Dynamic Neural State Transitions Predict Psychedelic Phenomenal Richness: Magnitude, Not Direction, Drives Subjective Intensity

Summary

The study found that the dynamic changes in neural integration and complexity, measured by the Consciousness Gradient Index (CGI), significantly predicted the intensity of experiences during DMT inhalation, specifically relating to ego dissolution. Static measures showed no correlation with phenomenal richness, while CGI dynamics were linked to bodily aspects like disembodiment and out-of-body experiences. This suggests that the way neural states change, rather than their specific levels, influences subjective experiences during altered states.

Study at a glance

Abstract

UPDATED 2026-06-09 Corrected dataset attribution from Timmermann et al. (2019) to Pallavicini et al. (2021) UPDATED 2026-01-21 Background: Psychedelic substances produce profound alterations in conscious experience, yet the neural mechanisms underlying phenomenal richness remain poorly understood. Static measures of neural integration and complexity have shown limited success in predicting subjective intensity, suggesting alternative approaches may be needed. Methods: We analyzed EEG data from 34 participants who inhaled N,N-Dimethyltryptamine (DMT) in naturalistic settings. We computed the Consciousness Gradient Index (CGI = √(φ × ρ)), where φ represents global cortical integration and ρ represents spectral entropy, across 30-second windows throughout the experience. We correlated CGI dynamics with validated phenomenological measures (5D-Altered States of Consciousness scale), examining both composite scores and individual subscales. Results: Static measures of integration (φ), complexity (ρ), and their combination (CGI) showed no correlation with phenomenal richness (all r < 0.10, p > 0.65). In contrast, CGI dynamics significantly predicted phenomenal intensity (r = 0.378, p = 0.028) and ego dissolution specifically (r = 0.453, 95% CI [0.113, 0.727]), but not mystical experience (r = 0.331, CI includes zero). Subscale analysis revealed that CGI dynamics predicted bodily aspects of ego dissolution—disembodiment (r = 0.422) and out-of-body experiences (OB1: r = 0.480; OB2: r = 0.452)—but not unity (r = 0.334) or any mystical subscale. Both CGI_MaxChange and CGI_MeanAbsChange performed equivalently (Δr = 0.073, 95% CI [-0.140, 0.283]). Critically, both increases and decreases in CGI predicted richness equally (z = 0.08, p = 0.94), indicating that the magnitude of neural state transitions—not their direction—drives subjective intensity. Conclusions: Phenomenal richness in psychedelic states depends on dynamic exploration of neural state space rather than occupation of specific integration or complexity levels. CGI dynamics specifically track bodily self-disruption (disembodiment, out-of-body experiences) rather than mystical unity or bliss. These findings challenge static theories of consciousness and support dynamic models emphasizing state-space traversal, with implications for understanding altered states and developing consciousness theories.

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