This neuroimaging study (n=20) aimed to understand the effects of DMT (20mg) on the human brain. The researchers used EEG-fMRI (electroencephalography-functional MRI) to measure brain activity before, during, and after administering DMT to healthy volunteers. They found that DMT increased global functional connectivity (GFC), network disintegration and desegregation, and a compression of the principal cortical gradient. These changes were associated with the brain’s transmodal association pole, which is linked to species-specific psychological advancements and high expression of 5-HT2A receptors.
Abstract of Human brain effects of DMT assessed via EEG-fMRI
“Psychedelics have attracted medical interest, but their effects on human brain function are incompletely understood. In a comprehensive, within-subjects, placebo-controlled design, we acquired multimodal neuroimaging [i.e., EEG-fMRI (electroencephalography-functional MRI)] data to assess the effects of intravenous (IV) N,N-Dimethyltryptamine (DMT) on brain function in 20 healthy volunteers. Simultaneous EEG-fMRI was acquired prior to, during, and after a bolus IV administration of 20 mg DMT, and, separately, placebo. At dosages consistent with the present study, DMT, a serotonin 2A receptor (5-HT2AR) agonist, induces a deeply immersive and radically altered state of consciousness. DMT is thus a useful research tool for probing the neural correlates of conscious experience. Here, fMRI results revealed robust increases in global functional connectivity (GFC), network disintegration and desegregation, and a compression of the principal cortical gradient under DMT. GFC × subjective intensity maps correlated with independent positron emission tomography (PET)-derived 5-HT2AR maps, and both overlapped with meta-analytical data implying human-specific psychological functions. Changes in major EEG-measured neurophysiological properties correlated with specific changes in various fMRI metrics, enriching our understanding of the neural basis of DMT’s effects. The present findings advance on previous work by confirming a predominant action of DMT—and likely other 5-HT2AR agonist psychedelics—on the brain’s transmodal association pole, i.e., the neurodevelopmentally and evolutionarily recent cortex that is associated with species-specific psychological advancements, and high expression of 5-HT2A receptors.”
Authors: Christopher Timmermann, Leor Roseman, Sharad Haridas, Fernando E. Rosas, Lisa Luan, Hannes Kettner, Jonny Martell, David Erritzoe, Enzo Tagliazucchi, Carla Pallavicini, Manesh Girn, Andrea Alamia, Robert Leech, David J. Nutt & Robin L. Carhart-Harris
Summary of Human brain effects of DMT assessed via EEG-fMRI
DMT is a classic serotonergic psychedelic drug that induces an intense and immersive altered state of consciousness, characterized by vivid and complex imagery, and a sense of being transported to an alternative reality or dimension, without any diminishment in wakefulness.
Clinical trials of psychedelic therapy have yielded consistently promising safety and efficacy findings, suggesting that 5-HT2A receptor agonism is the trigger event in psychedelics’ therapeutic action.
Most human research with pure DMT involves an intravenous mode of administration. Previous functional MRI studies revealed decreased within-network functional connectivity (FC) and increased between-network FC (a globally hyperconnected brain state).
Find this paper
Human brain effects of DMT assessed via EEG-fMRI
https://doi.org/10.1073/pnas.2218949120
Open Access | Google Scholar | Backup | 🕊
Cite this paper (APA)
Timmermann, C., Roseman, L., Haridas, S., Rosas, F. E., Luan, L., Kettner, H., ... & Carhart-Harris, R. L. (2023). Human brain effects of DMT assessed via EEG-fMRI. Proceedings of the National Academy of Sciences, 120(13), e2218949120.
Study details
Compounds studied
DMT
Topics studied
Neuroscience
Study characteristics
Original
Placebo-Controlled
Single-Blind
Randomized
Participants
20
Humans
Authors
Authors associated with this publication with profiles on Blossom
Chris TimmermannChris Timmerman is a postdoc at Imperial College London. His research is mostly focussed on DMT.
David Nutt
David John Nutt is a great advocate for looking at drugs and their harm objectively and scientifically. This got him dismissed as ACMD (Advisory Council on the Misuse of Drugs) chairman.
Robin Carhart-Harris
Dr. Robin Carhart-Harris is the Founding Director of the Neuroscape Psychedelics Division at UCSF. Previously he led the Psychedelic group at Imperial College London.
Institutes
Institutes associated with this publication
Imperial College LondonThe Centre for Psychedelic Research studies the action (in the brain) and clinical use of psychedelics, with a focus on depression.
Compound Details
The psychedelics given at which dose and how many times
DMT 20 mg | 1xLinked Research Papers
Notable research papers that build on or are influenced by this paper
Autonomic nervous system activity correlates with peak experiences induced by DMT and predicts increases in well-beingThis re-analysis of a single-blind study (n=17) investigates the role of the autonomic nervous system in DMT-induced peak experiences (20mg, iv). It finds that balanced activity between the "fight-or-flight" and "rest-and-digest" systems (sympathovagal coactivation) is linked to stronger feelings of spirituality and insight during DMT sessions and improved well-being two weeks later. The study also notes that a person's nervous system (sympathovagal) balance before taking DMT can predict how insightful their experience will be.
Interrupting the Psychedelic Experience Through Contextual Manipulation to Study Experience Efficacy
This secondary analysis from a DMT study explores the impact of intentional cognitive interruptions on psychedelic experiences. The study investigates whether increasing cognitive load during the experience affects subjective ratings, hypothesizing that higher task demands would lower these ratings. Additionally, it examines whether reduced task demands correlate with larger reductions in long-term depressive symptoms.
Brain substates induced by DMT relate to sympathetic output and meaningfulness of the experience
This pre-print single-blind study (n=14) used multimodal neuroimaging techniques (fMRI + EKG) to investigate brain activity and autonomic physiology during DMT (20mg) altered state of consciousness. Results reveal unique brain activity substates, with increased superior temporal lobe activity and hippocampal deactivation under DMT, correlating with auditory distortions and meaningfulness of the experience, respectively. Moreover, increased heart rate under DMT correlates with hippocampal and medial parietal deactivation, suggesting a potential link between sympathetic regulation and positive mental health outcomes following psychedelic administration.
DMT induces a transient destabilization of whole-brain dynamics
This pre-print computational fMRI study (n=15) examines brain dynamics after DMT (iv; 20mg) administration, focusing on the onset of the psychedelic state. It reveals a peak destabilization of brain dynamics around 5 minutes post-administration and identifies a heightened reactivity phase, primarily affecting fronto-parietal and visual regions. The study links these changes to serotonin 5HT2a receptor density, suggesting these dynamics underpin the psychedelic state's complexity and flexibility.
Time-resolved network control analysis links reduced control energy under DMT with the serotonin 2a receptor, signal diversity, and subjective experience
This re-analysis (n=14) applies a receptor-informed network control theory framework to investigate the effects of DMT on the brain's control energy landscape. It reveals that DMT, like LSD and psilocybin, reduces global control energy, with these trajectories correlating with EEG signal diversity and subjective intensity ratings. Furthermore, the regional effects of DMT correlate with serotonin 2a receptor density, demonstrating a potential proof-of-concept for predicting pharmacological intervention effects on brain dynamics using control models.