Chapter 10. Vision: From Eye to Brain

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Sara Reardon Cuttlefish are masters at altering their appearance to blend into their surroundings. But the cephalopods can no longer hide their inner thoughts, thanks to a technique that infers a cuttlefish’s brain activity by tracking the ever-changing patterns on its skin. The findings, published in Nature on 17 October1, could help researchers to better understand how the brain controls behaviour. The cuttlefish (Sepia officinalis) camouflages itself by contracting the muscles around tiny, coloured skin cells called chromatophores. The cells come in several colours and act as pixels across the cuttlefish’s body, changing their size to alter the pattern on the animal’s skin. The cuttlefish doesn’t always conjure up an exact match for its background. It can also blanket itself in stripes, rings, mottles or other complex patterns to make itself less noticeable to predators. “On any background, especially a coral reef, it can’t look like a thousand things,” says Roger Hanlon, a cephalopod biologist at the Marine Biological Laboratory in Chicago, Illinois. “Camouflage is about deceiving the visual system.” To better understand how cuttlefish create these patterns across their bodies, neuroscientist Gilles Laurent at the Max Planck Institute for Brain Research in Frankfurt, Germany, and his collaborators built a system of 20 video cameras to film cuttlefish at 60 frames per second as they swam around their enclosures. The cameras captured the cuttlefish changing colour as they passed by backgrounds such as gravel or printed images that the researchers placed in the tanks. © 2018 Springer Nature Limited.

Keyword: Vision; Brain imaging
Link ID: 25589 - Posted: 10.18.2018

By Carolyn Y. Johnson Kiara Eldred sometimes compares her nine-month-long scientific experiments, growing tiny human retinas in a laboratory dish, to raising children. Eldred, a graduate student at Johns Hopkins University, starts by growing thousands of stem cells and feeding them nutrients and chemicals that will steer them to develop into the retina, the part of the eye that translates light into the signals that lead to vision. After two weeks of painstaking cultivation, those cells typically generate 20 to 60 tiny balls of cells, called retinal organoids. As they mature, these nascent retinas get dirty and slough off lots of cells, so they also need to be washed off when they’re fed every other day — at least for the first month and a half. After nine months of assiduous care, Eldred has a batch of miniature human retinas that respond to light, are about two millimeters in diameter and are shaped like a tennis ball cut in half. But growing the organoids is only the first step. In a new study in the journal Science, Eldred and colleagues described using this system to understand a fundamental question about vision that has remained surprisingly mysterious: How does color vision develop? © 1996-2018 The Washington Post

Keyword: Vision; Development of the Brain
Link ID: 25565 - Posted: 10.12.2018

Doris Tsao is a neuroscientist who uses brain imaging technology, electrical recording techniques, and mathematical modeling. Though Tsao has explored several aspects of visual processing, such as the perception of depth and color, her most notable line of research has focused on uncovering the fundamental neural principles that underlie one of the brain’s most highly specialized and socially important tasks: recognizing a face. Prior neuroscientific research has identified regions in the inferior temporal cortex of monkeys that are particularly responsive to faces. These earlier studies, however, shed little light on how face-responsive cells within these regions might be organized and integrated into a system. Early in her career, Tsao confirmed with functional magnetic resonance imaging (fMRI) that the visual cortex of the macaque monkey shows face-selective activation in six small “patches” in each hemisphere of the brain. She then used data from fMRI brain scans as a map to guide the placement of single-neuron, electrical recording probes, which demonstrated that certain neurons display highly attuned sensitivity to faces, but not to other categories of objects, and that different patches across the brain’s cortex are integrated in a network dedicated to the visual processing of faces. Through other elegantly designed experiments, Tsao showed that the sensitivity of specific neurons can be further analyzed by measuring their responses to cartoon representations of faces with subtle variations in features and that certain features, such as facial shape and inter-eye distance, elicit particularly frequent and robust responses. © 2018 John D. and Catherine T. MacArthur Foundation

