On 8/25/12, nitesh gupta <[email protected]> wrote: > 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 > >
-- thanks Hi! I admire your effort, thanks allot for sharing this valuable information with all of us. Siddharthkumar Keshri. Email, [email protected] 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
