Canadian researchers have found out how to restore normal vision to kittens with a lazy eye without using an eye patch. The cure was relatively simple — putting the kittens in complete darkness for 10 days. Once the kittens were returned to daylight, they regained normal vision in the lazy eye within a week, reported researchers at Dalhousie University in Halifax in the journal Current Biology this month. Lazy eye is a condition where the brain effectively turns off one eye. It affects about four per cent of the population in humans, and the most common treatment is fix the vision problem (for example, by using glasses) and then patch the good eye, forcing the person to use their bad eye. Kevin Duffy, a neuroscientist who co-authored the new study, told CBC's Quirks & Quarks that the condition is typically the result of a vision problem such as a cataract, a misalignment of the eyes, or poor focus in one eye, which then causes the brain to develop abnormally. "If the eye is providing abnormal vision, then the circuits that connect to that eye are going to develop abnormally," he said. The brain "becomes effectively disconnected." © CBC 2013

Keyword: Vision; Aggression
Link ID: 17833 - Posted: 02.23.2013

By Susan Milius Slight electric fields that form around flowers may lure pollinators much as floral colors and fragrances do. In lab setups, bumblebees learned to distinguish fake flowers by their electrical fields, says sensory biologist Daniel Robert at the University of Bristol in England. Combining an electrical charge with a color helped the bees learn faster, Robert and his colleagues report online February 21 in Science. Plants, a bit like lightning rods, tend to conduct electrical charges to the ground, Robert says. And bees pick up a positive charge from the atmosphere’s invisible rain of charged particles. “Anything flying through the air, whether it’s a baseball, 767 jumbo jet, or a bee, acquires a strong positive electrostatic charge due to interaction with air molecules,” says Stephen Buchmann of the University of Arizona in Tucson. Robert and his colleagues checked whether bees could choose flowers based solely on the electric fields the plants produce. Purple metal disks (encased in plastic so as not to shock bees) stood in for flowers. Half of them, wired for 30 volts, held sips of sugar water. The unwired ones offered a bitter quinine solution that bees don’t like. Bombus terrestris bumblebees learned to choose sweet, wired disks more than 80 percent of the time. When researchers unplugged the wired disks, the bees bumbled, scoring sugar only by chance. © Society for Science & the Public 2000 - 2013

Keyword: Vision
Link ID: 17832 - Posted: 02.23.2013

by Gisela Telis A stint in the dark may be just what the doctor ordered—at least if you have "lazy eye." Researchers report that kittens with the disorder, a visual impairment medically known as amblyopia that leads to poor sight or blindness in one eye, can completely recover their vision by simply spending 10 days in total darkness. "It's a remarkable study, with real potential to change how we think about recovery from amblyopia," says neuroscientist Frank Sengpiel of Cardiff University in the United Kingdom who was not involved in the work. Amblyopia affects about 4% of the human population. It's thought to start with an imbalance in vision early in life: If one eye doesn't see as well as the other—because, for example, of a cataract or astigmatism—the brain reroutes most of the connections needed for visual processing to the "good" eye. Doctors often treat the condition by patching the good eye and forcing the brain to rely on the other eye, but the treatment risks damaging vision in the good eye, and if it doesn't succeed or occur early enough in a child's visual development, the vision loss in the impaired eye can be permanent. Earlier studies with cats, whose complex visual systems are good stand-ins for human vision, showed that neurons in the brain's visual centers shrink when the brain decides to disconnect from the bad eye, but that they grow again when the cats are placed in darkness. So neuroscientists Kevin Duffy and Donald Mitchell of Dalhousie University in Halifax, Canada, set out to test darkness itself as a treatment. © 2010 American Association for the Advancement of Science

