Investigating the Transcutaneous vs. Transcranial Mechanisms of Trigeminal Nerve Stimulation (eTNS) Using fMRI

Recruiting now · Not applicable · Has a placebo group

Conditions studied: Healthy Volunteers, Neurophysiology, fMRI Research

In brief

Transcutaneous Trigeminal Nerve Stimulation (eTNS) is a non-invasive technique that modulates brain activity by applying electrical currents to the forehead. However, it remains unclear whether its effects are primarily driven by activating peripheral nerves in the skin (the transcutaneous pathway) or by the electrical current passing directly through the skull into the brain (the transcranial pathway). This study aims to differentiate these two mechanisms in healthy volunteers. Participants will complete two separate MRI scanning sessions. In one session, a local anesthetic (lidocaine) will be applied to numb the skin over the forehead (specifically the supraorbital nerve branch) to temporarily block the peripheral nerve signals. In the other session, no anesthesia will be used. During both sessions, participants will receive active direct current eTNS (DC-eTNS) and a sham (inactive) stimulation while inside a 3T MRI scanner. Researchers will simultaneously measure brain activity (fMRI) and physiological signals (breathing and heart rate). By comparing the brain and bodily responses between the anesthetized and non-anesthetized conditions, the study seeks to determine exactly how eTNS signals travel to and affect the brainstem, cortex, and autonomic nervous system.

Key facts

Study ID

NCT07657260

Run by

Xidian University

People needed

25

Starts

2026-06-21

Expected to finish

2026-07-05

Last updated by the study team

2026-06-18

Who can join

Age: 18 and older, up to 35. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Healthy volunteers, aged 18 to 40 years old.
• Right-handed.
• Generally healthy with no history of neurological, psychiatric, or severe cardiovascular diseases.
• Normal physical and neurological examinations.
• Capable of understanding the study procedures and voluntarily signing the written informed consent form.

You may not qualify if…

• Known allergy, hypersensitivity, or adverse reactions to Lidocaine or other amide-type local anesthetics. (Crucial for this specific study design)
• Contraindications to MRI scanning (e.g., claustrophobia, cardiac pacemakers, artificial cochlea, metallic braces, or any other ferromagnetic implants).
• Female participants who are pregnant, lactating, or suspect they might be pregnant.
• Contraindications to transcranial or transcutaneous electrical stimulation (e.g., personal or family history of epilepsy/seizures, implanted brain stimulators).
• Any active skin disease, inflammation, lesions, cuts, or abrasions on the forehead (specifically over the supraorbital area), which could alter electrical impedance or anesthetic absorption.
• History of trigeminal neuralgia, facial nerve palsy, or chronic facial pain. Current or recent (within the past month) use of any medications known to affect the central nervous system, autonomic nervous system, or pain perception (e.g., analgesics, antidepressants, beta-blockers, or sedatives).
• History of substance abuse, heavy smoking, or excessive daily consumption of alcohol or caffeine.
• Irregular sleep patterns, shift work, or severe sleep deprivation within 24 hours prior to the scanning sessions.

Where it is running

• Xidian University — Xi'an, Shaanxi, China (enrolling)

Full record on ClinicalTrials.gov

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