Early-age social play influences rat cognition

lab animal Research highlights Social behavior https://doi.org/10.1038/s41684-026-01734-5 Early-age social play influences rat cognition Check for updates Play fighting, or rough-and-tumble play (RTP), is a highly studied form of social play in mammals and is well characterized in rats. RTP consists of competitive interactions, such as biting, moderated by cooperation, reciprocity and frequent role reversals, distinguishing play from serious fighting. RTP emerges shortly before weaning, peaks during the juvenile period and declines with sexual maturation, coinciding with a developmental window during which social experience strongly influences brain maturation. However, it remains unclear why individuals with similar play opportunities show divergent long-term social outcomes and how individual differences in play engagement shape prefrontal cortical development. In a study in Behavioral Brain Research, researchers examined how juvenile play Lab Animal | Volume 55 | May 2026 | 159 experience relates to adult social competence and medial prefrontal cortex (mPFC) neuronal architecture. They classified adult rats as socially “competent” or “incompetent” by evaluating their behavior in a stranger encounter test, including escalation to aggression and emission of 22-kHz vocalizations. Neuronal morphology was then quantified in mPFC pyramidal neurons. Socially incompetent rats showed enlarged dendritic arbors compared with competent animals. Quantitative analyses showed an increase in convex hull volume and surface area across total, basilar and apical dendritic projections in incompetent rats, consistent with reduced dendritic pruning in the mPFC. Juvenile play behavior was analyzed retrospectively in the same individuals. Despite being reared in large social groups with ample opportunity to play, approximately 20% of rats failed to benefit from playing and tended to escalate playful encounters into aggression. This indicates that the long-term benefits of juvenile play depend not only on play quantity and availability but also on how play interactions are regulated and reciprocated. Overall, the results show that individual differences in juvenile play quality might help predict adult social competence and mPFC neuronal refinement. The data suggest that early-life factors shaping cooperative play may have lasting consequences for sociocognitive function. Jorge Ferreira Original reference: Ham, J.R., Ivaniuk, A. N. & Pellis, S. M. Behav. Brain Res. 508, 116198 (2026) 159  (...truncated)