Chapter 10. Vision: From Eye to Brain

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By NEIL GENZLINGER Anne M. Treisman, whose insights into how we perceive the world around us provided some of the core theories for the field of cognitive psychology, died on Friday at her home in Manhattan. She was 82. Her daughter Deborah Treisman said the cause was a stroke after a long illness. Dr. Treisman considered a fundamental question: How does the brain make sense of the bombardment of input it is receiving and focus attention on a particular object or activity? What she came up with is called the feature integration theory of attention, detailed in a much-cited 1980 article written with Garry Gelade in the journal Cognitive Psychology, then refined and elaborated on in later work. “Perhaps Anne’s central insight in the field of visual attention was that she realized that you could see basic features like color, orientation and shape everywhere in the visual field, but that there was a problem in knowing how those colors, orientations, shapes, etc., were ‘bound’ together into objects,” Jeremy M. Wolfe, director of the Visual Attention Lab of Harvard Medical School and Brigham and Women’s Hospital, explained in an email. “Her seminal feature integration theory,” he continued, “proposed that selective attention to an object or location enabled the binding of those features and, thus, enabled object recognition. Much argument has followed, but her formulation of the problem has shaped the field for almost four decades.” Dr. Treisman did not merely theorize about how perception works; she tested her ideas with countless experiments in which subjects were asked, for instance, to pick a particular letter out of a visual field, or to identify black digits and colored letters flashing by. The work showed not only how we perceive, but also how we can sometimes misperceive. © 2018 The New York Times Company

Keyword: Attention; Vision
Link ID: 24657 - Posted: 02.14.2018

By Susana Martinez-Conde The latest illusion to go viral in social media depicts two side-by-side stretches of a narrow road, receding in the distance. Both images depict the retreating road at an oblique angle, but the right road’s slant is a lot more pronounced than the slant on the left road. These are two identical photos of a road in Mexico. Credit: Daniel Picon Or is it? In fact, both pictures are identical. As user djeclipz put it, upon sharing the soon-to-become global sensation on Reddit: “This is the same photo, side by side. They are not taken at different angles. Both sides are the same, pixel for pixel.” Advertisement So why do they look so different? The illusion, created in 2010 by the French artist Daniel Picon and entitled “Roads in Mexico,” is a powerful variant of an earlier perceptual phenomenon discovered in 2007 by vision scientists Frederick Kingdom, Ali Yoonessi, and Elena Gheorghiu (all of them then at McGill University). Kingdom and his colleagues dubbed the effect the “Leaning Tower Illusion,” because they first noticed it in a pair of identical photos of the Leaning Tower of Pisa. But, as Kingdom, Yoonesi, and Gheorghiu noted in an excellent Scholarpedia article about their discovery, “the illusion works with any image of a receding object,” including tram lines, train tracks and roads in Mexico. The Leaning Tower Illusion won First Prize in the 2007 Best Illusion of the Year Contest, and is featured prominently in our recent book about the annual competition, Champions of Illusion. An excerpt of Champions of Illusion follows, concerning the bases of this effect: © 2018 Scientific American,

Keyword: Vision
Link ID: 24646 - Posted: 02.12.2018

by Ben Guarino Praying mantises do not perceive the world as you and I do. For starters, they're not very brainy — they're insects. A human brain has 85 billion neurons; insects such as mantises have fewer than a million. But mantises, despite their neuronal drought, have devised a way to see in three dimensions. They have a unique sort of vision unlike the 3-D sight used by primates or any other known creature, scientists at the University of Newcastle in Britain discovered recently. The scientists say they hope to apply this visionary technique to robots, allowing relatively unintelligent machines to see in 3-D. “Praying mantises are really specialized visual predators,” said Vivek Nityananda, an animal behavior expert at the university's Institute of Neuroscience. They are ambush hunters, waiting in stillness to strike at movement. Yet unlike other insects, they have two large, forward-facing eyes — the very feature that enables vertebrates to sense depth. Previous research had suggested that praying mantises use 3-D vision, also called stereopsis. Stereo vision, Nityananda said, is “basically comparing the slightly different views of each eye to be able to work out how far things are from you.” Uncovering the particulars of mantis stereo vision required a lot of patience and a little beeswax. Luckily, Nityananda and his teammates had both. Using the beeswax like glue — in a way that did not harm the insects — they affixed lenses to their faces. The lenses, similar to old-fashioned 3-D movie glasses, had one blue filter paired with one green filter. The mantises then were placed in front of a screen — an insect cinema, the researchers called it. © 1996-2018 The Washington Post

