Psychedelics May Reduce Brain Network Boundaries

A new study published in Nature challenges the long-held belief that psychedelics cause chaotic brain activity. Researchers from Monash University tested whether the brain’s networks become disordered under psilocybin, a common psychedelic compound found in certain fungi.

The study involved 62 participants who had never taken a psychedelic before. They were given 19 milligrams of psilocybin and had their brains scanned. AI was used to analyze the brain scans both while sober and under the influence of the drug.

The results showed that the brain’s activity was not chaotic but rather showed a different kind of organization. Researchers observed that sensory regions lost influence while associative regions gained dominance when participants had their eyes closed.

The team also noted that connections within each brain network weakened, while connections between networks strengthened. This change in brain modularity was consistent across all four parts of the experimental sequence.

Further analysis revealed that under psilocybin, the brain’s activity became more organized over time and was clearly differentiated by context. The team used a machine-learning tool to track individual brain activity and found it could be classified into four distinct clusters corresponding to rest, meditation, music, and a visual stimulus.

The study also found that the depth of participants’ reported experiences correlated with how well the classifier could distinguish between different contexts. This suggests that the brain’s organization under psilocybin may be linked to the subjective experience of the drug.

Researchers identified the default mode network and the visual network as key areas responsible for the observed changes. These networks are associated with the sense of self and external perception, respectively. Under psilocybin, these networks became less differentiated, which the team believes explains the feeling of being 'embedded' in both internal and external worlds.

Participants also reported positive psychological changes the day after the session, including increased feelings of connection, peace, and creativity. The team plans to explore how these findings could be applied in therapeutic settings, though more research is needed to determine how to tailor these effects for different individuals and conditions.