For about a decade, psychedelics were thought to throw brain networks into chaos. In a recent Nature study, researchers at Monash University tested that idea by scanning 62 first-time psilocybin users after a 19 mg dose. Instead of giving participants cognitive tasks, the team let them lie at rest, meditate, listen to music, and watch clouds move across a sky—an attempt to capture an authentic, uninterrupted trip. Half of participants rated the session among the most meaningful experiences of their lives, and 24 placed it in their top five.
Using standard analyses, the scans did show signs of chaos: connectivity within networks weakened, connectivity between networks strengthened, and the brain's modularity dropped across all four settings. But when the team used a machine-learning tool called CEBRA to compress moment-by-moment activity from 332 brain regions, each individual's brain activity traced an ordered path through a three-dimensional space. The apparent disorder hid structure that conventional averaging over time and people tends to miss.
Under psilocybin, the difference between eyes-open and eyes-closed connectivity in the visual network shrank by 85 percent, and EEG alpha-band activity fell by nearly half. The researchers interpret this as a blurring of the boundary between internal and external experience, which could help explain why people report meaningful imagery and insight. They caution that this interpretation is hypothetical, but the finding offers a new way to think about how psychedelics produce lasting psychological change.