Intranasal oxytocin drives coordinated social approach

Coordinated responses to challenge are essential to survival for bonded monogamous animals and may depend on behavioral compatibility. Oxytocin (OT) context-dependently regulates social affiliation and vocal communication, but its role in pair members’ decision to jointly respond to challenge is unclear. To test for OT effects, California mouse females received an intranasal dose of OT (IN-OT) or saline after bonding with males either matched or mismatched in their approach response to an aggressive vocal challenge. Pair mates were re-tested jointly for approach response, time spent together, and vocalizations. Females and males converged in their approach after pairing, but mismatched pairs with females given a single dose of IN-OT displayed a greater convergence that resulted from behavioral changes by both pair members. Unpaired females given IN-OT did not change their approach, indicating a social partner was necessary for effects to emerge. Moreover, IN-OT increased time spent approaching together, suggesting behavioral coordination beyond a further increase in bonding. This OT-induced increase in joint approach was associated with a decrease in the proportion of sustained vocalizations, a type of vocalization that can be associated with intra-pair conflict. Our results expand OT’s effects on behavioral coordination and underscore the importance of emergent social context.

Neuronal response variability as a product of divisive normalization; neurobiological implications at a macroscale level

The occurrence of neuronal spikes recorded directly from sensory cortex is highly irregular within and between presentations of an invariant stimulus. The traditional solution has been to average responses across many trials. However, with this approach, response variability is downplayed as noise, so it is assumed that statistically controlling it will reveal the brain’s true response to a stimulus. A mounting body of evidence suggests that this approach is inadequate. For example, experiments show that response variability itself varies as a function of stimulus dimensions like contrast and state dimensions like attention. In other words, response variability has structure, is therefore potentially informative and should be incorporated into models which try to explain neural encoding. In this article we provide commentary on a recently published study by Coen-Cagli and Solomon that incorporates spike variability in a quantitative model, by explaining it as a function of divisive normalization. We consider the potential role of neural oscillations in this process as a potential bridge between the current microscale findings and response variability at the mesoscale/macroscale level.

REINFORCEMENT OF APPROACHING CONSPECIFICS IN ZEBRAFISH (DANIO RERIO) USING A REAL-TIME 3D TRACKING SYSTEM.

Zebrafish offer a promising animal model for examining relations between biological and behavioral processes. In addition to their fully sequenced genome, general principles of behavior observed in other species appear also in zebrafish. The fish also exhibit social behavior when placed together with conspecifics. The present research investigated whether reinforcement contingencies increase the approach to conspecifics with four pairs of zebrafish. For each pair, a male and a female fish were placed in different compartments of an aquarium separated by a thin glass partition. Their movement was tracked in 3D and in real time. Food reinforcers were delivered on their approach toward each other. For two of the four pairs, the approach response was higher in the presence of the reinforcement contingency than when food was absent or presented independently of approach responses. The other two pairs initially showed an increase in the approach response upon the introduction of the reinforcement contingency but the response was not maintained. Despite unreliability in the acquisition of the approach response, improvements in the experimental setup discussed herein could provide more reliable tests of how reinforcement contingencies influence the approach response. Relations of approaching conspecifics to social behavior are discussed.