INVESTIGATING DORSOMEDIAL STRIATAL DOPAMINE RELEASE AND UNIT SPIKING DURING COST-BENEFIT BEHAVIOR

Despite the importance of striatal dopamine to reward-processing in cortico-basal ganglia circuits, the precise relationship between dopamine release and the activity of striatal neurons is not well-defined. Dopamine release could have instantaneous effects on striatal activity and consequently ongoing behavior, as suggested by classical rate-based models of basal ganglia circuits. Alternatively, the effect of dopamine release could predominantly be to modulate synaptic plasticity and influence future actions. However, few studies have recorded both dopamine release and unit activity in the same area of striatum during behavior, which is necessary to address the relative influence of these two processes. To this end, we recorded sub-second dopamine release and striatal units simultaneously in dorsomedial striatum while freely moving rats engaged in a cost-benefit task, where both the reward and effort size were varied. Both dopamine release and unit activity varied in response to different behavioral events. Our results show heterogeneous instantaneous relationships between striatal activity and dopamine release; some neurons displayed strong correlations with dopamine transients, while others showed no apparent modulation. Together, these findings suggest dopamine release has a more nuanced and cell-specific influence on striatal output than classical theories suggest, with important implications for our understanding of basal ganglia function.