Sun Sai, Cai Chuhua, Yu Rongjun
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, 980-8578, Japan; Research Institute of Electrical Communication, Tohoku University, Sendai, 980-8577, Japan.
School of Psychology, Center for Studies of Psychological Application and Key Laboratory of Mental Health and Cognitive Science of Guangdong Province, South China Normal University, Guangzhou, 510631, China.
Neuroimage. 2022 Dec 1;264:119731. doi: 10.1016/j.neuroimage.2022.119731. Epub 2022 Nov 7.
When faced with uncertainty, individuals' value-based decisions are influenced by the expected rewards and risks. Understanding how reward and risk are processed and integrated at the behavioral and neural levels is essential for building up utility theories. Using a modified monetary incentive delay task in which the mean of two possible outcomes (expected reward) and the standard deviation (SD) of the possible outcomes (risk) were parametrically manipulated and orthogonalized, we measured eye movements, response times (RTs), and brain activity when participants seek to secure a reward. We found that RTs varied as a function of the mean but not the SD of the potential reward, suggesting that expected rewards are the main driver of RTs. Moreover, the difference between gazes focused on high vs. low value rewards became smaller when the magnitude of the potential reward (mean of possible outcomes) was larger and when risk (SD of possible outcomes) became smaller, highlighting that reward and risk have different effects on attention deployment. Processing the mean reward activated the striatum. The positive striatal connectivity to the amygdala and negative striatal connectivity to the superior frontal gyrus were correlated with individuals' sensitivity to the expected reward. In contrast, processing risk activated the anterior insula. Its positive connectivity to the ventromedial prefrontal cortex and negative connectivity to the anterior midcingulate cortex were correlated with individual differences in risk sensitivity, further suggesting the functional dissociation of reward and risk at the neural level. Our findings, based on several different measures, delineate the distinct representations of reward and risk in non-decision contexts and provide insight into how these utility parameters modulate attention, motivation, and brain networks.
面对不确定性时，个体基于价值的决策会受到预期奖励和风险的影响。了解奖励和风险在行为和神经层面是如何被处理和整合的，对于构建效用理论至关重要。我们使用了一种改良的货币激励延迟任务，其中两个可能结果的均值（预期奖励）和可能结果的标准差（SD，风险）被参数化操纵并正交化，在参与者寻求获取奖励时，我们测量了他们的眼动、反应时间（RTs）和大脑活动。我们发现，反应时间随潜在奖励的均值而非标准差变化，这表明预期奖励是反应时间的主要驱动因素。此外，当潜在奖励的幅度（可能结果的均值）较大且风险（可能结果的标准差）较小时，聚焦于高价值与低价值奖励的注视之间的差异会变小，这突出表明奖励和风险对注意力分配有不同影响。处理平均奖励会激活纹状体。纹状体与杏仁核的正性连接以及与额上回的负性连接，与个体对预期奖励的敏感性相关。相比之下，处理风险会激活前脑岛。它与腹内侧前额叶皮层的正性连接以及与前扣带中部皮层的负性连接，与风险敏感性的个体差异相关，这进一步表明奖励和风险在神经层面的功能分离。我们基于多种不同测量方法得出的研究结果，描绘了非决策情境中奖励和风险的不同表征，并深入揭示了这些效用参数如何调节注意力、动机和大脑网络。
