Dissociating neural circuits of social and prosocial reward in rat helping behavior

TL;DR

The study shows that rats can help others without social reward, revealing distinct brain circuits for prosocial and social behaviors.

Contribution

A new behavioral test and neurobiological insights dissociate social and prosocial reward circuits in rats.

Findings

Rats equally help ingroup and outgroup members when social contact is prevented.

The nucleus accumbens is not essential for helping behavior but affects affiliative actions.

Oxtr+ cells in sensory cortices are involved in prosocial behavior but not in frontal regions.

Abstract

Helping behavior in rodents provides a powerful model for studying neurobiological underpinnings of prosocial motivation. Previously, rats allowed to release a trapped conspecific demonstrated prosocial motivation selectively toward ingroup members. Here, a refined version of the helping behavior test (HBT) allowed trapped rats to be freed without ensuing social contact, dissociating social from prosocial reward. In this “separated” HBT (SHBT), helping was not biased, as rats equally released ingroup and outgroup members. Whole-brain c-Fos mapping revealed a subset of the standard HBT prosocial brain network engaged in the SHBT. Observed absence of activity in the nucleus accumbens (NAc) instigated a chemogenetic investigation of this region. NAc activity was not necessary for helping, but significantly reduced affiliative behavior. The recruitment of Oxtr+ cells in sensory cortices suggests modulated sensory processing. Together, these findings dissociate neural circuits underlying social and prosocial motivation and provide a mechanistic framework for studying mammalian prosocial behavior.

•Rats similarly release ingroup and outgroup conspecifics without social reward•Helping without social reward engages the prosocial brain network but not the NAc•NAc inhibition reduces affiliative behavior but not helping behavior•Helping recruit Oxtr+ cells in sensory but not frontal cortices

Rats similarly release ingroup and outgroup conspecifics without social reward

Helping without social reward engages the prosocial brain network but not the NAc

NAc inhibition reduces affiliative behavior but not helping behavior

Helping recruit Oxtr+ cells in sensory but not frontal cortices

Neuroscience; Behavioral neuroscience

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