Keyword: Vision
Link ID: 25532 - Posted: 10.05.2018

By Kelly Servick PHILADELPHIA, PENNSYLVANIA—While artificial intelligence (AI) has been busy trouncing humans at Go and spawning eerily personable Alexas, some neuroscientists have harbored a different hope: that the types of algorithms driving those technologies can also yield some insight into the squishy, wet computers in our skulls. At the Conference on Cognitive Computational Neuroscience here this month, researchers presented new tools for comparing data from living brains with readouts from computational models known as deep neural networks. Such comparisons might offer up new hypotheses about how humans process sights and sounds, understand language, or navigate the world. “People have fantasized about that since the 1980s,” says Josh McDermott, a computational neuroscientist at the Massachusetts Institute of Technology (MIT) in Cambridge. Until recently, AI couldn’t come close to human performance on tasks such as recognizing sounds or classifying images. But deep neural networks, loosely inspired by the brain, have logged increasingly impressive performances, especially on visual tasks. That “brings the question back to mind,” says neuroscientist Chris Baker of the National Institute of Mental Health in Bethesda, Maryland. Deep neural networks work by passing information between computational “nodes” that are arranged in successive layers. The systems hone skills on huge sets of data; for networks that classify images, that usually means collections of labeled photos. Performance improves with feedback as the systems repeatedly adjust the strengths of the connections between nodes. © 2018 American Association for the Advancement of Science

Keyword: Attention; Vision
Link ID: 25466 - Posted: 09.18.2018

By Emily Underwood On a moonless night, the light that reaches Earth is a trillion–fold less than on a sunny day. Yet most mammals still see well enough to get around just fine—even without the special light-boosting membranes in the eyes of cats and other nocturnal animals. A new study in mice hints at how this natural night vision works: Motion-sensing nerve cells in the retina temporarily change how they wire to each other in dark conditions. The findings might one day help visually impaired humans, researchers say. Scientists already knew a bit about how night vision works in rabbits, mice, humans, and other mammals. Mammalian retinas can respond to “ridiculously small” numbers of photons, says Joshua Singer, a neuroscientist at the University of Maryland in College Park who was not involved in the new study. A single photon can activate a light-sensitive cell known as a rod cell in the retina, which sends a minute electrical signal to the brain through a ganglion cell. One kind of ganglion cell specializes in motion detection—a vital function if you’re a mouse being hunted by an owl, or a person darting to avoid oncoming traffic. Some of these direction-selective ganglion cells (DSGCs) get excited only when an object is moving upward. Others fire only when objects are moving down, or to the left or right. Together, the cells decide where an object is headed and relay that information to the brain, which decides how to act. © 2018 American Association for the Advancement of Science

Keyword: Vision; Evolution
Link ID: 25449 - Posted: 09.14.2018

By Ben Guarino A blight of bad eyesight plagues urban centers in China and other East Asian countries. In Hong Kong and Singapore, the rate of myopia, or nearsightedness, is as high as 90 percent in young adults. Though things aren't as blurry in the United States — about a third of the population has trouble seeing distant objects — rates have doubled since the 1970s. If current trends continue, half of the world could be myopic by 2050. China blames video games for the eyeglass epidemic and recently took them to task. The state-run Xinhua News Agency wrote this week that the "vision health of our country’s young people has always been of great concern" to Xi Jinping, the Communist Party general secretary and China's president. Chinese media distributors, the New York Times reported Friday, will limit the number of new games approved for sale. By singling out video games, China has taken a somewhat "extreme stance," according to Aaron M. Miller, a pediatric ophthalmologist and a clinical spokesman for the American Academy of Ophthalmology. "There's not a direct correlation or a clear relationship between video games, screen time and nearsightedness development." The scientific literature can offer only a fuzzy picture of myopia's causes. Diet and genes influence myopia; myopic parents are more likely to have myopic children. Behaviors can play a role, too. Some ophthalmologists look to activities lumped together under a term called "near-work" — any prolonged focus on a nearby object, as when reading, checking phones, studying and, yes, watching screens. Researchers have observed higher rates of myopia in college students, post-literate societies and, in one study, people who frequently use microscopes. © 1996-2018 The Washington Post

