Associate Editor Sandra Upson takes a second, equally skeptical look at a mouth-watering technology in search of an application.

Sandra Upson

Back in January we wrote about a plan to enable blind people to "see" with their tongues. The idea was to turn a pixilated signal from a camera into buzzing patterns on an array of electrodes in the mouth. We thought it sounded kooky, a shoo-in for the "loser" designation in our January "Winners & Losers" issue.

It turns out not everyone agreed. Some scientists in the lab of Yohan Payan at TIMC-IMAG (Techniques de l'Ingénierie Médicale et de la Complexité—Informatique, Mathématique et Applications), in Grenoble, France, want to use the tongue display to enable surgeons to keep their eyes on their hands while also following images from another source. The specific application is minimally invasive surgery, in which surgeons make a small incision and then guide a tube tipped with a surgical tool into a patient's body, where it can do its job without causing much collateral damage. The tool carries infrared markers whose output can be tracked and displayed on a screen.

It would be better, say the French researchers, to display that information instead on the tongue. The surgeon would suit up, slip a retainer over his teeth and guide the surgical tool based on the pattern of buzzes from the electrodes, itself determined by a computer-vision algorithm. The electrodes would buzz according to the direction in which the needle drifts off a pre-charted course. Is this really the best way to present simultaneous images to the surgeon's mind? Wouldn't it be more straightforward to point a camera at the patient and display the image on a screen next to the one showing the needle's position? Or devise a projection system able to superimpose the image onto the patient's body?

Let's suppose, just for the sake of argument, that computer-defined direction is indeed the way of the future. Even so, there are better ways to accomplish it than by shocking the doctor's tongue. The computer could give spoken commands, much as auto navigation systems announce upcoming driving directions.

But that's not all.

Some of the French researchers have also tried using the tongue device to prevent sores from forming on the buttocks of paraplegics. In a 2006 paper, they proposed that the patient sit on a pressure-sensitive pad with the strip of electrodes in the patient's mouth. The electrode array would map to the user's derriÿre, and the pressure-sensitive pad would signal the tongue whenever the butt ran the risk of developing pressure sores.

As we reported in January, both scientists and potential users roundly rejected the idea of gearing up one's mouth for the sake of ersatz vision. Certainly the tongue is more sensitive and has better resolution than, say, an equal span of skin on the arm or lower back. But that doesn't mean that we should all be putting electronics in our mouths.

Once again, tongue vision seems like a solution in search of a problem.


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