2Hz Transcutaneous Trigeminal Nerve Stimulation: Active electrical stimulation applied over the skin of the forehead targeting the branches of the trigeminal nerve. The stimulation frequency is set at 2Hz. It is synchronized with the fMRI sequence and continuous physiological monitoring (respiration and photoplethysmography).
120Hz Transcutaneous Trigeminal Nerve Stimulation: Active electrical stimulation applied over the skin of the forehead targeting the branches of the trigeminal nerve. The stimulation frequency is set at 120Hz. It is synchronized with the fMRI sequence and continuous physiological monitoring (respiration and photoplethysmography).
Sham Transcutaneous Trigeminal Nerve Stimulation: An inactive or sensory-matched sham electrical stimulation designed to mimic the physical sensation of the device being active without delivering the therapeutic frequencies (2Hz or 120Hz). It is administered synchronously with the fMRI BOLD sequence and physiological monitoring to serve as a baseline comparator.
Study summary
This study aims to investigate how different frequencies of transcutaneous Trigeminal Nerve Stimulation (eTNS) affect brain activity and the autonomic nervous system in healthy individuals. Participants will undergo a 3T functional magnetic resonance imaging (fMRI) scan while receiving three different types of nerve stimulation: 2Hz eTNS, 120Hz eTNS, and a sham (inactive) stimulation. The order of these stimulations will be randomly assigned. During the brain scan, researchers will simultaneously monitor the participants' breathing and heart rhythms (using a finger sensor). The main goal is to understand how changing the frequency of eTNS influences the connection between the brain's networks and the body's unconscious physiological responses.
Eligibility
Sex
ALL
Min age
18 Years
Max age
35 Years
Healthy volunteers
Accepted
Inclusion Criteria:
1. Healthy volunteers, aged 18 to 40 years old.
2. Right-handed.
3. Generally healthy with no history of neurological, psychiatric, or severe cardiovascular diseases.
4. Normal physical and neurological examinations.
5. Capable of understanding the study procedures and voluntarily signing the written informed consent form.
Exclusion Criteria:
1. Contraindications to MRI scanning (e.g., claustrophobia, cardiac pacemakers, artificial cochlea, metallic braces, or any other ferromagnetic implants).
2. Female participants who are pregnant, lactating, or suspect they might be pregnant.
3. Contraindications to transcutaneous electrical stimulation (e.g., personal or family history of epilepsy/seizures, trigeminal neuralgia, facial skin lesions, or active skin diseases on the forehead).
4. Current or recent (within the past month) use of any medications known to affect the central nervous system or the autonomic nervous system (e.g., antidepressants, beta-blockers, sedatives, or sympathomimetics).
5. History of substance abuse, heavy smoking, or excessive daily consumption of alcohol or caffeine.
6. Irregular sleep patterns, shift work, or severe sleep deprivation within 24 hours prior to the scanning session.
Primary outcome measure(s)
Difference in Blood Oxygenation Level-Dependent (BOLD) Signal Amplitude in the Brainstem — During the 7-minute and 30-second fMRI scan for each stimulation condition. The metric is the percent signal change in BOLD amplitude within predefined Regions of Interest (ROIs) of the brainstem (e.g., trigeminal nuclei, locus coeruleus, nucleus tractus solitarii). It is calculated as the BOLD signal difference between the 30-second stimulation "ON" blocks and the 30-second "OFF" blocks. Data will be aggregated as the mean percentage of BOLD signal change for each stimulation condition.
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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