Time-resolved neural and experience dynamics of medium- and high-dose DMT
Bekinschtein, T., Bruno, N., Cavanna, F., Copa, D., D'Amelio, T., de la Fuente, L. A., Lewis-Healey, E., Muller, S., Pallavicini, C., Tagliazucchi, E.
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.
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.