Chapter 7. Vision: From Eye to Brain

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By Phil Plait Thanks to my evil twin Richard Wiseman (a UK psychologist who specializes in studying the ways we perceive things around us, and how easily we can be fooled), I saw this masterful illusion video that will keep you guessing on what’s real and what isn’t. It’s only two minutes long, so give it a gander: Cool, eh? The reason you got fooled, at least twice, is that we get confused when our three-dimensional world is translated into two dimensions. We perceive distance for nearby objects using binocular vision, which depends on the angles between our eyes and the objects. If you create a picture of an object that is carefully distorted to match those changing angles, you can fool the brain into thinking it’s seeing a real object when in fact it’s a flat representation. We’re actually very good at taking subtle cues and turning them into three-dimensional interpretations. However, because of that very sensitivity, it’s easy to throw a monkey in the wrench, messing up our perception. Still don’t believe me? Then watch this, and if it doesn’t melt your brain, I can no longer help you. Our brains are very, very easy to fool. I’ll note that the way we see color is very easy to trick, too. I wrote an article about a fantastic, astonishing color illusion back in 2009, and it spurred a lot of arguments in the comments, even when I showed clearly how it works. Amazing. © 2013 The Slate Group, LLC

Keyword: Vision
Link ID: 18825 - Posted: 10.23.2013

by Susan Milius Your calamari, it turns out, may have come from a temporary transvestite with rainbows in its armpits. Well, not armpits, but spots just below where the fins flare out. “Finpits,” cell biologist Daniel DeMartini nicknamed them. He and his colleagues have documented unusual color-change displays in female California market squid, popular in restaurants. Squids, octopuses and cuttlefishes are nature’s iPads, changing their living pixels at will. DeMartini, of the University of California, Santa Barbara, saw so many sunset shimmers, blink-of-an-eye blackouts and other marvels in California’s Doryteuthis opalescens that it took him a while to notice that only females shimmered the finpit stripe. It shows up now and then during life, and reliably for about 24 hours after decapitation, DeMartini found. The squid are color-blind, and what prompts their display is known only to them. But the researchers have figured out how it works. The squid make rainbows when color-change cells called iridocytes lose water. Other kinds of color-change cells work their magic via pigments, but not iridocytes. “If you take a bunch of iridocyte cells in red, blue, green or yellow and you grind them up, then you wouldn’t see any color,” DeMartini says. Instead, little stacks of protein plates inside the cells turn colorful only when water rushes out of the stack. How closely the plates snug together determines whether the stack looks blue, scarlet or anything in between. © Society for Science & the Public 2000 - 2013

Keyword: Vision; Sexual Behavior
Link ID: 18818 - Posted: 10.22.2013

By Brian Palmer Myopia isn’t an infectious disease, but it has reached nearly epidemic proportions in parts of Asia. In Taiwan, for example, the percentage of 7-year-old children suffering from nearsightedness increased from 5.8 percent in 1983 to 21 percent in 2000. An incredible 81 percent of Taiwanese 15-year-olds are myopic. If you think that the consequences of myopia are limited to a lifetime of wearing spectacles—and, let’s be honest, small children look adorable in eyeglasses—you are mistaken. The prevalence of high myopia, an extreme form of the disorder, in Asia has more than doubled since the 1980s, and children who suffer myopia early in life are more likely to progress to high myopia. High myopia is a risk factor for such serious problems as retinal detachment, glaucoma, early-onset cataracts, and blindness. The explosion of myopia is a serious public health concern, and doctors have struggled to identify the source of the problem. Nearsightedness has a strong element of heritability, but the surge in cases shows that a child’s environment plays a significant role. A variety of risk factors has been linked to the disorder: frequent reading, participation in sports, television watching, protein intake, and depression. When each risk factor was isolated, however, its overall effect on myopia rates seemed to be fairly minimal. Researchers believe they are now closing in on a primary culprit: too much time indoors. In 2008 orthoptics professor Kathryn Rose found that only 3.3 percent of 6- and 7-year-olds of Chinese descent living in Sydney, Australia, suffered myopia, compared with 29.1 percent of those living in Singapore. The usual suspects, reading and time in front of an electronic screen, couldn’t account for the discrepancy. The Australian cohort read a few more books and spent slightly more time in front of the computer, but the Singaporean children watched a little more television. On the whole, the differences were small and probably canceled each other out. The most glaring difference between the groups was that the Australian kids spent 13.75 hours per week outdoors compared with a rather sad 3.05 hours for the children in Singapore. © 2013 The Slate Group, LLC.

