Play and the development of the brain's social skills

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The most common form of play in non-human animals is "rough-and-tumble" play or "play fighting", which is a non-injurious form of competitive interaction in which partners compete for some advantage over one another, such as being able to bite their partner gently. Behavioural mechanisms exist that reduce the risk of play fighting escalating into serious fighting by incorporating some level of cooperation into the competition; this juxtaposition of competition and cooperation makes the repeated bodily contact present in play rewarding. When animals such as rats are deprived in the juvenile period of the opportunity to engage in peer-peer play, they have impoverished social skills as adults, such that their ability to mate successfully or negotiate dominance relationships is diminished. My work has shown that damage to the prefrontal cortex of socially reared rats produces social deficits similar to those present in rats that had been deprived of play. My laboratory has also shown that the anatomy of the neurons of the prefrontal cortex is modified when varying the experiences of play that animals have had as juveniles. Therefore, I theorize that experience with play fighting as juveniles is necessary for the development of those areas of the brain that are critical for social competency. In the proposed research, I will use laboratory rats to investigate what aspects of the play experience are critical for the development of the brain and characterize the mechanisms by which a more competent social brain executes more competent social behaviour. For example, improved performance may arise from the enhanced ability to sequence together complex movements or by attenuating the effects of fear arising from novel and unpredictable social contexts. Improved social competence may also arise from improved interpretation and/or delivery of social signals, such as the myriad 50-kHz calls that rats emit during social interactions, including play. I will also conduct a comparative analysis of play in a diverse range of primates to determine whether the organization of play fighting differs among species depending on the complexity of their social behaviour. Based on my preliminary findings, I hypothesize that species with more complex social systems, ones requiring them to negotiate more varied social relationships, have patterns of play as juveniles that are modified in ways that provide training for the social skills they will need as adults. These studies will characterize how social competence develops and the contribution made to this development by the experience of play as juveniles. The critical role of play in developing social skills and negotiating relationships leads this research to have implications beyond its value in basic science to include improvements in housing captive social animals and in developing strategies to facilitate experiences helpful to children.