David Cyranoski A Japanese woman in her forties has become the first person in the world to have her cornea repaired using reprogrammed stem cells. At a press conference on 29 August, ophthalmologist Kohji Nishida from Osaka University, Japan, said the woman has a disease in which the stem cells that repair the cornea, a transparent layer that covers and protects the eye, are lost. The condition makes vision blurry and can lead to blindness. How iPS cells changed the world To treat the woman, Nishida says his team created sheets of corneal cells from induced pluripotent stem (iPS) cells. These are made by reprogramming adult skin cells from a donor into an embryonic-like state from which they can transform into other cell types, such as corneal cells. Nishida said that the woman’s cornea remained clear and her vision had improved since the transplant a month ago. Currently people with damaged or diseased corneas are generally treated using tissue from donors who have died, but there is a long waiting list for such tissue in Japan. Japan has been ahead of the curve in approving the clinical use of iPS cells, which were discovered by stem-cell biologist Shinya Yamanaka at Kyoto University, who won a Nobel prize for the work. Japanese physicians have also used iPS cells to treat spinal cord injury, Parkinson’s disease and another eye disease. © 2019 Springer Nature Publishing AG

Keyword: Vision; Stem Cells
Link ID: 26564 - Posted: 09.03.2019

By Michelle Roberts Health editor, BBC News online Experts are warning about the risks of extreme fussy eating after a teenager developed permanent sight loss after living on a diet of chips and crisps. Eye doctors in Bristol cared for the 17-year-old after his vision had deteriorated to the point of blindness. Since leaving primary school, the teen had been eating only French fries, Pringles and white bread, as well as an occasional slice of ham or a sausage. Tests revealed he had severe vitamin deficiencies and malnutrition damage. Extreme picky eater The adolescent, who cannot be named, had seen his GP at the age of 14 because he had been feeling tired and unwell. At that time he was diagnosed with vitamin B12 deficiency and put on supplements, but he did not stick with the treatment or improve his poor diet. Three years later, he was taken to the Bristol Eye Hospital because of progressive sight loss, Annals of Internal Medicine journal reports. Dr Denize Atan, who treated him at the hospital, said: "His diet was essentially a portion of chips from the local fish and chip shop every day. He also used to snack on crisps - Pringles - and sometimes slices of white bread and occasional slices of ham, and not really any fruit and vegetables. "He explained this as an aversion to certain textures of food that he really could not tolerate, and so chips and crisps were really the only types of food that he wanted and felt that he could eat." Dr Atan and her colleagues rechecked the young man's vitamin levels and found he was low in B12 as well as some other important vitamins and minerals - copper, selenium and vitamin D. He was not over or underweight, but was severely malnourished from his eating disorder - avoidant-restrictive food intake disorder. "He had lost minerals from his bone, which was really quite shocking for a boy of his age." He was put on vitamin supplements and referred to a dietitian and a specialist mental health team. In terms of his sight loss, he met the criteria for being registered blind. "He had blind spots right in the middle of his vision," said Dr Atan. "That means he can't drive and would find it really difficult to read, watch TV or discern faces. © 2019 BBC.

Keyword: Vision
Link ID: 26563 - Posted: 09.03.2019

By Stephen L. Macknik In normal vision, light falls on the retinas inside the eyes, and is immediately transduced into electrochemical signals before being uploaded to the brain through the optic nerves. So you do not see light itself, but the brain's interpretation of electrochemical signals in the visual parts of the brain. It follows that, if your eyes do not work, but your brain is stimulated just so, your visual neurons will activate (and you will be able to see) just the same as if your eyes were in perfect condition. Sounds easy, but can we do that? Building on decades of research in visual neuroscience, my lab, in collaboration with Susana Martinez-Conde’s, has now conducted some of the studies that validate this idea, completing some of the most important preliminary steps towards a new kind of visual prosthetic. Francis Collins, the Director of the National Institutes of Health, has just posted a blog that highlights our approach. He took notice of our work when we first presented it at this year's meeting for the Principal Investigators of the BRAIN Initiative—the NIH led government funding initiative meant to spur research along on topics like brain implants. The BRAIN Initiative funds several agencies including the NIH, including the National Science Foundation, who kindly funded the grant driving our research thus far. Our starting premise is that vision is fundamentally a thumbnail sketch. Even if 99.9% of your retina works fine, but the central 1/1000th of your visual field is broken, you will be legally blind. That central 0.1% of your visual field is about the same size as your thumbnail held up at arm's length. Because that central 0.1% of the retina is the visual sweet spot, it is the place where the visual magic happens. In fact, much of the remaining 99.9% of the retina’s main job is to help you detect where to move your eyes next. This means that we need to restore central vision in the blind, or we are not really restoring functional vision at all. © 2019 Scientific American

