Characterization of Altered Waking States of Consciousness in Healthy Humans

This randomised, double-blind, placebo-controlled trial (n=30) studied the characterisation of altered waking states of consciousness induced by psilocybin (up to 20mg) in healthy humans.

Conducted by the University of Zurich, this study seeks to identify the neural basis of consciousness using a novel measure called ‘perturbational complexity index’ (PCI), based on integrated information theory. The study will utilise transcranial magnetic stimulation (TMS) combined with high-density electroencephalography (hd-EEG) to assess electrocortical responses.

Participants will receive a single dose of psilocybin (20mg) or placebo. The primary objective is to measure PCI in the psilocybin-induced state compared to placebo. The study will also investigate psilocybin’s effects on resting state EEG and its correlation with insightfulness and spiritual experiences. Healthy male and female volunteers aged 18-40 years, without any major psychiatric or medical conditions, are eligible to participate. The study involves three visits over three weeks, with follow-up 12 weeks after the last visit.

Topic Healthy Subjects
Compound Psilocybin Placebo
Country Switzerland
Visit trial
Status Completed
Results Published Yes
Start date 08 July 2020
End date 25 April 2021
Phase Not Applicable
Design Blinded
Type Interventional
Generation First
Participants 30
Sex All
Age 18- 40
Therapy No

Trial Details

Altered waking states of consciousness and its underlying functional organization have gained increasing interest in recent years, i.e. in identifying the neural basis of consciousness. To overcome fundamental shortcomings of current methods to objectively assess the level of consciousness, the investigators propose here to apply a novel and empirically validated measure called 'perturbational complexity index' (PCI) based on the integrated information theory (IIT). This involves a combination of transcranial magnetic stimulation (TMS) and highdensity electroencephalography (hd-EEG) to measure electrocortical responses as distributed cerebral interactions ('integration') and spatiotemporal pattern ('information'). Given the finding of subjectively expanded consciousness as induced here by psilocybin, the investigators hypothesize that the PCI may be higher in such states. This will be the first TMS/hd-EEG study to investigate quantitatively the level of consciousness in a pharmacologically altered waking state of consciousness.

NCT Number NCT03853577

Sponsors & Collaborators

University of Zurich
Within the Department of Psychiatry, Psychotherapy and Psychosomatics at the University of Zurich, Dr Mialn Scheidegger is leading team conducting psychedelic research and therapy development.

Papers

The Influence of Psilocybin on Subconscious and Conscious Emotional Learning
This double-blind, placebo-controlled study (n=30) investigates the learning effects of psilocybin (up to 20 mg) in a probabilistic cue-reward task with emotional cues. It finds that psilocybin preserves learning effects, is non-inferior to placebo, and suggests higher exploratory behaviour. The 20 mg group showed significantly better learning rates than placebo.

Data attribution

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