Psychedelics are becoming more clinically relevant, and a slew of recent research has explored the effects of psilocybin in ever-greater detail, revealing that it has the ability to imprint lasting, meaningful changes in brain activity.
Psilocybin, the psychoactive powerhouse in 'magic mushrooms', is thought to induce brain plasticity, reorganizing neural connections and signaling pathways to potentially alter our otherwise stagnant mind states.
Indeed, some users have reported increased universal immersion: a deconstruction and interconnection of the senses of space, time, and selfhood – a melding of one's identity into the cosmic milieu, if you will.
If this sounds a bit chaotic, some scientists agree. The brain disruptions caused by psilocybin have generally been considered disorganized and entropic, with some brain networks shifting from an orderly, rigid state to a more disordered, flexible one (at least temporarily).
But that apparent disorder is not the whole story, according to the largest single-site psychedelic brain study to date, just published in the journal Nature.
"We uncovered hidden order within that disruption," explains Devon Stoliker, a neuroscientist and consciousness researcher at Monash University in Australia and the study's lead author.
"Under psilocybin, brain networks that help us process our inner world and the world around us became less distinct, but reorganised into patterns that reflected what people were experiencing."
"This was strongest in people who had more positive psychedelic experiences and felt less separate from the world around them."
In a five-year study at Monash University, researchers used functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), along with machine learning models and questionnaires, to explore how the mind naturally responds after a psilocybin dose.
The study involved 62 healthy adults with no previous psychedelic experiences. They had their brains scanned before and after receiving psilocybin treatment while they rested, meditated, listened to music, or watched a silent movie of moving clouds.
By mapping blood-oxygen signals across different brain regions, the researchers detected a drop in functional modularity, the usual segregation of brain activity into distinct networks.
The default mode network (DMN), a linkage of brain regions, appears to be a central mediator. The DMN is like a neurological flight controller, integrating information from different brain areas that perceive heady concepts like space, time, and identity. It's especially active during daydreaming and introspection.
Psilocybin seems to relax the division between brain networks, allowing novel neurological interactions.
The psychedelic may therefore alter a brain gradient encompassing the introspective DMN and the outward visual network – responsible for processing the things we see – to facilitate a shift between our internal and external focus.
In relation to the experimental conditions, the greatest global brain organization seemed to occur in response to listening to "ethereal" music.
The effects were attenuated when participants were watching a movie, with less disruption to neural networks, compared to when participants had their eyes closed, resting, meditating, or listening to music.
In other words, the added visual stimuli affected their psychedelic experience.
"This shows that context is not just background to the psychedelic experience. What a person is doing and focusing on shapes how their brain responds," explains Adeel Razi, a computational neuroscientist at Monash University and the study's senior author.
"For treatment, that reinforces why the environment and what a person does and experiences during the psychedelic session matter."
The researchers stress the importance of a state they call embeddedness: "a perceptual and cognitive realization of being part of a unified whole."
Psilocybin appears to engender a sense of unity with the world and environment, a potentially essential therapeutic aspect that may help dispel the existential distress caused by the sense of separation – no hallucinations necessary.
Additionally, the researchers suggest that experiences, such as the dissolution of one's selfhood and the breakdown of existential boundaries, may be key drivers of psilocybin's observed effects.
"People who showed strong reorganisation also reported greater positive psychological changes the following day," Stoliker says, noting that this nuance has not been apparent in previous brain-imaging studies which may have assessed average effects across groups.
It's worth noting the study involved healthy adults, not patients, and it was open-label, meaning there was no placebo group. Nevertheless, these findings could improve psychedelic-based healthcare strategies.
Studies have found that psilocybin can ease the symptoms of depression for months after just a single dose. Such evidence led Australia to legalize the use of psilocybin as a prescription therapy for treatment-resistant depression (and MDMA therapy for PTSD) in 2023.
Other therapeutic potentials also appear promising. For example, animal models suggest psilocybin could offer a treatment option for anorexia nervosa, but human studies are needed.
And as clinical studies have shown, not everyone responds to these much-promised psychedelic therapies in the same way.
Related: Huge Psilocybin Dose Has Incredible Effect on Elderly Dementia Patient
The latest findings from the Monash study provide a possible explanation as to why some people benefit from psychedelic-assisted therapy more than others, and a way to potentially measure those differences.
"The finding that the organization of brain activity tracks [with] the transformative quality of subjective experience helps to elucidate how the psychedelic state translates into psychological change," the researchers conclude.
If those brain scan measures can be translated into patients, Razi adds, "this could eventually help clinicians understand how someone is responding and predict who is most likely to benefit." This research was published in * Nature*.
This article was fact-checked by Clare Watson and edited by Clare Watson. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.