Open Psilocybin Study (OPS)

The Open Psilocybin Study is a randomised, double-blind, placebo-controlled crossover trial investigating how psilocybin changes the brain, the body and self-perception in healthy volunteers. Combining fMRI, EEG, pharmacokinetic modelling and a battery of behavioural and psychometric tasks, the OPS tests predictions derived from the REBUS/predictive-processing account of psychedelic action — that psilocybin relaxes top-down priors and amplifies bottom-up signalling — across multiple levels of analysis simultaneously.

The study is a collaboration between the PRSM lab (Faculty of Social and Behavioural Sciences, Leiden University) and the Centre for Human Drug Research (CHDR), with MRI acquisition at the LUMC. It is funded by the Norrsken Mind Foundation, with co-funding from CHDR and Leiden University.