Psilocybin reduces the hierarchical organization of the brain, broadening sensory information flow.

“In addition to that, there's a reduction in what's called the hierarchical organization of the brain. Typically sensory information comes in from the outside environment. [...] When psilocybin is present in the system, there's a broadening of the flow of that information from the bottom up as well.”

“The brain's top-down hierarchy, originating in the pre-frontal cortex, was attenuated. This reduced predictive filtering, leading to a flood of bottom-up sensory information and heightened bodily perception”