Psilocybin increases optimistic engagement over time: computational modelling of behaviour in rats.
Translational psychiatry – September 30, 2024
Source: PubMed
Summary
Psilocybin helps rats maintain optimistic behavior by reducing their aversion to losses and improving their ability to adapt to changing situations. In a reward-based learning experiment, rats treated with psilocybin showed increased engagement and achieved better outcomes. The compound appears to work by adjusting how the brain updates beliefs and processes negative experiences, suggesting a mechanism for its antidepressant effects.
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 active inference and reinforcement learning computational models to a novel two-armed bandit reversal learning task capable of capturing engagement behaviour in rats. The model revealed that after receiving psilocybin, rats 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.