Nagano-Saito A, Cisek P, Perna AS, Shirdel FZ, Benkelfat C, Leyton M, Dagher A. From anticipation to action, the role of dopamine in perceptual decision making: an fMRI-tyrosine depletion study. J Neurophysiol 108: 501-512, 2012. First published May 2, 2012; doi:10.1152/jn.00592.2011.-During simple sensorimotor decision making, neurons in the 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 to maximize reward. Human volunteers underwent functional MRI 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 corticostriatal activation and eliminated the correlation between striatal activity and decision threshold. These observations provide direct evidence that some reward-related functional MRI signals in the striatum are the result of dopamine neuron activity and demonstrate that mesolimbic dopamine transmission can influence perceptual and decision-making neural processes engaged to maximize reward harvest. basal ganglia; reward; motion discrimination; functional magnetic resonance imaging BRAINS MAKE PREDICTIONS about upcoming events to optimize behavioral choices (Llinas 2002). Prior information about likely outcomes can bias behavioral choice as can contextual information such as the likelihood of reward, allowing individuals to maximize the ratio of effort to reward. Reward anticipation can influence motivational states, decision making, and behavior. This transfer, from anticipation to action, is thought to involve the basal ganglia (Kawagoe et al. 1998;Lau and Glimcher 2008;Lauwereyns et al. 2002;Mogenson et al. 1980;Samejima et al. 2005;Satoh et al. 2003;Takikawa et al. 2002). Basal ganglia and frontal lobes form a corticostriatal system involved in both motor control and reward learning, making this network ideally suited to bias actions and decisions in favor of potentially rewarding outcomes. Dopamine plays a key role in this process, as dopamine released in the striatum by reward predicting cues appears to drive and promote the In recent models, it has been proposed that simple decisions involve an accumulation of neural activity building to a decision threshold (Bogacz and Gurney 2007;Carpenter and Williams 1995;Cisek 2007;Cisek et al. 2009;Lo and Wang 2006;Ratcliff 1978;Reddi et al. 2003;Shadlen et al. 1996;...