New hope for the blind from neuroscientists?
Scientists in the Texas Medical Center believe that there may be a way to use mental images to help some of the estimated 39 million people worldwide who are blind.
Scientists in the laboratories of Michael Beauchamp, Ph.D., an associate professor of neurobiology and anatomy at the The University of Texas Health Science Center at Houston (UTHealth) Medical School, and Daniel Yoshor, M.D., an associate professor of neurosurgery and neuroscience at Baylor College of Medicine, have discovered a neural mechanism for conscious perception that could use the brain’s image-generating ability.
“While much work remains to be done, the possibilities are exciting,” said Beauchamp, the study’s lead author. “If successful, we would in essence bypass eyes that no longer work and stimulate the brain to generate mental images. This type of device is known as a visual prosthetic.”
Filed under vision mental images prosthetics phosphene blindness neuroscience science
Electrical stimulation of the visual cortex may one day give image perception to blind people.
Work presented at the Society for Neuroscience meeting in New Orleans today suggests a way to create a completely new kind of visual prosthetic—one that restores vision by directly activating the brain.
In a poster session, researchers presented results showing how electrical stimulation of the visual cortex can evoke the sensation of simple flashes of light—including spatial information about those flashes.
While other researchers are trying to develop artificial retinas that feed visual signals into existing sensory pathways (see “A Retinal Prosthetic Powered by Light" and "Now I See You" for instance), the team behind the new work, from the Baylor College of Medicine and the University of Texas Health Science Center in Houston, is exploring the possibility of bypassing those routes all together. This could be vital for those whose retinas are unable to receive retinal stimulation.
The researchers used electrodes to stimulate the brains of three patients who were already undergoing brian surgery to treat epilepsy. All three were able to detect bright spots of light, called phosphenes, when certain regions of their brains were stimulated. And, in seven out of eight trials, the patients were able to correctly see the orientation of a phosphene—in one of two orientations, depending on the stimulation they received.
The work builds upon a study published by the same team in Nature Neuroscience this summer. In that study, the researchers defined which areas of the brain produce phosphene perception when patients’ brains were electrically stimulated.
A press release related to the earlier work says that the researchers “plan to conduct a larger patient study and create multiple flashes of light at the same time. Twenty-seven or so simultaneous flashes might allow participants to see the outline of a letter.”
Filed under blindness neuroscience prosthetics retina vision visual perception Neuroscience 2012 science
Nobel Winner’s Stem Cells to Be Tested in Eye Malady in 2013
Stem cells derived from a mouse’s skin won Shinya Yamanaka the Nobel Prize. Now researchers in Japan are seeking to use his pioneering technology for an even greater prize: restoring sight.
Scientists at the Riken Center for Developmental Biology in Kobe plan to use so-called induced pluripotent stem cells in a trial among patients with macular degeneration, a disease in which the retina becomes damaged, resulting in loss of vision, Yamanaka told reporters in San Francisco.
Companies including Pfizer Inc. (PFE) are already planning trials of stem cells derived from human embryos. The Japanese study will be the first to use a technology that mimics the power of embryonic cells while avoiding the ethical controversy that accompanies them.
“The work in that area looks very encouraging,” John B. Gurdon, 79, a professor at the University of Cambridge who shared the Nobel with Yamanaka, said in an interview in London.
Yamanaka and Gurdon shared the 8 million Swedish kronor ($1.2 million) award for experiments 50 years apart that showed that mature cells retain in latent form all the DNA they had as immature stem cells, and that they can be returned to that potent state, offering the potential for a new generation of therapies against hard-to-treat diseases such as macular degeneration.
Filed under stem cells pluripotent stem cells vision blindness macular degeneration ECs neuroscience science
Easier test for blindness cause
Scientists from Australia’s Vision Centre have demonstrated a quick, accurate test under lights for one of the world’s leading causes of blindness.
A new study shows that age-related macular degeneration (AMD) can be just as effectively and more rapidly and inexpensively diagnosed under bright lights, instead of requiring patients to sit for 20 minutes in a darkened room.
