"Psychedelics are thought of as 'mind-expanding' drugs so it has commonly been assumed that they work by increasing brain activity," said David Nutt of Imperial College London, who gave a briefing about the studies on Monday. "But, surprisingly, we found that psilocybin actually caused activity to decrease in areas that have the densest connections with other areas."

These so-called "hub" regions of the brain are known to play a role in constraining our experience of the world and keeping it orderly, he said.

"We now know that deactivating these regions leads to a state in which the world is experienced as strange."
...
It found activity decreased in "hub" regions and many volunteers described a feeling of the cogs being loosened and their sense of self being altered.

Brains are cool.