Time-resolved neural and experience dynamics of medium- and high-dose DMT

Summary

Both 20mg and 40mg doses of N,N-Dimethyltryptamine (DMT) led to rapid changes in subjective experiences, with the higher dose resulting in more intense visual hallucinations and emotional experiences. Interestingly, the expected neural marker, lempel-ziv complexity, showed the weakest association with these psychedelic states, indicating a more complicated relationship between brain dynamics and conscious experiences than previously thought.

Study at a glance

Abstract

N,N-Dimethyltryptamine (DMT) is a fast-acting psychedelic drug that induces a radical reorganisation of conscious contents and brain dynamics. However, our understanding of how brain dynamics support psychedelic-induced conscious states remains unclear. We therefore present 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 sessions in a blinded, counterbalanced order. Electroencephalography (EEG) data and time-resolved measures of subjective experience (Temporal Experience Tracing) were collected. Both doses of DMT induced rapid changes in experience dimensions, with the 40mg dose inducing more extreme visual hallucinations and emotionally intense experiences. Strikingly, lempel-ziv complexity, previously hailed as a robust phenomenological correlate within the psychedelic-state, was the least strongly associated neural marker. These findings suggest that the relationship between neural complexity and phenomenology in psychedelic states is less clear than originally hypothesised.