Keyword: Vision; Aggression
Link ID: 17808 - Posted: 02.16.2013

By PAM BELLUCK The device allows people with a certain type of blindness to detect crosswalks on the street, the presence of people or cars, and sometimes even large numbers or letters. The approval of the system marks a milestone in a new frontier in vision research, a field in which scientists are making strides with gene therapy, optogenetics, stem cells and other strategies. “This is just the beginning,” said Grace Shen, a director of the retinal diseases program at the National Eye Institute, which helped finance the artificial retina research and is supporting many other blindness therapy projects. “We have a lot of exciting things sitting in the wings.” The artificial retina is a sheet of electrodes implanted in the eye. The patient is also given glasses with an attached camera and a portable video processor. This system, called Argus II, allows visual signals to bypass the damaged portion of the retina and be transmitted to the brain. With the artificial retina or retinal prosthesis, a blind person cannot see in the conventional sense, but can identify outlines and boundaries of objects, especially when there is contrast between light and dark — fireworks against a night sky or black socks mixed with white ones. “Without the system, I wouldn’t be able to see anything at all, and if you were in front of me and you moved left and right, I’m not going to realize any of this,” said Elias Konstantopolous, 74, a retired electrician in Baltimore, one of about 50 Americans and Europeans who have been using the device in clinical trials. He said it helps him differentiate curbs from roads, and detect contours of objects and people. “When you have nothing, this is something. It’s a lot.” The F.D.A. approved Argus II, made by Second Sight Medical Products, to treat people with severe retinitis pigmentosa, in which photoreceptor cells, which take in light, deteriorate. © 2013 The New York Times Company

Keyword: Vision; Aggression
Link ID: 17807 - Posted: 02.16.2013

The latest bionic superhero is a rat: its brain hooked up to an infrared detector, it's become the first animal to be given a sixth sense. Developed by Miguel Nicolelis and colleagues at Duke University in Durham, North Carolina, the system connects a head-mounted sensor to a brain region that normally processes touch sensations from whiskers. As shown in this video, the rat's brain is tricked when infrared light is detected, giving it a new sense organ. "Instead of seeing, the rats learned how to touch the light," says Nicolelis. Even though the touch-processing brain area acquires a new role, the team found that it continues to process touch sensations from whiskers, somehow dividing its time between both types of signal. "The adult brain is a lot more plastic than we thought," says Nicolelis. The finding could lead to new brain prostheses that restore sight in humans with a damaged visual cortex. By bypassing the damaged part of the brain altogether, it might be possible to wire up a video camera to a part of the brain that processes touch, letting people "touch" what the camera sees. According to Nicolelis, it could also lead to superhero powers for humans. "It could be X-rays, radio waves, anything," he says. "Superman probably had a prosthetic device that nobody knew of." © Copyright Reed Business Information Ltd.

Keyword: Vision; Aggression
Link ID: 17805 - Posted: 02.14.2013

If optimists see the world through rose-colored lenses, some birds see it through ultraviolet ones. Avians have evolved ultraviolet vision quite a few times in history, a new study finds. Birds depend on their color vision for selecting mates, hunting or foraging for food, and spotting predators. Until recently, ultraviolet vision was thought to have arisen as a one-time development in birds. But a new DNA analysis of 40 bird species, reported Feb. 11 in the journal BMC Evolutionary Biology, shows the shift between violet (shorter wavelengths on the electromagnetic spectrum) and ultraviolet vision has occurred at least 14 times. "Birds see color in a different way from humans," study co-author Anders Ödeen, an animal ecologist at Uppsala University in Sweden, told LiveScience. Human eyes have three different color receptors, or cones, that are sensitive to light of different wavelengths and mix together to reveal all the colors we see. Birds, by contrast, have four cones, so "they see potentially more colors than humans do," Ödeen said. Birds themselves are split into two groups based on the color of light (wavelength) that their cones detect most acutely. Scientists define them as violet-sensitive or ultraviolet-sensitive, and the two groups don't overlap, according to Ödeen. Birds of each group would see the same objects as different hues. The specialization of color vision has its advantages. For instance, a bird with ultraviolet-sensitive vision might have spectacularly bright plumage in order to impress a female, but that same plumage might appear dull to predator birds that see only in the violet range. © 2013 Discovery Communications, LLC.

Keyword: Vision; Aggression
Link ID: 17788 - Posted: 02.12.2013

Steve Connor Scientists believe they may be able to discover why children who spend much of their time indoors rather than playing outside are more likely to develop short-sightedness following a breakthrough study into the genetics of myopia. More than two dozen genes have been linked to an increased risk of developing myopia, a finding that may finally allow researchers to understand why children today are more likely to become short-sighted than children in the past. Myopia now affects about one in three people in the West and up to 80 per cent of people in Asia. In some countries in the Far East as many as 90 per cent of children are short-sighted, compared to less than 20 per cent a couple of decades ago. Although short-sightedness tends to run in families and has a strong inherited component, the explosive increase in the condition over recent years has been linked with an increase in the time that children spend indoors either studying or playing computer games and watching TV, scientists believe. A study of more than 45,000 people from Europe and Asia has identified 24 new genes that appear to be involved in triggering the onset of myopia. It has also confirmed the role of two further genes that were already suspected of being involved with short-sightedness, the scientists said. © independent.co.uk

