Thank q Sir for sharing this important information. I do also have retna problem. if u will get any information regarding retna problem, pl let me know also on my personal email id :[email protected] thank q once again.
On 8/22/12, jaison bellarmine <[email protected]> wrote: > Artificial Retina Can Restore Normal Vision > TEHRAN (FNA)- Two researchers at Weill Cornell Medical College have > deciphered a mouse's retina's neural code and coupled this information > to a novel prosthetic device to restore sight to blind mice. > > > > The researchers say they have also cracked the code for a monkey > retina -- which is essentially identical to that of a human -- and > hope to quickly design and test a device that blind humans can use. > > The breakthrough, reported in the Proceedings of the National Academy > of Sciences (PNAS), signals a remarkable advance in longstanding > efforts to restore vision. Current prosthetics provide blind users > with spots and edges of light to help them navigate. This novel device > provides the code to restore normal vision. > > The code is so accurate that it can allow facial features to be > discerned and allow animals to track moving images. > > The lead researcher, Dr. Sheila Nirenberg, a computational > neuroscientist at Weill Cornell, envisions a day when the blind can > choose to wear a visor, similar to the one used on the television show > Star Trek. The visor's camera will take in light and use a computer > chip to turn it into a code that the brain can translate into an > image. > > "It's an exciting time. We can make blind mouse retinas see, and we're > moving as fast as we can to do the same in humans," says Dr. > Nirenberg, a professor in the Department of Physiology and Biophysics > and in the Institute for Computational Biomedicine at Weill Cornell. > The study's co-author is Dr. > Chethan Pandarinath, who was a graduate student with Dr. Nirenberg and > is currently a postdoctoral researcher at Stanford University. > > This new approach provides hope for the 25 million people worldwide > who suffer from blindness due to diseases of the retina. Because drug > therapies help only a small fraction of this population, prosthetic > devices are their best option for future sight. "This is the first > prosthetic that has the potential to provide normal or near-normal > vision because it incorporates the code," Dr. Nirenberg explains. > > Discovering the Code > Normal vision occurs when light falls on photoreceptors in the surface > of the retina. The retinal circuitry then processes the signals from > the photoreceptors and converts them into a code of neural impulses. > These impulses are then sent up to the brain by the retina's output > cells, called ganglion cells. The brain understands this code of > neural pulses and can translate it into meaningful images. > > Blindness is often caused by diseases of the retina that kill the > photoreceptors and destroy the associated circuitry, but typically, in > these diseases, the retina's output cells are spared. > > Current prosthetics generally work by driving these surviving cells. > Electrodes are implanted into a blind patient's eye, and they > stimulate the ganglion cells with current. But this only produces > rough visual fields. > > Many groups are working to improve performance by placing more > stimulators into the patient's eye. The hope is that with more > stimulators, more ganglion cells in the damaged tissue will be > activated, and image quality will improve. > > Other research teams are testing use of light-sensitive proteins as an > alternate way to stimulate the cells. These proteins are introduced > into the retina by gene therapy. Once in the eye, they can target many > ganglion cells at once. > > But Dr. Nirenberg points out that there's another critical factor. > "Not only is it necessary to stimulate large numbers of cells, but > they also have to be stimulated with the right code -- the code the > retina normally uses to communicate with the brain." > > This is what the authors discovered -- and what they incorporated into > a novel prosthetic system. > > Dr. Nirenberg reasoned that any pattern of light falling on to the > retina had to be converted into a general code -- a set of equations > -- that turns light patterns into patterns of electrical pulses. > "People have been trying to find the code that does this for simple > stimuli, but we knew it had to be generalizable, so that it could work > for anything -- faces, landscapes, anything that a person sees," Dr. > Nirenberg says. > > Vision = Chip Plus Gene Therapy > In a eureka moment, while working on the code for a different reason, > Dr. Nirenberg realized that what she was doing could be directly > applied to a prosthetic. She and her student, Dr. Pandarinath, > immediately went to work on it. They implemented the mathematical > equations on a "chip" and combined it with a mini-projector. The chip, > which she calls the "encoder" converts images that come into the eye > into streams of electrical impulses, and the mini-projector then > converts the electrical impulses into light impulses. These light > pulses then drive the light-sensitive proteins, which have been put in > the ganglion cells, to send the code on up to the brain. > > The entire approach was tested on the mouse. The researchers built two > prosthetic systems -- one with the code and one without. > "Incorporating the code had a dramatic impact," Dr. Nirenberg says. > "It jumped the system's performance up to near-normal levels -- that > is, there was enough information in the system's output to reconstruct > images of faces, animals -- basically anything we attempted." > > In a rigorous series of experiments, the researchers found that the > patterns produced by the blind retinas in mice closely matched those > produced by normal mouse retinas. > > "The reason this system works is two-fold," Dr. Nirenberg says. "The > encoder -- the set of equations -- is able to mimic retinal > transformations for a broad range of stimuli, including natural > scenes, and thus produce normal patterns of electrical pulses, and the > stimulator (the light sensitive protein) is able to send those pulses > on up to the brain." > > "What these findings show is that the critical ingredients for > building a highly-effective retinal prosthetic -- the retina's code > and a high resolution stimulating method -- are now, to a large > extent, in place," reports Dr. Nirenberg. > > Dr. Nirenberg says her retinal prosthetic will need to undergo human > clinical trials, especially to test safety of the gene therapy > component, which delivers the light-sensitive protein. But she > anticipates it will be safe since similar gene therapy vectors have > been successfully tested for other retinal diseases. > > "This has all been thrilling," Dr. Nirenberg says. "I can't wait to > get started on bringing this approach to patients." > > > -- > skype ID: jaison.ayk > > > Search for old postings at: > http://www.mail-archive.com/[email protected]/ > > To unsubscribe send a message to > [email protected] > with the subject unsubscribe. > > To change your subscription to digest mode or make any other changes, please > visit the list home page at > http://accessindia.org.in/mailman/listinfo/accessindia_accessindia.org.in > > Search for old postings at: http://www.mail-archive.com/[email protected]/ To unsubscribe send a message to [email protected] with the subject unsubscribe. To change your subscription to digest mode or make any other changes, please visit the list home page at http://accessindia.org.in/mailman/listinfo/accessindia_accessindia.org.in