Keyword: Vision; Development of the Brain
Link ID: 18809 - Posted: 10.19.2013

Monya Baker When Cris Niell said that he wanted to study how mice see, it did not go over well with more-senior neuroscientists. Mice are nocturnal and navigate largely using their noses and whiskers, so many researchers believed that the nursery rhyme — Three Blind Mice — was true enough to make many vision experiments pointless. The obvious alternative model was monkeys, which have large, forward-looking eyes and keen vision. What's more, scientists could rely on decades of established techniques using primates, and it is relatively straightforward to apply the results to the human visual system. “People were saying, 'studying vision in mice, that's crazy,'” Niell recalls. But he was convinced that the rodents offered unique opportunities. Since the 1960s, researchers have used cats and monkeys to uncover important clues about how the brain turns information from the eyes into images recognized by the mind. But to investigate that process at the cellular level, researchers must be able to manipulate and monitor neurons precisely — difficult in cats and monkeys, much easier in mice. If mice and primates turned out to process visual stimuli similarly, Niell thought, that discovery could unleash a torrent of data about how information is extracted from stimuli — and even, more generally, about how the brain works. He found a rare supporter in Michael Stryker at the University of California, San Francisco, who had already seen his share of crazy experiments in mouse vision. Stryker offered Niell a postdoctoral position in his lab, and the pair began setting up experiments in 2005. Nearly a decade later, the two researchers are in better company. At last year's annual meeting of the Society for Neuroscience, Niell attended packed sessions on mouse vision. © 2013 Nature Publishing Group

Keyword: Vision
Link ID: 18782 - Posted: 10.12.2013

By Tanya Lewis, Look closely at the FedEx logo and you'll notice the space between the "E" and the "x" creates the outline of an arrow. Now, a new study reveals the part of the brain that creates such invisible shapes. The FedEx arrow is just one example of a common optical illusion, whereby the brain "sees" shapes and surfaces within a fragmented background, although they don't exist. Scientists studied the effect in monkeys, finding a group of neurons in part of the visual cortex that fire when the animals viewed an illusion pattern. Besides monkeys, studies have shown that a host of other animals experience shape illusions, including cats, owls, goldfish and honeybees. Scientists think the mental quirk might have evolved to help animals spot predators or prey in the bushes. "Basically, the brain is acting like a detective," study leader Alexander Maier, a psychologist at Vanderbilt University in Nashville, Tenn., said in a statement. "It is responding to cues in the environment and making its best guesses about how they fit together. In the case of these illusions, however, it comes to an incorrect conclusion." The visual cortex, a part of the brain at the back of the head, processes visual information in mammals. Scientists often divide the visual cortex into five regions labeled V1 through V5. Visual signals from the eyes go to the primary visual cortex, V1, which detects their orientation, color and spatial arrangement. The brain splits that information into two streams, known as the dorsal and ventral streams. Both pathways go to V2, which makes some connections to V3.

Keyword: Vision
Link ID: 18723 - Posted: 10.01.2013

By DENISE GELLENE Dr. David Hubel, who was half of an enduring scientific team that won a Nobel Prize for explaining how the brain assembles information from the eye’s retina to produce detailed visual images of the world, died on Sunday in Lincoln, Mass. He was 87. The cause was kidney failure, his son Carl said. Dr. Hubel (pronounced HUGH-bull) and his collaborator, Dr. Torsten Wiesel, shared the 1981 Nobel in Physiology or Medicine with Roger Sperry for discovering ways that the brain processes information. Dr. Hubel and Dr. Wiesel concentrated on visual perception, initially experimenting on cats; Dr. Sperry described the functions of the brain’s left and right hemispheres. Dr. Hubel’s and Dr. Wiesel’s work further showed that sensory deprivation early in life can permanently alter the brain’s ability to process images. Their findings led to a better understanding of how to treat certain visual birth defects. Dr. Hubel and Dr. Wiesel collaborated for more than two decades, becoming, as they made their discoveries, one of the best-known partnerships in science. “Their names became such a brand name that H&W rolled off the tongue as easily in the lab as A&W root beer did at lunch,” Robert H. Wurtz, a neuroscientist, wrote in a review article about their work. Before Dr. Hubel and Dr. Wiesel started their research in the 1950s, scientists had long believed that the brain functioned like a movie screen — projecting images exactly as they were received from the eye. Dr. Hubel and Dr. Wiesel showed that the brain behaves more like a microprocessor, deconstructing and then reassembling details of an image to create a visual scene. © 2013 The New York Times Company