“AMD accounts for half of the legal blindness cases in Australia,” says Professor Ted Maddess from The Vision Centre and The Australian National University. “It affects one in seven people over the age of 50, costing the nation $2.6 billion a year. Globally, it affects 25 to 30 million people, with an annual cost of $343 billion.
“While current tests for AMD are done in the light, scientists have proposed that it might be better if the patient has their vision adapted to the dark prior to the test,” he says.
“This is because they had found that rod receptors – vision cells that we use to see in black and white and in low light – die earlier in AMD than the cone receptors we use to see in colour during the day. So it had been suggested that AMD tests would be more accurate if they were based on the health of a person’s rods.”
Filed under vision AMD macular degeneration blindness vision loss neuroscience science
How Do Blind People Picture Reality?
Paul Gabias has never seen a table. He was born prematurely and went blind shortly thereafter, most likely because of overexposure to oxygen in his incubator. And yet, Gabias, 60, has no trouble perceiving the table next to him. “My image of the table is exactly the same as a table,” he said. “It has height, depth, width, texture; I can picture the whole thing all at once. It just has no color.”
If you have trouble constructing a mental picture of a table that has no color — not even black or white — that’s probably because you’re blinded by your ability to see. Sighted people visualize the surrounding world by detecting borders between areas rich in different wavelengths of light, which we see as different colors. Gabias, like many blind people, builds pictures using his sense of touch, and by listening to the echoes of clicks of his tongue and taps of his cane as these sounds bounce off objects in his surroundings, a technique called echolocation.
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Filed under brain vision blindness reality mental representation perception neuroscience psychology science
Artificial cornea gives the gift of vision
Blindness is often caused by corneal diseases. The established treatment is a corneal transplant, but in many cases this is not possible and donor corneas are often hard to come by. In the future, an artificial cornea could make up for this deficiency and save the vision of those affected.
“We are in the process of developing two different types of artificial corneas. One of them can be used as an alternative to a donor cornea in cases where the patient would not tolerate a donor cornea, let alone the issue of donor material shortage,” says IAP project manager Dr. Joachim Storsberg.
The scientist has considerable expertise in developing and testing of next-generation biomaterials. Between 2005 and 2009 he collaborated with interdisciplinary teams and private companies to successfully develop an artificial cornea specifically for patients whose cornea had become clouded – a condition that is extremely difficult to treat. Such patients are unable to accept a donor cornea either due to their illness or because they have already been through several unsuccessful transplantation attempts. Dr. Storsberg was awarded the Josef-von-Fraunhofer Prize 2010 for this achievement. “A great many patients suffering from a range of conditions will be able to benefit from our new implant, which we’ve named ArtCornea®. We have already registered ArtCornea® as a trademark,” reports Storsberg.
Filed under artificial cornea blindness corneal diseases implants neuroscience science technology transplants vision ArtCornea
Surgeons at UC Davis Medical Center have successfully implanted a new telescope implant in the eye of a patient with end-stage age-related macular degeneration (AMD), the most advanced form of the disease and a leading cause of blindness in older Americans.
The device, approved by the Food and Drug Administration in 2010, is the only medical/surgical option available that restores a portion of vision lost to the disease. UC Davis Health System’s Eye Center, in collaboration with the Society for the Blind, is one of the few in California and the nation to offer the innovative procedure.
Filed under brain vision macular degeneration retina vision loss blindness ageing neuroscience science
Duchess the elephant has UK’s first cataract op
Zookeepers are carefully monitoring an elephant who was the first in the UK to undergo an eye operation, to discover how much of her sight has returned.
Duchess was said to be recovering well after yesterday’s operation to remove a cataract from her left eye.
Paignton Zoo’s 42-year-old African elephant had her right eye removed in 2011 because of glaucoma, and has lately become practically blind.
Neil Bemment, curator of mammals and director of operations at the zoo, said staff had high hopes for the operation’s success. “It couldn’t have gone better,” he said. “She went down very smoothly under the anaesthetic and the operation went as well as we could hope.”
