Ohmann Hanno Andreas, Kuper Niclas, Wacker Jan
Faculty of Psychology and Human Movement Science, Universität Hamburg, Hamburg, Germany.
Faculty of Psychology and Sports Science, Universität Bielefeld, Bielefeld, Germany.
Personal Neurosci. 2020 Jun 23;3:e7. doi: 10.1017/pen.2020.7. eCollection 2020.
Dopamine (DA) is known to be involved in various aspects of reward processing and goal-directed behavior. The present preregistered study aims at directly accessing the causal influence of DA activity on reward motivation in humans, while also accounting for trait extraversion. Therefore, we examined the effect of a single dose of the DA D2 receptor antagonist sulpiride (200 mg) on effort allocation in a modified version of the Effort-Expenditure for Reward Task (EEfRT). Based on its presumably DA increasing action, we expected the low dose of sulpiride to increase participants' willingness to allocate effort during the modified EEfRT relative to placebo, especially in trials with low probability of reward attainment. Further, we expected a moderating effect of trait extraversion on the effects of sulpiride. Two hundred and three healthy male participants were tested in a randomized, double-blind between-subjects design. Contrary to our expectations, sulpiride reduced the average number of clicks within the modified EEfRT and did not interact with reward attributes, suggesting a more global and not reward-specific effect of sulpiride. Furthermore, trait extraversion did not moderate the effect of sulpiride. Our results provide initial support for the validity of the modified version of the EEfRT, suggesting a possible inhibiting effect of a low dose of sulpiride on approach motivation regardless of trait extraversion. However, given the mixed pattern of findings and the possible confounding role of motoric abilities, further studies examining these effects are clearly warranted.
多巴胺（DA）已知参与奖励处理和目标导向行为的各个方面。本项预先注册的研究旨在直接探究DA活性对人类奖励动机的因果影响，同时也考虑特质外向性因素。因此，我们在奖励任务努力投入（EEfRT）的改良版实验中，研究了单剂量DA D2受体拮抗剂舒必利（200mg）对努力分配的影响。基于其可能增加DA的作用，我们预期低剂量舒必利会使参与者在改良EEfRT中相对于安慰剂更愿意投入努力，尤其是在奖励获得概率较低的试验中。此外，我们预期特质外向性会对舒必利的效果产生调节作用。203名健康男性参与者通过随机双盲被试间设计进行测试。与我们的预期相反，舒必利减少了改良EEfRT中的平均点击次数，且未与奖励属性产生交互作用，这表明舒必利具有更广泛而非特定于奖励的效应。此外，特质外向性并未调节舒必利的效果。我们的结果为改良版EEfRT的有效性提供了初步支持，表明低剂量舒必利可能对趋近动机具有抑制作用，且不受特质外向性的影响。然而，鉴于研究结果的混合模式以及运动能力可能存在的混杂作用，显然有必要进一步开展研究来检验这些效应。
