By Nicole Wetsman If a sign tells you To follow the purple skull to your destination, the answer seems simple: Veer left. But isolate the stripes that make up the skulls, and you’ll find neither skull has purple bones; in fact, all the bones are the same color. Slot them back into the banded setting, and they shift to purple and orange. The pigments morph because of the ­Munker-​White illusion, which shifts the perception of two identical color tones when they’re placed against different surrounding hues. No one knows for sure, but the illusion probably results from what David Novick, a computer scientist at the University of Texas at El Paso, calls the color-completion effect. The phenomenon causes an image to skew toward the color of the objects that surround it. In a black-and-white image, a gray element would appear lighter when it’s striped with white, and darker when banded with black. Many neuroscientists think that neural ­signals in charge of relaying information about the pigments in our visual field get averaged—creating a color somewhere in the middle. Here, one skull is covered by blue stripes in the foreground and the other with yellow ones. When the original skulls take on the characteristics of the separate surroundings, they look like different colors entirely. Don’t be fooled: Follow both skulls by going straight. Copyright © 2018 Popular Science

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25806 - Posted: 12.21.2018

Scientists at the National Eye Institute (NEI) have found that neurons in the superior colliculus, an ancient midbrain structure found in all vertebrates, are key players in allowing us to detect visual objects and events. This structure doesn’t help us recognize what the specific object or event is; instead, it’s the part of the brain that decides something is there at all. By comparing brain activity recorded from the right and left superior colliculi at the same time, the researchers were able to predict whether an animal was seeing an event. The findings were published today in the journal Nature Neuroscience. NEI is part of the National Institutes of Health. Perceiving objects in our environment requires not just the eyes, but also the brain’s ability to filter information, classify it, and then understand or decide that an object is actually there. Each step is handled by different parts of the brain, from the eye’s light-sensing retina to the visual cortex and the superior colliculus. For events or objects that are difficult to see (a gray chair in a dark room, for example), small changes in the amount of visual information available and recorded in the brain can be the difference between tripping over the chair or successfully avoiding it. This new study shows that this process – deciding that an object is present or that an event has occurred in the visual field – is handled by the superior colliculus. “While we’ve known for a long time that the superior colliculus is involved in perception, we really wanted to know exactly how this part of the brain controls the perceptual choice, and find a way to describe that mechanism with a mathematical model,” said James Herman, Ph.D., lead author of the study.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25723 - Posted: 11.27.2018

By Michael Price Patient BAA, who is 35, lost her sight when she was 27. She can still detect light and dark, but for all intents and purposes, she is blind. Now, she—and other formerly sighted people—may one day regain a limited form of vision using electrodes implanted in the brain. In a new study, such electrodes caused parts of BAA’s and other people’s visual cortexes to light up in specific patterns, allowing them to see shapes of letters in their mind’s eyes. The work is a step forward in a field that emerged more than 40 years ago but has made relatively little progress. The findings suggest technical ways to stimulate images in the brain “are now within reach,” says Pieter Roelfsema, a neuroscientist who directs the Netherlands Institute for Neuroscience in Amsterdam and wasn’t involved in the work. Research to electrically spur blind people’s brains to see shapes began in the 1970s, when biomedical researcher William Dobelle, then at The University of Utah in Salt Lake City, first implanted electrodes in the brain to stimulate the visual cortex. Typically, the rods and cones in retinas translate light waves into neural impulses that travel to the brain. Specialized layers of cells there, known as the visual cortex, process that information for the rest of the brain to use. Dobelle’s implants took advantage of a phenomenon known as retinal mapping. The visual field—the plane of space you see when you look out into the world—roughly maps onto a segment of the visual cortex. By electrically stimulating parts of this brain map, Dobelle could cause flashes of light called phosphenes to appear in the minds of people who were blind, but who had experienced at least a few years of vision. By stimulating different electrodes, he could get phosphenes to flash in different parts of a person’s visual field. © 2018 American Association for the Advancement of Science