Keyword: Vision
Link ID: 25412 - Posted: 09.04.2018

By Bahar Gholipour Milena Canning can see steam rising from a coffee cup but not the cup. She can see her daughter’s ponytail swing from side to side, but she can’t see her daughter. Canning is blind, yet moving objects somehow find a way into her perception. Scientists studying her condition say it could reveal secrets about how humans process vision in general. Canning was 29 when a stroke destroyed her entire occipital lobe, the brain region housing the visual system. The event left her sightless, but one day she saw a flash of light from a metallic gift bag next to her. Her doctors told her she was hallucinating. Nevertheless, “I thought there must be something happening within my brain [allowing me to see],” she says. She went from doctor to doctor until she met Gordon Dutton, an ophthalmologist in Glasgow, Scotland. Dutton had encountered this mystery before—in a 1917 paper by neurologist George Riddoch describing brain-injured World War I soldiers. To help enhance Canning’s motion-based vision, Dutton prescribed her a rocking chair. Canning is one of a handful of people who have been diagnosed with the “Riddoch phenomenon,” the ability to perceive motion while blind to other visual stimuli. Jody Culham, a neuroscientist at Western University in Ontario, and her colleagues launched a 10-year investigation into Canning’s remarkable vision and published the results online in May in Neuropsychologia. The team confirmed that Canning was able to detect motion and its direction. She could see a hand moving toward her, but she could not tell a thumbs-up from a thumbs-down. She was also able to navigate around obstacles, reach and grasp, and catch a ball thrown at her. © 2018 Scientific American

Keyword: Attention; Vision
Link ID: 25409 - Posted: 09.01.2018

By Raymond Zhong BEIJING — It started this week with a call to action from China’s leader, Xi Jinping. Too many of the country’s children need glasses, he said, and the government was going to do something about it. It ended on Friday with billions of dollars being wiped from the market value of the world’s largest video game company. New controls on online games were among Chinese authorities’ recommendations for reducing adolescent nearsightedness on Thursday, sending shares in the country’s leading game publisher, Tencent, tumbling the next day. Shares of Japanese game makers like Capcom, Konami and Bandai Namco also fell on Friday, a sign of the size and importance of the Chinese market. The sell-off is the latest in a series of government-related stumbles for Tencent, one of the world’s largest technology companies. Chinese state media has blamed video games for causing young people to become addicted, lowering their grades and worse. An incident last year, in which a 17-year-old in the southern city of Guangzhou died after playing a smartphone game for 40 hours straight, received wide attention. As the biggest game distributor in the world’s biggest game market, Tencent has grown fantastically rich in recent years. It has bought up game developers around the world, including the makers of influential titles such as League of Legends and Clash of Clans. It owns a stake in Epic Games, creator of the international blockbuster Fortnite. Back at home, Tencent also operates China’s most popular messaging app, WeChat, and processes a big chunk of the smartphone payments that are now used to make transactions of all kinds in the country. But over the last year, Tencent's hugely profitable game business has come under fire as Beijing takes a more forceful approach to guiding Chinese culture — a reminder of the state’s growing role in deciding the fortunes of the country’s largest and most innovative private companies. © 2018 The New York Times Company

Keyword: Vision
Link ID: 25406 - Posted: 08.31.2018

Scientists funded by the National Eye Institute (NEI) report a novel gene therapy that halts vision loss in a canine model of a blinding condition called autosomal dominant retinitis pigmentosa (adRP). The strategy could one day be used to slow or prevent vision loss in people with the disease. NEI is part of the National Institutes of Health. “We’ve developed and shown proof-of-concept for a gene therapy for one of the most common forms of retinitis pigmentosa,” said William Beltran, D.V.M., Ph.D., of the University of Pennsylvania School of Veterinary Medicine, Philadelphia, a lead author of the study, which appears online today in the Proceedings of the National Academy of Sciences. Retinitis pigmentosa refers to a group of rare genetic disorders that damage light-sensing cells in the retina known as photoreceptors. Rod photoreceptor cells enable vision in low light and require a protein called rhodopsin for their light-sensing ability. People with adRP caused by mutations in the rhodopsin gene usually have one good copy of the gene and a second, mutated copy that codes for an abnormal rhodopsin protein. The abnormal rhodopsin is often toxic, slowly killing the rod cells. As the photoreceptors die, vision deteriorates over years or decades. Scientists have identified more than 150 rhodopsin mutations that cause adRP, challenging efforts to develop effective therapies. Beltran generated a gene therapy construct that knocks down the rod cells’ ability to produce rhodopsin using a technology known as shRNA (short-hairpin RNA) interference. Gene therapy introduces genetic material, like shRNA, into cells to compensate for abnormal genes or to make a beneficial protein. Often adapted from viruses, vectors are engineered to effectively deliver this genetic material into cells without causing disease.

