In a new study, Johns Hopkins Medicine researchers analyzed the brain scans of people after they took psilocybin, the active compound in psychedelic (magic) mushrooms, to see what happens in the brain when people are on psychedelics.
The team focused on a part of the brain known as the claustrum, taken from the Latin word for “hidden or shut away.” The claustrum is an extremely thin sheet of neurons deep within the cortex, yet it reaches out to every other region of the brain.
Its true purpose remains “hidden away” as well, with researchers speculating about its functions. For example, Dr. Francis Crick, the British biologist and neuroscientist who proposed the double helix structure of the DNA molecule, believed that the claustrum was the seat of consciousness, responsible for awareness and sense of self.
What is known is that this region contains a large number of receptors targeted by psychedelic drugs such as LSD or psilocybin.
To see what happens in the claustrum when people are on psychedelics, the researchers compared the brain scans of people after they took psilocybin with their scans after taking a placebo.
The scans after psilocybin use showed that the claustrum was less active, meaning the area of the brain believed responsible for setting attention and switching tasks is turned down when on the drug.
The researchers say that this ties in with what people report as typical effects of psychedelic drugs, including feelings of being connected to everything and reduced senses of self or ego.
“Our findings move us one step closer to understanding mechanisms underlying how psilocybin works in the brain,” says Frederick Barrett, Ph.D., assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and a member of the school’s Center for Psychedelic and Consciousness Research.
“This will hopefully enable us to better understand why it’s an effective therapy for certain psychiatric disorders, which might help us tailor therapies to help people more.”
Because of its deep-rooted location in the brain, the claustrum has been difficult to access and study. Last year, Barrett and his colleagues at the University of Maryland, Baltimore, developed a method to detect brain activity in the claustrum using functional magnetic resonance imaging (fMRI).
In this study, the researchers used fMRI with 15 people and observed the claustrum brain region after the participants took either psilocybin or a placebo. They found that psilocybin reduced neural activity in the claustrum by 15% to 30%.
This reduced activity also appeared to be linked to the stronger subjective effects of the drug, such as emotional and mystical experiences. The team also found that psilocybin changed the way that the claustrum communicated with brain regions involved in hearing, attention, decision-making and remembering.
With the highly detailed imaging of the claustrum provided by fMRI, the researchers hope to look at this mysterious brain region in people with certain psychiatric disorders such as depression and substance use disorder.
The aim of this research would be to see what roles, if any, the claustrum plays in these conditions. The team also plans to observe the claustrum’s activity when under the influence of other psychedelics, such as salvinorin A, a hallucinogen derived from a Mexican plant.
The findings are published online in the journal NeuroImage.
Source: Johns Hopkins Medicine