Keyword: Vision; Robotics
Link ID: 26553 - Posted: 08.29.2019

By Anil K. Seth On the 10th of April this year Pope Francis, President Salva Kiir of South Sudan and former rebel leader Riek Machar sat down together for dinner at the Vatican. They ate in silence, the start of a two-day retreat aimed at reconciliation from a civil war that has killed some 400,000 people since 2013. At about the same time in my laboratory at the University of Sussex in England, Ph.D. student Alberto Mariola was putting the finishing touches to a new experiment in which volunteers experience being in a room that they believe is there but that is not. In psychiatry clinics across the globe, people arrive complaining that things no longer seem “real” to them, whether it is the world around them or their own selves. In the fractured societies in which we live, what is real—and what is not—seems to be increasingly up for grabs. Warring sides may experience and believe in different realities. Perhaps eating together in silence can help because it offers a small slice of reality that can be agreed on, a stable platform on which to build further understanding. Advertisement We need not look to war and psychosis to find radically different inner universes. In 2015 a badly exposed photograph of a dress tore across the Internet, dividing the world into those who saw it as blue and black (me included) and those who saw it as white and gold (half my lab). Those who saw it one way were so convinced they were right—that the dress truly was blue and black or white and gold—that they found it almost impossible to believe that others might perceive it differently. We all know that our perceptual systems are easy to fool. The popularity of visual illusions is testament to this phenomenon. Things seem to be one way, and they are revealed to be another: two lines appear to be different lengths, but when measured they are exactly the same; we see movement in an image we know to be still. The story usually told about illusions is that they exploit quirks in the circuitry of perception, so that what we perceive deviates from what is there. Implicit in this story, however, is the assumption that a properly functioning perceptual system will render to our consciousness things precisely as they are. © 2019 Scientific American

Keyword: Consciousness; Vision
Link ID: 26549 - Posted: 08.29.2019

By Cara Giaimo Peppered moth caterpillars live across the Northern Hemisphere, from the forests of China to the backyards of North America. But if you’ve never seen one, don’t feel bad: They’re experts at blending in. Each caterpillar mimics the twig it perches on, straightening its knobbly body into a stick-like shape. It also changes its hue to match the twig’s color, whether birch white, willow green or dark oak brown. They’re so good at this, in fact, that they can do it blindfolded — literally. According to a paper published in Communications Biology in early August, the caterpillars sense the color of their surroundings not only with their eyes, but also with their skin. While other animals, including cuttlefish and lizards, have similar abilities, this is “the most complete demonstration so far that color change can be controlled by cells outside the eyes,” said Martin Stevens, a professor of sensory and evolutionary ecology at the University of Exeter. Dr. Stevens, who was not involved in the study, added that the exact mechanism remains a mystery. The adult peppered moth is famous for a completely different color journey; After soot from the Industrial Revolution darkened tree bark in Britain, peppered moths there evolved to be darker, too. Ilik Saccheri, a professor of ecological genetics at the University of Liverpool and an author of the new paper, normally studies the adult moth. This requires keeping a lot of caterpillars around. Years of observation sparked his curiosity about their color-changing abilities, which happen individually and in a matter of minutes rather than over generations. Each caterpillar hatches tiny and black, and in its early days is blown around by the wind. Once it falls on a plant, it must camouflage itself to avoid being spotted by hungry birds. This process, which involves producing new pigments, plays out over a period of days or weeks. “I was a bit disbelieving that they could change that accurately only using their eyes,” which are quite simple at the larval stage, Dr. Saccheri said. © 2019 The New York Times Company

