Psilocybin increases optimistic engagement over time: computational modelling of behavior in rats

Rats treated with psilocybin achieved more rewards in a decision-making task, driven by increased task engagement, altered forgetting rates, and reduced loss aversion. Computational modeling of the rats' behavior revealed that psilocybin may induce an optimism bias through changes in how beliefs are updated. This finding has potential relevance for clinical populations characterized by a lack of optimism, such as those with depression.

Study at a glance

Abstract

Abstract Psilocybin has shown promise as a novel pharmacological intervention for treatment of depression, where post-acute effects of psilocybin treatment have been associated with increased positive mood and decreased pessimism. Although psilocybin is proving to be effective in clinical trials for treatment of psychiatric disorders, the information processing mechanisms affected by psilocybin are not well understood. Here, we fit computational models of underlying decision-making mechanisms to behaviour in rats. The model revealed that rats treated with psilocybin achieve more rewards through increased task engagement, mediated by modification of forgetting rates and reduced loss aversion. These findings suggest that psilocybin may afford an optimism bias that arises through altered belief updating, with translational potential for clinical populations characterised by lack of optimism.