Stress and Motivation: An fMRI Study on the Effects of Stress on Effort-Based Decision- Making
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2020-08-28
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en
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Abstract
Reaching desired goals requires effort. In daily life, we often face important decisions
on whether to engage in effortful yet rewarding actions (e.g., studying hard to obtain a
university degree or accepting a demanding job with a great salary). These decisions are
often made under considerable stress, such as when having financial uncertainty. Previous
studies have shown that effort-based decision-making implicates a cortico-subcortical
network involving the prefrontal cortex and midbrain catecholamine (noradrenaline and
dopamine). Stress is known to affect both prefrontal activity and catecholamine levels.
Despite these commonalities, the effect of stress on effort-based decision-making and
its neural correlates are surprisingly understudied. In this study, the effects of stress on
effort-based decision-making were investigated, focusing on behaviour, neural activity,
and noradrenergic release measured by pupil dilation. Using a within-subjects design
with acute stress induction, we hypothesized that stress would decrease the willingness
to engage in mental effort, and that this would be linked with alterations in prefrontal
activity and pupil dilation. Participants performed an effort-based decision-making task
in the functional magnetic resonance imaging (fMRI) scanner during a control condition
or an experimentally induced acute stress condition. The results showed that stress
reduced the willingness to engage in effort. Pupil dilation increased with task difficulty
during calculations, but did not change under stress. Unexpectedly, no difference was
observed between stress and control at the whole-brain level. An a-priori region-ofinterest
analysis revealed no significant effect of stress on effort or reward coding in
the anterior cingulate cortex (ACC). A significant decrease in effort coding under stress
in the dorsolateral prefrontal cortex (DLPFC) was observed. However, this was specific
to the high reward condition and for participants who experienced the control session
first. Overall, these results suggest that acute stress reduces the willingness to engage
in mental effort, with preliminary evidence of alterations in DLPFC.
KEYWORDS stress, effort-based decision-making, DLPFC, MPFC, ACC, motivation, effort, reward
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Faculteit der Sociale Wetenschappen