A selective role for dopamine in reward learning

Individuals make choices and prioritize goals using complex processes that assign value to rewards and associated stimuli. During Pavlovian learning, previously neutral stimuli that predict rewards can acquire motivational properties, whereby they themselves become attractive and desirable incentive stimuli. But individuals differ in whether a cue acts solely as a predictor that evokes a conditional response, or also serves as an incentive stimulus, and this determines the degree to which a cue might bias choice or even promote maladaptive behavior. Here we use rats that differ in the incentive motivational properties they attribute to food cues to probe the role of the neurotransmitter dopamine in stimulus-reward learning. We show that intact dopamine transmission is not required for all forms of learning in which reward cues become effective predictors. Rather, dopamine acts selectively in a form of reward learning in which “incentive salience ” is assigned to reward cues. In individuals with a propensity for this form of learning, reward cues come to powerfully motivate and control behavior. This work provides insight into the neurobiology of a form of reward learning that confers increased susceptibility to disorders of impulse control. Dopamine is central for reward-related processes1,2, but the exact nature of its role remains controversial. Phasic neurotransmission in the mesolimbic dopamine system is initially triggered by the receipt of reward (unconditional stimulus; US), but shifts to a cue predictive of reward (conditional stimulus; CS) after associative learning3,4. Dopamine responsiveness appears to encode discrepancies between rewards received and those predicted, consistent Users may view, print, copy, download and text and data- mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use