RT Journal Article SR Electronic T1 Asymmetric reinforcement learning: computational and neural bases of positive life orientation JF bioRxiv FD Cold Spring Harbor Laboratory SP 038778 DO 10.1101/038778 A1 Germain Lefebvre A1 Maël Lebreton A1 Florent Meyniel A1 Sacha Bourgeois-Gironde A1 Stefano Palminteri YR 2016 UL http://biorxiv.org/content/early/2016/02/03/038778.abstract AB While forming and updating beliefs about future life outcomes, people tend to consider good news and to disregard bad news. This tendency is supposed to support the optimism bias. Whether learning bias is specific to “high-level” abstract belief update or a particular expression of a more general “low-level” reinforcement learning process is unknown. Here we report evidence in favor of the second hypothesis. In a simple instrumental learning task, participants incorporated worse-than-expected outcomes at a lower rate compared to better-than-expected ones. This asymmetry was correlated across subjects with standard measure of dispositional optimism. Multimodal imaging indicated that inter-individual variability in the expression of asymmetric update relies on the dorsomedial prefrontal cortex at both morphological and functional levels. Our results constitute a new step in the understanding of the genesis of optimism bias at the neurocomputational level.