Visual Surround Suppression and Perceptual Expectation Under Psilocybin

NCT04424225 | Terminated Phase 1 Results DMC FDA Drug

• 1 other identifier: PSYCH-2019-28235
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

The prospective pilot study will address the critical need for more precise characterizations of the acute visual effects of the drug psilocybin by measuring the impact of acute psilocybin intoxication on a perceptual task known as visual surround suppression, compared to an active placebo control.

Conditions

Perception Disturbance; Visual Suppression; Psychedelic Experiences

Outcome Measures

Primary Outcomes (6)

• Psychophysical Descrimination Threshold - No Surround Suppression (NS) Dose 1

  No surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. .

  3 hours after dose 1

• Psychophysical Descrimination Threshold - No Surround Suppression (NS) Dose 2

  No surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. .

  3 hours after dose 2

• Psychophysical Descrimination Threshold - Orthogonal Surround Suppression (OS) Dose 1

  Orthogonal surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Orthogonal surround suppression condition (OS).

  3 hours after dose 1

• Psychophysical Descrimination Threshold - Orthogonal Surround Suppression (OS) Dose 2

  Orthogonal surround suppression condition for visual psychophysics tasks, consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Orthogonal surround suppression condition (OS).

  3 hours after dose 2

• Psychophysical Descrimination Threshold - Parallel Surround Suppression (PS) Dose 1

  Parallel surround suppresion condition for visual psychophysics tasks consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Parallel surround suppression condition (PS). .

  3 hours after dose 1

• Psychophysical Descrimination Threshold - Parallel Surround Suppression (PS) Dose 2

  Parallel surround suppresion condition for visual psychophysics tasks consisting of perceptual judgments (e.g., subject reported which of two visual stimuli presented appeared to have higher contrast). Based on these responses, psychophysical discrimination thresholds are calculated using an adaptive staircase technique and reported in units of percent contrast. Parallel surround suppression condition (PS). .

  3 hours after dose 2

Study Arms (2)

Psilocybin First

EXPERIMENTAL

Participants in this arm will receive psilocybin first, then niacin

Drug: Psilocybin; Drug: Niacin

Niacin First

EXPERIMENTAL

Participants in this arm will receive niacin first, then psilocybin

Drug: Psilocybin; Drug: Niacin

Interventions

Psilocybin DRUG

25 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)

Niacin First; Psilocybin First

Niacin DRUG

100 mg capsules (white opaque, Capsugel Vcaps Plus HPMC size 2)

Also known as: Vitamin B3

Niacin First; Psilocybin First

Eligibility Criteria

• Age: 25 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Have given written informed consent
• Have at least a high-school level of education or equivalent (e.g. GED), and be able to read and write in English
• General health status: Participants should be in good physical (BMI between 20.0 and 28.0 kg/m2) and psychiatric health.
• Experience taking psilocybin (at the PI's discretion).
• Participants must also have a person that can reliably transport them to and from the CRU for dosing session days.
• Geographic location: Minnesota counties that are approximately within 1 hour driving distance to Twin Cities, including not limited to Hennepin, Ramsey, Washington, Anoka, Wright, Carver, Scott, Dakota, Sherburn
• Participants must be willing to wear a face mask at all times during in-person study visits, except for dosing sessions, to ensure COVID-19 protection.
• Participants must be willing to get a COVID-19 test and share results with the study team prior to all in-person visits.
• Participants must be up-to-date on COVID-19 vaccines, per CDC guidelines, and share a copy of their proof of vaccination status with the study team prior to the consenting visit.
• Agrees to refrain from using recreational drugs while enrolled in the study, including, but not limited to, hallucinogens, ketamine, and marijuana.

You may not qualify if:

• Current or past history of meeting DSM-5 criteria for schizophrenia spectrum or other psychotic disorders (except due to another medical condition), or Bipolar I or II Disorder, personality disorder, major depressive disorder, posttraumatic stress disorder, panic disorder, obsessive compulsive disorder, dysthymic disorder.
• Current or past history within the last 5 years of meeting DSM-5 criteria for a moderate or severe alcohol or drug use disorder (excluding caffeine, nicotine, and hallucinogens)
• Those with a first or second-degree relative with a current or past history of meeting DSM-5 criteria for schizophrenia or other psychotic disorders or bipolar I or II disorder, because they might have an underlying genetic susceptibility for psychosis.
• Presence of symptoms of the following DSM-5 disorders within the past 6 months (as assessed by the MINI-7):
• Major depressive Episode
• Suicidality
• Manic and Hypomanic Episodes
• Panic disorder
• Agoraphobia
• Social Anxiety Disorder
• Obsessive-Compulsive Disorder
• Posttraumatic Stress Disorder
• Alcohol Use Disorder
• Substance Use Disorder (Non-Alcoholic)
• Psychotic Disorders and Mood Disorders with Psychotic Features

Sponsors & Collaborators

• University of Minnesota: lead
• Heffter Research Institute: collaborator

Study Sites (1)

University of Minnesota

Minneapolis, Minnesota, 55455, United States

Location

Related Publications (2)

• Swanson LR, Jungers S, Varghese R, Cullen KR, Evans MD, Nielson JL, Schallmo MP. Enhanced visual contrast suppression during peak psilocybin effects: Psychophysical results from a pilot randomized controlled trial. J Vis. 2024 Nov 4;24(12):5. doi: 10.1167/jov.24.12.5.

  PMID: 39499526 RESULT

• Cotten SW, Strathmann FG, Barrett FS, Labay L, Mullally J, Sherwood AM, Wiegand F. Psychedelics for Medicinal Use: How Will This Alter the Collective Laboratory Consciousness? Clin Chem. 2023 Apr 3;69(4):319-326. doi: 10.1093/clinchem/hvad016. No abstract available.

  PMID: 36881769 DERIVED

MeSH Terms

Interventions

Psilocybin; Niacin; Niacinamide

Intervention Hierarchy (Ancestors)

Indole Alkaloids; Alkaloids; Heterocyclic Compounds; Indoles; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Tryptamines; Indolizidines; Indolizines; Nicotinic Acids; Acids, Heterocyclic; Pyridines; Heterocyclic Compounds, 1-Ring

Limitations and Caveats

The study was terminated early due to lack of funding. Data from primary outcome for psychophysics and secondary analysis for visual event related potentials (vERP) are for the first 6 participants, as part of Dr. Link Swansons dissertation. Raw neuroimaging data will be deposited into OpenNeuro for ongoing data analysis and data sharing with the broader research community.

Results Point of Contact

• Title: Jessica Nielson
• Organization: University of Minnesota

jnielson@umn.edu

714-904-7939

Study Officials

• Jessica Nielson, PhD

  University of Minnesota

  PRINCIPAL INVESTIGATOR

• Link Swanson, PhD(c)

  University of Minnesota

  STUDY DIRECTOR

• Sophie Jungers, BS

  University of Minnesota

  STUDY DIRECTOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 5, 2020
• First Posted: June 9, 2020
• Study Start: August 30, 2021
• Primary Completion: September 1, 2023
• Study Completion: September 1, 2023
• Last Updated: June 27, 2025
• Results First Posted: June 27, 2025

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will share

Locations

US (1)