence societal dynamics. Social recognition memory plays a central role in this process, maintaining social order by allowing individuals to distinguish familiar members within their group. Notably, social recognition memory exhibits differences: within a group, individuals form detailed memories of each member (individualized memory), while for out-group members, a more generalized memory of the entire group forms (categorized memory). Although this phenomenon has been explored in human studies, current research techniques and methods have limited investigations into the underlying neural mechanisms, especially their plasticity and regulatory mechanisms. This study utilizes mice to establish an experimental model for investigating differences in social recognition memory and its neural basis. We demonstrate that mice also exhibit social identity-driven memory recognition patterns. Mice form individualized memories for same-strain individuals but categorized memories for different strains, and the type of social recognition memory could be regulated by oxytocin level of ventrolateral periaqueductal gray. These findings demonstrate that oxytocin and its receptors in the ventrolateral periaqueductal gray are essential for constructing and plastically regulating intergroup social memory in mice.