Keyword: Vision; Genes & Behavior
Link ID: 25358 - Posted: 08.21.2018

Genevieve Fox Paola Peretti is losing her eyesight and she wouldn’t have it any other way. When she was 14, she became very short-sighted, virtually overnight. Three years later came the diagnosis of Stargardt macular dystrophy, a degenerative disease that destroys central vision, damages colour perception and results in blindness. Two years ago, finding herself in a place of both “desperation and hope,” the 32-year-old Italian language teacher and debut novelist decided to step out from the shadow of her hereditary condition, which she only ever aired with her family, and confront her fear of the dark. The Distance Between Me and the Cherry Tree is the result: a captivating, wise and highly visual children’s novel about living in the face of fear. Its heroine, nine-year-old Mafalda, also has Stargardt disease. A bewitching, brave little girl, she will lose her sight completely within six months, as Peretti was expecting to do at some unspecified point in her own life when she began the novel. The eponymous cherry tree is next to Mafalda’s school. Each day, she has to get closer to it before it comes into focus. As her short-sightedness increases, so does her fear of the future. “She is losing her life as she knows it,” says Peretti, who explains that she herself can see “half of what other people see”. Mafalda has blank patches in both eyes, and they get bigger. Peretti has a blank patch in her right eye. I am seated a couple of feet from her as we talk in her publisher’s office. She says I am partially blurred. © 2018 Guardian News and Media Limited

Keyword: Vision; Emotions
Link ID: 25352 - Posted: 08.20.2018

By Kelly Servick Nestled in the backs of our eyes, there are cells that might be able to repair damage from some vision-impairing diseases. But so far, scientists haven’t managed to kick them into gear. Now, a team of researchers claims to have prompted these cells, called Müller glia, to regenerate one type of light receptor cell in the eyes of mice. According to their study, published today in Nature, these new cells could detect incoming light and network with other cells in the eye to relay signals to the brain, a potential step toward reversing certain genetic eye conditions and injuries. But others are skeptical of that claim and argue the signals could have come from existing light-sensing cells in the eye—not new ones. “Nobody more than me wants this to be true,” says Seth Blackshaw, a neuroscientist at Johns Hopkins University’s School of Medicine in Baltimore, Maryland, “but I have serious concerns about this study.” The new work is part of a long effort to regenerate photoreceptors, neurons in the retina that transform incoming light into electrical signals. Cone receptors are responsible for our daytime vision and perception of colors, and the more sensitive rod receptors enable vision in low light. The destruction of these cells—or of the retinal ganglion cells that transmit their signals to the brain—can diminish vision and even cause blindness. © 2018 American Association for the Advancement of Science

Keyword: Vision; Glia
Link ID: 25340 - Posted: 08.16.2018

Scientists say they have found how blue light from smartphones, laptops and other digital devices damages vision and can speed up blindness. Research by the University of Toledo in the US has revealed that prolonged exposure to blue light triggers poisonous molecules to be generated in the eye’s light-sensitive cells that can cause macular degeneration – an incurable condition that affects the middle part of vision. Blue light, which has a shorter wavelength and more energy compared with other colours, can gradually cause damage to the eyes. Dr Ajith Karunarathne, an assistant professor in the university’s department of chemistry and biochemistry, said: “We are being exposed to blue light continuously and the eye’s cornea and lens cannot block or reflect it. “It’s no secret that blue light harms our vision by damaging the eye’s retina. Our experiments explain how this happens, and we hope this leads to therapies that slow macular degeneration, such as a new kind of eye drop.” Macular degeneration, which affects around 2.4% of the adult population in the UK, is a common condition among those in their 50s and 60s that results in significant vision loss. It is caused by the death of photoreceptor, ie light-sensitive cells, in the retina. Age-related macular degeneration is the leading cause of blindness in the US and while it does not cause total blindness, it can make everyday activities such as reading and recognising faces difficult. © 2018 Guardian News and Media Limite

