Contextual gating of motivationally-relevant stimuli in the mouse nucleus accumbens

Abstract

AbstractNeural activity in the nucleus accumbens (NAc) is thought to track fundamentally value-centric quantities such as current or future expected reward, reward prediction errors, the value of work, opportunity cost, and approach vigor. However, the NAc also contributes to flexible behavior in ways that are difficult to explain based on value signals alone, raising the question of if and how non-value signals are encoded in NAc. We recorded NAc neural ensembles while head-fixed mice performed a biconditional discrimination task, and extracted single-unit and population-level correlates of task features. We found coding for context-setting cues that modulate the stimulus-outcome association of subsequently presented reward-predictive cues. This context signal occupied a subspace orthogonal to classic value representations, suggesting that it does not interfere with value-related NAc output. Finally, we show that the context signal is predictive of subsequent value coding, supporting a circuit-level gating model for how the NAc contributes to behavioral flexibility and providing a novel population-level perspective from which to view NAc computations.