Keyword: Vision; Aggression
Link ID: 17783 - Posted: 02.11.2013

By Sam McNerney and Txchnologist Why do humans see colors? For years the leading hypothesis was that color vision evolved to help us spot nutritious fruits and vegetation in the forest. But in 2006, evolutionary neurobiologist Mark Changizi and colleagues proposed that color vision evolved to perceive oxygenation and hemoglobin variations in skin in order to detect social cues, emotions and the states of our friends or enemies. Just think about the reddening and whitening of the face called blushing and blanching. They elicit distinct physiological reactions that would be impossible without color vision. A few years ago Changizi left Rensselaer Polytechnic Institute where he was professor to co-found 2AI Labs with Dr. Tim Barber. Their Boise, Idaho-based research institute, funded via technology spin-offs coming out of their work, aimed at solving foundational problems in cognitive science and artificial intelligence. The move allowed Changizi to continue to conduct academic work with more intellectual freedom and less of a reliance on grants. Last summer the team at 2AI developed three pairs of glasses called O2Amps based on Changizi’s color vision theory. By visually enhancing oxygenated blood and blood pooling, the lenses amplify the social cues that allow users to perceive emotions more clearly. The eyewear is being used for a number of innovative applications. The first is medical. The lenses enhance vasculature beneath skin, helping nurses identify veins; they also amplify trauma and bruising that might be invisible to the naked eye. Many hospitals are putting the O2Amps through trials, and seeing positive results. The eyewear is also potentially useful for police and security officers– imagine if a TSA agent could more easily perceive nervousness– as well as poker players. © 2013 Scientific American,

Keyword: Vision
Link ID: 17773 - Posted: 02.06.2013

By Melissa Dahl, NBC News Scarlet fever plays the villain in some of the best children's books: It got "Little Women's" Beth March. It got the child in "The Velveteen Rabbit" (although the kid survives, so, really, the fever got the stuffed rabbit). And it robbed Mary Ingalls, sweet sister of "Little House" series author Laura Ingalls Wilder, of her sight. Or so we were told. But today, the journal Pediatrics asserts that it wasn't scarlet fever that caused Mary's blindness -- it was viral meningoencephalitis, an inflammatory disease that attacks the brain. This is the sort of thing that is extremely interesting if you are interested in this sort of thing. And we'd wager many people are: The "Little House" books have remained in print ever since the initial publication of "Little House in the Big Woods" in 1932, and they're still popular today, with three titles landing on the School Library Journal's 2012 list of best children's chapter books. Even if you never read the books, you probably remember the TV series, which aired from 1974 to 1983. Dr. Beth Tarini, assistant professor of pediatrics at the University of Michigan, and her co-authors make their claim after scouring epidemiological data on blindness and infectious disease around the time of Mary's illness, plus analyzing local newspapers and Laura's unpublished memoir, "Pioneer Girl." For Tarini, it's the culmination of a project she began in medical school 10 years ago, after a confusing conversation with a professor. © 2013 NBCNews.com

Keyword: Vision
Link ID: 17757 - Posted: 02.05.2013

By Christof Koch Blindness is a private matter between a person and the eyes with which he or she was born. The sentiment expressed by the late Portuguese writer José Saramago in his famous novel Blindness may be appropriate for a person born unable to see. But what about the tens of millions of people worldwide who suffer from a variety of degenerative diseases that progressively rob them of their eyesight? The problem arises in the nerve cells that line the back of their eyes, their retinas. Fortunately, help is on the way to restore some of the lost vision using advanced neuroengineering. The hallmark of the two most common forms of adult-onset blindness in the West, age-related macular degeneration and retinitis pigmentosa, is that the photoreceptors responsible for converting the incoming rays of light into nervous energy gradually die off. Yet the roughly one million ganglion cells, whose output wires bundle up and leave the eyeball in the form of the optic nerve, remain intact. So visionary (pun intended) clinical ophthalmologists have paired up with technologists to bypass the defective parts of the retina by directly stimulating ganglion cells via advanced electronics. One of the most successful of such prosthetic devices, manufactured by a California company called Second Sight, uses a camera integrated into eyeglasses to convert images into electronic patterns. These patterns are sent to a small, 10- by six-pixel microelectrode array surgically positioned onto the retina. It stimulates neural processes that relay their information in the form of binary electrical pulses, so-called action potentials or spikes, to the brain proper. © 2013 Scientific American,

