OPEN Foundation

REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics

Share This Post

Share on facebook
Share on linkedin
Share on twitter
Share on email

Abstract

This paper formulates the action of psychedelics by integrating the free-energy principle and entropic brain hypothesis. We call this formulation relaxed beliefs under psychedelics (REBUS) and the anarchic brain, founded on the principle that—via their entropic effect on spontaneous cortical activity—psychedelics work to relax the precision of high-level priors or beliefs, thereby liberating bottom-up information flow, particularly via intrinsic sources such as the limbic system. We assemble evidence for this model and show how it can explain a broad range of phenomena associated with the psychedelic experience. With regard to their potential therapeutic use, we propose that psychedelics work to relax the precision weighting of pathologically overweighted priors underpinning various expressions of mental illness. We propose that this process entails an increased sensitization of high-level priors to bottom-up signaling (stemming from intrinsic sources), and that this heightened sensitivity enables the potential revision and deweighting of overweighted priors. We end by discussing further implications of the model, such as that psychedelics can bring about the revision of other heavily weighted high-level priors, not directly related to mental health, such as those underlying partisan and/or overly-confident political, religious, and/or philosophical perspectives.

Significance Statement Psychedelics are capturing interest, with efforts underway to bring psilocybin therapy to marketing authorisation and legal access within a decade, spearheaded by the findings of a series of phase 2 trials. In this climate, a compelling unified model of how psychedelics alter brain function to alter consciousness would have appeal. Towards this end, we have sought to integrate a leading model of global brain function, hierarchical predictive coding, with an often-cited model of the acute action of psychedelics, the entropic brain hypothesis. The resulting synthesis states that psychedelics work to relax high-level priors, sensitising them to liberated bottom-up information flow, which, with the right intention, care provision and context, can help guide and cultivate the revision of entrenched pathological priors.

Carhart-Harris, R. L., & Friston, K. J. (2019). REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics. Pharmacological reviews71(3), 316-344., /10.1124/pr.118.017160
Link to full text

OPEN Foundation

Join ICPR 2022 Online!

ICPR features world-leading experts from many academic disciplines, including psychiatry, psychology, neuroscience, anthropology, ethnobotany, and philosophy who come together to give a scientific conference for academics, therapists, researchers, clinicians, policymakers, and members of the public. Get your ICPR 2022 livestream ticket today and use the code OPENLIVE30 at checkout for a €30 discount.

Learn More

INTERESTED IN PSYCHEDELIC RESEARCH AND THERAPIES?

Subscribe to our new OPEN-Minded newsletter to stay in the loop, hear about our events, and become a part of a community dedicated to advancing psychedelics.

By clicking subscribe, I confirm to receive emails from the OPEN Foundation and agree with its privacy policy.

2 April - New Insights on Addiction & Psychedelic Healing Followed by a Live Q&A!

X