Keyword: Vision; Evolution
Link ID: 26547 - Posted: 08.27.2019

By Alison Abbott Marco Tamietto was aware that animal rights activists might target him after his team won ethical approval for an experiment in monkeys on blindness. But he hadn’t anticipated the threats of violence. “I found photographs of my face, my mobile phone number, and home address on Facebook posts,” he says, “with messages like: ‘We will find you and kill you.’” Tamietto, a neuroscientist at the University of Turin in Italy, is under police protection. Now, his colleagues may face similar threats. He learned this month that the Italian Ministry of Health, which approved the experiment in October 2018, has released the names and university affiliations of others involved in the study to Lega Anti Vivisezione (LAV), an animal rights group in Rome. “It’s unpleasant that a public office would do such a thing,” says Roberto Caminiti, a neuroscientist at Sapienza University of Rome whose monkey lab was filmed by undercover activists in 2014. “And paradoxical that the ministry that authorized the research would actually expose those doing the research to danger.” Lawyers at the University of Turin and University of Parma—where the monkey experiments will be carried out—say they are considering civil proceedings in relation to the leak of sensitive information and intellectual property associated with the experimental protocols. Animal research regulations in Italy are already the strictest in Europe. Yet in the past few years, activists have pressed their advantage. Tamietto’s case is a sign that they have a sympathetic ear in government: Minister of Health Giulia Grillo, a member of the populist Five Star party and a declared friend of animal rights groups. © 2019 American Association for the Advancement of Science

Keyword: Animal Rights; Vision
Link ID: 26529 - Posted: 08.22.2019

By Susana Martinez-Conde If you’re older than forty, chances are that reading texts or playing with your smart phone is now harder than it used to be. Such difficulty with near focusing is usually the result of presbyopia, the hardening of the lens of the eye that starts to take place in middle age. From eyeglasses to refractive surgery, many available solutions allow GenXers and baby boomers to read small print and conduct other near-vision tasks to their hearts’ content. The problem is, one of the most prevalent treatments for presbyopia could make you less safe on the road. Broadly, people suffering from presbyopia can opt for eyeglasses, contact lenses or surgery. Eyeglasses include reading glasses (used for close-up vision only), as well as glasses with bifocal, multifocal or progressive lenses (which are worn all day and allow vision at a range of distances). Contact lens correction can work just like with eyeglasses, but it also offers an alternative solution for presbyopia, called monovision. In monovision, one eye is corrected for close-up viewing, and the other eye for long-distance viewing. Thus, at any distance (near or far), at least one eye offers clear vision even when the image from the other eye is blurred. Eventually, the brain learns to suppress the blurred images and rely on the crisp images only, so people can enjoy clear vision at all distances. Finally, those with presbyopia can opt for refractive eye surgery, including monovision LASIK, which typically corrects the nondominant eye for near vision while leaving the dominant eye able to see long distance. Among baby boomers, monovision is the most popular contact lens correction for presbyopia, and monovision LASIK is also on the rise for eligible people over the age of 40. Yet, according to new research by Johannes Burge, Victor Rodriguez-Lopez, and Carlos Dorronsoro at the University of Pennsylvania, monovision corrections could present previously unidentified safety concerns, especially while driving. The reason is related to a century-old illusion called the Pulfrich effect. © 2019 Scientific American

Keyword: Vision
Link ID: 26489 - Posted: 08.12.2019

By Frank Bruni CHIOS, Greece — Over my 54 years, I’ve pinned my hopes on my parents, my teachers, my romantic partners, God. I’m pinning them now on a shrub. It’s called mastic, it grows in particular abundance on the Greek island of Chios and its resin — the goo exuded when its bark is gashed — has been reputed for millenniums to have powerful curative properties. Ancient Greeks chewed it for oral hygiene. Some biblical scholars think the phrase “balm of Gilead” refers to it. It has been used in creams to reduce inflammation and heal wounds, as a powder to treat irritable bowels and ulcers, as a smoke to manage asthma. I’m now part of a clinical trial in the United States to determine if a clear liquid extracted from mastic resin can, through regular injections, repair ravaged nerves. That would have profound implications for millions of Alzheimer’s patients, stroke survivors — and me. The vision in my right eye was ruined by a condition that devastated the optic nerve behind it, and I’m at risk of the same happening on the left side, in which case I wouldn’t be able to see a paragraph like this one. Will a gnarly evergreen related to the pistachio tree save me? That’s unclear. But in the meantime, I thought I should hop on a plane and meet my medicine. Chios has just 50,000 or so year-round residents. It lies much closer to Turkey than to the Greek mainland. And there’s no separating its history from that of mastic. ImageA 17th-century rendering of the island of Chios. A 17th-century rendering of the island of Chios.CreditBridgeman Images In the 1300s and 1400s, when Chios was governed by the Republic of Genoa, the punishment for stealing up to 10 pounds of mastic resin was the loss of an ear; for more than 200 pounds, you were hanged. The stone villages in the southern part of the island, near the mastic groves, were built in the manner of fortresses — with high exterior walls, only a few entrances and labyrinthine layouts — to foil any attempts by invaders to steal the resin stored there. © 2019 The New York Times Company

