People who are under the influence of a psychedelic drink known as ayahuasca often experience vivid visual and auditory hallucinations, as well as the feeling that they are in a dream. Now, a new study published in Scientific Reports has shown that the drug alters the user's wakefulness patterns in the brain, creating a mental state that researchers describe as a “waking dream”.
Ayahuasca is a bitter Brazilian vine tea banisteriopsis caapi, colloquially known as the "spiritual vine", used in shamanistic spiritual ceremonies among the indigenous people of the Amazon basin. Its main active ingredient is dimethyltryptamine (DMT). This is the secret to the powerful psychedelic effects of ayahuasca, which can also cause feelings of delight and fear, or a sense of insight or psychological breakthrough. However, these mind-altering properties are worth the price. Ceremonies are often advised to bring a bucket, as nausea and vomiting (and sometimes diarrhea) are common reactions to tea.
The brain controls perception and communication throughout the body using chemical neurotransmitters. Each neurotransmitter attaches to corresponding areas on nerve cells known as receptors. For example, LSD targets brain serotonin receptors. Ayahuasca contains a compound (banisterin) that traps dopamine receptors in the brain. (That's why banisterin has the potential to treat Parkinson's disease, which destroys dopamine receptors.)
Several previous studies involving people who have studied the brain have shown that psychedelics disrupt the normal functioning of the brain and stimulate the accidental activation of neurons in the visual cortex. For example, a study conducted in 2012 by David Nutt and his colleagues at the London Center for Psychedelic Research (CPR) at Imperial College scanned the brain of 30 subjects (all experienced users of psychedelics) under the influence of psilocybin – aka magic mushrooms. The laboratory then compared these images with those taken after the subjects swallowed a placebo with sea water. The overall activity of the brain decreases in the so-called "default mode", a set of highly interconnected neural networks that usually work together when the brain is at rest. Psilocybin disrupted this synchronization, which could cause dissociative aspects – the often reported, disintegrating feeling of oneself or ego – hallucinogenic drugs.
In 2016, Nutt and others, published the results of a second MRI study, this time with subjects under the influence of LSD, compared with placebo. Once again, there was less synchronization (total brain activity) among neurons in the default mode. But the researchers also found that some disparate areas of the brain that did not usually communicate with each other did so under the influence of LSD, especially the visual cortex. This may explain the vividly convoluted hallucinations experienced by people tripping over acid. The effect seems to be separate from the effect of ego dissolution, however; it is possible to experience one without the other.
Another study conducted in Scientific Reports the following year found a sudden increase in randomness in brain activity in subjects under the influence of psychedelic drugs. This is possible evidence of an increased state of consciousness, usually associated with psychedelics. And earlier this year, a group of Swiss researchers used MRI to examine the brain under the influence of acid. The results confirm the idea that hallucinogens cause the destruction of a system that helps the brain track which information comes from the real world and which is generated by the brain itself.
As Ars John Timmer said in February: “Instead of a general flooding of the cerebral cortex, they found that a limited number of certain areas observed increased activity. This suggests that conditions caused by hallucinogens differ from conditions such as anesthesia and sleep, which lead to widespread changes in the cortex. "
This article is the most recent study of imperial China. The study involved 13 people who were wearing EEG caps and electrodes to monitor their brain activity during intravenous infusion of DMT. The team found that the DMT caused a noticeable drop in alpha waves, a sign of wakefulness, as well as a corresponding short-term increase in brain theta waves, indicating a state of sleep.
In addition, although it has been shown that brain activity in subjects decreases under the influence of psilocybin and LSD, researchers from Imperial College found more chaotic brain activity in subjects under the influence of DMT. Perhaps this is why ayahuasca users report brighter visuals and a greater sense of immersion than other psychedelics usually experience.
“We saw an emerging rhythm that was present during the most intense part of the experience, suggesting an emerging order among other chaotic patterns of brain activity,” said lead author Christopher Timmermann. “From the altered brain waves and the messages of the participants, it is clear that these people are completely immersed in their experience – it is like a dream, only much more vivid and exciting, it is like a dream, but with eyes open.”
Future studies may include increasing the time that subjects spend on DMT to collect even more brainwave data, or providing participants with MRI images during DMT, as has already been done with psilocybin and LSD.
“It's hard to catch and convey what it feels like for people with DMT, but it’s useful to compare it with sleep when he is awake or on the verge of death,” said Robin Carhart-Harris, co-author and head of the checkpoint. “We believe that DMT research can provide important information on the relationship between brain activity and consciousness, and this small study is the first step on this path.”
DOI: Scientific Reports, 2019.10.1038 / s41598-019-51974-4 (About DOI).