Eugenia Poh

Guest speaker: Eugenia Poh, postdoc Willuhn lab

Ventromedial striatal dopamine dynamically integrates motivated action and reward proximity

Abstract

Dopamine release in the ventromedial striatum (VMS) both invigorates actions and encodes rewardrelated 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 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 estimation of spatial – but not temporal – proximity to rewards.