Hi All,
For your information. Appended is an article on retinal implant research
in Wired Science today.
Best wishes,
Peter Meijer
Seeing with Sound - The vOICe
http://www.seeingwithsound.com/winvoice.htm
SAN DIEGO — A new type of prosthetic eye may someday allow blind people
to
seamlessly see the broad sweep of an ocean or the dimples in a baby’s
face. The
approach, presented Nov. 13 at the Society for Neuroscience’s annual
meeting,
may benefit the estimated 25 million people worldwide who have lost sight
due to
retinal diseases.
“This is a spectacular example of what we all hoped to be able to do,”
said
Jonathan Victor, a computational-systems neuroscientist who was not
involved in
the new work. “It’s a solution to an abstract problem” that could be
useful in
many kinds of systems.
Sheila Nirenberg and Chethan Pandarinath, both of Weill Medical College
of
Cornell University in New York City, tested their new retinal prosthetic
in
blind mice and found that it allowed the mice to see a baby’s face.
Current prosthetics are limited to reproducing simple features, such as
bright
spots or edges, but miss much of a scene. Many scientists are intent on
boosting
the retinal prosthetics’ power, so that the message from the artificial
eye to
the brain is stronger. But Nirenberg’s work suggests that a second,
underappreciated area is also important: the pattern of cell activity in
the
retina, something she called “a big problem lurking in the background.”
Normally, cells that respond to light, called photoreceptors, pick up
signals
and transfer that information to ganglion cells. These cells then create
a
complex code for each visual signal that goes into the brain, where the
scene is
reconstructed. Spotting a dog creates a particular code, for example,
different
from the code for a teacup or a baby’s face. When a retina is
degenerated,
these
photoreceptor cells die and there is no message to send.
Nirenberg’s new system mimics the complex behavior of the frontline
photoreceptor cells, creating a more natural artificial message for the
ganglion
cells to interpret. Other prosthetics produce simpler, less recognizable
codes,
Nirenberg said. These simplified patterns aren’t what the brain is used
to
receiving, so while they can reproduce simple features, they can’t
reproduce
natural scenes. Because the new prosthetic speaks the language that the
ganglion
cells are accustomed to, the ganglion output — and the image — is more
accurate.
“If you want to really restore normal vision, you have to know the retina’s
code,” Nirenberg said. “Once you have that, the door is open to the
possibility
of restoring normal vision.”
To test its prosthetic system, the team decoded the output of the
ganglion
cells
by measuring cellular activity when an image of a baby’s face was
presented to
the retinas of blind mice. Patterns measured from the mice with the new
prosthetic reproduced a baby’s face in much finer detail than the
standard
method did. Instead of the standard method’s highly pixelized, blurry
version of
the face, the new prosthetic captured a smooth, clear view of the baby’s
quizzical expression. “Not only can you tell it’s a baby’s face, you can
tell
it’s this baby’s face,” Nirenberg said.
The researchers are currently testing the prosthetic on primates and plan
eventually to provide the technology to human patients. That would
probably
require gene therapy.
“Obviously it’s not in humans yet,” said Victor, also of Weill Medical
College.
“Everyone else is working on putting the signal into humans, and now they
have
the signal to put in. It’s extremely exciting.”
Source URL:
http://www.wired.com/wiredscience/2010/11/blind-vision-implant/
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