Summary: The researchers studied the brain activity of healthy participants under the influence of nitrous oxide, comparing it to data from studies of ketamine and LSD to see if the neurobiology of the psychedelic experience was similar. They found that the patterns of activity associated with the different substances overlapped, indicating a common underlying biology, which could inform future research into the therapeutic use of psychedelics.
Source: University of Michigan
Nitrous oxide, colloquially known as laughing gas, has been used clinically as an anesthetic for dull pain since the 19th century.
However, in smaller amounts, it can induce mind-altered experiences, including feelings of happiness, spirituality, and feelings of being outside of one’s body, much like those induced by the psychedelics LSD and ketamine.
A study led by George Mashour, MD, Ph.D. and Richard Harris, Ph.D., of the newly founded Michigan Psychedelic Center at the University of Michigan Medical School, takes a closer look at the neurobiology of psychedelic experiences.
Using fMRI, the team examined the brain activity of healthy people who were given nitrous oxide and compared this activity to data collected from participants in different studies who received ketamine and LSD to see if the neurobiology of the psychedelic experience was similar.
Additionally, these data were compared to a control group of participants who received propofol, a commonly used anesthesia drug, to discriminate between brain changes unrelated to the psychedelic experience.
The team noted that participants under the influence of each psychedelic drug had reduced connectivity within a particular network, but increased connectivity between various networks. Although there were notable differences, each psychedelic increased connectivity between the right temporoparietal junction and the intraparietal sulcus in both hemispheres of the brain and between the precuneus and the left intraparietal sulcus.
These nodes, they note, are located in the so-called cortical “hot zone” of the brain, an area proposed as critical in determining the content of conscious experience. This could help explain the altered states of consciousness described by people to whom these psychedelics were administered.
The fact that the activity patterns associated with nitrous oxide, ketamine and LSD overlap suggests a common underlying biology, they add. Further research to determine the specifics of this biology could help researchers determine how best to use psychedelics as therapeutics.
About this neuroscience research news
Author: Press office
Source: University of Michigan
Contact: Press Office – University of Michigan
Picture: Image is in public domain
Original research: Free access.
“Classical and non-classical psychedelic drugs induce common network changes in the human cortex” by Rui Dai et al. NeuroImage
Abstract
Classic and non-classic psychedelic drugs induce common network changes in the human cortex
The neurobiology of the psychedelic experience is not fully understood. Identify common brain network changes induced by the two classics (i.e., acting at the level of 5-HT2 receptor) and non-classical psychedelics would provide mechanistic insight into state-specific characteristics.
We analyzed whole-brain functional connectivity based on human resting-state fMRI data acquired before and during administration of nitrous oxide, ketamine, and lysergic acid diethylamide. .
We report that, despite distinct molecular mechanisms and modes of delivery, the three psychedelics reduced functional connectivity within the network and improved functional connectivity between the networks.
Specifically, all three drugs increased connectivity between the right temporoparietal junction and the bilateral intraparietal sulcus as well as between the precuneus and the left intraparietal sulcus. These regions are part of the posterior cortical “hot zone”, thought to mediate the qualitative aspects of experience.
Thus, both classical and non-classical psychedelics modulate networks in an area of known relevance to consciousness, identifying a biologically plausible candidate for their subjective effects.