Keyword: Vision; Aggression
Link ID: 17733 - Posted: 01.30.2013

By Nathan Seppa Rogers Hornsby, one of the best hitters ever to swing a baseball bat, had a reputation for being standoffish. Teammates complained that he didn’t socialize, even balking at attending movies — prime entertainment during the 1920s. Sitting in a dark theater watching a bright screen made it difficult to hit a baseball, Hornsby used to say. Hard to argue with a guy who reportedly had terrific eyesight and who finished three seasons with a batting average better than .400. Hornsby might have been onto something that scientists are only now coming to embrace: Too much time spent indoors may contribute to nearsightedness, also called myopia. Nearsightedness has increased steadily in North America and Europe in recent decades, with one-third of adults in the United States now nearsighted. That figure alone is cause for concern. But the rise of myopia in East Asia is downright alarming. Recent studies of young men in Seoul and college students in Shanghai find that more than 95 percent are nearsighted. Increases also have shown up across other urban centers in the Far East. Studies first uncovered a link between myopia and limited outdoor time during childhood just a few years ago. At the time, many researchers were taken aback. The notion that child’s play might promote normal eye growth seemed almost magical. “Certainly, before five years ago, I don’t think anybody had taken much notice of how much time people spent outdoors,” says Jeremy Guggenheim, an optometrist who has researched myopia in Wales and is currently at Hong Kong Polytechnic University. He believes the findings offer a “new and exciting direction” for research. © Society for Science & the Public 2000 - 2013

Keyword: Vision; Aggression
Link ID: 17719 - Posted: 01.28.2013

By James Gallagher Health and science reporter, BBC News People who regularly take aspirin for many years, such as those with heart problems, are more likely to develop a form of blindness, researchers say. A study on 2,389 people, in the journal JAMA Internal Medicine, showed aspirin takers had twice the risk of "wet" age-related macular degeneration. The disease damages the 'sweet spot' in the retina, obscuring details in the centre of a patient's field of vision. The researchers said there was not yet enough evidence to change aspirin use. Taking low doses of aspirin every day does reduce the risk of a stroke or heart attack in patients with cardiovascular disease. There are even suggestions it could prevent cancer. One in 10 people in the study, conducted at the University of Sydney, were taking aspirin at least once a week. On average the participants were in their mid-60s. Eye tests were performed after five, 10 and 15 years. By the end of the study, the researchers showed that 9.3% of patients taking aspirin developed wet age-related macular degeneration (AMD) compared with 3.7% of patients who did not take aspirin. Their report said: "The increased risk of [wet] AMD was detected only after 10 or 15 years, suggesting that cumulative dosing is important. BBC © 2013

Keyword: Vision
Link ID: 17704 - Posted: 01.22.2013

By James Gallagher Health and science reporter, BBC News Light passing through the body and into the womb has an important role in the developing eye, US researchers have discovered. A study, published in the journal Nature, showed that mice spending pregnancy in complete darkness had babies with altered eye development. It indicated tiny quantities of light were needed to control blood vessel growth in the eye. The researchers hope the findings will aid understanding of eye disorders. Light or dark? If you could journey inside a mouse or a person, there would not be enough light to see. However, tiny quantities of light do pass through the body. This effect has already been used to film an infection spreading through the body. Now scientists - at the University of California, San Francisco, and Cincinnati Children's Hospital Medical Center - believe that body-penetrating light can alter the development of the eye, at least in mice. Normally, a network of blood vessels known as the hyaloid vasculature is formed to help nourish the retina as it is constructed. However, the blood vessels would disrupt sight if they remained, so they are later removed - like scaffolding from a finished building. BBC © 2013

Keyword: Vision; Aggression
Link ID: 17685 - Posted: 01.17.2013

By Cheryl Murphy Enhancing your level of vision on demand sounds like something out of a comic book. Superman, if you recall, had the power to turn his x-ray vision on and off like a light switch. So is x-ray vision possible? I’m sorry to say: no. The ability of our naked eyes to see through layers of objects remains an idea conjured up in the minds of science fiction writers. However, the possibility of training your brain to flip to a heightened level of visual discrimination and detection whenever you want may in fact be a reality. Last month, researchers in Switzerland found that participants who were successfully trained to consciously up-regulate the level of activity in their early visual cortex as seen by neurofeedback on fMRI in real time were also able to voluntarily give their level of visual discrimination and detection a boost. This study may sound like science fiction but it is not. Here is how it was done. Sixteen, young healthy participants with normal or corrected-to-normal vision were told to focus on a central fixation light while they imagined high resolution pictures of changing color, shape and intensity in a particular part of their visual field which the researchers called the target region of interest. They visualized such things as writing their name in the air, a boat sailing on the ocean, patterns of spinning wheels and spirals, a model walking down the runway or their pet. They received on-the-spot visual feedback indicating how well their visualizations were boosting their brain activity to aid in their brain training. By imagining these detailed objects, seven out of the sixteen participants were able to train themselves to consciously up-regulate activity in areas of their early visual cortex over the course of a series of separate training sessions. In essence what the participants did was learn how to jump-start their visual cortex. Once their visual cortex was held at a higher state of activity, it was more sensitive and could better detect other stimuli in the target region of interest where they projected their visualizations. © 2013 Scientific American

