真实和虚拟金钱奖赏下风险决策的神经机制研究

Understanding how the brain takes risk and makes decision poses an important question and a major challenge for multiple disciplines including psychology, neuroscience, and economics. Although both real and hypothetical monetary rewards have been widely used, it remains unclear whether real and hypothetical rewards have the same effects on risk taking and decision making behavior and the underlying brain function. The balloon analogue risk task (BART) is an ecologically valid paradigm and provides objective measurement of individual risk taking propensity for in laboratory studies. The BART has been successfully used for fMRI and ERP studies to examine the neural mechanism underlying risk taking and decision making. Our preliminary behavioral and ERP data have suggested differential effects of real and hypothetical monetary rewards on risky decision making. In this study, we will further use fMRI and ERP to investigate the neural bases for risk taking and decision making with real or hypothetical monetary rewards. The results from this proposal will enrich our understanding of the motivation effects of monetary rewards on risky decision making in the human brain. The findings may also inform the utility of monetary rewards to modify real life risk taking and decision making behavior.

理解人脑在有风险的情境下如何决策是心理学、神经科学、经济学等多学科的重要研究问题。已有众多研究采用真实或虚拟金钱作为奖赏强化物来探索风险决策行为的过程和机制, 但对金钱奖赏真实性如何影响决策了解很少。我们近期发展和改进了以仿真气球冒险任务BART(Balloon Analogue Risk Task)为主的一些生态性较高的风险决策实验范式，可以在实验室条件下有效测量个体的风险偏好水平，并通过与fMRI和ERP等脑研究技术的结合来研究风险决策的神经机制。我们初步的行为实验和ERP研究结果发现，真实和虚拟金钱奖赏对风险决策行为可能有显著不同的影响效应。因此，本研究计划采用ERP和fMRI技术进一步开展真实和虚拟金钱奖赏下风险决策的神经机制研究。本研究对深入理解金钱在决策中的激励效应及其神经机制这个问题有重要的科学意义，研究结果也将为未来研究和实际应用中如何采用金钱奖赏调控决策行为提供科学依据。

本课题组通过一系列研究探索真实和虚拟金钱对风险决策的影响并发现：(1)行为结果：与虚拟金钱奖赏相比，真实金钱奖赏情境下的个体表现出显著的风险规避，决策损失会引起更强的学习效应，且受到奖赏幅度的调控，随着真实金钱奖赏幅度的增加，风险规避越趋明显；(2) ERP结果：与虚拟金钱奖赏相比，真实金钱奖赏损失诱发更大的FRN，且受损失幅度的调控，与小幅度的真实金钱损失相比，大幅度的真实金钱损失诱发更强的FRN；(3) fMRI结果：与虚拟金钱损失相比，真实金钱损失导致包括奖赏网络在内的诸多脑功能区(insula, caudate, thalamus, ACC )更强的激活，且真实金钱奖赏的幅度变化引起背外侧前额叶(DLPFC)和纹状体(striatum)的激活更强。我们进一步的探索性研究还发现，主动选择比被动选择有更强的情感体验，个体在主动决策情境下的金钱盈利与损失诱发的FRN效应差异显著大于被动决策。与心理疲劳前相比，默认网络(DMN)的低频振幅(ALFF)在疲劳后显著下降，而丘脑(thalamus)的低频振幅(ALFF)在疲劳后显著增强。与道德水平较低相比，后习俗(post-conventional)水平个体在腹内侧前额叶皮层(vmPFC)和膝下前扣带回(sgACC)的灰质体积增加，且高道德水平个体的杏仁核(amygdala)与腹内侧前额叶(vmPFC)的功能连接显著增强，后习俗道德水平个体的腹侧纹状体(ventral striatum)和腹内侧前额叶(vmPFC)的脑血流量显著增强。