Keyword: Development of the Brain; Vision
Link ID: 18703 - Posted: 09.25.2013

By PETER ANDREY SMITH In a cavernous basement laboratory at the University of Minnesota, Thomas Stoffregen thrusts another unwitting study subject — well, me — into the “moving room.” The chamber has a concrete floor and three walls covered in faux marble. As I stand in the middle, on a pressure sensitive sensor about the size of a bathroom scale, the walls lurch inward by about a foot, a motion so disturbing that I throw up my arms and stumble backward. Indeed, the demonstration usually throws adults completely off balance. I’m getting off lightly. Dr. Stoffregen, a professor of kinesiology, uses the apparatus to study motion sickness, and often subjects must stand and endure subtle computer-driven oscillations in the walls until they are dizzy and swaying. Dr. Stoffregen’s research has also taken him on cruises — cruise ships are to motion sickness what hospitals are to pneumonia. “No one’s ever vomited in our lab,” he said. “But our cruises are a different story.” For decades now, Dr. Stoffregen, 56, director of the university’s Affordance Perception-Action Laboratory, has been amassing evidence in support of a surprising theory about the causes of motion sickness. The problem does not arise in the inner ear, he believes, but rather in a disturbance in the body’s system for maintaining posture. The idea, once largely ignored, is beginning to gain grudging recognition. “Most theories say when you get motion sick, you lose your equilibrium,” said Robert Kennedy, a psychology professor at the University of Central Florida. “Stoffregen says because you lose your equilibrium, you get motion sick.” Motion sickness is probably a problem as old as passive transportation. The word “nausea” derives from the Greek for “boat,” but the well-known symptoms arise from a variety of stimuli: lurching on the back of a camel, say, or riding the Tilt-a-Whirl at a fair. “Pandemonium,” the perpetually seasick Charles Darwin called it. Copyright 2013 The New York Times Company

Keyword: Hearing; Vision
Link ID: 18691 - Posted: 09.24.2013

At Pimlico Race Course in Baltimore every May, the winning horse in the Preakness Stakes is draped with a blanket covered with what appear to be the Maryland state flower, the black-eyed Susan. But the flower doesn't bloom until later in the season. Those crafting the victory blanket must resort to using yellow Viking daisies — and painting the centers black. That might fool race fans, but bees can see through the ruse. With eyes equipped to detect ultraviolet light, a bee can pick out an additional band in the black-eyed Susan's bull's-eye. The insect's livelihood depends on it. At the center of the target is the flower's nutritional payload, nectar and pollen, which also glows in UV light. As with other members of the sunflower family, black-eyed Susan flower heads are composed of two kinds of florets. The dark center is made up of numerous disc florets, each of which contains male and female reproductive components. When a bee or other pollinator fertilizes a disc floret, it develops a single seed that ripens and falls from the flower head in the autumn. Seeds can remain viable for more than 30 years. Circling the disc florets are bright yellow ray florets, which flag down pollinators and act as landing strips. The inner portion of each ray floret contains several compounds that absorb UV rays. The outer portion reflects UV rays, contributing a visually energetic outer ring to the pattern — provided you're a bee. Black-eyed Susan, Rudbeckia hirta. © 1996-2013 The Washington Post

Keyword: Vision; Evolution
Link ID: 18690 - Posted: 09.24.2013

By Philip Yam The harvest moon is almost upon us—specifically, September 19. It’s the full moon closest to the autumnal equinox, and it has deep significance in our cultural histories. Namely, it enabled our ancestral farmers to toil longer in the fields. (Today, electricity enables us to toil longer in the office—thanks, Tom Edison.) One enduring belief is that the harvest moon is bigger and brighter than any other full moon. That myth is probably the result of the well-known illusion in which the moon looks bigger on the horizon than it does overhead. Back when I was taking psych 101, my professor explained that the moon illusion was simply a function of having reference objects on the horizon. But then I saw this TED-Ed video by Andrew Vanden Heuvel. It turns out that the explanation from my college days really isn’t sufficient to explain the illusion. In fact, scientists really aren’t sure, and there is much debate. Check it out and see what you think. © 2013 Scientific American

