Indima ye-dopamine kwi-accumbens eyintloko ekubonakaliseni iimpendulo zePavlovian. (2012)

Abstract

The role of dopamine in reward is a topic of debate. For example, some have argued that phasic dopamine signaling provides a prediction-error signal necessary for stimulus-reward learning, whereas others have hypothesized that dopamine is not necessary for learning per se, but for attributing incentive motivational value (‘incentive salience’) to reward cues. These psychological processes are difficult to tease apart, because they tend to change together. To disentangle them we took advantage of natural individual variation in the extent to which reward cues are attributed with incentive salience, and asked whether dopamine (specifically in the core of the nucleus accumbens) is necessary for the nkulumo of two forms of Pavlovian-imeko approach behavior – one in which the cue acquires powerful motivational properties (sign-tracking) and another closely related one in which it does not (goal-tracking). After acquisition of these imeko responses (CRs), i-intra-accumbens injection ye-dopamine receptor antagonist flupenthixol markedly impaired the nkulumo of a sign-tracking CR, but not a goal-tracking CR. Furthermore, dopamine antagonism did not produce a gradual extinction-like decline in behavior, but maximally impaired nkulumo of a sign-tracking CR on the very first trial, indicating the effect was not due to new learning (i.e. it occurred in the absence of new prediction-error computations). The data support the view that dopamine in the accumbens core is not necessary for learning stimulus-reward associations, but for attributing incentive salience to reward cues, transforming predictive conditional stimuli into incentive stimuli with powerful motivational properties.