Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, The Netherlands.
Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands.
Psychopharmacology (Berl). 2022 Feb;239(2):465-478. doi: 10.1007/s00213-021-06017-0. Epub 2021 Nov 4.
We constantly need to decide not only which actions to perform, but also how vigorously to perform them. In agreement with an earlier theoretical model, it has been shown that a significant portion of the variance in our action vigor can be explained by the average rate of rewards received for that action. Moreover, this invigorating effect of average reward rate was shown to vary with within-subject changes in dopamine, both in human individuals and experimental rodents.
Here, we assessed whether individual differences in the effect of average reward rate on vigor are related to individual variation in a stable measure of striatal dopamine function in healthy, unmedicated participants.
Forty-four participants performed a discrimination task to test the effect of average reward rate on response times to index vigor and completed an [F]-DOPA PET scan to index striatal dopamine synthesis capacity.
We did not find an interaction between dopamine synthesis capacity and average reward rate across the entire group. However, a post hoc analysis revealed that participants with higher striatal dopamine synthesis capacity, particularly in the nucleus accumbens, exhibited a stronger invigorating effect of average reward rate among the 30 slowest participants.
Our findings provide converging evidence for a role of striatal dopamine in average reward rate signaling, thereby extending the current literature on the mechanistic link between average reward rate, vigor, and dopamine.
我们不仅需要不断决定要执行哪些操作，还需要决定执行操作的力度。根据早期的理论模型，我们的行为活力的大部分差异可以用该行为的平均奖励率来解释。此外，在人类个体和实验啮齿动物中，都表明这种平均奖励率的激励效应随多巴胺的个体内变化而变化。
在这里，我们评估了在健康、未用药参与者中，平均奖励率对活力的影响的个体差异是否与纹状体多巴胺功能的稳定测量个体差异有关。
44 名参与者执行了一项辨别任务，以测试平均奖励率对反应时间的影响，以指示活力，并完成了[F]-DOPA PET 扫描以指示纹状体多巴胺合成能力。
我们没有发现整个组中多巴胺合成能力和平均奖励率之间的相互作用。然而，事后分析表明，纹状体多巴胺合成能力较高的参与者，尤其是伏隔核中的参与者，在 30 名最慢的参与者中，平均奖励率的激励效应更强。
我们的研究结果为纹状体多巴胺在平均奖励率信号中的作用提供了确凿的证据，从而扩展了关于平均奖励率、活力和多巴胺之间的机制联系的当前文献。
