The uncertain path to reward: Neural mechanisms of intolerance of uncertainty in reward processing

Reward processing is a neurocognitive process involving the evaluation of and response to rewarding stimuli, which is critical for learning and motivated behavior. This cognitive mechanism is also influenced by mental health. Intolerance of uncertainty (IU) is a dispositional tendency to perceive uncertainty as distressing and respond negatively to uncertain situations. Proposed as a transdiagnostic factor for internalizing disorders, IU may help explain shared features across these conditions. This study investigated the influence of IU on electrocortical responses to reward (feedback-related ERP) using the Doors Task, which incorporated varying levels of uncertainty (i.e., risk) regarding rewards. In 203 participants, we found that risk levels significantly influenced ERPs, particularly following reward feedback, with high-risk trials eliciting larger (i.e. more positive) ERPs compared to ambiguous or low-risk trials. While total IU did not correlate with feedback-related brain activity, its subfactors showed distinct effects after reward and no-reward feedback: higher prospective IU scores were associated with increased brain activity, whereas higher inhibitory IU scores were linked to decreased activity. These effects persisted after accounting for related internalizing traits, including worry, depression, and trait anxiety. Additionally, depressive symptoms were associated with blunted feedback-related ERPs, particularly following no-reward feedback. Taken together, the findings suggest a more nuanced and complex role of IU and its subfactors in reward processing and demonstrate the impact of risk on electrocortical responses to reward outcomes.