Keyword: Vision
Link ID: 25315 - Posted: 08.10.2018

By Susana Martinez-Conde The house cricket (Acheta domesticus) walked around the arena comfortably, certain of its surroundings. It looked about, perhaps hoping for food or mates, ignoring the scattered, browning, dead leaves. On previous visits to the arena, the cricket had been wary of the dead leaves, not knowing what to make of them. Then, after a prudent interval, it had ventured to feel them with its segmented antennae—tentatively at first, and later with growing confidence. Once the cricket determined the leaves were neither edible nor harmful, it quickly lost interest in them. Now it rarely bothered to explore the leaves, but took no great pains to avoid them either. The cricket’s conviction about the safety of the leaves was its fatal mistake: on this visit, one seemingly dead leaf lying on the arena was no such, but a masquerading ghost mantis (Phyllocrania paradoxa) waiting in ambush. Unaware of the concealed peril, the cricket drew ever closer to the predator. That’s when the mantis struck forth, grasping the cricket by one of its long jumping legs. As the cricket struggled against the mantis’ clutch, the predator started to feed. Dr John Skelhorn, Lecturer in Animal Cognition, has witnessed dozens of similar life-and-death encounters in his lab at Newcastle University’s Institute of Neuroscience. Skelhorn and his colleagues previously found that some animals masquerade as inanimate, inedible objects, to look less appealing to potential predators. Some examples include the orb web spider (Cyclosa ginnaga) and the larva of the giant swallowtail butterfly (Papilio cresphontes), both of which masquerade as bird droppings, and the larva of the feathered thorn moth (Selenia dentaria), which masquerades as a twig. © 2018 Scientific American

Keyword: Vision; Evolution
Link ID: 25299 - Posted: 08.06.2018

By Donald G. McNeil Jr. GETA, Nepal — Fifteen years ago, Shiva Lal Rana walked 20 miles to Geta Eye Hospital to ask doctors to pluck out all his eyelashes. Trachoma, a bacterial infection, had swollen and inverted his eyelids. With every blink, his lashes raked his corneas. “The scratching hurt my eyes so much I could barely go out in the sun to plow,” he said. “I was always rubbing them.” Worse, he feared the fate that others with the infection had suffered. The tiny scratches could accumulate and ultimately blind him. Instead, doctors performed what was then a new operation: They sliced open his eyelids, rolled them back and sutured them with the lashes facing outward again. And they gave him antibiotics to clear up the infection. “My vision is much better now,” said Mr. Rana, a tiny, lively man who guessed he was about 65. “I can recognize people. I can work.” His personal triumph parallels his nation’s. In May, the World Health Organization declared that Nepal had eliminated trachoma as a public health problem, making it the sixth country to do so. In June, Ghana became the seventh. Quietly, in the shadow of fights against better-known diseases like Ebola, AIDS and malaria, the 20-year battle against trachoma is chalking up impressive victories. Those successes, experts say, show the wisdom of advocating and enforcing basic public health practices, rather than waiting for a miracle cure or a new vaccine. © 2018 The New York Times Company

