Nano-Biotechnology

Bionic Vision Could Bypass Eyes

Minielectrodes directly attached to the brain

By Stefan Anitei, Science Editor

25th of April 2007, 08:02 GMT

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Future prosthetic visual device: two small digital video cameras mounted on a set of glasses and connected to a signal processor that transmits visual impulses wirelessly to an implanted stimulator

The bionic eye would be the solution for the vision impaired people in the technology era. But a new research shows that bringing back vision to blind people could completely bypass the eyes.

The brain visual cortex was found to understand electric signals received directly from a video device like the visual neuronal signals.
The problem with the prosthetic devices (bionic eyes) is that they have to stimulate what's left of the neurons in the retina, eye's light-sensitive lining, with miniature electrodes, but retinal tissue is extremely fragile and hard to manipulate.

Another approach inserted microelectrodes into the visual cortex and activated visual nerves with electrical impulses. But these methods could only trigger simple behavioral responses in lab animals.

But now Harvard researchers have tested a new approach. They managed to make experiment animals follow preselected artificial visual signals using their eyes, like they would have been watching lights flashing on a real video screen, by inserting them two minielectrodes into the lateral geniculate nucleus (LGN) of the thalamus, a relay station for visual signals before they reach the visual cortex.

"The experiment used sighted monkeys so the researchers could compare their responses to real images with artificial signals," said neuroscientist and co-author John Pezaris.

"Although the team only used two electrodes as proof of concept, the monkeys followed both the real and artificial signals in exactly the same way."

In case the method is proved really effective in animals, the team could make the jump to humans and could develop it into an increasingly complex technique. A complete developed artificial vision system could be made of twin digital video cameras like a pair of glasses that pass the information wirelessly to an implanted neural stimulator connected to the minielectrodes. The research represents "a fundamental advance toward a visual prosthesis," said neurobiologist Nicholas Hatsopoulos of the University of Chicago in Illinois.

"For one thing, the thalamus is easier to stimulate than the retina and is much less prone to tissue damage."

TAGS:

bionic | vision | minielectrodes

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