Reward integration in prefrontal-cortical and ventral-hippocampal nucleus accumbens inputs cooperatively modulates engagement

Abstract

The NAc, a highly integrative brain region controlling motivated behavior, is thought to receive distinct information from various glutamatergic inputs yet strong evidence of functional specialization of inputs is lacking. While circuit neuroscience commonly seeks specific functions for specific circuits, redundancy can be highly adaptive and is a critical motif in circuit organization. Using dual-site fiber photometry in an operant reward task, we simultaneously recorded from two NAc glutamatergic afferents to assess circuit specialization. We identify a common neural motif that integrates reward history in medial prefrontal cortex (mPFC) and ventral hippocampus (vHip) inputs to NAc. Then, by systematically degrading task complexity, dissociating reward from choice and action, we identify key circuit-specificity in the behavioral conditions that recruit encoding. While mPFC-NAc invariantly encodes reward, vHip-NAc encoding is uniquely anchored to loss. Ultimately, using optogenetic stimulation we demonstrate that both inputs co-operatively modulate task engagement. We illustrate how similar encoding, with differential gating by behavioral state, supports state-sensitive tuning of reward-motivated behavior.