Decreased Directed Functional Connectivity in the Psychedelic State
OpenAlex – July 16, 2019
Source: OpenAlex
Summary
The psychedelic state dramatically alters brain communication. Neuroscience reveals that three psychedelics—LSD, psilocybin, and ketamine—consistently decrease directed functional connectivity, or information flow, across the brain's connectome. This suggests a breakdown in typical functional organization. Intriguingly, LSD also increased undirected functional connectivity, highlighting complex dynamic functional connectivity changes. These neuroimaging findings, vital for cognitive psychology and drug studies, demonstrate how neurotransmitter receptor influence on behavior, understood through biochemical analysis, manifests as altered brain networks, informing artificial intelligence models.
Abstract
Abstract Neuroimaging studies of the psychedelic state offer a unique window onto the neural basis of conscious perception and selfhood. Despite well understood pharmacological mechanisms of action, the large-scale changes in neural dynamics induced by psychedelic compounds remain poorly understood. Using source-localised, steady-state MEG recordings, we describe changes in functional connectivity following the controlled administration of LSD, psilocybin and low-dose ketamine, as well as, for comparison, the (non-psychedelic) anticonvulsant drug tiagabine. We compare both undirected and directed measures of functional connectivity between placebo and drug conditions. We observe a general decrease in directed functional connectivity for all three psychedelics, as measured by Granger causality, throughout the brain. These data support the view that the psychedelic state involves a breakdown in patterns of functional organisation or information flow in the brain. In the case of LSD, the decrease in directed functional connectivity is coupled with an increase in undirected functional connectivity, which we measure using correlation and coherence. This surprising opposite movement of directed and undirected measures is of more general interest for functional connectivity analyses, which we interpret using analytical modelling. Overall, our results uncover the neural dynamics of information flow in the psychedelic state, and highlight the importance of comparing multiple measures of functional connectivity when analysing time-resolved neuroimaging data.