Keyword: Vision
Link ID: 24636 - Posted: 02.09.2018

Research into curious bright spots in the eyes on stroke patients’ brain images could one day alter the way these individuals are assessed and treated. A team of scientists at the National Institutes of Health found that a chemical routinely given to stroke patients undergoing brain scans can leak into their eyes, highlighting those areas and potentially providing insight into their strokes. The study was published in Neurology. “We were kind of astounded by this – it’s a very unrecognized phenomenon,” said Richard Leigh, M.D., an assistant clinical investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the paper’s senior author. “It raises the question of whether there is something we can observe in the eye that would help clinicians evaluate the severity of a stroke and guide us on how best to help patients.” The eyes glowed so brightly on those images due to gadolinium, a harmless, transparent chemical often given to patients during magnetic resonance imaging (MRI) scans to highlight abnormalities in the brain. In healthy individuals, gadolinium remains in the blood stream and is filtered out by the kidneys. However, when someone has experienced damage to the blood-brain barrier, which controls whether substances in the blood can enter the brain, gadolinium leaks into the brain, creating bright spots that mark the location of brain damage. Previous research had shown that certain eye diseases could cause a similar disruption to the blood-ocular barrier, which does for the eye what the blood-brain barrier does for the brain. Dr. Leigh’s team discovered that a stroke can also compromise the blood-ocular barrier and that the gadolinium that leaked into a patient’s eyes could provide information about his or her stroke.

Keyword: Stroke; Vision
Link ID: 24631 - Posted: 02.08.2018

By Carly Ledbetter Two years after “the dress” divided people over its color, the internet is back with another puzzling wardrobe question. What color are these shoes? Some people think these Vans sneakers look gray and mint (or teal), while others see pink and white. For some, the color changes the more they stare at the shoes: While others are dead-set on the color they see: Twitter user @dolansmalik explained one theory about why the shoes look like different colors to some people: “THE REAL SHOE IS PINK & WHITE OKAY?!” she wrote on Twitter. “The second pic was with flash & darkened, so it looks teal & gray. (depends on what lighting ur in).” Bevil Conway is an investigator with the National Eye Institute who helped contribute to a study on the differences in color perception for the famous “dress” controversy two years ago. He told HuffPost how and why our eyes play tricks on us, in situations like “the dress” and the shoes above. “This is related to the famous dress insofar as both are related to issues of color constancy,” he explained. “Basically your visual system is constantly trying to color correct the images projected on the retina, to remove the color contamination introduced by the spectral bias in the light source.” Conway explained just how and why some people see turquoise in the shoes, while others see pink. “In that manipulated photograph there is a lot of the turquoise cast over the whole image. When you first look at it, after having looked at the pink version, your visual system is still adapted to the lighting conditions of the pink version and so you see the turquoise in the other version, and you attribute this to the shoe itself,” he said. “But after a while, your visual system adapts to the turquoise across the whole of that image and interprets it as part of the light source, eventually discounting it and restoring the shoe to the original pink version (or at least pinker).” ©2018 Oath Inc.

