A dopaminergic reward prediction error signal shapes maternal behavior in mice

How social contact is perceived as rewarding and subsequently modifies interactions is unclear. Dopamine (DA) from the ventral tegmental area (VTA) regulates sociality, but the ongoing, unstructured nature of free behavior makes it difficult to ascertain how. Here, we tracked the emergence of a repetitive stereotyped parental retrieval behavior and conclude that VTA DA neurons incrementally refine it by reinforcement learning (RL). Trial-by-trial performance was correlated with the history of DA neuron activity, but DA signals were inconsistent with VTA directly influencing the current trial. We manipulated the subject's expectation of imminent pup contact and show that DA signals convey reward prediction error, a fundamental component of RL. Finally, closed-loop optogenetic inactivation of DA neurons at the onset of pup contact dramatically slowed emergence of parental care. We conclude that this component of maternal behavior is shaped by an RL mechanism in which social contact itself is the primary reward

A reinforcement learning algorithm shapes maternal care in mice

The neural substrates for processing classical rewards such as food or drugs of abuse are well-understood. In contrast, the mechanisms by which organisms perceive social contact as rewarding and subsequently modify their interactions are unclear. Here we tracked the gradual emergence of a repetitive and highly-stereotyped parental behavior and show that trial-by-trial performance correlates with the history of midbrain dopamine (DA) neuron activity. We used a novel behavior paradigm to manipulate the subject’s expectation of imminent pup contact and show that DA signals conform to reward prediction error, a fundamental component of reinforcement learning (RL). Finally, closed-loop optogenetic inactivation of DA neurons at the onset of pup contact dramatically slowed emergence of parental care. We conclude that this prosocial behavior is shaped by an RL mechanism in which social contact itself is the primary reward