Keyword: Vision; Attention
Link ID: 18654 - Posted: 09.17.2013

By Melissa Hogenboom Science reporter, BBC News Smaller animals tend to perceive time in slow-motion, a new study has shown. This means that they can observe movement on a finer timescale than bigger creatures, allowing them to escape from larger predators. Insects and small birds, for example, can see more information in one second than a larger animal such as an elephant. The work is published in the journal Animal Behaviour. "The ability to perceive time on very small scales may be the difference between life and death for fast-moving organisms such as predators and their prey," said lead author Kevin Healy, at Trinity College Dublin (TCD), Ireland. The reverse was found in bigger animals which may miss things that smaller creatures can rapidly spot. In humans, too, there is variation among individuals. Athletes, for example, can often process visual information more quickly. An experienced goalkeeper would therefore be quicker than others in observing where a ball comes from. The speed at which humans absorb visual information is also age-related, said Andrew Jackson, a co-author of the work at TCD. "Younger people can react more quickly than older people, and this ability falls off further with increasing age." The team looked at the variation of time perception across a variety of animals. They gathered datasets from other teams who had used a technique called critical flicker fusion frequency, which measures the speed at which the eye can process light. BBC © 2013

Keyword: Attention; Vision
Link ID: 18651 - Posted: 09.16.2013

By Philip Yam If you’re a fan of optical illusions and perceptual tricks, check out this AsapSCIENCE video. As usual, producers Michael Moffitt and Gregory Brown do a great job distilling the essential ideas and presenting them in a fun, entertaining and informative way. Here, they show you how your brain judges brightness and color in context. Visit their YouTube channel to see more (including a frequency test for your ears). You can also check out our compilation of the 169 best illusions (ia sampling of them is on our site) as well as our Illusions Chasers blog, by Susana Martinez-Conde and Steven Macknik, which explore illusions each week. © 2013 Scientific American

Keyword: Vision
Link ID: 18645 - Posted: 09.14.2013

By Sandra G. Boodman, Amy Epstein Gluck remembers how relieved she felt when it seemed that the vision of her youngest child, 9-month-old Sam, might turn out to be normal. Months earlier, doctors had worried that he was blind, possibly as the result of an inherited disorder or a brain tumor. But subsequent tests and consultations with pediatric specialists in Washington and Baltimore instead suggested a temporary developmental delay. Epstein Gluck and her husband, Ira Gluck, were so thrilled with Sam’s progress that they threw a big party to celebrate the end of an arduous year and, they hoped, their son’s frightening problem. But two months later, on Sam’s first birthday in February 2006, the pediatric ophthalmologist who had been treating him delivered news that made it clear a celebration had been premature. “It was such a blow,” Epstein Gluck recalled. On the way to Johns Hopkins, the couple had discussed finding a specialist closer to their Bethesda home, assuming they no longer needed a neuro-ophthalmologist. The ride home was somber: “I was so upset I couldn’t even recount the conversation,” she said. “I had thought we were done.” Instead, they were struggling with the implications of an unexpected finding that, more than a year later, would culminate in a new diagnosis. In March 2005, when Sam was about 5 weeks old, his mother noticed that his eyes would periodically oscillate back and forth. Epstein Gluck, whose other children were then 3 and 5, called her pediatrician. © 1996-2013 The Washington Post

Keyword: Vision; Development of the Brain
Link ID: 18626 - Posted: 09.10.2013

By Neuroskeptic An intriguing new paper in the Journal of Neuroscience introduces a new optical illusion – and, potentially, a new way to see ones own brain activity. The article is called The Flickering Wheel Illusion: When α Rhythms Make a Static Wheel Flicker by Sokoliuk and VanRullen. Here’s the illusion: It’s a simple black and white “wheel” with 32 spokes. To see the illusion, get the wheel in your peripheral vision. Look around the edge of your screen and maybe a bit beyond – you should find a ‘sweet spot’ at which the center of the wheel starts to ‘flicker’ on and off like a strobe light. Remarkably, it even works as an afterimage. Find a ‘sweet spot’, stare at that spot for a minute, then look at a blank white wall. You should briefly see a (color-reversed) image of the wheel and it flickers like the real one (I can confirm it works for me). By itself, this is just a cool illusion. There are lots of those around. What makes it neuroscientifically interesting is that – according to Sokoliuk and VanRullen – that flickering reflects brain alpha waves. First some background. Alpha (α) waves are rhythmical electrical fields generated in the brain. They cycle with a frequency of about 10 Hz (ten times per second) and are strongest when you have your eyes closed, but are still present whenever you’re awake. When Hans Berger invented the electroencephalograph (EEG) and hooked it up to the first subjects in 1924, these waves were the first thing he noticed – hence, “alpha”. They’re noticable because they’re both strong and consistent. They’re buzzing through your brain right now. But this raises a mystery – why don’t we see them? Alpha waves are generated by rhythmical changes in neuronal activity, mainly centered on the occipital cortex. Occipital activity is what makes us see things. So why don’t we see something roughly 10 times every second?

