Complex slow waves in the human brain under 5-MeO-DMT

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is among the most potent and rapidly acting psychedelic compounds known, with a history of ritual use dating back over 1,000 years and increasing involvement in contemporary clinical trials for depression, bipolar disorder, and alcohol use disorder. Its subjective effects — characterised by a radical dissolution of the axes of time, space, and selfhood — are qualitatively distinct from those of DMT or psilocybin, which typically involve richly structured geometric visual experiences. At the peak of the 5-MeO-DMT experience, users report entering an ineffable state in which even the awareness of being a subject is suspended, suggesting a global deconstruction rather than reduction of consciousness. Despite this phenomenological distinctiveness and growing clinical relevance, 5-MeO-DMT had not been studied using human neuroscience methods at the time of this investigation. The researchers aimed to characterise the electroencephalographic (EEG) signatures of the acute 5-MeO-DMT brain state, with particular interest in distinguishing it from states of unconsciousness and examining how spatiotemporal neural dynamics relate to the compound's unique subjective effects.

EEG data were recorded from 64 channels in participants before and after inhaled 5-MeO-DMT (n = 19); 10 participants were excluded due to movement artefacts, yielding n = 13 for peak-window analyses (1.5-2.5 minutes post-inhalation). To avoid the limitations of conventional Fourier-based spectral methods — which assume stationarity and sinusoidality — the researchers applied empirical mode decomposition (EMD) and the Hilbert-Huang transform (HHT) to extract intrinsic oscillatory modes across 0.5-50 Hz. Results were corroborated using multitaper fast Fourier transform. Spatiotemporal wave propagation was characterised by interpolating instantaneous amplitude and phase onto a uniform scalp grid and computing velocity fields using fluid-dynamics mathematics. Global and local phase synchrony (coherence) and metastability were quantified using a Kuramoto-like formalism across a range of spatial radii. Broadband neural stability was assessed using four complementary measures: the decay time of the auto-mutual information function (intrinsic timescale), the maximum Lyapunov exponent (sensitivity to initial conditions), PCA eigenvalue analysis (dimensionality), and mean-squared displacement (MSD) energy landscape analysis. Subjective experience was assessed using 25 custom visual analog scale items, with dominance regression used to identify the strongest neural predictors of self-report scores.

5-MeO-DMT produced rapid increases in both slow (<1.5 Hz) and fast (>20 Hz) oscillatory power, emerging within 20 seconds of inhalation and decaying after 8-10 minutes. The lowest-frequency bin (0.5 Hz) increased by 415% relative to baseline at the peak of the drug effect. Spectral distance analyses confirmed that the 5-MeO-DMT state maintained a distinct and consistent profile for approximately the first four minutes. Spatiotemporal analyses revealed that 5-MeO-DMT markedly reduced the phase synchrony (global coherence) and metastability of slow, delta, and ultra-slow wave modes (all p_FDR < 0.05), collapsing the topographic hierarchy of synchronisation across spatial scales. Rather than producing simple, coherent, globally propagating waves as seen in anaesthesia, 5-MeO-DMT generated complex, incoherent, and spatially fragmented wave patterns that failed to propagate through the cortical hierarchy. The intrinsic timescale of broadband activity doubled under 5-MeO-DMT (221.9 to 495.3 ms; p_FDR = 0.018), the maximum Lyapunov exponent decreased (p_FDR = 0.046), and variance explained by the first principal component increased (p_FDR = 0.027), together indicating that cortical dynamics became more stable and low-dimensional. Energy landscape analysis showed a significantly increased energetic cost for large global activity deviations (p_FDR = 0.001, d = 1.193). Ultra-slow wave field heterogeneity was the strongest neural predictor of subjective reports of ego dissolution (R² > 0.7 for top items including "body felt not my own" and "experienced sense of void").

The results demonstrate that 5-MeO-DMT produces a neurodynamic state that is qualitatively distinct from both baseline consciousness and states of unconsciousness such as anaesthesia. The induction of complex, spatiotemporally disorganised, low-frequency wave patterns — rather than the simple coherent slow oscillations associated with loss of consciousness — challenges the view that diffuse high-amplitude slow activity is universally indicative of unconsciousness. The researchers propose that this pattern of wave disorganisation underlies the environmental disconnection characteristic of the 5-MeO-DMT experience, in which subjective experience becomes decoupled from sensory input without being eliminated. The shift towards more stable, low-dimensional broadband dynamics parallels the subjective quality of the state: a world stripped of the usual axes of variation. The researchers interpret this as consistent with enhanced parallel but poorly integrated information processing, speculating that local collision-based computation may be enhanced whilst global integration is diminished. This work underscores the limitations of univariate spectral measures — such as alpha power suppression — as universal markers of psychedelic effects, and advocates for comprehensive spatiotemporal frameworks capable of capturing the full diversity of human brain states. The relationship between ultra-slow wave heterogeneity and ego dissolution is highlighted as a promising neural correlate of altered self-referential processing.

This investigation presents the first detailed human neuroscientific study of 5-MeO-DMT, reporting novel disruptions in the spatiotemporal organisation of low-frequency cortical waves that underlie the compound's radically deconstructed state of consciousness. The findings emphasise the need for both a revised understanding of slow wave functions in subjective experience and more comprehensive spatiotemporal analytical methods in neuroscience to adequately characterise the full diversity of human brain states.