Curley, J. | Search bioRxiv

bioRxiv2019

Temporal microstructure of dyadic social behavior during relationship formation in mice

Understanding the temporal dynamics of how unfamiliar animals establish dominant-subordinate relationships and learn to modify their behavior in response to their social partner in context-appropriate manners is critical in biomedical research concerning social competence. Here we observe and analyze the microstructure of social and non-social behaviors as 21 pairs of outbred CD-1 male mice (Mus Musculus) establish dominant-subordinate relationships during daily 20-minute interaction for five consecutive days. Using Kleinberg burst detection algorithm, we demonstrate aggressive and subordinate interactions occur in bursting patterns followed by quiescence period rather than in uniformly distributed across social interactions. Further, we identify three phases of dominant-subordinate relationship development (pre-, middle-, and post-resolution) by combining phi-coefficient and difference methods used to determine at which bursting event mice resolve dominant-subordinate relationships. Using First Order Markov Chains within individuals we show dominant and subordinate animals establish significantly different behavioral repertoire once they resolve the relationships. In both dominant and subordinate mice, the transitions between investigative and agonistic behavior states are not common. Lastly, we introduce Forward Spike Time Tiling Coefficient, the strength of association between the given behavior of one individual with the target behavior of the other individual within a specified time window. With this method, we describe the likelihood of a mouse responding to a behavior with another behavior differ in pre- and post-resolution phases. The data suggest that subordinate mice learn to exhibit subordinate behavior in response to dominant partners behaviors while dominant mice become less likely to show subordinate behaviors in response to their partners action. Overall, with the tool we present in this study, the data suggest CD-1 male mice are able to establish dominance relationships and modify their behaviors even to the same social cues under different social contexts competently.

animal behavior and cognition↗

bioRxiv2019

Social status in mouse social hierarchies is associated with variation in oxytocin and vasopressin 1a receptor densities

The neuropeptides oxytocin and vasopressin and their receptors have established roles in the regulation of mammalian social behavior including parental care, sex, affiliation and pair-bonding, but less is known regarding their relationship to social dominance and subordination within social hierarchies. We have previously demonstrated that male mice can form stable linear dominance hierarchies with individuals occupying one of three classes of social status: alpha, subdominant, subordinate. Alpha males exhibit high levels of aggression and rarely receive aggression. Subdominant males exhibit aggression towards subordinate males but also receive aggression from more dominant individuals. Subordinate males rarely exhibit aggression and receive aggression from more dominant males. Here, we examined whether variation in social status was associated with levels of oxytocin (OTR) and vasopressin 1a (V1aR) receptor binding in socially relevant brain regions. We found that socially dominant males had significantly higher OTR binding in the nucleus accumbens core than subordinate animals. Alpha males also had higher OTR binding in the anterior olfactory nucleus, posterior part of the cortical amygdala and rostral lateral septum compared to more subordinate individuals. Conversely, alpha males had lower V1aR binding in the rostral lateral septum and lateral preoptic area compared to subordinates. These observed relationships have two potential explanations. Preexisting individual differences in the patterns of OTR and V1aR binding may underlie behavioral differences that promote or inhibit the acquisition of social status. More likely, the differential social environments experienced by dominant and subordinate animals may shift receptor expression, potentially facilitating the expression of adaptive social behaviors. HighlightsO_LIMice living in social hierarchies express different levels of oxytocin receptor (OTR) and vasopressin 1a receptor (V1aR) binding in various brain regions according to their social status. C_LIO_LIAlphas and subdominants have higher OTR binding in the nucleus accumbens compared to subordinates. C_LIO_LIAlphas have higher OTR binding in the anterior olfactory nucleus compared to subdominants and subordinates. C_LIO_LIAlphas have higher OTR and lower V1aR binding in the rostral lateral septum compared to subordinates. C_LIO_LIAlphas have lower V1aR binding in the lateral preoptic area compared to subordinates. C_LI

neuroscience↗