Norman Doidge’s tongue device: what it is today
Norman Doidge's The Brain That Changes Itself (2007) opens with a chapter called "A Woman Perpetually Falling". It is the most quoted chapter in the book, and it is also the reason a good share of our enquiries arrive. People finish it and ask: does that device exist? where is it? can I actually get this treatment? Here are the answers, in order.
What the chapter is about
Its subject is Cheryl Schiltz. In 1997, at thirty-nine, she developed a post-operative infection and was treated with gentamicin — an antibiotic with a rare but severe side effect: it is toxic to the vestibular system. Cheryl lost almost all vestibular function. Not hearing, not vision, not strength in her legs — the sense of balance that healthy people never think about.
What follows is hard to picture until you see it. She cannot stand still: she feels permanently as though she is falling, and because of that feeling she does fall. Holding the vertical consumes so much of her brain's capacity that little is left for memory, arithmetic or reasoning.
The device described in the book
In the chapter Cheryl puts on something resembling a construction hard hat with an accelerometer inside, and places a thin plastic strip covered with electrodes on her tongue. Doidge, who tried the device himself, calls that strip a tongue display and compares the sensation to the bubbles of champagne.
The logic is simple. The sensor measures head tilt. A computer converts the tilt into a pattern of dots. The pattern is delivered to the tongue as light tingling. Upright, the tingle sits in the centre; lean forward and the pattern moves forward. Information about body position reaches the brain not through the destroyed vestibular organ but through the tongue. The tongue is not an arbitrary choice: it is densely innervated, permanently moist, which helps conduction, and it has no insensitive patches. Its inventor described the tongue as an interface between brain and machine.
Who Paul Bach-y-Rita was
The man behind all of this was the American neuroscientist Paul Bach-y-Rita. In the 1960s he built a chair with a grid of vibrating stimulators in its back: a camera filmed a scene and the image was delivered to a blind person's back as a pattern of vibration. People learned to recognise faces and shadows and to judge which object was closer. The idea is called sensory substitution: if one channel of perception is destroyed, information can be routed into the brain through another, and the brain will work out the rest. At the time almost nobody believed it. The bulky back-mounted grid was later replaced by the thin strip on the tongue.
Yuri Danilov — the "Yuri" in the chapter
In the experiment scene, the team's biophysicist is at the computer. Doidge names him — Yuri — notes that he was born in Russia, and quotes his assessment that the patient has lost between ninety-five and a hundred per cent of her vestibular function. That is Yuri Danilov.
He went on to lead the Tactile Communication and Neurorehabilitation Laboratory at the University of Wisconsin–Madison for many years, and carried the method from a laboratory rig to a portable device and into clinical trials. Today he is the scientific supervisor of the method at RehaLine and a co-author of our publications.
The residual effect — the most important thing in the chapter
The first time, Cheryl wore the device for one minute. She took it off and her balance held for about twenty seconds. Two minutes of use gave roughly forty seconds. Twenty minutes gave not the seven minutes the researchers expected, but a full hour — three times the length of the session itself.
That is the key to the whole method. The device does not stand in for the lost function the way glasses stand in for a lens. It triggers reorganisation: given the cue, the brain starts solving the problem itself and keeps solving it after the cue is withdrawn. With accumulated sessions the residual effect grows. This is exactly why the method is delivered as a course rather than a single session, and always together with exercise — stimulation without movement is pointless.
What happened to the method after the book
The device for blind users became BrainPort. The device for movement and balance was named PoNS, for Portable Neuromodulation Stimulator — an abbreviation that echoes the pons, the brainstem structure the method acts on. In the medical literature the technique is called translingual neurostimulation (TLNS) or translingual stimulation.
Since the book it has reached randomised trials in post-stroke ataxia, use in children after neurosurgery, and independent work elsewhere — including a study of 64 patients after removal of large and giant vestibular schwannomas carried out at the Polenov Institute of Neurosurgery together with our centre.
An honest word about expectations
Doidge's book is excellent popular science, not a clinical guideline. Cheryl Schiltz's story is the story of one person and should not be read as a promise of the same outcome. The real picture is more modest and more complicated: the method produces measurable improvement in balance and gait in a proportion of patients, works better early, requires a course and exercise, and has contraindications. It does not rebuild destroyed structures and does not replace the rest of treatment.
If you came here after the book
Write to us and tell us what happened and when. We will look at the documents and say plainly whether a course makes sense in your case. How the method works, which conditions it is used for and what the contraindications are: the translingual neurostimulation page. Recovery after cerebellopontine angle surgery: acoustic neuroma. Balance and gait problems of other origin: ataxia. How our device compares with PoNS: TLNS vs PoNS.