Psilocybin desynchronizes brain networks

This pre-print functional mapping study (n=24) examined brain changes in healthy adults before, during, and up to 3 weeks after taking oral psilocybin (25mg) and methylphenidate (Ritalin), with a follow-up 6+ months later. Psilocybin caused over 3-fold greater acute changes in functional networks than Ritalin, with the most significant disruptions observed in the default mode network (DMN), linked to our sense of self. While a perceptual task reduced these changes, suggesting a way to ground individuals during psychedelic therapy, the acute effects of psilocybin were consistent with distortions of space-time and self. Notably, psilocybin led to a persistent decrease in connectivity between the anterior hippocampus and cortex, especially the DMN, lasting weeks but normalizing after six months, potentially explaining its pro-plasticity and anti-depressant effects.

Abstract of Psilocybin desynchronizes brain networks

“The relationship between the acute effects of psychedelics and their persisting neurobiological and psychological effects is poorly understood. Here, we tracked brain changes with longitudinal precision functional mapping in healthy adults before, during, and for up to 3 weeks after oral psilocybin and methylphenidate (17 MRI visits per participant) and again 6+ months later. Psilocybin disrupted connectivity across cortical networks and subcortical structures, producing more than 3-fold greater acute changes in functional networks than methylphenidate. These changes were driven by desynchronization of brain activity across spatial scales (area, network, whole brain). Psilocybin-driven desynchronization was observed across association cortex but strongest in the default mode network (DMN), which is connected to the anterior hippocampus and thought to create our sense of self. Performing a perceptual task reduced psilocybin-induced network changes, suggesting a neurobiological basis for grounding, connecting with physical reality during psychedelic therapy. The acute brain effects of psilocybin are consistent with distortions of space-time and the self. Psilocybin induced persistent decrease in functional connectivity between the anterior hippocampus and cortex (and DMN in particular), lasting for weeks but normalizing after 6 months. Persistent suppression of hippocampal-DMN connectivity represents a candidate neuroanatomical and mechanistic correlate for psilocybin’s pro-plasticity and anti-depressant effects.”

Authors: Joshua S. Siegel, Subha Subramanian, Demetrius Perry, Benjamin Kay, Evan Gordon, Timothy Laumann, Rick Reneau, Caterina Gratton, Christine Horan, Nicholas Metcalf, Ravi Chacko, Julie Schweiger, Dean Wong, David Bender, Jonah Padawer-Curry, Charles Raison, Marcus Raichle, Eric J. Lenze, Abraham Z Snyder, Nico U. F. Dosenbach &Ginger Nicol

Summary of Psilocybin desynchronizes brain networks