Psychedelics appear to temporarily reconfigure cooperation among large-scale brain networks by boosting cross-talk between them. During acute effects, higher association systems like the default mode and frontoparietal networks show stronger coupling with visual, somatomotor, and attention networks, indicating a more integrated yet differently organized state.
This picture comes from an international mega-analysis of 11 resting-state fMRI datasets across psilocybin, LSD, DMT, ayahuasca, and mescaline, reported in Nature Medicine. The most robust finding was increased connectivity between networks. Decreases within some sensory and motor networks were present but less consistent. Subcortical regions such as thalamus, striatum, and cerebellum also showed altered coupling with sensorimotor systems.
Across compounds, psilocybin and LSD looked similar; DMT appeared stronger, mescaline partly similar, and ayahuasca more distinct, though these differences rested on small samples. Bayesian modeling was used to highlight effects that were more likely to be reliable. These results describe acute brain states and do not, on their own, establish therapeutic mechanisms.
In short, psychedelics do not switch networks off but briefly reshuffle how networks communicate.