A new study found that brain activity during the effects of psilocybin appears disordered when analyzed using conventional methods, but reveals an organized pattern when studied moment by moment and without obscuring individual differences. The work suggests that the profound psychological experiences associated with psychedelic drugs may arise from a temporary rearrangement of relationships between brain networks, rather than from pure randomness.
Devon Stoliker and his team at Monash University led an experiment involving 62 people who had never used a psychedelic substance. Participants received 19 milligrams of psilocybin, then underwent magnetic resonance brain imaging about 80 minutes after the dose and EEG recording about 150 minutes afterward. The same experiment was repeated in a normal waking state and included four phases: lying down, guided meditation, an 11-minute music playlist, and watching a video of moving clouds with the eyes kept open.
Blurrier Boundaries Between the Internal and External
The measurements showed that connectivity within each brain network weakened, while connectivity between networks increased, and the brain’s “modularity”—that is, the degree to which it remained divided into clearly specialized units—decreased. When the eyes were closed, the influence of sensory regions declined, while the influence of association regions involved in constructing reality and imagination and in the sense of self increased; the researchers emphasize that interpreting this finding remains hypothetical.
The usual difference between brain activity with the eyes closed and during film viewing also narrowed. In the visual network, the gap between the two states decreased by 85 percent, while alpha-band activity in the EEG, an indicator usually associated with filtering visual inputs, fell by about half. These findings are consistent with participants’ descriptions of a less distinct sense of separation between the internal and external worlds.
How Did the Hidden System Appear?
Rather than reducing the scanning minutes to a single average, the team used the machine-learning tool CEBRA to analyze the sequential activity of 332 brain regions while preserving the order of events. For each participant, the tool produced a trajectory in three-dimensional space, revealing four distinct clusters corresponding to rest, meditation, music, and video. An automated classifier was able to identify the context in which a person was situated based on a moment of their brain activity.
Most importantly, the classifier’s accuracy was associated with the depth of the experience described by participants. When the activity of a brain network was replaced with its version in the normal state, the researchers found that the default mode network and the visual network each contributed more than 20 percent of this effect. The team believes that the convergence of these two networks may help explain the feeling that the self and the external world have become less separate, a state Stoliker called “embeddedness.”
What Changes in Practice?
The following day, the vast majority of participants reported positive psychological changes, such as a heightened sense of connection to themselves, others, or nature, along with peace, acceptance, and creativity. The classifier’s indicators were also associated with the magnitude of these changes, raising the possibility that context—including the room, music, and instructions—may be an influential part of the experience rather than merely its backdrop.
However, the study does not yet establish how these findings could be used therapeutically. The participants were healthy rather than ill, and two people reporting the same degree of “embeddedness” may have had entirely different experiences. Researchers also do not yet know how music, images, or instructions should be controlled, or whether optimal settings differ according to the individual or diagnosis. The value of the current study therefore remains primarily explanatory: it offers a way to see hidden temporal organization beneath the appearance of chaos, not a ready-made therapeutic protocol.