Time-resolved Neural and Experience Dynamics of Medium- and High-dose N,N-Dimethyltryptamine
This repeated-measures dose-dependent study (n=19) investigates DMT's subjective and neural dynamics under naturalistic conditions. Participants received 20mg or 40mg doses of freebase DMT in a blinded, counterbalanced design, with EEG data and time-resolved subjective measures collected. The 40mg dose produced more intense visual hallucinations and emotional responses. Neural analyses revealed alpha power and permutation entropy were most associated with subjective experiences, whereas lempel-ziv complexity was less predictive, challenging prior assumptions about its role in psychedelic states.
Authors
- Enzo Tagliazucchi
- Claudio Pallavicini
- Federico Cavanna
Published
Abstract
N,N-Dimethyltryptamine (DMT) is a potent and fast-acting psychedelic drug that induces a radical reorganisation of the contents of consciousness, comprising the dissolution of time and space and perceptual immersion into an ‘alternate reality’. While contemporary research has somewhat advanced our understanding of DMT, and psychedelics more broadly, there is little research that integrates time-resolved measures of subjective experience with temporally fine-grained brain imaging. We therefore present the current study, a repeated-measures dose-dependent study of the subjective and neural dynamics induced through DMT under naturalistic conditions. Nineteen participants received either a 20mg or 40mg dose of freebase DMT across two dosing sessions in a blinded, counterbalanced order, with blinding rates consistent across doses. Electroencephalography (EEG) data was collected, as well as time-resolved retrospective measures of subjective experience (Temporal Experience Tracing). Both doses of DMT induced rapid changes in experience dimensions. However, the 40mg dose induced significantly more extreme visual hallucinations and emotionally intense experiences. Further, we computed a variety of neural markers on the EEG data, and found that oscillatory alpha power and permutation entropy were most strongly associated with continuous subjective experience dimensions. Strikingly, lempel-ziv complexity, a previously hailed as a robust correlate of subjective experiences within the psychedelic-state, was the least strongly associated neural marker. These findings provide an important insight into how distinct neural dynamics may contribute to this radical and intense altered state of consciousness.
Research Summary of 'Time-resolved Neural and Experience Dynamics of Medium- and High-dose N,N-Dimethyltryptamine'
Introduction
Lewis-Healey and colleagues position serotonergic psychedelics as tools to probe the neural basis of consciousness because they produce rapid, reversible and profound reorganisations of subjective experience. N,N-Dimethyltryptamine (DMT), when inhaled as freebase or given intravenously, can produce brief but intense experiences characterised by loss of normal temporal and spatial structure, vivid visual phenomena and reports of perceived entities. Prior neurophysiological work has associated psychedelic states with broadband spectral changes, reductions in alpha oscillatory power, increased functional connectivity, and higher measures of neural complexity, leading to theories such as the Entropic Brain Theory which links neural entropy to phenomenological richness. However, most prior studies have relied on discrete rating scales that inadequately capture the continuous, time-varying nature of psychedelic phenomenology. To address this gap, the investigators combined Temporal Experience Tracing (TET), a retrospective method that yields continuous, multidimensional time series of subjective experience, with high-temporal-resolution electroencephalography (EEG) in a within-subject, dose-manipulated study of inhaled freebase DMT. The primary aim was to map time-resolved associations between multiple neural markers (information-theoretic, spectral and connectivity measures) and continuous experience dimensions across two doses (20mg, 40mg) under naturalistic conditions, testing which neural features best track phenomenological dynamics induced by DMT.
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Study Details
- Study Typeindividual
- Journal
- Compounds
- Topic
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- APA Citation
Lewis-Healey, E., Pallavicini, C., Cavanna, F., D'Amelio, T., De La Fuente, L. A., Copa, D., Müller, S., Bruno, N., Tagliazucchi, E., & Bekinschtein, T. (2025). Time-resolved Neural and Experience Dynamics of Medium- and High-dose N,N-Dimethyltryptamine. Journal of Cognitive Neuroscience, 1-20. https://doi.org/10.1162/JOCN.a.2423
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