Navigating the chaos of psychedelic fMRI brain-entropy via multi-metric evaluations of acute psilocybin effects
OpenAlex – July 03, 2023
Source: OpenAlex
Summary
Psilocybin's impact on brain entropy is surprisingly nuanced. A study of 121 fMRI scans from 28 participants revealed that while some mathematical metrics, like Shannon entropy, increased, sample entropy showed divergent patterns, and 8 of 13 measures had no significant change. This challenges the idea of universal brain complexity increase, instead highlighting specific neural activity patterns. These neuroscience findings, relevant to cognitive psychology, pattern recognition, underscore the complex interplay of psilocybin with neurotransmitter receptors, deepening psychedelic drug studies and informing artificial intelligence.
Abstract
A prominent theory of psychedelics is that they increase brain entropy. Twelve studies have evaluated psychedelic effects on fMRI brain entropy quantifications, no findings have been replicated. Here we evaluated these metrics in an independent 28-participant healthy cohort with 121 pre- and post-psilocybin fMRI scans. We assessed relations between brain entropy and plasma psilocin, brain serotonin 2A receptor occupancy, and a subjective drug intensity rating using linear mixed-effects models. We observed significant positive associations for Shannon entropy of path-length, instantaneous correlation distributions, and divergent associations of sample entropy at varying time-scales. We did not observe significant effects for 8 of 13 entropy metrics. Brain entropy quantifications showed limited inter-measure correlations. Our observations support a nuanced acute psychedelic effect on brain entropy, underscoring the need for replication and that these metrics do not reflect a singular construct. Our findings highlight candidate brain entropy metrics that may mediate clinical effects of psychedelics.