Neural and Physiological Correlates of Psychedelic Sub-states (i2)

June 3, 2026 updated by: Robin Carhart-Harris, PhD, MA

Multivariate Neural and Physiological Correlates of Psychedelic Sub-states: a Within-subjects, Healthy Volunteer Study With Experience-sampling

The main purpose of this study is to gain a better understanding of the distinct mental states and physical reactions that can arise during a psychedelic experience. By repeatedly assessing the same participants in an MRI while under the effects of psilocybin, the investigators want to identify reliable brain and body reactions arising during these psychedelic experiences. It is hoped that this will provide an insight to inspire future research on psilocybin and related psychedelics as well as inform on their therapeutic action. This study will involve up to 12 healthy volunteers with previous psychedelic experience. Participants in this study will be given four doses of psilocybin, with breaks of at least seven days in between dosing visits. The first dosing visit will feature a 10 mg dose of psilocybin, which can be considerate a low to moderate dose, whereas the remaining three dosing visits will feature 25 mg psilocybin, a high dose that is consistent with the dosage chosen for several modern clinical trials with psilocybin. From the initial in-person screening visit to the final follow-up, participants will be in this study for approximately 6-12 weeks and visit the research site 5 times. The first visit will be an in-person screening visit, during which the investigators will assess participants' eligibility to be enrolled. There will be 4 subsequent visits to the scan center for dosing and magnetic resonance imaging (MRI) scanning, and there will be a final remote follow up. Each of the four dosing visits will include four periods of lying within the MRI scanner for scanning, each of these 'in-scanner' sessions will last for ~ 45 minutes. Actual scans, which are also called 'runs' last for ~ 12 mins. During these 'runs', the investigators will ask participants two brief questions about how positive or negative their current experience is every 100 seconds. They will be able to record their answers using a button box which they will be operating with their hand. One day after each dosing visit, the investigators will schedule a phone call with the participant to check how they are doing and perform an informal interview focused on their experience while under the effects of psilocybin.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
12

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: Robin Carhart-Harris, PhD
  • Phone Number: (415) 476-1000
  • Email: insight2@ucsf.edu

Study Locations

  • United States
    • California
      • San Francisco, California, United States, 94158
        • University of California, San Francisco

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

21 years to 70 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Have had previous experiences with psychedelic substances
  • Mentally and physically healthy
  • Have had prior experiences with MRI machines (optional but preferred)
  • Flexible schedule- able to commit to scans once or twice per week for 4 weeks in a row
  • Are between 21 and 70 years of age
  • Are fluent in speaking and reading English
  • Can swallow pills/capsules
  • If able to become pregnant, must be non-lactating, have a negative pregnancy test at study entry and prior to each Experimental Session and must agree to an adequate form of birth control and contraception over the course of the study. Adequate forms of birth control or contraception include intrauterine device (IUD), injected, implanted, intravaginal, or transdermal hormonal methods, abstinence, oral hormones plus a barrier contraception, vasectomized sole partner, or double barrier contraception. Two forms of contraception are required with any barrier method or oral hormones (i.e. condom plus diaphragm, condom or diaphragm plus spermicide, oral hormonal contraceptives plus spermicide or condom). Not of childbearing potential is defined as documented hysterectomy, bilateral salpingectomy, bilateral oophorectomy, and/or tubal ligation), permanently sterile by medical device such as Essure, postmenopausal, or male by birth. Contraception applies to males as well as females and male participants must not be planning sperm donation within the study period.
  • Able and willing to provide informed consent
  • Able and willing to use computers and tablets or phones to enter electronic data
  • Agree to inform the investigators within 48 hours of any new or changed medical conditions.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Psilocybin
Healthy volunteers will receive up to four doses of psilocybin separated from each other by at least one week. The first dosing session will involve 10 mg psilocybin, the remaining three dosing sessions will receive up to 25mg psilocybin.
Drug: Psilocybin
Multiple dosing of healthy volunteers with up to 25 mg psilocybin separated from each other by at least one week. Participants will be scanned before and after receiving psilocybin on each dosing day. Surveys will be performed on dosing days and after dosing.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Brain-averaged normalized global signal complexity
Time Frame: Peak effects (120 min post dosing) vs pre-dose
Signal complexity of brain activity derived from resting-state fMRI
Peak effects (120 min post dosing) vs pre-dose

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
EEG-derived signal complexity of brain activity
Time Frame: Peak effects (120 min post-dose) vs pre-dose fMRI runs
Measure of brain complexity derived from EEG
Peak effects (120 min post-dose) vs pre-dose fMRI runs
Psychological insight
Time Frame: Peak effects (120-min post-dose) vs predose
Measure of psychological insight
Peak effects (120-min post-dose) vs predose

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Robin Carhart-Harris, PhD, MA

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Robin Carhart-Harris, PhD, University of California, San Francisco

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 31, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 30, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 13, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 13, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 26, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 5, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 3, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 21-35696
  • 157762 (Other Identifier: FDA IND)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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