Striatal cell-type specific stability and reorganization underlying agency and habit

Adaptive decision making requires agency, knowledge that actions produce particular outcomes. For well-practiced routines, agency is relinquished in favor of habit. Here, we asked how dorsomedial striatum D1⁺ and D2/A2A⁺ neurons contribute to agency and habit. We imaged calcium activity of these neurons as mice learned to lever press with agency and formed habits with overtraining. Whereas many D1⁺ neurons stably encoded actions throughout learning and developed encoding of reward outcomes, A2A⁺ neurons reorganized their encoding of actions from initial action-outcome learning to habit formation. Chemogenetic manipulations indicated that both D1⁺ and A2A⁺ neurons support action-outcome learning, but only D1⁺ neurons enable the use of such agency for adaptive, goal-directed decision making. These data reveal coordinated dorsomedial striatum D1⁺ and A2A⁺ function for the development of agency, cell-type specific stability and reorganization underlying agency and habit, and important insights into the neuronal circuits of how we learn and decide.