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.