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

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.