This study investigates the dopaminergic mechanisms underlying human reinforcement learning and action selection using a combined pharmacological neuroimaging approach in male volunteers (n=31). Contrary to some previous findings, L-dopa showed little effect on learning from gains and neural prediction error signals. However, reinforcement learning drift diffusion models revealed consistent decision threshold reductions under both L-dopa and haloperidol, suggesting dopamine regulates decision thresholds during reinforcement learning, bridging action selection and response vigor accounts of dopamine.

Karima Chakroun, Antonius Wiehler, Ben Wagner, David Mathar, Florian Ganzer, Thilo van Eimeren, Tobias Sommer, Jan Peters