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Abstract In most species, individuals must be able to identify threats, peers, and potential mates to survive. The distinction of kin from non‐kin and novel conspecifics from familiars is essential to the successful categorization of these identities. Although oxytocin (OXT) signaling has been implicated in social recognition, little is known about the contributions of distinct OXT‐producing cell groups to distinguishing conspecific type. To determine whether OXT‐producing neuronal populations differentially respond to novelty or kinship status, we conducted immediate early gene tests in male spiny mice (Acomys dimidiatus), a communally breeding species that we previously showed distinguishes between novelty and kinship status. Immunohistochemical analysis of brain tissue revealed that the OXT cell populations in the paraventricular nucleus of the hypothalamus and the anterior hypothalamus did not differentially respond to the kinship or novelty status of same‐sex conspecifics. However, while OXT‐producing neurons in the bed nucleus of the stria terminalis did not distinguish between kin and non‐kin spiny mice, this cell group was more responsive to familiar than novel conspecifics. These results suggest that extrahypothalamic OXT neurons may be involved in aspects of processing the novelty status of a conspecific. 

Despite the prevalence of large group-living in the animal kingdom, we know surprisingly little about how the brain facilitates grouping behavior, particularly in mammals. In this brief communication, I provide an update on advancements in the study of the neural mechanisms underlying mammalian grouping behavior. I discuss the benefits of using non-traditional organisms in the laboratory and provide examples of how using non-standard, large housing and testing apparatuses produces more ethologically-relevant behavioral datasets. Further, with advancements in computer vision-based automated tracking and increasing availability of wireless neural recording and manipulation tools, scientists can now generate unprecedented neurobehavioral datasets from multiple interacting animals. Together, recent advancements in behavioral and neural approaches hold great promise for expanding our understanding of how the brain modulates complex, mammalian grouping behaviors. 

A growing body of literature suggests that testosterone (T) rapidly modulates behavior in a context-specific manner. However, the timescales in which T can rapidly mediate distinct types of behavior, such as pro- vs. anti- social responses, has not been studied. Thus, here we examined acute T influences on social behavior in male and female Mongolian gerbils in nonreproductive contexts. Females and males received an injection of either saline or T and were first tested in a social interaction test with a same-sex, familiar peer. 5 min after the peer interaction, subjects then underwent a resident-intruder test with a novel, same-sex conspecific. After another 5 min, gerbils were tested in a novel object task to test context-specificity (i.e., social vs. nonsocial) of T effects on behavior. Within 1 h, males and females injected with T exhibited more huddling with a peer but more active avoidance of and less time spent in proximity of an intruder than did animals injected with saline. T effects on behavior were specific to social contexts, such that T did not influence investigation of the novel object. Together these findings show that T rapidly promotes pro-social responses to a familiar peer and anti-social responses to an intruder in the same individuals within 5 min of experiencing these disparate social contexts. This demonstrates that T rapidly facilitates behavior in a context-appropriate manner outside the context of reproduction and reveals that rapid effects of T on behavior are not restricted to males. 

Rationale Early life social rearing has profound consequences on offspring behavior and resilience. Yet, most studies examining early life development in rodents use species whose young are born immobile and do not produce complex social behavior until later in development. Furthermore, models of rearing under increased social complexity, rather than deprivation, are needed to provide alternative insight into the development of social neural circuitry. Objectives To understand precocial offspring social development, we manipulated early life social complexity in the communal spiny mouse Acomys cahirinus and assessed long-term consequences on offspring social behavior, exploration, and neural responses to novel social stimuli. Methods Spiny mouse pups were raised in the presence or absence of a non-kin breeding group. Upon adulthood, subjects underwent social interaction tests, an open field test, and a novel object test. Subjects were then exposed to a novel conspecific and novel group and neural responses were quantified via immunohistochemical staining in brain regions associated with social behavior. Results Early life social experience did not influence behavior in the test battery, but it did influence social processing. In animals exposed to non-kin during development, adult lateral septal neural responses toward a novel conspecific were weaker and hypothalamic neural responses toward a mixed-sex group were stronger. Conclusions Communal species may exhibit robust behavioral resilience to the early life social environment. But the early life environment can affect how novel social information is processed in the brain during adulthood, with long-term consequences that are likely to shape their behavioral trajectory. 

Abstract In complex social environments, individuals may interact with not only novel and familiar conspecifics but also kin and non-kin. The ability to distinguish between conspecific identities is crucial for most animals, yet how the brain processes conspecific type and how animals may alter behavior accordingly is not well known. We examined whether the communally breeding spiny mouse (Acomys cahirinus) responds differently to conspecifics that vary in novelty and kinship. In a group interaction test, we found that males can distinguish novel kin from novel non-kin, and preferentially spend time with novel kin over familiar kin and novel non-kin. To determine whether kinship and novelty status are differentially represented in the brain, we conducted immediate early gene tests, which revealed the dorsal, but not ventral, lateral septum differentially processes kinship. Neither region differentially processes social novelty. Further, males did not exhibit differences in prosocial behavior toward novel and familiar conspecifics but exhibited more prosocial behavior with novel kin than novel non-kin. These results suggest that communally breeding species may have evolved specialized neural circuitry to facilitate a bias to be more affiliative with kin, regardless of whether they are novel or familiar, potentially to promote prosocial behaviors, thereby facilitating group cohesion.