Keyword: Vision
Link ID: 24575 - Posted: 01.26.2018

By Matthew Hutson Imagine searching through your digital photos by mentally picturing the person or image you want. Or sketching a new kitchen design without lifting a pen. Or texting a loved one a sunset photo that was never captured on camera. A computer that can read your mind would find many uses in daily life, not to mention for those paralyzed and with no other way to communicate. Now, scientists have created the first algorithm of its kind to interpret—and accurately reproduce—images seen or imagined by another person. It might be decades before the technology is ready for practical use, but researchers are one step closer to building systems that could help us project our inner mind’s eye outward. “I was impressed that it works so well,” says Zhongming Liu, a computer scientist at Purdue University in West Lafayette, Indiana, who helped develop an algorithm that can somewhat reproduce what moviegoers see when they’re watching a film. “This is really cool.” Using algorithms to decode mental images isn’t new. Since 2011, researchers have recreated movie clips, photos, and even dream imagery by matching brain activity to activity recorded earlier when viewing images. But these methods all have their limits: Some deal only with narrow domains like face shape, and others can’t build an image from scratch—instead, they must select from preprogrammed images or categories like “person” or “bird.” This new work can generate recognizable images on the fly and even reproduce shapes that are not seen, but imagined. © 2018 American Association for the Advancement of Science.

Keyword: Vision; Brain imaging
Link ID: 24518 - Posted: 01.11.2018

Phil Plait I can't think of a better way to start off a new year than scrambling your brains. Just a little bit! But still: enough to make you scratch your head and wonder just what is wrong with that sack of wrinkly pink goo in your skull. One of my favorite optical illusionists is Akiyoshi Kitaoki. He has created hundreds, maybe thousands, of guaranteed brain-melting illusions that will make you swear that what you're seeing is real when it really, really isn't. He has ones that appear to move, that warp your sense of shape and size, destroy your notion of color, and will make you seriously question whether your eyes and brain are talking to each other in any sort of coherent way. He just posted a new one to Twitter, and I love it for its simplicity and efficiency: It creates two illusions at once. Are you ready? Here it is: I don't know about you, but when I look at this I see alternating squarish shapes (Kitaoka called them turtles, so I'll go with that) arranged like a chessboard, with half darked and half lighter. What's disturbing immediately though is that they don't appear to be separated along straight lines. The vertical border of the turtles on the left appear to curve to the right a bit, and the ones on the right curve left. It makes it look like there's a mound or bulge in the middle of the image.

Keyword: Vision
Link ID: 24484 - Posted: 01.04.2018

By Katherine Sellgren BBC News Kids seem to spend endless hours on smartphones, games consoles, computers and tablets these days. Playing on electronic devices certainly doesn't help their waistlines, but do you ever wonder what regular device use is doing to their eyesight? While there isn't much research out there yet about the impact of screens on eyesight - after all the iPhone was first unveiled by Apple in only 2007 - experts are concerned about growing levels of short-sightedness in children. And they suggest the best thing parents can do to prevent it is to encourage youngsters to spend more time outdoors in the sunlight. How short-sightedness is on the rise There has been a massive rise around the globe in short-sightedness - or myopia as it's officially known - over recent decades. "We know that myopia or short-sightedness is becoming more common," says Chris Hammond, professor of ophthalmology at King's College London and consultant ophthalmic surgeon at St Thomas' Hospital. "It has reached epidemic levels in East Asia, Singapore, Taiwan, South Korea, where approaching 90% of 18-year-olds are now short-sighted. "In Europe, it's potentially getting up to 40% to 50% of young adults in their mid-20s who are short-sighted now in Western Europe. It's been gradually rising over the decades of the 20th Century from around 20-30%." Why has it become so much more common? Annegret Dahlmann-Noor, consultant ophthalmologist at Moorfields Eye Hospital in London says lack of natural light seems to be the key issue. "The main factor seems to be a lack of exposure to direct sunlight, because children who study a lot and who use computers or smartphones or tablet computers a lot have less opportunity to run around outside and are less exposed to sunshine and because of that seem to be at more risk of developing short-sightedness." Prof Hammond says: "It may be that there's no coincidence that in East Asian countries, the most myopic ones all correlate with the maths league tables. "These kids are being pushed with very intensive education from a very young age and spend a lot of time indoors studying everything close up and very little time outdoors. © 2017 BBC.

