Perception is in the Details: A Predictive Coding Account of the Psychedelic Phenomenon

Psychedelic substances are used for clinical applications (e.g., treatment of addictions, anxiety and depression) as well as an investigative tool in neuroscientific research. Recently it has been proposed that the psychedelic phenomenon stems from the brain reaching an increased entropic state. In this paper, we use the predictive coding framework to formalize the idea of an entropic brain. We propose that the increased entropic state is created when top-down predictions in affected brain areas break up and decompose into many more overly detailed predictions due to hyper activation of 5-HT2A receptors in layer V pyramidal neurons. We demonstrate that this novel, unified theoretical account can explain the various and sometimes contradictory effects of psychedelics such as hallucination, heightened sensory input, synesthesia, increased trait of openness, ‘ego death’ and time dilation by up-regulation of a variety of mechanisms the brain can use to minimize prediction under the constraint of decomposed prediction.