The psychedelic drug DMT rapidly reorganizes conscious experience and brain activity, but the link between brain dynamics and subjective effects remains unclear. In a blinded, dose-dependent study, 19 participants received 20 mg or 40 mg of DMT. The higher dose produced more intense visual hallucinations and emotional experiences. Electroencephalography data showed that alpha power and permutation entropy best tracked moment-to-moment changes in subjective experience, while Lempel-Ziv complexity—previously thought to be a strong correlate—showed the weakest association. The findings indicate that the relationship between neural complexity and psychedelic phenomenology is less straightforward than hypothesized.
A dose of the fast-acting psychedelic drug DMT rapidly reorganizes both conscious experience and brain activity. In a blinded, counterbalanced study, 19 participants received either 20 mg or 40 mg of freebase DMT. The higher dose caused more extreme visual hallucinations and emotionally intense experiences. Electroencephalography showed that changes in alpha brainwave power and a measure of signal irregularity (permutation entropy) were most strongly linked to moment-by-moment changes in subjective experience. Surprisingly, a measure of neural signal complexity (Lempel-Ziv complexity), previously thought to be a robust marker of psychedelic states, showed the weakest link to experience. This suggests the connection between brain complexity and conscious experience during psychedelic states is less straightforward than previously assumed.
A multi-level oddball task reveals that local and global prediction-error responses interact, challenging the view that the global effect reflects a distinct processing mode beyond predictive coding. Sedation modulates this interaction, suggesting conscious awareness may not be confined solely to the global processing level.