Keyword: Vision
Link ID: 24460 - Posted: 12.28.2017

By Rebecca Keogh Imagine you are at Ikea to pick up a sofa for your new flat. You see one you like, a wine-coloured two-seater with big soft cushions. You imagine what it would look like with your current furniture, and decide that’s the sofa you want. As you continue meandering through the store you find a nice industrial-style lamp and coffee table, so you try to imagine what they might look like with the sofa. But imagining all three items together is more difficult than just imagining the sofa alone. How many pieces of furniture do you think you could rearrange in your mind? Is there a limit to how much we can imagine at once, or is our imagination truly unlimited? viewpoints Limitations to our imagery can constrain what we are able to achieve, both in daily life and in therapeutic interventions. This is the question that my supervisor and I tried to answer in our lab at the University of New South Wales recently. Instead of furniture, we used simple shapes known as Gabor patches, which are essentially circles with lines through them. We also used a visual illusion known as binocular rivalry. Binocular rivalry occurs when two different images are shown, one to each eye, and instead of seeing a mix of the two images you see only one of them, either the image that was presented to the left eye or the image presented to the right eye. Previous work by Joel Pearson (my supervisor) has shown that simply imagining a Gabor patch, or seeing a very weak Gabor patch, will make you more likely to see that image in a subsequent binocular rivalry display. Copyright 2017 Undark

Keyword: Vision; Attention
Link ID: 24452 - Posted: 12.22.2017

By NICHOLAS BAKALAR A new study suggests that vigorous physical activity may increase the risk for vision loss, a finding that has surprised and puzzled researchers. Using questionnaires, Korean researchers evaluated physical activity among 211,960 men and women ages 45 to 79 in 2002 and 2003. Then they tracked diagnoses of age-related macular degeneration, from 2009 to 2013. Macular degeneration, the progressive deterioration of the central area of the retina, is the leading cause of vision loss in the elderly. They found that exercising vigorously five or more days a week was associated with a 54 percent increased risk of macular degeneration in men. They did not find the association in women. The study, in JAMA Ophthalmology, controlled for more than 40 variables, including age, medical history, body mass index, prescription drug use and others. The authors write that excessive exercise might affect the eye’s choroid, a sensitive vascular membrane that surrounds the retina, but “epidemiologic studies cannot provide any evidence for the mechanism or pathology.” The authors acknowledge that the study depends partly on self-reports, which are not always reliable, and that it is an observational study that does not prove cause and effect. © 2017 The New York Times Company

Keyword: Vision
Link ID: 24425 - Posted: 12.15.2017

Nell Greenfieldboyce At least one young woman suffered eye damage as a result of unsafe viewing of the recent total solar eclipse, according to a report published Thursday, but it doesn't appear that many such injuries occurred. Doctors in New York say a woman in her 20s came in three days after looking at the Aug. 21 eclipse without protective glasses. She had peeked several times, for about six seconds, when the sun was only partially covered by the moon. The area between the yellow brackets in the top photo shows the damage to the center part of the retina. The middle image is a type of visual field test and the bottom image uses optical coherence tomography. Courtesy of New York Eye and Ear Infirmary of Mount Sinai Four hours later, she started experiencing blurred and distorted vision and saw a central black spot in her left eye. The doctors studied her eyes with several different imaging technologies, described in the journal JAMA Ophthalmology, and were able to observe the damage at the cellular level. "We were very surprised at how precisely concordant the imaged damage was with the crescent shape of the eclipse itself," noted Dr. Avnish Deobhakta, a retina surgeon at New York Eye and Ear Infirmary of Mount Sinai in New York, in an email to NPR. © 2017 npr

