This concerns Functional Connectivity[0], which is basically a measure of how temporally correlated regions are; those that fire in sync or in a strongly correlated pattern are functionally connected.
Essentially, the TL;DR of this study is that psilocybin's 5-HT2A agonism seems to reduce synchronized FC activity not just in neurons but the whole brain: psilocybin makes parts of the brain overall that otherwise work together (in a time-correlated sense) stop displaying time-correlation. These results were seen most in the Default Mode[1] network, which is more or less the brain system in operation when you are inside your head — daydreaming, thinking, remembering, etc. — as opposed to processing visual cues or observing the physical world.
Essentially, the TL;DR of this study is that psilocybin's 5-HT2A agonism seems to reduce synchronized FC activity not just in neurons but the whole brain: psilocybin makes parts of the brain overall that otherwise work together (in a time-correlated sense) stop displaying time-correlation. These results were seen most in the Default Mode[1] network, which is more or less the brain system in operation when you are inside your head — daydreaming, thinking, remembering, etc. — as opposed to processing visual cues or observing the physical world.
[0]: https://en.wikipedia.org/wiki/Dynamic_functional_connectivit...
[1]: https://en.wikipedia.org/wiki/Default_mode_network — this article is one of those that just blows my mind clean out my ears (heh); the brain is such a wonder.