Keyword: Vision; Aggression
Link ID: 17659 - Posted: 01.08.2013

By James Gallagher Health and science reporter, BBC News Totally blind mice have had their sight restored by injections of light-sensing cells into the eye, UK researchers report. The team in Oxford said their studies closely resemble the treatments that would be needed in people with degenerative eye disease. Similar results have already been achieved with night-blind mice. Experts said the field was advancing rapidly, but there were still questions about the quality of vision restored. Patients with retinitis pigmentosa gradually lose light-sensing cells from the retina and can become blind. The research team, at the University of Oxford, used mice with a complete lack of light-sensing photoreceptor cells in their retinas. The mice were unable to tell the difference between light and dark. Reconstruction They injected "precursor" cells which will develop into the building blocks of a retina once inside the eye. Two weeks after the injections a retina had formed, according to the findings presented in the Proceedings of the National Academy of Sciences journal. Prof Robert MacLaren said: "We have recreated the whole structure, basically it's the first proof that you can take a completely blind mouse, put the cells in and reconstruct the entire light-sensitive layer." BBC © 2013

Keyword: Vision; Aggression
Link ID: 17655 - Posted: 01.07.2013

By Christof Koch Unless you have been deaf and blind to the world over the past decade, you know that functional magnetic resonance brain imaging (fMRI) can look inside the skull of volunteers lying still inside the claustrophobic, coffinlike confines of a loud, banging magnetic scanner. The technique relies on a fortuitous property of the blood supply to reveal regional activity. Active synapses and neurons consume power and therefore need more oxygen, which is delivered by the hemoglobin molecules inside the circulating red blood cells. When these molecules give off their oxygen to the surrounding tissue, they not only change color—from arterial red to venous blue—but also turn slightly magnetic. Activity in neural tissue causes an increase in the volume and flow of fresh blood. This change in the blood supply, called the hemodynamic signal, is tracked by sending radio waves into the skull and carefully listening to their return echoes. FMRI does not directly measure synaptic and neuronal activity, which occurs over the course of milliseconds; instead it uses a relatively sluggish proxy—changes in the blood supply—that rises and falls in seconds. The spatial resolution of fMRI is currently limited to a volume element (voxel) the size of a pea, encompassing about one million nerve cells. Neuroscientists routinely exploit fMRI to infer what volunteers are seeing, imagining or intending to do. It is really a primitive form of mind reading. Now a team has taken that reading to a new, startling level. A number of groups have deduced the identity of pictures viewed by volunteers while lying in the magnet scanner from the slew of map­like representations found in primary, secondary and higher-order visual cortical regions underneath the bump on the back of the head. © 2012 Scientific American

Keyword: Vision; Aggression
Link ID: 17647 - Posted: 01.01.2013

A simple eye test may offer a fast and easy way to monitor patients with multiple sclerosis (MS), medical experts say in the journal Neurology. Optical Coherence Tomography (OCT) is a scan that measures the thickness of the lining at the back of the eye - the retina. It takes a few minutes per eye and can be performed in a doctor's surgery. In a trial involving 164 people with MS, those with thinning of their retina had earlier and more active MS. The team of researchers from the Johns Hopkins University School of Medicine say larger trials with a long follow up are needed to judge how useful the test might be in everyday practice. The latest study tracked the patients' disease progression over a two-year period. Unpredictable disease Multiple sclerosis is an illness that affects the nerves in the brain and spinal cord causing problems with muscle movement, balance and vision. In MS, the protective sheath or layer around nerves, called myelin, comes under attack which, in turn, leaves the nerves open to damage. There are different types of MS - most people with the condition have the relapsing remitting type where the symptoms come and go over days, weeks or months. Usually after a decade or so, half of patients with this type of MS will develop secondary progressive disease where the symptoms get gradually worse and there are no or very few periods of remission. BBC © 2012

