Role of the Serotonin 2A Receptor in Psilocybin-induced Altered States of Consciousness

40mg Ketanserin oral will be administered followed by 40mg Psilocybin.

Placebo oral followed by 40mg Psilocybin one hour later.

Placebo oral followed by 20mg Psilocybin one hour later.

Placebo oral followed by 10mg Psilocybin oral one hour later.

Placebo oral followed by 5mg Psilocybin one hour later

Oral Placebo followed by oral Placebo one hour later