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

奖励和痛苦可以被认为是一个享乐连续体的两端。因此，奖赏刺激已显示出对疼痛感知的抑制作用，有证据表明，慢性疼痛与奖赏加工受损有关。奖赏和痛苦的处理涉及到重叠的大脑区域。此外，神经递质多巴胺在奖赏和疼痛的处理中扮演着重要的角色。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，在前人工作的基础上，该项目的目标是研究奖赏和疼痛知觉的相互作用及其神经元关联，以及多巴胺能神经传递的作用。为了深入了解痛苦和回报的相互作用，我们将采用两种不同类型的奖励，即内在的(知觉的，在痛苦系统内)缓解疼痛的奖励和外在的金钱奖励。此外，疼痛感知将通过主观疼痛报告进行明确评估，此外，还将隐含地评估参与者的行为。假设内源性和外源性奖赏对显性和隐性痛觉及其伴随的神经元相关有不同的影响。24名年轻、健康的志愿者将在两次实验中使用功能磁共振成像(FMRI)进行测试。在这些测试环节中，参与者将玩一款财富之轮游戏，通过这款游戏，可以测试内在和外在奖励对显性和隐性评估疼痛感知的影响。此外，为了诱导D2受体阻断，D2受体拮抗剂舒必利将在其中一次测试中使用，而参与者在另一次测试中使用安慰剂(随机顺序，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).