Value-based decision-making between affective memories

Affective biases can influence how past events are recalled from memory. However, the mechanisms underlying how discrete affective events shape memory formation and subsequent recall are not well understood. Further understanding this is important given the central role of negative biases in affective memory recall in depression and antidepressant drug action. In order to capture cognitive processes associated with affective memory formation and recall, we studied value-based decision-making between affective memories in two within-subject experiments (n=45 and n=74). Our findings suggest that discrete affective events, created by large magnitude Wheel of Fortune (WoF) outcomes, influence affective memory formation processes during reinforcement-learning (RL). After 24 hours, we show that healthy volunteers display stable preferences during value-based recall of affective memories in a binary decision-making task. Computational modelling of these preferences demonstrated a positive bias during value-based recall, induced by previously winning in the WoF. We further showed that value-based decision-making between affective memories engages the pupil-linked central arousal systems, leading to pupil constriction prior to, and differential pupil dilation after the decision onset depending on the valence of the chosen options. Taken together, we demonstrate that mechanisms underlying human affective memory systems can be described by RL and probability weighting models. This approach could be used as a translational assay to study the effects of novel antidepressants.