The role of the hippocampus in decision-making is beginning to be more understood. Because of its prospective and inferential functions, we hypothesized that it might be required specifically when decisions involve the evaluation of uncertain values. A group of individuals with autoimmune limbic encephalitis—a condition known to focally affect the hippocampus—were tested on how they evaluate reward against uncertainty compared to reward against another key attribute: physical effort. Across four experiments requiring participants to make trade-offs between reward, uncertainty and effort, patients with acute limbic encephalitis demonstrated blunted sensitivity to reward and effort whenever uncertainty was considered, despite demonstrating intact uncertainty sensitivity. By contrast, the valuation of these two attributes (reward and effort) was intact on uncertainty-free tasks. Reduced sensitivity to changes in reward under uncertainty correlated with the severity of hippocampal damage. Together, these findings provide evidence for a context-sensitive role of the hippocampus in value-based decision-making, apparent specifically under conditions of uncertainty.

人们开始更多地了解海马体在决策中的作用。由于其前瞻性和推理功能，我们假设当决策涉及不确定值的评估时可能特别需要它。一组患有自身免疫性边缘脑炎（一种已知会局部影响海马体的疾病）的个体接受了测试，测试他们如何评估针对不确定性的奖励，以及针对另一个关键属性（体力努力）的奖励。在要求参与者在奖励、不确定性和努力之间进行权衡的四项实验中，急性边缘脑炎患者在考虑不确定性时表现出对奖励和努力的敏感性减弱，尽管他们表现出完整的不确定性敏感性。相比之下，在无不确定性任务中，这两个属性（奖励和努力）的评估完好无损。不确定性下对奖励变化的敏感性降低与海马损伤的严重程度相关。总之，这些发现为海马体在基于价值的决策中发挥情境敏感的作用提供了证据，这一作用在不确定的条件下尤其明显。