Detailed brain imaging data from 20 healthy volunteers has revealed how DMT increased connectivity across the brain, with more communication between different areas and systems.
The study, carried out at the Centre for Psychedelic Research at Imperial College London, is the first to track brain activity before, during and after the DMT experience in such detail.
Data demonstrated that the changes to brain activity were most prominent in areas linked with ‘higher level’ functions, such as imagination.
The researchers explain that the study, which has been published in the journal PNAS, provides further evidence of how DMT, and psychedelics more generally, exert their effects by disrupting high-level brain systems.
Dr Chris Timmerman, from the Centre for Psychedelic Research at Imperial College London, and first author, stated: “This work is exciting as it provides the most advanced human neuroimaging view of the psychedelic state to date.
“One increasingly popular view is that much of brain function is concerned with modelling or predicting its environment. Humans have unusually big brains and model an unusually large amount of the world.
“For example, like with optical illusions, when we’re looking at something, some of what we’re actually seeing is our brain filling in the blanks based on what we already know. What we have seen with DMT is that activity in highly evolved areas and systems of the brain that encode especially high-level models becomes highly dysregulated under the drug, and this relates to the intense drug ‘trip’.”
The brain on psychedelics
How DMT alters brain function to account for its effects – such as intense and immersive altered states of consciousness characterised by vivid and bizarre visions, a sense of ‘visiting’ alternative realities or dimensions, and similarities with near death experiences – has been unclear.
In the latest study, 20 healthy volunteers were given an injection of DMT while the researchers captured detailed imagery of their brains.
Volunteers received a high dose of DMT (20mg, given intravenously), while simultaneously undergoing two types of brain imaging: functional magnetic resonance imaging (fMRI) and electroencephalography (EEG).
The total psychedelic experience lasted about 20 minutes, and at regular intervals, volunteers provided a rating of the subjective intensity of their experience.
The fMRI scans found changes to activity within and between brain regions in the volunteers, with effects including increased connectivity across the brain, with more communication between different areas and systems.
These phenomena, termed ‘network disintegration and desegregation’ and increased ‘global functional connectivity’, align with previous studies with other psychedelics. The changes to activity were most prominent in brain areas linked with ‘higher level’, human-specific functions, such as imagination.
The authors write: “Regions with the densest expression of serotonin 2A receptors as determined via independent positron emission tomography (PET) data, were most affected by DMT, and overlapped with regions related to evolved cognitive functions such as language and semantic processing. These results support the notion that psychedelics impact a principal axis of brain organization, and relatedly, the quality of human conscious experience.”
Professor Robin Carhart-Harris of University of California, San Francisco, founder of the Centre for Psychedelic Research at Imperial College London, and senior author on the paper, commented: “Motivated by, and building on our previous research with psychedelics, the present work combined two complementary methods for imaging the brain imaging.
“fMRI allowed us to see the whole of the brain, including its deepest structures, and EEG helped us view the brain’s fine-grained rhythmic activity.
“Our results revealed that when a volunteer was on DMT there was a marked dysregulation of some of the brain rhythms that would ordinarily be dominant. The brain switched in its mode of functioning to something altogether more anarchic.
“It will be fascinating to follow up on these insights in the years to come. Psychedelics are proving to be extremely powerful scientific tools for furthering our understanding of how brain activity relates to conscious experience.”
The Imperial team is now exploring how to prolong the peak of the psychedelic experience through continuous infusion with DMT, and some are also advising on a commercially run trial to assess DMT for patients with depression.
The research was funded by a donation from Patrick Vernon, mediated by The Beckley Foundation.