An investigation has created a 3D map of the brain that processes the subjective experiences caused by psychedelics, thus opening the possibility of creating altered states of consciousness for therapeutic purposes at will.
Research led by McGill University in Canada has mapped for the first time how psychedelics produce certain effects in the human brain. The results are published in the journal Science Advances.
For thousands of years, humans have been drawn to the use of hallucinogenic or psychedelic substances to deliberately alter states of consciousness.
These drug-induced states of mind frequently involve mystical experiences, the blurring of boundaries between self and the world, changes in socioemotional perception, and a dramatic heightening of sensory capacity.
The subjective alterations of reality produced by these drugs are highly variable between individuals and depend on life history, worldview and the environment in which each experience unfolds: the same drug can induce unlimited feelings of joy and love in some sessions, but terror and panic in other sessions, the authors of this research point out in their article.
altered state of consciousness
In addition to subject-related factors for interindividual variability, the nature of the drug-induced experience also depends on the chemical compounds of each drug.
Numerous clinical studies have shown that psychedelic drugs show promise as treatments for a variety of psychiatric conditions: they alleviate Post-Traumatic Stress Disorder (PTSD) and treatment-resistant depression.
The main therapeutic value of psychedelic drugs refers to their apparent ability to alter the state of consciousness: Ego dissolution is a hallmark of hallucinogenic states of consciousness.
Due mainly to the therapeutic value of these substances, science has become increasingly interested in discovering the molecular mechanisms that underpin the neuronal processes associated with these chemicals.
At the macroscopic level, hallucinogens are thought to elicit the associated psychological effects through changes in functional coupling between large-scale brain networks.
The largest studio in the world
To get to the bottom of these brain processes, a team of researchers developed the world’s largest study of psychedelic effects on the brain and demonstrated that drug-induced changes in subjective consciousness are anatomically rooted in specific neurotransmitter receptor systems .
The researchers gathered 6,850 testimonials from people who took a variety of 27 different psychedelic drugs. In a first-of-its-kind study, they designed a machine learning strategy to extract commonly used words from their testimonials and link them to neurotransmitter receptors (proteins) that convey their meaning to the nervous system.
By encoding words like “happy” or “color,” the researchers were able to track the impact of a typical “high” experience on the brain for each of the 27 drugs tested.
Thus they discovered that these experiences the brain recorded in the lowest and deepest layers of the crustthe gray substance that covers the surface of the cerebral hemispheres and that processes perception, imagination, thought, judgment and decision making.
3D map
Using thousands of gene transcription probes, the team created a 3D map of brain receptors, and the subjective experiences linked to them, throughout the brain.
Although it is known that the psychedelic experience varies widely from person to person, the large set of testimonial data made it possible to link coherent states of conscious experiences with receptors and brain regions in each of the individuals.
This finding supports the theory that new hallucinogenic drug compounds can be designed to reliably create desired mental states.
For example, a promising effect of some psychedelics for psychiatric intervention is ego dissolution, the feeling of being separate from oneself.
therapeutic possibilities
The study found that this feeling was most associated with the serotonin 5-HT2A receptor. However, other serotonin receptors (5-HT2C, 5-HT1A, 5-HT2B), the adrenergic receptors Alpha-2A and Beta-2, as well as the D2 receptor were also related to the sensation of ego dissolution.
A drug that targets these receptors can reliably create this sensation in patients that doctors think might benefit from it, the researchers say.
Danilo Bzdok, lead author of this research, said in a statement: “Our study provides a first step, a proof of principle, that we can build machine learning systems that can accurately predict which combinations of neurotransmitter receptors should be stimulated, to induce a specific state of conscious experience in a given person”.
Reference
Trips and neurotransmitters: Discovering principled patterns across 6850 hallucinogenic experiences. Galen Ballentine et al. Science Advances, 16 Mar 2022; Vol 8, Issue 11. DOI:10.1126/sciadv.abl6989