Keyword: Vision
Link ID: 24404 - Posted: 12.08.2017

By JANE E. BRODY After 72 very nearsighted years, 55 of them spent wearing Coke-bottle glasses, Jane Quinn of Brooklyn, N.Y., is thrilled with how well she can see since having her cataracts removed last year. “It’s very liberating to be able to see without glasses,” Ms. Quinn told me. “My vision is terrific. I can even drive at night. I can’t wait to go snorkeling.” And I was thrilled to be able to tell her that the surgery very likely did more than improve her poor vision. According to the results of a huge new study, it may also prolong her life. The 20-year study, conducted among 74,044 women aged 65 and older, all of whom had cataracts, found a 60 percent lower risk of death among the 41,735 women who had their cataracts removed. The findings were published online in JAMA Ophthalmology in October by Dr. Anne L. Coleman and colleagues at the Stein Eye Institute of the David Geffen School of Medicine at the University of California, Los Angeles, with Dr. Victoria L. Tseng as lead author. A cataract is a clouding and discoloration of the lens of the eye. This normally clear structure behind the iris and pupil changes shape, enabling incoming visual images to focus clearly on the retina at the back of the eye. When cataracts form, images get increasingly fuzzy, the eyes become more sensitive to glare, night vision is impaired, and color contrasts are often lost. One friend at 74 realized she needed cataract surgery when she failed to see the yellow highlighted lines in a manuscript she was reading; for her husband, then 75, it was his ophthalmologist who said “it’s time.” Cataracts typically form gradually with age, and anyone who lives long enough is likely to develop them. They are the most frequent cause of vision loss in people over 40. Common risk factors include exposure to ultraviolet radiation (i.e., sunlight), smoking, obesity, high blood pressure, diabetes, prolonged use of corticosteroids, extreme nearsightedness and family history. © 2017 The New York Times Company

Keyword: Vision; Alzheimers
Link ID: 24390 - Posted: 12.05.2017

By Shawna Williams Neurodegenerative diseases are tough nuts to crack, not just because of the inherent difficulties of sorting through what has gone awry, and why, but also due to a dearth of biomarkers that could help spot the diseases and track their progression. This inability to easily diagnose many forms of neurodegeneration means that the diseases can’t be treated early in their progression. The lack of biomarkers also hinders the certainty with which researchers running clinical trials can assess whether and how well experimental treatments of the diseases are working. A simple, noninvasive eye scan now being developed for Alzheimer’s disease (AD), however, may help address both shortcomings. AD researchers already utilize amyloid positron emission tomography (PET), in which tracers are injected into patients’ brains to make the disease’s characteristic amyloid plaques detectable by PET imaging. But the scans are very expensive, spurring the continuing hunt for biomarkers. “What we now know is that the disease essentially occurs about 20 years before a patient becomes symptomatic,” says Cedars-Sinai Medical Center neuroscientist and neurosurgeon Keith Black. “And by the time one is symptomatic, they’ve already lost a lot of their brain weight; they’ve already lost a significant number of brain cells; they’ve already lost a significant amount of connectivity.” What’s needed, he says, is a way to detect the disease early so it can be treated—with drugs, lifestyle interventions, or both—before it’s too late. © 1986-2017 The Scientist

Keyword: Alzheimers; Vision
Link ID: 24376 - Posted: 11.29.2017

The ready availability of technology may make the children of today faster at configuring a new smartphone, but does all of that screen time affect the development of their eyes? While conventional wisdom dictates that children should do less up-close viewing, sit farther from the television and perhaps even wear their eyeglasses less, we have found in recent studies that another factor may be at play: Kids need to go outside and, if not play, at least get some general exposure to outdoor light. To our surprise, more time outdoors had a protective effect and reduced the chances that a child would go on to need myopic refractive correction. The size of the effect was impressive. What causes nearsightedness? Myopia, or nearsightedness, is a condition in which you can’t see far away but can see up close without glasses or contact lenses. It typically starts during the early elementary-school years. Because kids don’t know how other kids see, they often think their blurry vision is normal, so regular eye examinations are important. With myopia, the eye is growing, but growing too long for distant rays of light to focus accurately on the back of the eye. A blurry image results. For children, eyeglasses or contact lenses move the focus back to the retina, and a clear image is formed. The too-long eye cannot be shrunk, so refractive correction is then a lifelong necessity. In adulthood, surgery is an option. © 1996-2017 The Washington Post

