Synthetic surprise as the foundation of the psychedelic experience
Neuroscience & Biobehavioral Reviews – January 15, 2024
Source: OpenAlex
Summary
Psychedelics like psilocybin profoundly alter consciousness, a surprising effect potentially explained by a "synthetic surprise" mechanism. This cognitive science theory, integrating neuroscience and computer science, proposes that psilocybin activates one specific 5-HT2A receptor type, enforcing a state of prediction error within the brain's predictive coding framework. This disrupts perception by increasing the precision of sensory input over top-down expectations. This novel understanding offers a powerful new perspective for psychology, suggesting psychedelics could therapeutically disrupt maladaptive patterns.
Abstract
Psychedelic agents, such as LSD and psilocybin, induce marked alterations in consciousness via activation of the 5-HT2A receptor (5-HT2ARs). We hypothesize that psychedelics enforce a state of synthetic surprise through the biased activation of the 5-HTRs system. This idea is informed by recent insights into the role of 5-HT in signaling surprise. The effects on consciousness, explained by the cognitive penetrability of perception, can be described within the predictive coding framework where surprise corresponds to prediction error, the mismatch between predictions and actual sensory input. Crucially, the precision afforded to the prediction error determines its effect on priors, enabling a dynamic interaction between top-down expectations and incoming sensory data. By integrating recent findings on predictive coding circuitry and 5-HT2ARs transcriptomic data, we propose a biological implementation with emphasis on the role of inhibitory interneurons. Implications arise for the clinical use of psychedelics, which may rely primarily on their inherent capacity to induce surprise in order to disrupt maladaptive patterns.