Intravenous DMT, a potent psychedelic and serotonin 2A receptor agonist, profoundly alters brain function in healthy volunteers. In a placebo-controlled study with 20 participants, multimodal neuroimaging (EEG-fMRI) showed that DMT robustly increases global functional connectivity, disrupts and desegregates brain networks, and compresses the principal cortical gradient. These changes overlapped with brain regions rich in serotonin 2A receptors and associated with human-specific psychological functions. EEG and fMRI measures correlated, linking neurophysiological changes to network-level effects. The findings indicate DMT predominantly acts on the brain's transmodal association cortex, the evolutionarily recent area tied to advanced cognition and high 5-HT2A receptor density.
The psychedelic drug DMT rapidly induces an immersive conscious state with vivid visual imagery. EEG recordings showed that DMT alters cortical traveling waves: the typical alpha-band backward wave of eyes-closed rest decreased, while a forward wave similar to that seen during visual stimulation increased. This supports a model where psychedelics reduce the precision-weighting of prior expectations, shifting the balance from top-down to bottom-up information flow. The findings suggest that backward traveling waves are correlates of precision weighting and that reduced backward and increased forward waves are a mechanistic principle of psychedelic-induced altered states.