Keyword: Vision; Development of the Brain
Link ID: 26461 - Posted: 07.29.2019

By Carl Zimmer In a laboratory at the Stanford University School of Medicine, the mice are seeing things. And it’s not because they’ve been given drugs. With new laser technology, scientists have triggered specific hallucinations in mice by switching on a few neurons with beams of light. The researchers reported the results on Thursday in the journal Science. The technique promises to provide clues to how the billions of neurons in the brain make sense of the environment. Eventually the research also may lead to new treatments for psychological disorders, including uncontrollable hallucinations. “This is spectacular — this is the dream,” said Lindsey Glickfeld, a neuroscientist at Duke University, who was not involved in the new study. In the early 2000s, Dr. Karl Deisseroth, a psychiatrist and neuroscientist at Stanford, and other scientists engineered neurons in the brains of living mouse mice to switch on when exposed to a flash of light. The technique is known as optogenetics. In the first wave of these experiments, researchers used light to learn how various types of neurons worked. But Dr. Deisseroth wanted to be able to pick out any individual cell in the brain and turn it on and off with light. So he and his colleagues designed a new device: Instead of just bathing a mouse’s brain in light, it allowed the researchers to deliver tiny beams of red light that could strike dozens of individual brain neurons at once. To try out this new system, Dr. Deisseroth and his colleagues focused on the brain’s perception of the visual world. When light enters the eyes — of a mouse or a human — it triggers nerve endings in the retina that send electrical impulses to the rear of the brain. There, in a region called the visual cortex, neurons quickly detect edges and other patterns, which the brain then assembles into a picture of reality. © 2019 The New York Times Company

Keyword: Vision
Link ID: 26433 - Posted: 07.19.2019

Laura Sanders A praying mantis depends on precision targeting when hunting insects. Now, scientists have identified nerve cells that help calculate the depth perception required for these predators’ surgical strikes. In addition to providing clues about insect vision, the principles of these cells’ behavior, described June 28 in Nature Communications, may also lead to advances in robot vision or other automated systems. So far, praying mantises are the only insects known to be able to see in 3-D. In the new study, neuroscientist Ronny Rosner of Newcastle University in England and colleagues used a tiny theater that played praying mantises’ favorite films — moving disks that mimic bugs. The disks appeared in three dimensions because the insects’ eyes were covered with different colored filters, creating minuscule 3-D glasses. As a praying mantis watched the films, electrodes monitored the behavior of individual nerve cells in the optic lobe, a brain structure responsible for many aspects of vision. There, researchers found four types of nerve cells that seem to help merge the two different views from each eye into a complete 3-D picture, a skill that human vision cells use to sense depth, too. One cell type called a TAOpro neuron possesses three elaborate, fan-shaped bundles that receive incoming visual information. Along with the three other cell types, TAOpro neurons are active when each eye’s view of an object is different, a mismatch that’s needed for depth perception. |© Society for Science & the Public 2000 - 2019.

Keyword: Vision
Link ID: 26422 - Posted: 07.16.2019

By Elizabeth Pennisi PROVIDENCE—Looking a squid in the eye is eerily like looking in a mirror. Squids, octopuses, and other cephalopods are on a very different part of the tree of life from vertebrates. But both have evolved sophisticated peepers that rely on a lens to focus light and provide excellent vision. This independent evolution of such complexity has puzzled biologists for centuries and has prompted searches for clues about how this might have come about. Evolutionary developmental biologists have now discovered that the genes that guide the initial formation of legs in us and other vertebrates also guide the formation of the squid’s lens (seen in cross section of eye above). The find is yet another example of how nature recruits genes used for one purpose to do another job for the body. The squid lens forms as extra-long membranes jutting out for specialized eye cells overlap to form a tight ball. Our lenses are actually degraded cells themselves packed with a clear protein. To learn how the squid lenses form, these researchers carefully tracked where, when, and which genes turn on and off as embryos of Doryteuthis pealeii, a squid commonly served as fried appetizers, develop. © 2019 American Association for the Advancement of Science