Keyword: Vision
Link ID: 18543 - Posted: 08.22.2013

By Ella Davies Reporter, BBC Nature An unusual caterpillar uses the sun to navigate as it jumps to safety, according to scientists. The larva of Calindoea trifascialis, a species of moth native to Vietnam, wraps itself in a leaf before dropping to the forest floor. It then spends three days searching for a suitable place to pupate, despite not being able to see out of its shelter. Experts found the insect used a piston-like motion to jump away from strong sunlight. "We believe the object of the jumping is to find shade - to avoid overheating and desiccation," explained Mr Kim Humphreys from the Royal Ontario Museum, Canada who conducted the research alongside Dr Christopher Darling. Their findings are published in the Royal Society journal Biology Letters. Although Mr Humphreys described the caterpillar as "non-descript" in appearance, he said its behaviour makes it unique in a number of ways. "Caterpillars or larvae that jump are rare in themselves," he said. "[This] caterpillar is remarkable for its jumping, which no other insect does in this way. It also makes its own vehicle [or] shelter to jump in." "It is also the only one I know of that jumps in an oriented way." BBC © 2013

Keyword: Animal Migration; Vision
Link ID: 18539 - Posted: 08.21.2013

The EnChroma Color Blindness Test measures the type and extent of color vision deficiency. The test takes between 2-5 minutes to complete. Your test results may be anonymously recorded on our server for quality assurance purposes. This test is not a medical diagnosis. Please consult an eye care professional for more information regarding color vision deficiency. Copyright 2013 EnChroma, Inc.

Keyword: Vision
Link ID: 18525 - Posted: 08.19.2013

A few weeks back, I wrote about special lenses that were developed to give doctors “a clearer view of veins and vasculature, bruising, cyanosis, pallor, rashes, erythema, and other variations in blood O2 level, and concentration,” especially in bright light. But these lenses turned out to have an unintended side effect: they “may cure red-green colorblindness.” I’m severely red-green colorblind, so I was eager to try these $300 lenses. Turns out they didn’t help me; the company said that my colorblindness is too severe. They have helped many others, though (their Amazon reviews makes that clear). After my column appeared, I heard from another company that makes color-enhancing glasses — this time, specifically for red-green colorblind folks. The company’s called EnChroma, and the EnChroma Cx sunglasses are a heartbeat-skipping $600 a pair. “Our lenses are specifically designed to address color blindness,” the company wrote to me, “and utilize a 100+ layer dielectric coating we engineered for this precise purpose by keeping the physiology of the eyes of colorblind people in mind.” I asked to try out a pair. (You can, too: there’s a 30-day money-back guarantee.) To begin, you figure out which kind of colorblindness you have — Protan or Deutan — by taking the test at Turns out I have something called Strong Protan. (“Protanomaly is a type of red-green color vision deficiency related to a genetic anomaly of the L-cone (i.e. the red cone).”) I’d never heard of it, but whatever. © 2013 The New York Times Company

Keyword: Vision
Link ID: 18524 - Posted: 08.19.2013

By Melinda Wenner Moyer Our world is determined by the limits of our five senses. We can't hear pitches that are too high or low, nor can we see ultraviolet or infrared light—even though these phenomena are not fundamentally different from the sounds and sights that our ears and eyes can detect. But what if it were possible to widen our sensory boundaries beyond the physical limitations of our anatomy? In a study published recently in Nature Communications, scientists used brain implants to teach rats to “see” infrared light, which they usually find invisible. The implications are tremendous: if the brain is so flexible it can learn to process novel sensory signals, people could one day feel touch through prosthetic limbs, see heat via infrared light or even develop a sixth sense for magnetic north. Miguel Nicolelis, a neurobiologist at Duke University, and his colleagues trained six rats to poke their nose inside a port when the LED light above it lit up. Then the researchers surgically attached infrared cameras to the rats' head and wired the cameras to electrodes they implanted into the rats' primary somatosensory cortex, a brain region responsible for sensory processing. When the camera detected infrared light, it stimulated the animals' whisker neurons. The stimulation became stronger the closer the rats got to the infrared light or the more they turned their head toward it, just as brain activation responds to light seen by the eyes. Then the scientists let the animals loose in their chambers, this time using infrared light instead of LEDs to signal the ports the rats should visit. At first, none of the rats used the infrared signals. But after about 26 days of practice, all six had learned how to use the once invisible light to find the right ports. © 2013 Scientific American

