An international team of neuropsychologists has improved a device named "Tongue Display Unit" (TDU) pioneered at the University of Wisconsin in Madison. The device consists of a grid of 144 gold-plated electrodes set in the mouth and able to activate the cerebral cortex, the area of brain normally used for vision, of blind people. In their experiments, blind people were able to "see letters with their tongue." This system has the potential to replace the Braille alphabet and to vastly improve the quality of life of blind persons.
After a few minutes of experimentation, you have to recognize that the system developed by neuropsychologist Maurice Ptito of Université de Montréal, together with colleagues in Denmark and the United States , to allow blind people to "see with their tongue" appears strangely effective. In just the first few minutes, the subject is able to build up a fairly clear picture of the letter "T" placed in various positions and transmitted by electrical impulses to the device on his tongue.
The Tongue Display Unit (TDU) can activate areas that are normally reserved for visual information and are unused when someone suffers from congenital blindness. "The tongue will never replace the eye, of course," says Prof. Ptito. "But for people born blind, the cerebral cortex, which is normally used for vision, is reactivated by this device. The electrical activity, recorded by a scan, is very clear about this."
For more details about the origin of the TDU, you can read this article from New Scientist, dated March 17, 2001.
Below are photographs of a 12x12 tongue-placed electrode array and a TDU, probably not up to date. These photographs come from this document, " Activation of visual cortex by electrotactile stimulation of the tongue in early-blind subjects."
What can we expect soon from such a system?
In the shorter term, we can imagine a system that would replace the Braille alphabet. In fact, if the tongue were capable of "reading" the letters of the alphabet, it would be able to read texts broadcast via electrical signals. When it has been perfected, this system could considerably improve the quality of life of blind persons. It would be a "hands-off" non-invasive system.
But Pfito also envisions other uses in a longer term.
When we press the researcher to find out more about possible applications of this system, he delights in describing a miniaturized system worthy of the Bionic Man. "We can imagine a camera installed in the eye, which transmits an image from a device worn on the belt. This would send an electrical stimulus to the lingual stimulator mounted on a trip indicator the user wears under the palate. To have access to the camera's images, all he would have to do is press his tongue against it."
French language readers might want to read the original version of the news release mentioned above, "Un œil sur la langue" or a previous news item, "Voir avec la langue."
Source: University of Montreal news release, June 2, 2004, via EurekAlert!; and various websites