Collapse of directed functional hierarchy under classical serotonergic psychedelics
bioRxiv – December 21, 2024
Source: medRxiv/bioRxiv/arXiv
Summary
Psychedelics like psilocybin, LSD, and DMT significantly alter how our brains process information. This study reveals that these substances reduce the brain's functional hierarchy, promoting greater flexibility in thought patterns. This shift may explain the unique cognitive experiences during and after psychedelic use, hinting at their therapeutic benefits.
Abstract
It has been proposed that psychedelics induce profound functional changes to the hierarchical organisation of the human brain. Yet the term hierarchy is currently not well-defined in neuroscience. Here, we use a precise definition of hierarchy, grounded in the theory of thermodynamics, which allows the quantification of temporal asymmetry in the directionality of information flow. We quantified the changes to the directed functional hierarchy of the brain under three classical serotonergic psychedelics – psilocybin, LSD and DMT. We found that all three psychedelics induce a reduction of the directed functional hierarchy, such that they display lower levels of global and network temporal asymmetry and a contraction of the two main patterns of variation of temporal asymmetry. Crucially, our results imply that the brain’s directed functional hierarchy is collapsed under psychedelics, interpreted as yielding a more flexible brain. This enhanced flexibility in brain organisation under psychedelics may underpin the altered cognition and behaviour observed during these states, and, possibly afterwards, be suggestive of therapeutic potential.