University of Iowa, Roy J. & Lucille A. Carver College of Medicine, Department of Psychiatry, Iowa City, IA, 52242, USA; Department of Psychology, University of Toronto, Toronto, ON, M5S 3G3, Canada.
Department of Psychology, University of Toronto, Toronto, ON, M5S 3G3, Canada.
Neuroimage. 2020 Jul 1;214:116764. doi: 10.1016/j.neuroimage.2020.116764. Epub 2020 Mar 20.
Understanding the neural implementation of value-based choice has been an important focus of neuroscience for several decades. Although a consensus has emerged regarding the brain regions involved, including ventromedial prefrontal cortex (vmPFC), posterior parietal cortex (PPC), and the ventral striatum (vSTR), the multifaceted nature of decision processes is one cause of persistent debate regarding organization of the value-based choice network. In the current study, we isolate neural activity related to valuation and choice selection using a gambling task where expected gains and losses are dissociated from choice outcomes. We apply multilevel mediation analysis to formally test whether brain regions identified as part of the value-based choice network mediate between perceptions of expected value and choice to accept or decline a gamble. Our approach additionally makes predictions regarding interregional relationships to elucidate the chain of processing events within the value-based decision network. Finally, we use dynamic causal modelling (DCM) to compare plausible models of interregional relationships in value-based choice. We observe that activity in vmPFC does not predict take/pass choices, but rather is highly associated with outcome evaluation. By contrast, both PPC and bilateral vSTR (bilaterally) mediate the relationship between expected value and choice. Interregional mediation analyses reveal that vSTR fully mediates between PPC and choice, and this is supported by DCM. Together these results suggest that vSTR, and not vmPFC nor PPC, functions as an important driver of choice.
几十年来，理解基于价值的选择的神经实现一直是神经科学的一个重要焦点。尽管人们已经就涉及的脑区达成了共识，包括腹内侧前额叶皮层（vmPFC）、顶后皮质（PPC）和腹侧纹状体（vSTR），但决策过程的多面性是导致基于价值的选择网络组织持续争论的原因之一。在当前的研究中，我们使用一种赌博任务来分离与估值和选择选择相关的神经活动，其中预期收益和损失与选择结果分离。我们应用多层次中介分析来正式检验作为基于价值的选择网络一部分的大脑区域是否在预期价值和接受或拒绝赌博之间的选择之间进行中介。我们的方法还对区域间关系做出了预测，以阐明基于价值的决策网络内的处理事件链。最后，我们使用动态因果建模（DCM）比较基于价值的选择中区域间关系的合理模型。我们观察到 vmPFC 的活动不能预测接受/拒绝选择，而是与结果评估高度相关。相比之下，PPC 和双侧 vSTR（双侧）均介导了预期价值和选择之间的关系。区域间中介分析表明，vSTR 完全介导了 PPC 和选择之间的关系，DCM 支持这一点。这些结果表明，vSTR 而不是 vmPFC 或 PPC 是选择的重要驱动因素。
