DMT-induced shifts in criticality correlate with self-dissolution

Introduction

The authors frame their study within recent interest in how classic psychedelics alter subjective experience and brain dynamics. They explain the concept of criticality — a dynamical regime in which correlations persist over long distances and timescales, producing scale-invariant, complex fluctuations — and note that the human brain is often thought to operate near criticality. Long-range temporal correlations (LRTCs) in oscillatory amplitude envelopes are presented as an empirical signature of proximity to criticality, and detrended fluctuation analysis (DFA) is introduced as a method for quantifying LRTCs. The introduction also notes that DFA alone cannot distinguish shifts toward inhibition-dominated (subcritical) versus excitation-dominated (supercritical) regimes, and that a recently developed functional excitatory/inhibitory (fE/I) ratio can provide directional information. This study set out to quantify markers of criticality in human EEG recordings under the influence of the short-acting psychedelic DMT, and to relate those markers to subjective reports of self-dissolution (measured with a specific visual analogue scale item). M. and colleagues combined two placebo-controlled, single-blind, within-participant EEG datasets to test whether DMT alters DFA-estimated LRTCs and fE/I, whether those changes indicate sub- or supercritical shifts, and whether such changes correlate with disruption of self-related processing during the psychedelic state. The authors emphasise that linking criticality metrics with subjective self-dissolution could provide novel neural correlates of self-related processing in altered states of consciousness.