RT Journal Article SR Electronic T1 L-DOPA Reduces Model-Free Control of Behavior by Attenuating the Transfer of Value to Action JF bioRxiv FD Cold Spring Harbor Laboratory SP 086116 DO 10.1101/086116 A1 Nils B. Kroemer A1 Ying Lee A1 Shakoor Pooseh A1 Ben Eppinger A1 Thomas Goschke A1 Michael N. Smolka YR 2016 UL http://biorxiv.org/content/early/2016/11/07/086116.abstract AB Dopamine is a key neurotransmitter in reinforcement learning and action control. Recent findings suggest that these components are inherently entangled. Here, we tested if increases in dopamine tone by administration of L-DOPA upregulate deliberative “model-based” control of behavior or reflexive “model-free” control as predicted by dual-control reinforcement-learning models. Alternatively, L-DOPA may impair learning as suggested by “value” or “thrift” theories of dopamine. To this end, we employed a two-stage Markov decision-task to investigate the effect of L-DOPA (randomized cross-over) on behavioral control while brain activation was measured using fMRI. L-DOPA led to attenuated model-free control of behavior as indicated by the reduced impact of reward on choice and increased stochasticity of model-free choices. Correspondingly, in the brain, L-DOPA decreased the effect of reward while prediction-error signals were unaffected. Taken together, our results suggest that L-DOPA reduces model-free control of behavior by attenuating the transfer of value to action.