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

奖赏和痛苦可以被认为是一个沿着享乐连续体的两端。因此，奖励刺激对疼痛感知有抑制作用，有证据表明慢性疼痛与奖励处理受损有关。奖赏和疼痛的处理涉及重叠的大脑区域。此外，神经递质多巴胺在奖赏和疼痛的处理中起着重要作用。然而，奖赏、疼痛和多巴胺能神经传递之间相互作用的确切潜在机制和神经元相关性仍不清楚。因此，基于以前的工作，该项目的目的是研究奖赏和疼痛感知的相互作用及其神经元相关性，以及多巴胺能神经传递的作用。为了深入了解疼痛和奖励的相互作用，将应用两种不同类型的奖励，即通过疼痛缓解的内在（感知，疼痛系统内）奖励和外在金钱奖励。此外，将通过主观疼痛报告明确评估疼痛感知，此外，还将通过参与者的行为进行隐性评估。据推测，内在和外在奖励有不同的影响显式和隐式评估的疼痛知觉及其伴随的神经元相关。24名年轻健康的志愿者将在一项使用功能性磁共振成像（fMRI）的实验中接受两次测试。在这些测试环节中，参与者将玩一个幸运之轮游戏，可以测试内在和外在奖励对显式和隐式评估的疼痛感知的影响。此外，为了诱导D2受体阻滞，将在其中一个试验阶段给予D2受体拮抗剂舒必利，而受试者在另一个试验阶段接受安慰剂（随机化顺序，双盲）。

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).