Comparing the ontogeny, neurobiology, and function of social play in hamsters and rats

Abstract

Syrian hamsters show complex social play behavior and provide a valuable animal model for delineating the neurobiological mechanisms and functions of social play. In this review, we compare social play behavior of hamsters and rats and underlying neurobiological mechanisms. Juvenile rats play by competing for opportunities to pin one another and attack their partner's neck. A broad set of cortical, limbic, and striatal regions regulate the display of social play in rats. In hamsters, social play is characterized by attacks to the head in early puberty, which gradually transitions to the flanks in late puberty. The transition from juvenile social play to adult hamster aggression corresponds with engagement of neural ensembles controlling aggression. Play deprivation in rats and hamsters alters dendritic morphology in mPFC neurons and impairs flexible, context-dependent behavior in adulthood, which suggests these animals may have converged on a similar function for social play. Overall, dissecting the neurobiology of social play in hamsters and rats can provide a valuable comparative approach for evaluating the function of social play.

Keywords: Medial prefrontal cortex; Mesocricetus auratus; Play deprivation; Social competency; Social play; Syrian hamster.

Figure 1.

Diagrams depict representative sequences of behavior during play bouts in A) Long-Evans rats and B) Syrian hamsters. In rats, play bouts are characterized by attempts to attack the nape of the neck and may be initiated from the front (column 1, images a, b, c, d) or from the rear (column 2, images a, b, c, d). In hamsters, playful attacks may be initially directed toward the head and cheeks (image a), although defensive behavior from the opponent often shifts the location of attacks toward the flank (images b, c, d, e), and the supine animal may counterattack the partner’s cheek (image f). Drawings were created from high-speed video of play bouts in 31-day old rats and 25-day old hamsters. (Images reprinted from Pellis and Pellis 1987 and Pellis and Pellis 1988b with permission from Wiley Online Library).

Figure 2.

The diagram summarizes available findings on the neurobiology of social play in Syrian hamsters. Abbreviations include serotonin (5-HT), medial prefrontal cortex (mPFC), medial amygdala (MeA), bed nucleus of stria terminalis (BNST), ventral medial hypothalamus lateral (VMHL), anterior hypothalamus (AH), lateral septum (LS), AVP (arginine vasopressin), corticotropin release factor type 1 receptor (CRF-R1). Findings are presented for ¹Delville et al 2003; ²Cheng et al 2008; ³Cheng & Delville 2009; ⁴Burleson et al 2016; ⁵Cheng & Delville 2010. Created with BioRender.com.