Dopaminergic drugs modulate learning rates and perseveration in Parkinson's patients in a dynamic foraging task.
Making appropriate choices often requires the ability to learn the value of available options from experience. Parkinson's disease is characterized by a loss of dopamine neurons in the substantia nigra, neurons hypothesized to play a role in reinforcement learning. Although previous studies have shown that Parkinson's patients are impaired in tasks involving learning from feedback, they have not directly tested the widely held hypothesis that dopamine neuron activity specifically encodes the reward prediction error signal used in reinforcement learning models. To test a key prediction of this hypothesis, we fit choice behavior from a dynamic foraging task with reinforcement learning models and show that treatment with dopaminergic drugs alters choice behavior in a manner consistent with the theory. More specifically, we found that dopaminergic drugs selectively modulate learning from positive outcomes. We observed no effect of dopaminergic drugs on learning from negative outcomes. We also found a novel dopamine-dependent effect on decision making that is not accounted for by reinforcement learning models: perseveration in choice, independent of reward history, increases with Parkinson's disease and decreases with dopamine therapy.
Rutledge
Robb B
RB
Center for Neural Science, New York University, New York, New York 10003, USA. robb@cns.nyu.edu
Lazzaro
Stephanie C
SC
Lau
Brian
B
Myers
Catherine E
CE
Gluck
Mark A
MA
Glimcher
Paul W
PW
D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D003216:Conditioning, Operant / Q000187:drug effects*; D003657:Decision Making / Q000187:drug effects* / Q000502:physiology; D015259:Dopamine Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011336:Probability; D011932:Reading; D012054:Reinforcement, Psychology
D015259:Dopamine Agents