Keyword: Vision
Link ID: 25222 - Posted: 07.18.2018

By Smitha Mundasad Global Health Correspondent, BBC News For many years, Dr Andrew Bastawrous could not see clearly enough to spot the leaves on trees or the stars in the sky. Teachers kept telling him he was lazy and he kept missing the football during games. Then, aged 12, his mother took him to have his eyes tested and that changed everything. Now he is a prize-winning eye doctor with a plan to use a smartphone app to bring better vision to millions of children around the world. Dr Bastawrous told the BBC: "I'll never forget that moment at the optometrist. I had trial lenses on and looked across the car park and saw the gravel on the road had so much detail I had had no idea about. "A couple of weeks later I got my first pair of glasses and that's when I saw stars for first time, started doing well at school and it completely transformed my life." Around the world 12 million children, like Dr Bastawrous, have sight problems that could be corrected by a pair of glasses. But in many areas, access to eye specialists is difficult - leaving children with visual impairments that can harm school work and, ultimately, their opportunities in later life. In rural Kenya, for example, there is one eye doctor for one million people. Meanwhile in the US, there is on average one ophthalmologist for every 15,800 people. In 2011 Dr Bastawrous - by now an eye doctor in England - decided to study the eye health of the population of Kitale, Kenya, as part of his PhD. He took about £100,000 of eye equipment in an attempt to set up 100 temporary eye clinics but found this didn't work, as reliable roads and electricity were scarce. It was realising that these same areas had great mobile phone coverage - with about 80% of the population owning a cell phone - that sparked the idea for Peek. © 2018 BBC.

Keyword: Vision
Link ID: 25204 - Posted: 07.14.2018

By JoAnna Klein Owl eyes are round, but not spherical. These immobile, tubular structures sit on the front of an owl’s face like a pair of built-in binoculars. They allow the birds to focus in on prey and see in three dimensions, kind of like humans — except we don’t have to turn our whole heads to spot a slice of pizza beside us. Although owls and humans both have binocular vision, it has been unclear whether these birds of prey process information they collect from their environments like humans, because their brains aren’t as complex. But in a study published in the Journal of Neuroscience on Monday, scientists tested the ability of barn owls to find a moving target among various shifting backgrounds, a visual processing task earlier tested only in primates. The research suggests that barn owls, with far simpler brains than humans and other primates, also group together different elements as they move in the same direction, to make sense of the world around them. “Humans are not so different from birds as you may think,” said Yoram Gutfreund, a neuroscientist at Technion Israel Institute of Technology who led the study with colleagues from his university and RWTH Aachen University in Germany. A critical part of perception is being able to distinguish an object from its background. One way humans do this is by grouping elements of a scene together to perceive each part as a whole. In some cases, that means combining objects that move similarly, like birds flying in a flock, or the single bird that breaks away from it. Scientists have generally considered this type of visual processing as a higher level task that requires complex brain structures. As such, they’ve only studied it in humans and primates. But Dr. Gutfreund and his team believed this ability was more basic — like seeing past camouflage. A barn owl, for example, might have evolved a similar mechanism to detect a mouse moving in a meadow as wind blows the grass in the same direction. © 2018 The New York Times Company

Keyword: Vision; Evolution
Link ID: 25174 - Posted: 07.05.2018

By Matt Warren Every day, humans make dozens of judgements, from deciding whether our clothes match to determining whether a shady character in the street is a threat. Such decisions aren’t based on hard-and-fast rules, a new study reveals. Instead, our concept of “threat”—and even of the color “blue”—is all relative. To make the find, researchers showed non–color-blind participants a series of 1000 dots ranging from very blue to very purple, and asked them to judge whether each dot was blue. For the first 200 trials, participants saw an equal number of dots from the blue and purple parts of the spectrum, but then the prevalence of blue dots gradually decreased to just a fraction of what it was before. By the end of the study, participants’ interpretation of the colors had changed: Dots that they had thought were purple in the first set of trials they now classified as blue, the authors report today in Science. That is, their concept of the color blue had expanded to also include shades of purple. Even when the researchers forewarned participants that blue dots would become rarer and promised them money if they kept their judgments consistent, the same shift occurred. And the team found similar results in more complex versions of the task, where participants had to judge whether a face was threatening or whether a research proposal was ethical. When threatening faces or unethical research proposals became less common, people started to consider previously benign examples as posing a threat or being unethical. © 2018 American Association for the Advancement of Science.

