Abstract

Introduction: DMT is a psychedelic, which at standard does, is notable for inducing immersive experiences which surpass in intensity those of other classic psychedelics. Its rich phenomenology is associated with subjective experiences of experiencing ‘alternate realms’ and communication with sensed presences or ‘entities’, in a state of partial disconnection from the external environment. We have performed 2 studies using EEG and fMRI to determine the neural correlates of the DMT experience.

Methods: Two studies were conducted involving a total of 38 healthy participants in which 59 intravenous doses of DMT and placebo have been administered. Brain activity was measured using EEG and fMRI and subjective responses were captured using realtime intensity ratings, questionnaires, and microphenomenological interviews. Finally, the effects of DMT on mental health were assessed using validated measures of depression, anxiety and well-being.

Results: Subjective intensity and visual experiences induced by DMT were inversely correlated with decreases in alpha power as well as increases in Lempel-Ziv complexity and delta/theta power. DMT also induced deactivation of most canonical resting-state networks measured with fMRI, while increasing integration between sensory and high-level networks and global connectivity in Salience, Default, and Frontoparietal Networks. Reverse inference showed that increased global connectivity was especially marked in areas related to language.

Discussion: Our results indicate that the immersive psychedelic state induced by DMT is associated with reduced modularity, increased global integration, and a higher repertoire of brain states, especially in high-order and language areas. These results suggest that DMT acts by freeing up cognitive resources in more evolved brain systems, shedding some light on the neuronal mechanisms associated with immersive states of consciousness.