Neuroscientist Paul Bach-y-Rita hypothesized in the 1960s that “we see with our brains not our eyes.” Now, a new device trades on that thinking and aims to partially restore the experience of vision for the blind and visually impaired by relying on the nerves on the tongue’s surface to send light signals to the brain.
Legal blindness is defined by U.S. law as vision that is 20/200 or worse, or has a field of view that is less than 20 degrees in diameter. The condition afflicts more than one million Americans over the age of 40, according to the National Institutes of Health. Adult vision loss costs the country about $51.4 billion per year.
About two million optic nerves are required to transmit visual signals from the retina—the portion of the eye where light information is decoded or translated into nerve pulses—to the brain’s primary visual cortex. With BrainPort, the device being developed by neuroscientists at Middleton, Wisc.–based Wicab, Inc. (a company co-founded by the late Back-y-Rita), visual data are collected through a small digital video camera about 1.5 centimeters in diameter that sits in the center of a pair of sunglasses worn by the user. Bypassing the eyes, the data are transmitted to a handheld base unit, which is a little larger than a cell phone. This unit houses such features as zoom control, light settings and shock intensity levels as well as a central processing unit (CPU), which converts the digital signal into electrical pulses—replacing the function of the retina.
From the CPU, the signals are sent to the tongue via a “lollipop,” an electrode array about nine square centimeters that sits directly on the tongue. Each electrode corresponds to a set of pixels. White pixels yield a strong electrical pulse, whereas black pixels translate into no signal. Densely packed nerves at the tongue surface receive the incoming electrical signals, which feel a little like Pop Rocks or champagne bubbles to the user…
Source for complete article: http://www.scientificamerican.com/article.cfm?id=device-lets-blind-see-with-tongues
text source: http://www.enhancedvision.com/low-vision-blog/2009/08/device-lets-the-blind-see-with-their-tongues/
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