Brain-imaging study finds psilocybin’s effects shift with a person’s surroundings

The study, published in Nature, examined how psilocybin affects brain activity during different kinds of experiences. Psilocybin is the psychedelic compound found in so-called magic mushrooms.

Researchers studied 62 adults at one imaging site. Participants had functional magnetic resonance imaging, or fMRI, which tracks changes linked to brain activity, and electroencephalography, or EEG, which records the brain’s electrical signals. They took part in scans while resting and while engaging with more structured experiences: meditation, music and a movie.

The measurements were collected before psilocybin and again on the day it was given. The fMRI session took place about 80 minutes after dosing, and the EEG session about 150 minutes after dosing.

The researchers used machine-learning methods to map changing patterns of brain activity in each person over time. Their central finding was that psilocybin did not simply make brain activity look more random. Instead, the activity formed patterns that were sensitive to context, meaning the patterns differed depending on whether a person was resting, meditating, listening to music or watching a film.

The team also reported less separation between brain networks normally involved in processing a person’s inner world and the outside environment. In some participants, those networks became more integrated. These people were more likely to describe a feeling of being continuous with, rather than separate from, their surroundings. The researchers called this experience “embeddedness.”

Stronger context-aligned brain patterns were associated with deeper reports of self-dissolving and boundary-dissolving experiences. They were also associated with a greater change in mindset reported the next day. About half of participants ranked the experience among the most meaningful in their lives, according to the abstract.

These results offer a detailed look at the connection between subjective experience and brain activity during a psychedelic experience. They also support the idea that setting and activity may matter, rather than being mere background details. Music, meditation, rest and a movie were linked with different brain-activity patterns under psilocybin.

Still, this was not a clinical treatment trial. The participants were adults in a research setting, and the supplied study record does not establish whether the findings would be the same for people receiving care for depression, post-traumatic stress disorder or another condition. It also does not show that a particular activity during a psychedelic session produces better health outcomes.

The reported links between brain organization, subjective experience and next-day mindset change are correlations. They do not prove that one caused the other. The abstract also does not provide details on dose, adverse events, participant characteristics, a placebo or comparison group, or longer-term outcomes.

More research would be needed to test whether these brain measures can reliably predict outcomes in patients, whether they hold up in larger and more diverse groups, and whether they are linked to lasting changes. For now, the study is best understood as a detailed human brain-imaging investigation of the acute, or immediate, effects of psilocybin—not evidence of a proven therapy.