From Anticipation to Action, the Role of Dopamine in Perceptual Decision-Making: an fMRI - Tyrosine Depletion Study.

J Neurophysiol. 2012 May 2;

Authors: Nagano-Saito A, Cisek P, Perna AS, Shirdel FZ, Benkelfat C, Leyton M, Dagher A

Abstract
During simple sensorimotor decision-making, neurons in parietal cortex extract evidence from sensory information provided by visual areas until a decision is reached. Contextual information can bias parietal activity during the task and change the decision-making parameters. One type of contextual information is the availability of reward for correct decisions. We tested the hypothesis that the frontal lobes and basal ganglia use contextual information to bias decision-making in order to maximize reward. Human volunteers underwent fMRI while making decisions about the motion of dots on a computer monitor. On rewarded trials subjects responded more slowly by increasing the threshold to decision. Rewarded trials were associated with activation in the ventral striatum and prefrontal cortex in the period preceding coherent dot motion, and the degree of activation predicted the increased decision threshold. Decreasing dopamine transmission, using a tyrosine-depleting amino acid mixture, abolished the reward-related cortico-striatal activation, and eliminated the correlation between striatal activity and decision threshold. These observations provide direct evidence that some reward-related fMRI signals in the striatum are the result of dopamine neuron activity. They also demonstrate that mesolimbic dopamine transmission can influence perceptual and decision-making neural processes engaged to maximize reward harvest.

PMID: 22552189 [PubMed - as supplied by publisher]