Study finds psilocybin makes the brain more sensitive to context

Psilocybin makes brain activity more responsive to what a person is doing and experiencing, according to a study reported by ERR. The findings may help explain why the psychedelic’s potential effects in treating mental health disorders depend so heavily on a person’s state of mind and surroundings.

Psilocybin is a psychedelic substance being studied for possible use in treating depression, anxiety and addictions. Researchers have often assumed that it simply makes brain activity more chaotic. The new study instead points to an underlying order: the brain begins to reflect more clearly what a person is doing and experiencing at the time.

The international research team was led by scientists from Monash University in Australia. The study involved 62 adults who had no previous experience with psychedelics. Researchers examined the participants’ brains using magnetic resonance imaging and EEG both before they received psilocybin and while it was taking effect. The participants rested, meditated, listened to music and watched a film.

Under the influence of psilocybin, the brain’s usual networks became less separate from one another. With their eyes closed, for example, the connectivity of brain regions linked to vision with the rest of the brain fell by up to 39 percent in some areas. At the same time, connectivity increased by up to 72 percent in regions associated with higher-level thinking.

The clearest pattern emerged when researchers used machine learning to track how brain activity changed over time during the measurements. The boundaries between the brain’s usual networks became less distinct, while brain activity became increasingly distinguishable according to what the person was doing, such as resting or watching a film.

This link was strongest among participants who found the blurring of the boundary between themselves and the surrounding world pleasant. Researchers found no similar connection with anxiety or impaired thinking. The stronger the brain activity’s alignment with the situation, the greater the change participants reported in their way of thinking the following day.

The findings are relevant to understanding psilocybin’s potential therapeutic use. They suggest that its effects depend not only on the substance itself, but also on the environment in which a person is and what they do during the experience. The researchers published their findings in the journal Nature.