Investigating the Effects of Transcranial Ultrasonic Stimulation of the Lateral Geniculate Nucleus on Visual Evoked Potentials in Healthy Adult Volunteers

Focused ultrasound and the visual brain — volunteers wanted

We are looking for healthy adult volunteers (aged 18–50) to take part in a research study at NeuroHarmonics investigating how brief, low-intensity focused ultrasound affects the brain's response to visual patterns.

The study uses transcranial ultrasonic stimulation (TUS), a non-invasive, painless form of brain stimulation, focused on a small visual relay deep in the brain called the lateral geniculate nucleus (LGN). The LGN is the brain's main visual relay, channelling signals from the eyes to the visual cortex, and understanding how it responds to stimulation is a foundational question in human neuroscience.

Unlike other non-invasive brain-stimulation methods, which only reach the surface of the brain, TUS can target structures deep in the brain with millimetre precision. TUS has an excellent safety record in human research.

During the session, EEG sensors on the scalp record your brain's response while the ultrasound is delivered through a multi-element research helmet designed for precise targeting through the skull.

The study at a glance

The study is a single in-person visit of about three hours at our London research site. Before your visit, we'll arrange a short phone call with one of the investigators to go through a safety screening questionnaire with you. On the day, we'll fit EEG sensors and position the research helmet, then run several blocks during which short pulses of focused ultrasound are delivered while you look at a flickering checkerboard pattern on a screen. We end with a brief observation period and a debrief, and check in with you by email or phone the next day.

You may be eligible if you

• Are aged 18–50.
• Are in generally good health.
• Have normal or corrected-to-normal vision.
• Have a recent (within 36 months) personal copy of research scans of your head, including a T1 MRI scan and a skull-image scan (a special MRI sequence such as PETRA, ZTE, or UTE, or alternatively a head CT), from a previous ethically-approved research study.

We use your existing scans to plan exactly where the ultrasound is focused for you. We do not perform any scans in this study. If you're not sure whether a scan you have qualifies, email us and we'll check.

You may not be eligible if you

• Have a personal or family history of epilepsy.
• Have an implanted electronic device (pacemaker, cochlear implant) or metallic implants in the head or neck.
• Are pregnant or could be pregnant.
• Take medication that affects the nervous system, or have a current neurological or psychiatric diagnosis.
• Have taken anti-malarial medication in the last 72 hours, or used recreational drugs in the last 24 hours.
• Have taken part in another brain-stimulation study in the last month.

The full list of eligibility criteria is in the Participant Information Sheet, which we will send you on request.

Compensation

• £200 for taking part.
• Reasonable travel reimbursed on production of receipts.

Ethical approval

This study has been reviewed and given a favourable ethical opinion by Portsmouth University Research Ethics Committee, reference 26/ETHICS/021.

Interested?

Please contact us at studies@neuroharmonics.com or visit https://neuroharmonics.com/studies. We will send you a Participant Information Sheet to read before you decide whether to take part.