Decision-making under stress: which brain system guides choice?

决策可以由不同的机制支持，这些机制的神经基础和处理的信息不同。信用分配也是如此，它描述了如何将结果（奖励或惩罚）恰当地分配给正确的选择。这个问题可以通过结果与其正确的因果选择之间的偶然关联来解决，这依赖于眶额皮质，或者（非偶然的）统计和启发式机制，分别由杏仁核和背外侧纹状体支持。尽管这些不同的机制可能会导致根本不同的决策，但决定这些机制对行为控制程度的因素却知之甚少。压力是认知的主要调节因子。具体来说，压力被认为会改变与记忆过程有关的不同系统的参与。基于这些数据，我们假设压力也可能调节决策中解剖学和功能上不同的机制的招募。为了验证这一假设，我们将让健康的参与者在执行信用分配任务之前暴露于标准化的压力源或控制操作，该任务已被证明可以揭示偶然和非偶然的学习机制。为了研究压力对这些不同机制影响的神经基础，志愿者将在任务执行过程中使用功能磁共振成像（fMRI）进行3T扫描。我们预测，压力将增加非偶然机制对行为的贡献，以牺牲精确的偶然学习为代价。在神经层面，我们预计压力会增加杏仁核，但减少外侧眶额皮质参与决策。除了它们与我们对压力如何影响决策的一般理解的相关性之外，这个项目的发现可能对与压力相关的精神病理学（其中决策缺陷很突出）以及与工作相关的环境（其中决策通常是在压力下做出的）具有重要意义。

Decision-making can be supported by separate mechanisms that differ in their neural substrate and in the information processed. This is also the case for credit assignment, which describes the problem of appropriately assigning outcomes, rewarding or punishing, to the correct choices. This problem can be solved using contingent associations between outcomes and their correct causal choices, which is reliant on orbitofrontal cortex, or by (non-contingent) statistical and heuristic mechanisms supported by amygdala and dorsolateral striatum, respectively. Although the recruitment of these distinct mechanisms may result in fundamentally different decisions, the factors that determine to what extent these mechanisms exert control over behavior is poorly understood. Stress is a major modulator of cognition. Specifically, stress is thought to alter the engagement of separate systems involved in memory processes. Based on these data, we hypothesize that stress may also modulate the recruitment of anatomically and functionally distinct mechanisms in decision-making. To test this hypothesis, we will expose healthy participants to a standardized stressor or a control manipulation before they perform a credit assignment task that has been shown to reveal both contingent and non-contingent learning mechanisms. In order to examine the neural basis of the influence of stress on these distinct mechanisms, volunteers will be scanned with fMRI at 3T during task performance. We predict that stress will increase the contribution of non-contingent mechanisms to behavior, at the expense of precise contingent learning. At the neural level, we expect that stress will increase amygdala but decrease lateral orbitofrontal cortex involvement in decision-making. Beyond their relevance for our general understanding of how stress shapes decision-making, the findings of this project may have important implications for stress-related psychopathologies, in which decision-making deficits are prominent, as well as for work-related settings, in which decisions are often made under stress.