Welcome to Eurotimes

Innovative impulse device enables tongue to ‘see’ by processing sensory data to the brain

IT sounds like something culled from the pages of Weekly World News - a "seeing tongue" capable of processing the type of sensory information normally reserved for the eyes.

Yet, far-fetched as the concept may seem, researchers are well advanced in their plans to produce a device capable of transforming the human tongue into a tactile environment for relaying data to and from the brain.

Leading the vanguard of research into tactile vision substitution systems (TVSS) is Paul Bach-y-Rita MD, a Professor of Rehabilitation Medicine and Biomedical Engineering at the University of Wisconsin, US who has been working in this area for the best part of four decades.

As he sees it, the tongue is a terrific portal to the brain. "You don’t see with your eyes, you see with your brain," said Dr Bach-y-Rita, who, with colleague Kurt Kaczmarek PhD has taken out patents for the device (US 6, 430, 450), which uses electrical impulses to route spatial information through the tongue to the brain.

Dr Bach-y-Rita sees numerous applications for the technology, such as helping blind people to navigate, giving Navy Seals directions in dim underwater environments and guiding urban search-and-rescue teams as they comb the confusion of smoke-filled buildings for people to rescue.

"The brain is very malleable. You can compensate for sensory loss by rehabilitating the brain and turning to surviving sensory systems such as the skin and the tongue to substitute for lost vision", he said.

Loaded with nerves and bathed in its own conductive saline solution, the tongue is an ideal surface for a tiny array of 144 electrodes that can, through the co-ordinated firing of mild electrical impulses, route images from a camera, computer or other device straight to the brain.

According to Dr Bach-y-Rita and Dr Kaczmarek, new miniaturised electronics will one day permit the device to be as small or smaller than a dental retainer and enable it to be built directly into the respirators used by divers and firefighters.
"The electrical stimulus on the tongue feels like a tingle or vibration; some users have said it feels like soda bubbles," Dr Kaczmarek said.

"The sensation is well-controlled and not painful unless the user deliberately turns up the level too high. Occasionally it will produce weak metallic taste sensations, a minor side effect. We have never observed any kind of tissue irritation with the gold-plated electrodes."

For blind people, it is hoped that the device might one day pave the way towards greater independence and autonomy by allowing them to perform simple tasks that the rest of the population take for granted.

"In much the same way that people can use their fingertips to read Braille letters, which are patterns of raised dots embossed onto a sheet of paper, people can recognise simple spatial patterns using comfortable electrical stimulation of the tongue," said Kaczmarek.

The tongue-stimulating system translates images detected by a camera into a pattern of electric pulses which trigger touch receptors. Scientists say that volunteers testing the prototype soon lose awareness of on-the-tongue sensations and perceive the stimulation as shapes and features in space.

Their goal ultimately is to develop a practical, cosmetically acceptable, wireless system for blind people, with a miniature TV camera, microelectronics and FM transmitter built into a pair of glasses, and the electro-tactile array fitted in a dental orthodontic retainer.
Dr Kaczmarek said considerable progress has already been made in this area, but that more needs to be done.

"Our colleague Prof Eliana Sampaio at the Conservatoire National Des Arts et Metiers, Paris, France has used our tongue stimulator with a small video camera and demonstrated an equivalent visual acuity of about 20/830, which is very poor vision, but possibly useful for certain limited activities with enough practice," he said.

Sampaio has previously shown that blind infants are capable of responding with appropriate motor behaviour to visual information presented to an intact sensory system. The next step is develop a baby TVSS built into a pacifier, with a wireless 2x2.0mm TV camera built into the external end and the electro-tactile display in contact with the tongue.

Another French team at the CNRS University of Grenoble TIM-C Laboratory (Imagery, Modelling and Cognition) is also currently exploring another potential application for the technology - developing a tactile tongue device for surgeons through which they can control equipment and receive information.

Most recently, the device was tested by surgeons-in-training operating on a foam rubber patient with the objective of correctly manipulating a renal probe, guided only by the location signals emitted by the surgical instruments and transmitted to the palate device.

Excited as he is by the multi-pronged developments of the technology, Dr Kaczmarek cautions that it will be some time yet before it makes a significant impact on the lives of the visually impaired.

"Our hope is that with technology improvements and a lot of practice by highly-motivated users, some of them may be able to perform certain kinds of simple visual tasks to enhance their independence. This will likely be many years in the future. Persons who are blind are not likely to trade in their long canes or guide dogs anytime soon as a result of this technology."