From Johns Hopkins Psychedelic Newsletter Fall 2021:
Last year, Dr. Frederick Barrett published a study that showed psilocybin reduced neural activity in the claustrum during the period of drug action.
The claustrum, once thought to be the seat of consciousness, is a thin sheet of gray matter in the brain that reaches out to every other region in the brain.
The results showed that both the default mode network and areas of the brain believed to be responsible for setting attention and switching tasks may be disrupted during the effects of psilocybin, and alterations in the claustrum may account for these changes.