Working-memory capacity protects model-based learning from stress
Working-memory capacity protects model-based learning from stress
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DOI：
10.1073/pnas.1312011110
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发表时间：
2013-12-24
影响因子：
11.1
通讯作者：
Daw, Nathaniel D.
中科院分区：
文献类型：
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作者：
Otto, A. Ross;Raio, Candace M.;Daw, Nathaniel D.
长期以来，对决策的描述一直假定，在控制选择行为的过程中，存在着独立的、相互竞争的评估系统。最近的理论和实验进展表明，习惯和目标导向（或者更一般地说，自动和控制）选择之间的经典区别可能源于强化学习的两种计算策略，即无模型学习和基于模型的学习。奖励处理的流行神经计算理论强调多巴胺能系统参与无模型学习，前额叶、中央执行依赖控制系统参与基于模型的选择。在这里，我们假设下丘脑-垂体-肾上腺（HPA）轴应激反应——被认为对前额皮质功能有不利影响——应该选择性地减弱基于模型的行为贡献。为了验证这一点，我们将急性压力源与顺序决策任务配对，以区分两种学习策略的相对贡献。我们评估了基线工作记忆（WM）能力，并使用唾液皮质醇水平来测量下丘脑轴的应激反应。我们发现，应激反应减弱了基于模型而非非模型对行为的贡献。此外，应激诱导的行为变化受个体WM能力的调节，即WM能力低的个体比WM能力高的个体更容易受到有害的应激影响。这些结果丰富了关于急性压力、工作记忆和前额叶功能之间相互作用的现有解释，并表明执行功能可能对急性压力的有害影响具有保护作用。
Accounts of decision-making have long posited the operation of separate, competing valuation systems in the control of choice behavior. Recent theoretical and experimental advances suggest that this classic distinction between habitual and goal-directed (or more generally, automatic and controlled) choice may arise from two computational strategies for reinforcement learning, called model-free and model-based learning. Popular neurocomputational accounts of reward processing emphasize the involvement of the dopaminergic system in model-free learning and prefrontal, central executive-dependent control systems in model-based choice. Here we hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis stress response-believed to have detrimental effects on prefrontal cortex function-should selectively attenuate model-based contributions to behavior. To test this, we paired an acute stressor with a sequential decision-making task that affords distinguishing the relative contributions of the two learning strategies. We assessed baseline working-memory (WM) capacity and used salivary cortisol levels to measure HPA axis stress response. We found that stress response attenuates the contribution of model-based, but not model-free, contributions to behavior. Moreover, stress-induced behavioral changes were modulated by individual WM capacity, such that low-WM-capacity individuals were more susceptible to detrimental stress effects than high-WM-capacity individuals. These results enrich existing accounts of the interplay between acute stress, working memory, and prefrontal function and suggest that executive function may be protective against the deleterious effects of acute stress.