Keyword: Multiple Sclerosis; Aggression
Link ID: 17639 - Posted: 12.27.2012

By Mark Changizi The human fascination with color never ceases to amaze me. Our perceptual experience is filled with shapes and pitches and textures and timbres and depths and on and on, yet color seems to get the lion share of our excitement and philosophical attention. Color seems somehow more artistic than our other perceptual dimensions; it’s simply wonderful to behold, as evinced by the double rainbow guy; and we can’t resist wondering what it would be like to see dimensions of color beyond our own. In fact, RadioLab recently put out a great show on color that nicely conveys the romance we all have toward it. Question is: Why do we find color so enthralling? One of the reasons may be that the world can seem arbitrarily labeled in color, as if a painter dabbed over everything in order to make it beautiful… and that naturally makes us wonder what a different artist might do. What sort of splendor is a bird—who has an extra dimension of color beyond ours—treated to, for example? While I, too, feel the wonder of color, I don’t share this above intuition about color and its arbitrariness. It’s an unfortunate intuition, one that seeps its way not only into the minds of laymen, but into our “enhancement” products and even the hallowed halls of philosophy. In trying to explain what’s wrong with the intuition, let me begin with a thought experiment concerning a product that gives the wearer “shape enhancement” vision. “With our sunglasses’ shape-enhancement filter, you’ll see the world with more vibrant and interesting shapes. Round things will be rounder, regular polygons more muted…”

Keyword: Vision
Link ID: 17608 - Posted: 12.17.2012

by Christian Jarrett, Ph.D in Brain Myths Back in the 1990s neuroscientists at the University of Parma identified cells in the premotor cortex of monkeys that had an unusual response pattern. They were activated when the monkeys performed a given action and, mirror-like, when they saw another individual perform that same movement. Since then, the precise function and influence of these neurons has become perhaps the most hyped topic in neuroscience. In 2000, Vilayanur Ramachandran, the charismatic neuroscientist, made a bold prediction: “mirror neurons will do for psychology what DNA did for biology.” He's at the forefront of a frenzy of excitement that has followed these cells ever since their discovery. For many, they have came to represent all that makes us human. Perhaps, in those early heady years, Ramachandran was just getting a little carried away? Not at all. For his 2011 book, The Tell-Tale Brain, Ramachandran took his claims further. In the chapter “The neurons that shaped civilisation”, he argues that mirror neurons underlie empathy, allow us to imitate other people, that they accelerated the evolution of the brain, that they help explain the origin of language, and most impressively of all, that they prompted the great leap forward in human culture that happened about 60,000 years ago. “We could say mirror neurons served the same role in early hominin evolution as the Internet, Wikipedia, and blogging do today,” he concludes. “Once the cascade was set in motion, there was no turning back from the path to humanity.” © Copyright 2002-2012 Sussex Directories, Inc

Keyword: Vision; Aggression
Link ID: 17591 - Posted: 12.11.2012

Amy Maxmen When Bob Marley sang, “I am redder than red,” he probably did not imagine that chemists would one day capture this imagined hue. But researchers have taken a step in that direction, by tweaking a colour-sensing pigment from the human eye to absorb reds of longer wavelengths than those that we can see. “We didn’t expect to get redder than red,” says Babak Borhan, a chemist at Michigan State University in East Lansing, who led the study published today in Science1. The researchers’ red was the product of experiments conducted to understand exactly how colour-sensing pigments in our eyes absorb different hues. The team targeted rhodopsin, a pigment found in the photoreceptor cells of the retina. A rhodopsin molecule is made of proteins called opsins and a chromophore — the part of the molecule responsible for absorbing different wavelengths of light . Together, the two parts translate light into signals for various colours, which are then interpreted by the brain. In the eye, a chromophore called retinal responds to wavelengths ranging from red, at about 560 nanometres, to blue, at about 420 nm. “The question has been: how can we see all of these colours using essentially one molecule, the chromophore?” Borhan says. The attached proteins somehow control the range of light that a chromophore can absorb — from red, to green, to blue; but no one knew exactly how they fine-tuned this absorption ability. Scientists have hypothesized that the shade the chromophore can receive shifts as a result of more than one interaction, such as a change in the shape of the chromophore–protein complex and a change in the positions of electrical charges along the protein molecule. © 2012 Nature Publishing Group

Keyword: Vision
Link ID: 17584 - Posted: 12.08.2012