Keyword: Vision; Attention
Link ID: 25154 - Posted: 06.29.2018

By Sean Coughlan BBC News education and family correspondent The colour cyan - between green and blue - is a hidden factor in encouraging or preventing sleep, according to biologists. University of Manchester researchers say higher levels of cyan keep people awake, while reducing cyan is associated with helping sleep. The impact was felt even if colour changes were not visible to the eye. The researchers want to produce devices for computer screens and phones that could increase or decrease cyan levels. Sleep researchers have already established links between colours and sleep - with blue light having been identified as more likely to delay sleep. There have been "night mode" settings for phones and laptops which have reduced blue light in an attempt to lessen the damage to sleep. But the research by biologists at the University of Manchester and in Basel in Switzerland, published in the journal Sleep, has shown the particular impact of the colour cyan. When people were exposed to more or less cyan, researchers were able to measure different levels of the sleep hormone melatonin in people's saliva. Prof Rob Lucas said that it was not necessary for someone to be able to see the difference in colours, as the body reacted to the change even if it was not visible to the naked eye. He said this could also affect other colours which were made using cyan. For instance, there are shades of green that can include cyan - which also can be achieved using other colour combinations. The researchers suggest that versions of the colour using cyan could be used on computer screens if the aim was to keep people awake - such as people working and required to stay alert at night. © 2018 BBC.

Keyword: Biological Rhythms; Sleep
Link ID: 25120 - Posted: 06.22.2018

By Roni Caryn Rabin Ever since he had Lasik surgery two years ago, Geobanni Ramirez sees everything in triplicate. The surgery he hoped would improve his vision left the 33-year-old graphic artist struggling with extreme light sensitivity, double vision and visual distortions that create halos around bright objects and turn headlights into blinding starbursts. His eyes are so dry and sore that he puts drops in every half-hour; sometimes they burn “like when you’re chopping onions.” His night vision is so poor that going out after dark is treacherous. But Mr. Ramirez says that as far as his surgeon is concerned, he is a success story. “My vision is considered 20/20, because I see the A’s, B’s and C’s all the way down the chart,” said Mr. Ramirez. “But I see three A’s, three B’s, three C’s.” None of the surgeons he consulted ever warned him he could sustain permanent damage following Lasik, he added. The Food and Drug Administration approved the first lasers to correct vision in the 1990s. Roughly 9.5 million Americans have had laser eye surgery, lured by the promise of a quick fix ridding them of nettlesome glasses and contact lenses. There is also a wide perception among patients, fostered by many eye doctors who do the surgery, that the procedure is virtually foolproof. As far back as 2008, however, patients who had received Lasik and their families testified at an F.D.A. meeting about impaired vision and chronic pain that led to job loss and disability, social isolation, depression — and even suicides. Even now, serious questions remain about both the short- and long-term risks and the complications of this increasingly common procedure. © 2018 The New York Times Company

Keyword: Vision
Link ID: 25080 - Posted: 06.12.2018

By Ruth Williams | The sun’s ultraviolet (UV) radiation is a major cause of skin cancer, but it offers some health benefits too, such as boosting production of essential vitamin D and improving mood. Today (May 17), a report in Cell adds enhanced learning and memory to UV’s unexpected benefits. Researchers have discovered that, in mice, exposure to UV light activates a molecular pathway that increases production of the brain chemical glutamate, heightening the animals’ ability to learn and remember. “The subject is of strong interest, because it provides additional support for the recently proposed theory of ultraviolet light’s regulation of the brain and central neuroendocrine system,” dermatologist Andrzej Slominski of the University of Alabama who was not involved in the research writes in an email to The Scientist. “It’s an interesting and timely paper investigating the skin-brain connection,” notes skin scientist Martin Steinhoff of University College Dublin’s Center for Biomedical Engineering who also did not participate in the research. “The authors make an interesting observation linking moderate UV exposure to . . . [production of] the molecule urocanic acid. They hypothesize that this molecule enters the brain, activates glutaminergic neurons through glutamate release, and that memory and learning are increased.” While the work is “fascinating, very meticulous, and extremely detailed,” says dermatologist David Fisher of Massachusetts General Hospital and Harvard Medical School, “it does not imply that UV is actually good for you. . . . Across the board, for humanity, UV really is dangerous.” © 1986-2018 The Scientist

Keyword: Intelligence; Vision
Link ID: 24993 - Posted: 05.18.2018