Keyword: Vision; Evolution
Link ID: 26421 - Posted: 07.16.2019

By Stephen L. Macknik When Susana Martinez-Conde and I talk to audiences about NeuroMagic—our research initiative to study the brain with magic (and vice-versa), people often ask us how we bring both fields together. They want to know in what ways magic tricks can inform neuroscience, and what a day in the life of a neuromagic scientist looks like. How do we run a neuromagic experiment, from collecting the data to using the results to gain knowledge about the mind's inner secrets? Our new study, led by Anthony Barnhart (aka Magic Tony) and just published in the Journal of Eye Movement Research, illustrates some of the ways in which we investigate magic in the lab. You can download the paper for free, but as it is written for academics, I'll give you the gist here. The experiment addresses how various neural circuits interact in your brain while you watch a magic performance. There's the visual system—critical for perception—there's the oculomotor system—critical for targeting and moving the eyes—and there's the attentional system—critical for filtering out irrelevant information and allowing you to literally and figuratively focus both the visual and oculomotor systems at the right place and at the right time. Without all three of these systems working together, you would be unable to conduct most visual tasks. Advertisement Magic is one of the inroads available to dissect the function of many perceptual and cognitive systems, and especially so in situations that are fairly similar to those we encounter in real life. This concept—ecological validity—is important to testing whether neuroscience theories will hold up outside of the lab, and one of the reasons why magic tricks are attractive for studying everyday perception and cognition. © 2019 Scientific American

Keyword: Vision; Attention
Link ID: 26412 - Posted: 07.13.2019

Partial sight has been restored to six blind people via an implant that transmits video images directly to the brain. Some vision was made possible – with the participants’ eyes bypassed – by a video camera attached to glasses which sent footage to electrodes implanted in the visual cortex of the brain. University College London lecturer and Optegra Eye Hospital surgeon Alex Shortt said it was a significant development by specialists from Baylor Medical College in Texas and the University of California Los Angeles. “Previously all attempts to create a bionic eye focused on implanting into the eye itself. It required you to have a working eye, a working optic nerve,” Shortt told the Daily Mail. “By bypassing the eye completely you open the potential up to many, many more people. “This is a complete paradigm shift for treating people with complete blindness. It is a real message of hope.” How eye-gaze technology brought creativity back into an artist's life The technology has not been proven on those born blind. The US team behind the study asked participants, each of whom has been completely blind for years, to look at a blacked-out computer screen and identify a white square appearing randomly at different locations on the monitor. The majority of the time, they can find the square. © 2019 Guardian News & Media Limited

Keyword: Vision; Robotics
Link ID: 26411 - Posted: 07.13.2019

By Chris Woolston When Sylvia Groth steps through the doors of the Vanderbilt Eye Institute in Nashville, she knows she has a tough day ahead. Before she goes home, she’ll likely have at least one hard talk with a person whose sight has been ravaged by glaucoma. “When I make a diagnosis of advanced glaucoma, I do it with a heavy heart,” the ophthalmologist says. “It’s such an empty feeling to not be able to do anything.” An incurable eye disease that kills vital nerve cells at the back of the retina, glaucoma is a leading cause of irreversible blindness in the world. More than 70 million people have it, and 3 million of them already are blind. Nothing can be done to restore vision once it’s lost, and even the best treatments can’t always slow disease progression. But researchers foresee a time when they can offer therapies to protect nerve cells in the eye and perhaps even restore lost sight. “We’re making advances with every different type of treatment,” ophthalmologist Leonard Levin of McGill University in Montreal says. Researchers have long understood the basics of the most common form of glaucoma, called open-angle glaucoma. The eye is nourished by a clear fluid called the aqueous humor that keeps the eyeball inflated, plump and healthy. But just like a tire, the eye can become overinflated. If the aqueous humor can’t drain properly, pressure inside the eye grows too high and can crush cells within the optic nerve — the sensory cable that carries images from the retina to the optical centers of the brain. Pressure probably hurts nerve cells in other ways too, ophthalmologist Harry Quigley of Johns Hopkins University says. © 1996-2019 The Washington Post

