Ventromedial striatal dopamine dynamically integrates motivated action and reward proximity
Dopamine release in the ventromedial striatum (VMS) both invigorates actions and encodes reward-related information, yet how these functions are integrated remains under active debate. To investigate this further, we designed four different versions of a rat Go/No-go task, where we systematically manipulated response requirements, temporal task demands, and controllability of reward pursuit. Dopamine release increased reliably during action initiation (Go) but was delayed during action suppression (No-go), and this difference was insensitive to augmented response demands or controllability. Following response completion, dopamine rose gradually until animals arrived at the reward location, irrespective of reward-delivery timing, prior action demands, or controllability. This proximity dopamine-signal was exaggerated after animals exhibited Pavlovian consummatory behavior during No-go trials, revealing a motivational signal component. Together, these findings indicate that in reward contexts, VMS-dopamine signals successively integrate the invigoration of action initiation with the continuous tracking of spatial - but not temporal - proximity to rewards.