Keyword: Vision; Robotics
Link ID: 18494 - Posted: 08.13.2013

Here's what the Swedish artist Oscar Reutersvard did. In 1934, he got himself a pen and paper and drew cubes, like this. He called this final version "Impossible Triangle of Opus 1 No. 293aa." I don't know what the "293aa" is about, but he was right about "impossible." An arrangement like this cannot take place in the physical universe as we know it. You follow the bottom row along with your eyes, then add another row, but when the third row pops in, where are you? Nowhere you have ever been before. At some step in the process you've been tricked, but it's very, very hard to say where the trick is, because what's happening is your brain wants to see all these boxes as units of a single triangle and while the parts simply won't gel, your brain insists on seeing them as a whole. It's YOU who's playing the trick, and you can't un-be you. So you are your own prisoner. At first, this feels like a neurological trap, like a lie you can't not believe. But when you think about for a bit, it's the opposite, it's a release. Twenty years later, the mathematician/physicist Roger Penrose (and his dad, psychologist Lionel Penrose) did it again. They hadn't seen Reutersvard's triangle. Theirs was drawn in perspective, which makes it even more challenging. Here's my version of their Penrose Triangle. What's cool about this? I'm going to paraphrase science writer John D. Barrow, in several places: We know that these drawings can't exist in the physical world. Even as we look at them, particularly when we look at them, we know they are impossible. And yet, we can imagine them anyway. Our brains, it turns out, are not prisoners of the world we live in; we can fly free! We can, any time we like, create the impossible. ©2013 NPR

Keyword: Vision; Attention
Link ID: 18484 - Posted: 08.10.2013

Richard Johnston Scientists have mapped the dense interconnections and neuronal activity of mouse and fruitfly visual networks. The research teams, whose work is published in three separate studies today in Nature1–3, also created three-dimensional (3D) reconstructions, shown in the video above. All three studies interrogate parts of the central nervous system located in the eyes. In one, Moritz Helmstaedter, a neurobiologist at the Max Planck Institute of Neurobiology in Martinsried, Germany, and his collaborators created a complete 3D map of a 950-cell section of a mouse retina, including the interconnections among those neuronal cells. To do so, the team tapped into the help of more than 200 students, who collectively spent more than 20,000 hours processing the images1. The two other studies investigated how the retinas of the fruitfly (Drosophila melanogaster) detect motion. Shin-ya Takemura, a neuroscientist at the Howard Hughes Medical Institute in Ashburn, Virginia, and his collaborators mapped four neuronal circuits associated with motion perception and found that each is wired for detecting motion in a particular direction — up, down, left or right2. In the third study, Matthew Maisak, a computational biologist at the Max Planck Institute of Neurobiology, and his colleagues mapped the same four cellular networks and tagged the cells of each with protein markers that fluoresce in red, green, blue or yellow in response to stimulation with light3. © 2013 Nature Publishing Group,

Keyword: Vision
Link ID: 18479 - Posted: 08.08.2013

Researchers have achieved dynamic, atomic-scale views of a protein needed to maintain the transparency of the lens in the human eye. The work, funded in part by the National Institutes of Health, could lead to new insights and drugs for treating cataract and a variety of other health conditions. Aquaporin proteins form water channels between cells and are found in many tissues, but aquaporin zero (AQP0) is found only in the mammalian lens, which focuses light onto the retina, at the back of the eye. The lens is primarily made up of unique cells called lens fibers that contain little else besides water and proteins called crystallins. Tight packing of these fibers and of the crystallin proteins within them helps create a uniform medium that allows light to pass through the lens, almost as if it were glass. Abnormal development or age-related changes in the lens can lead to cataract — a clouding of the lens that causes vision loss. Besides age, other risk factors for cataract include smoking, diabetes, and genetic factors. Mutations in the AQP0 gene can cause congenital cataract and may increase the risk of age-related cataract. “The AQP0 channel is believed to play a vital role in maintaining the transparency of the lens and in regulating water volume in the lens fibers, so understanding the molecular details of how water flows through the channel could lead to a better understanding of cataract,” said Dr. Houmam Araj, who oversees programs on lens, cataract and oculomotor systems at NIH’s National Eye Institute (NEI), which helped fund the research.

Keyword: Vision
Link ID: 18465 - Posted: 08.06.2013