How your rTMS target and dose are chosen

The short answer

Your dose is a percentage of your own motor threshold, which we measure in the room. Your target is whichever candidate site your own heart responds to most clearly. Neither number is copied from an average.

That is the whole of what personalised means here. It is a description of two measurements, not a claim about outcomes.

Why a fixed scalp coordinate is a compromise

The common approach is to place the coil at a fixed scalp coordinate, the same position on every head. It is quick, it is reproducible between clinics, and it is easy to teach.

Its limitation is structural. A fixed coordinate assumes that the same point on every scalp sits above the same functional tissue in every brain. Heads differ in size and shape, so that assumption is a convenience rather than a finding.

It is also a one-way instruction. The coil goes where the protocol says, and nothing about the placement asks your brain whether the intended circuit was reached. You get a position, but you get no feedback about it.

Motor threshold: the dose that belongs to you

Before a course begins, the coil sits over the part of your brain that controls hand movement. The pulse strength is raised in steps until a small visible twitch appears in your hand. The lowest strength that reliably produces it is your motor threshold.

Every dose you receive afterwards is expressed as a percentage of that figure. Two people on the same protocol can therefore receive quite different absolute pulse strengths, because the protocol is written in percentages rather than in machine units.

The reason your hand is involved at all is practical. Stimulating the movement area of the brain produces something visible. Stimulating the front of the brain, which is where treatment is actually aimed, produces nothing you can see from the outside.

So the movement area is borrowed as a calibration point. It gives a usable number, measured in the room, in a few minutes, without imaging.

This part is not novel and we do not present it as such. If you want the reference practice for how rTMS is delivered, the international consensus guidelines by Lefaucheur and colleagues in Clinical Neurophysiology, 2020, are the standard text.

What a heart rate deceleration indicates

The dorsolateral prefrontal cortex is the usual target for stimulation in depression and anxiety, because it connects to the deeper networks that regulate mood. The question is which part of it, on your head, on the day.

So we test. Several candidate sites over the dorsolateral prefrontal cortex are stimulated in turn, and your heart rate is watched at each one. Where a site produces a clear brief slowing, that is a signal the network linking the front of the brain to the vagus nerve has engaged.

The vagus nerve is the main nerve of the parasympathetic nervous system, and it carries the signals that slow the heart. This is why the heart is readable as a proxy. It is downstream of a circuit we cannot see directly, and it responds within seconds.

The site producing the clearest deceleration is the one we treat for the rest of the course.

Where this method comes from

The approach is grounded in published research, including work from our own scientific advisor. We believe we are the first clinic in London to make it standard practice for every patient, rather than something reserved for selected cases.

Our scientific advisor is Professor Alexander Sack. The Telegraph described him as “a global leader in neuromodulation who directs the Academy of Brain Stimulation, advises Naya Health and trains their clinicians.”

What we will not tell you is that we invented or validated this. We did not. We read the literature, adopted the method, and made it routine.

What gets recorded

Your motor threshold, the candidate sites tested, what your heart did at each one, and the site finally chosen all form part of your record. You can ask to see them. You can ask again at reassessment whether anything has been changed.

Heart rate variability then keeps running in the background. It is the variation in time between consecutive heartbeats, and higher variability generally indicates a nervous system that can shift between alert and settled states. During a programme here it is recorded continuously by a wearable ring rather than sampled once in a clinic room.

That gives two views of the same system. One lasts a few seconds and is used to choose a target. The other runs for weeks and is used to track change.

Why the word personalised needs pinning down

Personalised is used in this field to mean anything from a tailored conversation to a genuinely individual measurement. That range is why it is worth asking a clinic what exactly is being personalised, and what number the personalising produces.

Here the answer is two numbers, and you can ask to see both. Anything else described to you as personalised, at any clinic, should come with the same kind of answer.

What the measurement does not tell you

A clear heart rate deceleration is a physiological signal that a circuit engaged. It is not a prediction that you will respond to treatment, and we should not let it be read as one.

It does not diagnose anything either. Nor does the NayaScore assessment that runs alongside it, which combines grip strength, continuous heart rate variability from a wearable ring, and cognitive testing across twelve domains. That is a measurement tool, not a diagnostic test, and results are interpreted alongside clinical judgement.

The honest gap is the comparative one. We are not aware of a published head-to-head trial comparing neurocardiac-guided targeting with a fixed scalp coordinate. Until there is one, we can describe the mechanism and the rationale, and we should not claim superior results.

What this changes about your course

Practically, it adds a step before treatment rather than during it. Motor threshold and target selection are done as part of your assessment, before the first treatment session, and the course then runs to the settings they produced.

It also means there is a specific answer if you ask why the coil is where it is. The answer is your own physiology on the day of your assessment, and your clinician can tell you which sites were tested and what each one did.

Bottom line

Personalised is a word that gets used loosely in this field, so it is worth pinning to something. Here it means one measured dose and one measured position, both derived from you.

That is a real difference from a standard setting at a standard coordinate. It is not, on the evidence available today, a promise of a better result, and we would rather say that now than imply otherwise.

Frequently asked questions

What is a motor threshold and why is it measured?

It is the lowest pulse strength that produces a small visible twitch in your hand when the coil sits over the movement area of your brain. It is measured for you individually, and every later dose is set as a percentage of it, so the strength used is calibrated rather than fixed.

Why does the clinic watch heart rate while choosing a target?

A brief slowing of heart rate in response to test pulses indicates that the network linking the front of the brain to the vagus nerve has engaged. Candidate sites over the dorsolateral prefrontal cortex are tested, and the site producing the clearest slowing is the one chosen for treatment.

Is this method proven to work better than a fixed coil position?

We are not aware of a published head-to-head trial comparing the two approaches, so we do not claim better outcomes. The method is grounded in published research, including work from our own scientific advisor. What we can say is that the target is chosen from your physiology rather than an average.

What does personalised actually mean at this clinic?

Two specific things, both measured. Your dose is a percentage of your own motor threshold rather than a standard setting. Your target is the candidate site your own heart responded to most clearly. Nothing about either number is inherited from a population average or a textbook coordinate.