Keyword: Vision
Link ID: 26376 - Posted: 07.02.2019

Millions of people in the UK are putting their sight at risk by continuing to smoke, warn specialists. Despite the clear connection, only one in five people recognise that smoking can lead to blindness, a poll for the Association of Optometrists (AOP) finds. Smokers are twice as likely to lose their sight compared with non-smokers, says the RNIB. That is because tobacco smoke can cause and worsen a number of eye conditions. How smoking can harm your eyes Cigarette smoke contains toxic chemicals that can irritate and harm the eyes. For example, heavy metals, such as lead and copper, can collect in the lens - the transparent bit that sits behind the pupil and brings rays of light into focus - and lead to cataracts, where the lens becomes cloudy. Smoking can make diabetes-related sight problems worse by damaging blood vessels at the back of the eye (the retina). Smokers are around three times more likely to get age-related macular degeneration - a condition affecting a person's central vision, meaning that they lose their ability to see fine details. And they are 16 times more likely than non-smokers to develop sudden loss of vision caused by optic neuropathy, where the blood supply to the eye becomes blocked. In the poll of 2,006 adults, 18% correctly said that smoking increased the risk of blindness or sight loss, while three-quarters (76%) knew smoking was linked to cancer. © 2019 BBC

Keyword: Drug Abuse; Vision
Link ID: 26375 - Posted: 07.02.2019

Laura Sanders Some nerve cells in the brain are multitaskers, responding to both color and shape, a survey of over 4,000 neurons in the visual systems of macaque monkeys finds. The finding, described in the June 28 Science, counters earlier ideas that vision cells nestled in the back of the brain each handle information about only one aspect of sight: an object’s color or its orientation, an element of shape. Some scientists had thought that those aspects were then put together by other brain cells in later stages of visual processing to form a more complete picture of the world. In the new experiment, four macaques looked at a series of sights made of moving lines on a screen. Each time, the lines were one of 12 possible colors and moved at particular angles, creating an effect similar to a spinning candy cane in two dimensions. Using genetic tricks that made nerve cells glow when active, the researchers watched for action among the monkeys’ cells in an area of the brain that handles vision. Called V1, this stretch at the back of the brain is one of the first areas to interpret sight signals. Most of the cells that had a favorite color, indicated by their activity, also had a favorite orientation of lines, the researchers found. “Thus, textbook models of primate V1 must be updated,” the team writes. PUTTING IT TOGETHER This video captures nerve cells in a monkey’s visual system firing off signals. Some of these cells respond both to a favorite color and favorite shape. The discovery counters previous ideas that information about color is processed separately from information about shape in the brain. |© Society for Science & the Public 2000 - 2019.

Keyword: Vision
Link ID: 26374 - Posted: 07.02.2019

Even if you know that looking at a phone, tablet or computer screen at night is bad for your sleep, it’s hard to stop. That’s one reason there has been a growing interest in glasses or apps that can block the blue parts of the light spectrum that experts say are especially bad for sleep. This light doesn’t necessarily appear blue; it’s part of any bright white light, says Charles Czeisler, chief of the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital in Boston. “Our light exposure between when the sun sets and the sun rises is probably the primary driver of sleep deficiency in our society,” Czeisler says. While that includes artificial light of all kinds, light from electronic devices that emit blue light — such as the LED displays in smartphones, tablets, and modern computer and TV screens — is particularly troublesome for sleep, he says. A number of studies indicate that using blue-blocking glasses and apps like f.lux or Apple’s Night Shift mode may improve sleep in certain cases, but they won’t cure insomnia on their own. Experts say much more research is needed on how well they work, who can benefit the most and how to best use them. Still, they may help, though thinking about light exposure throughout the day may be even more useful. “It just depends on how many problems a person is having with their sleep,” says Lisa Ostrin, an assistant professor at the University of Houston College of Optometry who has conducted research into ways that blocking blue light affects sleep. To understand how glasses or apps affect sleep, it helps to understand light’s role in the first place. © 1996-2019 The Washington Post