Mr Bemment said Duchess was still “disorientated” from the procedure and was being kept out of view with plenty of reassurance from staff.
"Her sight had deteriorated to the point where she could only tell the difference between light and shade," Mr Bemment said. "We’re hoping that his will restore her sight for most distances. She won’t be able to read about herself in the newspaper, but we’re hopeful that she will be more familiar in her surroundings."
(Source: thisisdevon.co.uk)
Filed under animals mammals vision cataract blindness neuroscience science
The real culprits of colour blindness are vision cells rather than unusual wiring in the eye and brain, recent research has shown.
The discovery brings scientists a step closer to restoring full colour vision for people who are colour blind – a condition that affects close to two million Australians, says Professor Paul Martin from The Vision Centre and The University of Sydney.
It may also help pave the way for an answer to one of the most common causes of blindness – age-related macular degeneration (AMD), which accounts for half of the legal blindness cases in Australia.
“There are millions of cones in our eyes – vision cells that pick up bright light and allow us to see colour,” Prof. Martin says. “They are nicknamed red, green and blue cones because they are sensitive to different wavelengths of light.
“We now know that in the macular region of the eye, each cone has its own ’private line’ into the optic nerve and the brain. Just as a painter can mix from three tubes of paint to produce a wide and vivid palette, our brain uses the ‘private lines’ from the three cone types to create thousands of colour sensations.
Scientists previously thought that full colour vision depends on specialised nerve wiring in the eye and brain, but animal studies show that the wiring is identical for monkeys whether they have normal or abnormal colour vision, Prof. Martin says.
“This tells us that there’s nothing wrong in the brain – it’s only working with the signals that it receives on the ‘private lines’,” he says. “So the only difference in normal and abnormal colour vision is caused by the first stage of sight, which points to faulty cones. Either they have failed to develop, or else they are picking up abnormal wavelengths.
“Now that we know faulty wiring isn’t the cause, we can concentrate on fixing the cones, which are controlled by genes – and thus prone to mutation or mistakes during cell replication. There are already promising results from gene therapy as a way to restore full colour vision in colour blind monkeys.”
“While we have still have some way to go, the benefits of this gene therapy – if successful – can potentially extend beyond providing complete colour vision,” he says.
“If we can get these genes to work in human eyes, it means that the same approach might be possible for other visual problems – including blinding diseases such as macular degeneration.”
"In macular degeneration, energy supplies to the macula can’t keep up with demand. So the ‘private line’ system must be very energy-intensive. Gene therapy could be used to turn down the cones’ energy demand, or to increase energy supply from supporting cells to cone cells,” Prof. Martin says.
“Together with clinical researchers at the Save Sight Institute, we are now working hard to find out exactly how many ‘private lines’ there are in humans. That can point us to where energy demand is highest and we can target gene therapy to the right place.
"So animal research on ‘private lines’ for colour vision has given new clues for understanding one of the most important visual diseases – macular degeneration – in humans."
(Source: scinews.com.au)
Filed under blindness brain color blindness color vision macular degeneration neuroscience vision science
Teaching the Blind to Find Their Way by Playing Video Games
Computer based video games are receiving great interest as a means to learn and acquire new skills. As a novel approach to teaching navigation skills in the blind, we have developed Audio-based Environment Simulator (AbES); a virtual reality environment set within the context of a video game metaphor. Despite the fact that participants were naïve to the overall purpose of the software, we found that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building using audio based cues alone. This was confirmed by a series of behavioral performance tests designed to assess the transfer of acquired spatial information to a large-scale, real-world indoor navigation task. Furthermore, learning the spatial layout through a goal directed gaming strategy allowed for the mental manipulation of spatial information as evidenced by enhanced navigation performance when compared to an explicit route learning strategy. We conclude that the immersive and highly interactive nature of the software greatly engages the blind user to actively explore the virtual environment. This in turn generates an accurate sense of a large-scale three-dimensional space and facilitates the learning and transfer of navigation skills to the physical world.
Filed under brain vision game play visual impairment blindness mental spatial representations AbES neuroscience science
