Neuronal correlates and the role of dopaminergic neurotransmission in the interaction of pain perception and extrinsic (monetary) and intrinsic (pain relief) reward

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Reward and pain can be considered to be at opposite ends along a hedonic continuum. Accordingly, rewarding stimuli have shown inhibitory effects on pain perception and evidence suggests that chronic pain is associated with impaired reward processing. Processing of reward and pain involves overlapping brain regions. Further, the neurotransmitter dopamine plays an important role in the processing of reward and pain. However, the precise underlying mechanisms and neuronal correlates of the interactions between reward, pain, and dopaminergic neurotransmission remain unclear. Therefore, based on previous work, the project’s aim is to investigate the interaction of reward and pain perception and their neuronal correlates as well as the role of dopaminergic neurotransmission. In order to gain insight in the interaction of pain and reward, two different types of reward will be applied, i.e. intrinsic (perceptual, within the pain system) reward by pain relief and extrinsic monetary reward. Moreover, pain perception will be assessed explicitly with subjective pain reports and, in addition, implicitly in the participant’s behavior. It is hypothesized that intrinsic and extrinsic rewards have different effects on the explicitly and implicitly assed pain perception and their accompanying neuronal correlates. Twenty-four young, healthy volunteers will be tested in two sessions in an experiment using functional magnetic resonance imaging (fMRI). In these testing sessions, the participants will play a Wheel of Fortune game, with which the influence of intrinsic and extrinsic reward on explicitly and implicitly assessed pain perception can be tested. In addition, for the purpose of inducing a D2-receptor blockade, the D2-receptor antagonist sulpiride will be administered in one of the testing sessions, while participants receive a placebo in the other session (randomized order, double-blind).