Keyword: Sleep; Vision
Link ID: 26353 - Posted: 06.25.2019

By Tim Vernimmen The image above, “A Sunday Afternoon on the Island of La Grande Jatte,” was painted in 1884 by French artist Georges Seurat. The black lines crisscrossing it are not the work of a toddler wreaking havoc with a permanent marker, but that of neuroscientist Robert Wurtz of the National Eye Institute in the US. Ten years ago, he asked a colleague to look at the painting while wearing a contact lens–like contraption that recorded the colleague’s eye movements. These were then translated into the graffiti you see here. Art lovers may cringe, yet it is likely that Seurat would have been intrigued by this augmentation of his work. The movement Seurat kick-started with this painting — Neo-Impressionism — drew inspiration from the scientific study of how our vision works. Particularly influential was the pioneering research of Hermann von Helmholtz, a German physician, physicist and philosopher and author of a seminal 1867 book, Handbook of Physiological Optics, on the way we perceive depth, color and motion. One of the questions that occupied Helmholtz, and quite possibly Seurat, is why we don’t perceive the constant eye movements we make when we are scanning our surroundings (or a painted representation of them). Consider that the lines above were drawn in just three minutes. If we saw all those movements as we made them, our view of the world would be a blur of constant motion. As Wurtz and his Italian colleagues Paola Binda and Maria Concetta Morrone explain in two articles in the Annual Review of Vision Science, there’s a lot we know about why that doesn’t happen — and more yet to learn.

Keyword: Vision
Link ID: 26341 - Posted: 06.20.2019

By Madison Dapcevich An optical illusion designed by researchers to test how contrast deceives the brain appears to show a diamond moving across the screen, twitching up and down and left to right, without ever physically changing location. Dubbed the “Perceptual Diamond”, the illusion “produces motion continuously and unambiguously” to trick the viewer into thinking it is moving around the screen, yet it remains steady and slightly illuminated. Rather, its motion is mimicked by changing the contrast between the edges of strips around the diamond’s edges and the background. Shifts in contrasts around the edges, like in this illusion, can create the perception of motion. The Perpetual Diamond illusion provides no clues as to its orientation or direction until it is animated, generating movement through contrast signals alone, wrote the authors in i-Perception. "We often take the perception of motion for granted because we assume that motion corresponds to objects shifting location in the real world," explained study author Arthur Shapiro, from the American University in Washington DC, in an email to IFLScience. "However, the brain has many processes that can lead to the perception of motion, and there are many types of images that can stimulate these processes." Depending on the combination of illuminated edges, the diamond will appear to move in different directions. For example, if the two top edges blink between black and white and the two bottom edges do the opposite, the diamond appears to continuously move upward.

Keyword: Vision
Link ID: 26337 - Posted: 06.19.2019

Strobe lighting at music festivals can increase the risk of epileptic seizures, researchers have warned. The Dutch team said even people who have not been diagnosed with epilepsy might be affected. Their study was prompted by the case of a 20-year-old, with no history of epilepsy, who suddenly collapsed and had a fit at a festival. The Epilepsy Society said festivals should limit lighting to the recommended levels. Epilepsy is a condition that affects the brain. There are many types, and it can start at any age. Around 3% of people with epilepsy are photosensitive, which means their seizures are triggered by flashing or flickering lights, or patterns. The Health and Safety Executive recommends strobe lighting should be kept to a maximum of four hertz (four flashes per second) in clubs and at public events. 'Life-affirming' The researchers studied electronic dance music festivals because they often use strobe lighting. They looked at data on people who needed medical care among the 400,000 visitors to 28 day and night-time dance music festivals across the Netherlands in 2015. The figures included 241,000 people who were exposed to strobe lights at night-time festivals. Thirty people at night-time events with strobe lighting had a seizure, compared with nine attending daytime events. The team, led by Newel Salet of the VU Medical Centre in Amsterdam, writing in BMJ Open, said other factors could increase the risk of seizures. But they added: "Regardless of whether stroboscopic lights are solely responsible or whether sleep deprivation and/or substance abuse also play a role, the appropriate interpretation is that large [electronic dance music] festivals, especially during the night-time, probably cause at least a number of people per event to suffer epileptic seizures." They advise anyone with photosensitive epilepsy to either avoid such events or to take precautionary measures, such as getting enough sleep and not taking drugs, not standing close to the stage, and leaving quickly if they experience any "aura" effects. © 2019 BBC

Keyword: Epilepsy; Vision
Link ID: 26323 - Posted: 06.12.2019