title: Working-memory capacity protects model-based learning from stress.
abstract: 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.
authors: Center for Neural Science and Department of Psychology, New York University, New York, NY 10003.
authors: A Ross
authors: AR
authors: Otto
authors: Candace M
authors: CM
authors: Raio
authors: Alice
authors: A
authors: Chiang
authors: Elizabeth A
authors: EA
authors: Phelps
authors: Nathaniel D
authors: ND
authors: Daw
mesh_terms: D000328:Adult; D002755:Choice Behavior / Q000502:physiology; D003657:Decision Making / Q000502:physiology*; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D007858:Learning / Q000502:physiology*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009518:New York; D012044:Regression Analysis; D012463:Saliva / Q000737:chemistry; D013315:Stress, Psychological / Q000503:physiopathology*
chemical_list: D006854:Hydrocortisone