Keyword: Vision; Development of the Brain
Link ID: 24320 - Posted: 11.13.2017

Laurel Hamers Light-sensitive cells in the eyes of some fish do double-duty. In pearlsides, cells that look like rods — the stars of low-light vision — actually act more like cones, which only respond to brighter light, researchers report November 8 in Science Advances. It’s probably an adaptation to give the deep-sea fish acute vision at dawn and dusk, when they come to the surface of the water to feed. Rods and cones studding the retina can work in tandem to give an animal good vision in a wide variety of light conditions. Some species that live in dark environments, like many deep-sea fish, have dropped cones entirely. But pearlside eyes have confused scientists: The shimmery fish snack at the water’s surface at dusk and dawn, catching more sun than fish that feed at night. Most animals active at these times of day use a mixture of rods and cones to see, but pearlside eyes appear to contain only rods. “That’s actually not the case when you look at it in more detail,” says study coauthor Fanny de Busserolles, a sensory biologist at the University of Queensland in Australia. She and her colleagues investigated which light-responsive genes those rod-shaped cells were turning on. The cells were making light-sensitive proteins usually found in cones, the researchers found, rather than the rod-specific versions of those proteins. |© Society for Science & the Public 2000 - 2017.

Keyword: Vision; Evolution
Link ID: 24312 - Posted: 11.10.2017

By Matthew Hutson Artificial intelligence has taken us one baby step closer to the mind-reading machines of science fiction. Researchers have developed “deep learning” algorithms—roughly modeled on the human brain—to decipher, you guessed it, the human brain. First, they built a model of how the brain encodes information. As three women spent hours viewing hundreds of short videos, a functional MRI machine measured signals of activity in the visual cortex and elsewhere. A popular type of artificial neural network used for image processing learned to associate video images with brain activity. As the women watched additional clips, the algorithm’s predicted activity correlated with actual activity in a dozen brain regions. It also helped the scientists visualize which features each area of the cortex was processing. Another network decoded neural signals: Based on a participant’s brain activity, it could predict with about 50% accuracy what she was watching (by selecting one of 15 categories including bird, airplane, and exercise). If the network had trained on data from a different woman’s brain, it could still categorize the image with about 25% accuracy, the researchers report this month in Cerebral Cortex. The network could also partially reconstruct what a participant saw, turning brain activity into pixels, but the resulting images were little more than white blobs. The researchers hope their work will lead to the reconstruction of mental imagery, which uses some of the same brain circuits as visual processing. Translating from the mind’s eye into bits could allow people to express vivid thoughts or dreams to computers or to other people without words or mouse clicks, and could help those with strokes who have no other way to communicate. © 2017 American Association for the Advancement of Science

Keyword: Vision; Brain imaging
Link ID: 24252 - Posted: 10.28.2017

By Virginia Morell Many wild bees prefer flowers in the violet-blue range—in part because these blossoms tend to produce high volumes of nectar. But it’s not easy for plants to produce blue flowers. Instead, a new study shows that many have evolved “blue halos” to allure bees, nanoscale structures on their petals that produce a blue glow when light hits them. The blue halo is created by tiny, irregular striations—usually lined up in parallel fashion—and is found in all major groups of flowering plants pollinated by insects, the scientists report today in Nature. They made their find by using scanning electron microscopy to examine every type of angiosperm—or flowering plant—including grasses, herbaceous plants, shrubs, and trees. The size and spacing of the nanoscale structures vary greatly, yet they all generate a blue or ultraviolet (UV) scattering effect particularly noticeable to bees, which have enhanced photoreceptor activity in the blue-UV parts of the spectrum. The scientists tested this attraction by exposing bumble bees to artificial flowers with three surfaces: smooth, iridescent, and striated to produce the blue halo. Despite the color of the flower, the bees preferred those with the blue halo. For us humans, the blue halo effect is most visible on flowers with dark pigments (like the South African Ursinia speciosa above), but not on lighter colored blooms. © 2017 American Association for the Advancement of Science

