Differential coding of reward and movement information in the dorsomedial striatal direct and indirect pathways

Abstract

To better understand striatal neural processes underlying reward-based learning and movement control, we examined the responses of direct and indirect pathway spiny projection neurons (dSPNs and iSPNs, respectively) in the dorsomedial striatum of mice performing a probabilistic Pavlovian conditioning task. These neurons, which express D1 and D2 receptors, respectively, showed diverse arrays of reward- and tongue movement-related activity, but with quantitative differences. dSPNs and iSPNs tended to increase and decrease activity as a function of reward value, respectively, suggesting striatal value representation by relative activity levels between dSPNs and iSPNs. dSPNs increased activity more strongly than iSPNs in association with lick offset, suggesting the involvement of dSPNs in suppressing on-going licking behavior. In addition, rapid responses to negative outcome and previous reward signals were stronger among iSPNs than dSPNs, suggesting stronger contributions of iSPNs to outcome-dependent behavioral adjustment. These findings provide new insights into the operations of striatal neural circuits that underlie reward-based learning and movement control.