Department of Psychiatry, Harvard Medical School, and Center for Depression, Anxiety and Stress Research, McLean Hospital, Belmont, MA, USA.
Department of Psychology, University of California Los Angeles, CA, USA.
Cereb Cortex. 2018 Dec 1;28(12):4281-4290. doi: 10.1093/cercor/bhx281.
Prior studies have shown that dopamine (DA) functioning in frontostriatal circuits supports reinforcement learning (RL), as phasic DA activity in ventral striatum signals unexpected reward and may drive coordinated activity of striatal and orbitofrontal regions that support updating of action plans. However, the nature of DA functioning in RL is complex, in particular regarding the role of DA clearance in RL behavior. Here, in a multi-modal neuroimaging study with healthy adults, we took an individual differences approach to the examination of RL behavior and DA clearance mechanisms in frontostriatal learning networks. We predicted that better RL would be associated with decreased striatal DA transporter (DAT) availability and increased intrinsic functional connectivity among DA-rich frontostriatal regions. In support of these predictions, individual differences in RL behavior were related to DAT binding potential in ventral striatum and resting-state functional connectivity between ventral striatum and orbitofrontal cortex. Critically, DAT binding potential had an indirect effect on reinforcement learning behavior through frontostriatal connectivity, suggesting potential causal relationships across levels of neurocognitive functioning. These data suggest that individual differences in DA clearance and frontostriatal coordination may serve as markers for RL, and suggest directions for research on psychopathologies characterized by altered RL.
先前的研究表明，前额叶纹状体回路中的多巴胺（DA）功能支持强化学习（RL），因为腹侧纹状体中的 DA 相位活动信号表示意外奖励，并可能驱动纹状体和眶额区域的协调活动，从而支持行动计划的更新。然而，RL 中 DA 功能的性质很复杂，特别是关于 DA 清除在 RL 行为中的作用。在这里，我们在一项具有健康成年人的多模态神经影像学研究中，采用个体差异方法来检查 RL 行为和前额叶纹状体学习网络中的 DA 清除机制。我们预测，更好的 RL 与纹状体多巴胺转运蛋白（DAT）可用性降低以及富含多巴胺的前额叶纹状体区域之间的内在功能连接增加有关。这些预测得到了支持，RL 行为的个体差异与腹侧纹状体中的 DAT 结合潜力以及腹侧纹状体和眶额皮层之间的静息状态功能连接有关。至关重要的是，DAT 结合潜力通过前额叶纹状体的连接对强化学习行为产生间接影响，这表明在神经认知功能的各个层面上存在潜在的因果关系。这些数据表明，DA 清除和前额叶纹状体协调的个体差异可能是 RL 的标志物，并为研究以 RL 改变为特征的精神病理学提供了方向。
