Together Again but No Need to Play: Dissociating Effects of Isolation and Separation on Social Interaction in Female Rats (Rattus norvegicus)

Play behavior has been extensively studied across species, but its direct role in social relationships remains unclear. Here we use an “isolation versus separation” protocol to identify behaviors associated with relationship renewal in adolescent female rats. Members of a dyad that had been separated for 24 hr, without isolation from other peers, initially increased investigative behaviors relative to nonseparated peers; however, in contrast with social isolation, separation by itself did not increase rough-and-tumble play. The data suggest that increased play following isolation depends on general motivations, rather than a “peer-specific” drive to renew relationships with an individual. This is consistent with a role of play in more general social learning rather than reestablishing bonds or expectations.