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

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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.