Acute Stress Enhances Expression of Instrumentally Conditioned Financial Preferences
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Background: Recent research suggests acute stress exposure can be associated with increased habit-based over goal-oriented decision-making. To date, research has focused on use of primary reinforcers (e.g., food) in devaluation-type experimental designs (e.g., Schwabe and Wolf, 2009, 2011). The current study examined if acute stress might also promote expression of habit-based decision-making using secondary reinforcers. Namely, simple financial preferences “overtrained” to habit.
Methods: Over three days participants were instrumentally conditioned to discriminate between simple visual stimuli probabilistically associated with monetary gains/losses. They then chose between pairs of stimuli for actual financial outcomes. On the fourth day after an acute stress or control procedure, participants performed the same learning and decision tasks during fMRI scanning, followed by two similar tasks in which monetary values associated with the stimuli were reversed.
Results: Participants in both groups successfully acquired stimuli contingencies; they to reliably chose the “better” option when presented with pairs of overtrained stimuli from Days 1 to 3 (reaching asymptote on Day 2), as well as on Day 4 prior to reversal. After reversal, acutely stressed participants made significantly more decisions consistent with original stimuli values despite that these were now financially detrimental. Thus, acutely stressed participants made more decisions consistent with their original overtrained preferences. In controls, at learning differential BOLD responses associated with stimuli valence were observed in regions associated with goal-directed and habit-based behaviors for both overtrained and post-reversal stimulus-outcome pairings. In the acute stress group, similar differential BOLD signals were limited to the putamen and only for overtrained pairings. During decision-making, increased BOLD was observed in dorsal anterior cingulate cortex and insula for “poor” versus “good” decisions in both groups. Further, stress-related alterations in dorsolateral prefrontal and entorhinal cortices were observed during decision-making.
Conclusions: The current study adds to research that demonstrates a propensity to rely on habitual behavior after exposure to acute stress, and that this may generalize to include also secondary reinforcers. Further, these findings suggest stress-induced neural changes take place during both the acquisition of stimuli contingencies and retrieval of reward-related information used to guide decision-making.