Keyword: Vision
Link ID: 24212 - Posted: 10.19.2017

French scientists claim they may have found a physiological, and seemingly treatable, cause for dyslexia hidden in tiny light-receptor cells in the human eye. In people with the condition, the cells were arranged in matching patterns in both eyes, which may be to blame for confusing the brain by producing “mirror” images, the co-authors wrote in the journal Proceedings of the Royal Society B. In non-dyslexic people, the cells are arranged asymmetrically, allowing signals from the one eye to be overridden by the other to create a single image in the brain. “Our observations lead us to believe that we indeed found a potential cause of dyslexia,” said the study’s co-author, Guy Ropars, of the University of Rennes. It offers a “relatively simple” method of diagnosis, he added, by simply looking into a subject’s eyes. Furthermore, “the discovery of a delay (of about 10 thousandths of a second) between the primary image and the mirror image in the opposing hemispheres of the brain, allowed us to develop a method to erase the mirror image that is so confusing for dyslexic people” – using an LED lamp. Like being left- or right-handed, human beings also have a dominant eye. As most of us have two eyes, which record slightly different versions of the same image, the brain has to select one of the two, creating a “non-symmetry”. Many more people are right-eyed than left, and the dominant eye has more neural connections to the brain than the weaker one. Image signals are captured with rods and cones in the eye – the cones being responsible for colour. © 2017 Guardian News and Media Limited

Keyword: Dyslexia; Vision
Link ID: 24208 - Posted: 10.18.2017

By Elizabeth Pennisi One man’s trash is another man’s treasure, even at the level of the cell. That’s where—according to new research—a waste product of the retina fuels part of the eye that powers the rods and cones that help us sense light. Without this waste, that part of the eye “steals” glucose from the retina, leading to the death of retinal cells and likely vision loss. The finding could help explain why eyesight degenerates with age—and in diseases such as macular degeneration and diabetes. “It’s almost a revolutionary concept” that there is such a tight coupling between the two parts of the eye, says Stephen Tsang, a retina specialist at Columbia University who was not involved in the work. Rods and cones are very active, and they need a lot of energy to do their jobs. Exactly how they get this energy has long been a mystery. In previous studies, researchers showed that a layer of cells beneath the retina, the retinal pigment epithelium (RPE), ferries glucose from the blood to the retina. But it was unclear why the RPE didn’t keep the glucose for itself. After a decade of study, biochemist James Hurley at the University of Washington in Seattle and his colleagues have now shown that the retina’s rods and cones burn the glucose, convert leftovers into a fuel called lactate, and then feed that back to the RPE. “There is a growing consensus that no cell exists on its own in complex tissues like the retina,” says Martin Friedlander, an ophthalmologist at The Scripps Research Institute in San Diego, California, who was not involved with the new work. © 2017 American Association for the Advancement of Science.

Keyword: Vision
Link ID: 24194 - Posted: 10.14.2017

Heidi Ledford The US government is considering whether to approve a gene therapy to prevent the degradation of cells in the retina (shown here in an image from a scanning electron microscope). Advisers to the US Food and Drug Administration (FDA) have paved the way for the agency’s first approval of a gene therapy to treat a disease caused by a genetic mutation. On 12 October, a panel of external experts unanimously voted that the benefits of the therapy, which treats a form of hereditary blindness, outweigh its risks. The FDA is not required to follow the guidance of its advisers, but it often does. A final decision on the treatment, called voretigene neparvovec (Luxturna), is expected by 12 January. An approval in the lucrative US drug market would be a validation that gene-therapy researchers have awaited for decades. “It’s the first of its kind,” says geneticist Mark Kay of Stanford University in California, of the treatment. “Things are beginning to look more promising for gene therapy.” Luxturna is made by Spark Therapeutics of Philadelphia, Pennsylvania, and is designed to treat individuals who have two mutated copies of a gene called RPE65. The mutations impair the eye’s ability to respond to light, and ultimately lead to the destruction of photoreceptors in the retina. The treatment consists of a virus loaded with a normal copy of the RPE65 gene. The virus is injected into the eye, where the gene is expressed and supplies a normal copy of the RPE65 protein. © 2017 Macmillan Publishers Limited

Keyword: Vision; Genes & Behavior
Link ID: 24192 - Posted: 10.14.2017