Social interactions are motivated behaviors that in many species facilitate learning. However, how the brain encodes the reinforcing properties of social interactions remains elusive. Here, using in vivo recording in freely moving mice, we show that dopamine (DA) neurons of the ventral tegmental area (VTA) increase their activity during interactions with an unfamiliar conspecific and display heterogeneous responses. Using a social instrumental task (SIT), we then show that VTA DA neuron activity encodes social prediction error and drives social reinforcement learning. Thus, our findings suggest that VTA DA neurons are a neural substrate for a social learning signal that drives motivated behavior.

No abstract

Social interactions motivate behavior in many species, facilitating learning, foraging and cooperative behavior. However, how the brain encodes the reinforcing properties of social interactions remains elusive. Here using in vivo recording in freely moving mice, we show that Dopamine (DA) neurons of the Ventral Tegmental Area (VTA) increase their activity during active interactions with unfamiliar conspecific. Using a social instrumental task, we then show that VTA DA neuron activity signals social reward prediction error and drives social reinforcement learning. Thereby, our findings propose that VTA DA neurons are a neural substrate for a social learning signal driving motivated behavior.the lever zone and in the interaction zone. Friedman test (χ 2 (49) = 61.27, P < 0.0001) followed by Bonferroni-Holm correction.

Disinhibitory neurons throughout the mammalian cortex are powerful enhancers of circuit excitability and plasticity. The differential expression of neuropeptide receptors in disinhibitory, inhibitory and excitatory neurons suggests that each circuit motif is controlled by distinct neuropeptidergic systems. Here, we reveal that a bombesin-like neuropeptide, gastrin-releasing peptide (GRP), recruits disinhibitory cortical microcircuits through selective targeting and activation of vasoactive intestinal peptide (VIP)-expressing cells. Using a newly-developed genetically-encoded GRP sensor and trans-synaptic tracing we reveal that GRP regulates VIP cells via extrasynaptic diffusion from several putative local and long-range sources. In vivo photometry and CRISPR/Cas9-mediated knockout of the GRP receptor (GRPR) in auditory cortex indicate that VIP cells are strongly recruited by novel sounds and aversive shocks, and that GRP-GRPR signaling enhances auditory fear memories. Our data establish peptidergic recruitment of selective disinhibitory cortical microcircuits as a mechanism to regulate fear memories.