Abstract The last decade has seen a remarkable resurgence of interest in psychedelic drugs such as psilocybin (from magic mushrooms) LSD and DMT (dimethyl tryptamine – the active ingredient of ayahuasca). This has been driven by the discovery that these psychedelics all act agonists of 5-HT2A receptors plus human imaging studies that reveal this action leads to profound alterations in brain...
Abstract Background The REBUS (RElaxed Beliefs Under pSychedelics) and the anarchic brain model of psychedelic drug action proposes that confidence in beliefs – and thus expectations (priors) – are relaxed under these drugs. The brain makes inferences to minimize surprise, or discrepant expectations and outcomes (prediction error [PE]), and better model the world. We recently showed that the...
Cortical 5HT2A receptors are largely expressed in layer 5 pyramidal neurons and appear to play a pivotal role in brain function in that they gate top-down descending inputs to local cortical microcircuits. There is evidence that they may play a role in depression in that the number of these receptors is increased in some people with depression and the augmenting action of atypical...