Causal Mechanisms of Odor-Guided Behavior in Humans (NCT07099092) | Clinical Trial Compass
Not Yet RecruitingEarly Phase 1
Causal Mechanisms of Odor-Guided Behavior in Humans
United States80 participantsStarted 2026-05-13
Plain-language summary
Background:
Little is known about how different regions of the brain responsible for the human sense of smell guide behaviors. In this study, researchers use a technique called transcranial ultrasound stimulation (TUS) to learn how odors affect the brain and behavior.
Objective:
To learn more about how the human sense of smell works.
Eligibility:
Healthy people aged 18 to 45 years who are right-handed.
Design:
Participants can volunteer for up to 2 different experiments. Each experiment requires 5 visits, each about 1 week apart. Food, alcohol, and caffeine may be limited before visits.
At the start of each visit, participants will answer questions about their health and how well they slept. Their sense of smell will be assessed.
Some visits may include tasks on a computer: While doing these tasks, participants may be asked to smell different odors, look at pictures, and listen to sounds. They will wear devices to track breathing, blood pressure, pulse, and other body responses to the tasks.
Some visits may include TUS: TUS uses ultrasound waves to briefly change brain activity. A gel will be applied to the scalp and hair, and a device will be placed against the participant s head. Participants may feel a tapping, pulling, and/or warm sensation on the skin underneath the device. They may also feel a twitch in their face, neck, arm, or leg muscles. Participants will do tasks before and after TUS.
Some visits will include functional magnetic resonance imaging (fMRI) scans. fMRI uses magnet and radio waves to capture images of the activity inside the brain. Participants will lie on a table that slides into a tube. They will perform tasks inside the scanner.
Who can participate
Age range18 Years – 45 Years
SexALL
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Inclusion criteria
✓. Willingness to comply with all study procedures and availability for the duration of the study.
✓. Aged 18-45 years old. Justification: Many neural processes change with age, and these changes could introduce unwanted variability in the measured signals.
✓. In good general health based on the assessment of the Medical Advisory Investigator (MAI).
✓. Agreement to adhere to Lifestyle Considerations throughout study duration. Consent signature will be documentation of meeting this criterion.
✓. Right-handed.
Exclusion criteria
✕. Any neurological disorder that would increase seizure risk from TUS such as stroke, brain lesions, previous neurosurgery, epilepsy, any history of seizure or fainting episode of unknown cause, frequent severe headache, or head trauma resulting in loss of consciousness, lasting over 30 minutes or with sequela lasting longer than one month. The MAI will also retain discretion to exclude based on a history of a neurological illness or trauma that may compromise safety or data integrity.
✕. Predisposition to seizures (e.g., first-degree family history of potentially hereditary epilepsy, etc.).
✕. Current use (any use in the past week, daily use for more than one week within past 3 months) of any investigational drug or of any medications with psychotropic (e.g., benzodiazepines, etc.), or anti or pro-convulsive action. This will be determined at the discretion of the MAI.
✕. Unable to undergo MRI, or TUS due to certain metallic or magnetic devices or implants in the body, claustrophobia, or other reasons.
✕. History of noise-induced hearing loss or tinnitus.
✕. Recent history (within past 12 months) of learning disability, major DSM-5 psychiatric disorder including major affective disorder, ADHD, obsessivecompulsive disorder, schizophrenia, or PTSD. This will be determined at the discretion of the MAI.
✕. Pattern of alcohol and drug use in the past 12 months that is indicative of harmful use, loss of control over use, or physical dependence.
✕. Daily nicotine, alcohol, or drug use (excluding caffeine) for at least 4 continuous weeks within the past 12 months.