Department of Experimental Psychology, Ghent University, Ghent, Belgium.
Integrative Model-Based Cognitive Neuroscience Research Unit, University of Amsterdam, Amsterdam, The Netherlands.
Sci Rep. 2019 Dec 18;9(1):19395. doi: 10.1038/s41598-019-55887-0.
Value-based decision-making is ubiquitous in every-day life, and critically depends on the contingency between choices and their outcomes. Only if outcomes are contingent on our choices can we make meaningful value-based decisions. Here, we investigate the effect of outcome contingency on the neural coding of rewards and tasks. Participants performed a reversal-learning paradigm in which reward outcomes were contingent on trial-by-trial choices, and performed a 'free choice' paradigm in which rewards were random and not contingent on choices. We hypothesized that contingent outcomes enhance the neural coding of rewards and tasks, which was tested using multivariate pattern analysis of fMRI data. Reward outcomes were encoded in a large network including the striatum, dmPFC and parietal cortex, and these representations were indeed amplified for contingent rewards. Tasks were encoded in the dmPFC at the time of decision-making, and in parietal cortex in a subsequent maintenance phase. We found no evidence for contingency-dependent modulations of task signals, demonstrating highly similar coding across contingency conditions. Our findings suggest selective effects of contingency on reward coding only, and further highlight the role of dmPFC and parietal cortex in value-based decision-making, as these were the only regions strongly involved in both reward and task coding.
基于价值的决策在日常生活中无处不在，并且严重依赖于选择及其结果之间的偶然性。只有当结果取决于我们的选择时，我们才能做出有意义的基于价值的决策。在这里，我们研究了结果偶然性对奖励和任务神经编码的影响。参与者进行了反转学习范式，其中奖励结果取决于逐次选择，并且进行了“自由选择”范式，其中奖励是随机的，不取决于选择。我们假设偶然结果增强了奖励和任务的神经编码，这是使用 fMRI 数据的多元模式分析进行测试的。奖励结果在包括纹状体、dmPFC 和顶叶皮层在内的大型网络中进行编码，并且这些表示确实因偶然奖励而放大。任务在决策时在 dmPFC 中进行编码，在随后的维持阶段在顶叶皮层中进行编码。我们没有发现任务信号的依赖于偶然性的调制的证据，表明在偶然性条件下具有高度相似的编码。我们的研究结果表明，偶然性仅对奖励编码具有选择性影响，并且进一步强调了 dmPFC 和顶叶皮层在基于价值的决策中的作用，因为这是唯一强烈参与奖励和任务编码的区域。
