Neural correlates of acute-induced stress and decision-making under risk: an fMRI study

Many situations in daily life require making risky decisions under stressful conditions. In the current behavioral literature, the effects of stress on risky decision-making are inconsistent, and there is limited research investigating post-stress risky decisions from a neural perspective. Identifying neural correlates of post-stress risky decision-making might help to improve the targeted behavioral interventions for risk adjustment. Furthermore, the investigation of post-stress risky decisions from a neuroscientific perspective might shed light on underlying neural/cognitive mechanisms that can moderate the impact of stress on decision-making and offer insights unattainable through behavioral methods alone. Thus, in this dissertation, functional Magnetic Resonance Imaging (fMRI) was employed to assess the neural correlates of stress as well as post-stress risky decision-making. The study consisted of four experimental blocks: stress, post-stress decision-making, control, and post control decision-making. The design was within-subject and all participants were subjected to stress and control conditions in a counterbalanced order. Both stress and control conditions were followed by a “decision-making under risk” task directly after the stress exposure in a single fMRI session with a concurrent Electrodermal Activity (EDA) measurement to confirm the stress manipulation. Stress was induced by asking participants to solve mental arithmetic tasks under time pressure & social-evaluative threat while receiving negative feedback. During the decision-making task, participants chose between a safe and a risky option (binary lottery task) with monetary incentives and known probabilities of winning. Self-reported stress levels and EDA data confirmed that the stress induction was successfully implemented. Participants took less risky decisions post-stress than post-control. An fMRI contrast analysis revealed that the right fronto-opercular and the left anterior part of the dorsolateral prefrontal cortex (dlPFC; an area critical for executive functioning and cognitive control) exhibited significantly lower activation during decisions post-stress than decisions post-control. The results indicate that decisions taken immediately after exposure to the acute stressor are associated with reduced activation in the regions of the dlPFC, possibly leading to less deliberate and less risky decision-making post-stress. Interventions to increase dlPFC activation might be suitable to improve the quality of decision-making post-stress, alleviating the effects of stress.