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25697 - Posted: 11.17.2018

Nicola Davis Children should be encouraged to spend time outdoors to reduce their risk of becoming shortsighted, experts have said. Shortsightedness is rising around the world, with the condition said to have reached epidemic proportions in east Asia: estimates suggest about 90% of teenagers and young adults in China have the condition. While genetics are thought to play a large role in who ends up shortsighted – a condition that is down to having an overly long eyeball – research also suggests environmental factors are important. Several studies have found children who spend more time outdoors have a lower risk of myopia. While some report that looking into the distance could be important, others say exposure to outdoor light is key. Experts say they have found new factors, and confirmed others, which could affect a child’s risk of becoming shortsighted. These include playing computer games, being born in the summer and having a more highly educated mother. “There is not much you can do about when your child is born … but periods indoors doing indoor activities does increase your risk of myopia,” said Katie Williams, an author of the study by King’s College London. “A healthy balance of time outdoors and a balance during early education is important.” Writing in the British Journal of Ophthalmology, Williams and her colleagues report how they used data from the twins early development study, which followed children born in England and Wales between 1994 and 1996. The project tracked their development, behaviour and education through questionnaires and tests, and studied their genetics. © 2018 Guardian News and Media Limited

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 4: Development of the Brain
Link ID: 25653 - Posted: 11.07.2018

By James Gorman If you love spiders, you will really love jumping spiders. (If you hate spiders, try reading this article on dandelions.) O.K., if you’re still here, jumping spiders are predators that stalk their prey and leap on them, like a cat. They are smart, agile and have terrific eyesight. It has been clear for a long time that their vision is critical to the way they hunt, and to the accuracy of their leaps. But a lot has remained unknown about the way their eyes work together. To find out more, Elizabeth Jakob, a spider biologist at the University of Massachusetts, led a team of researchers from the United States, Kenya and New Zealand in an investigation of spider vision. The first step was getting a custom-built spider eye tracker, similar to ones used on humans, to follow a spider’s gaze. Actually, Dr. Jakob had two made, probably the only two in the world. She has one and her colleagues in New Zealand have the other. Jumping spiders have eight eyes. Two big eyes, right in the center of what you might call the spider’s forehead, are the principal ones, and they pick up detail and color. Of the other three pairs, a rear set looks backward, a middle set is as yet a bit of a mystery, and the foremost detect motion. The lenses of the main eyes are attached by flexible tubes to retinas. A camera was set up to look down those tubes and see the activity of the retinas, which look a bit like boomerangs. The inside of the spider’s head was lit by ultraviolet light, which penetrates the outer carapace. But as accurate as the main eyes are, they only see what is in front of them. If they had to find prey, it would be like using a narrow flashlight beam to explore a dark room. Not very efficient. The researchers found that the front pair of secondary eyes, the motion detectors, tell the main pair of eyes where to look. When they were painted over temporarily and the spider was presented with moving images, it had no idea where to look. © 2018 The New York Times Company

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25648 - Posted: 11.06.2018

Amanda B. Keener If Leonardo da Vinci had a good eye doctor, he might not have become such a great artist. At least that’s what an analysis of paintings and sculptures believed to be modeled after da Vinci suggests. Visual neuroscientist Christopher Tyler of the City University of London examined six pieces of art, including Salvator Mundi and Vitruvian Man. Five of the pieces depict an eye misalignment consistent with a disorder called exotropia that can interfere with three-dimensional vision, Tyler reports online October 18 in JAMA Ophthalmology. Exotropia, in which one eye turns slightly outward, is one of several eye disorders collectively called strabismus. Today, strabismus, which affects 4 percent of people in the United States, is treated with special glasses, eye patches or surgery. Tyler calculated the differences in eye alignment using the same sorts of measurements that an optometrist does when tailoring a pair of glasses. Most of the portraits showed the eyes misaligned, but Vitruvian Man by da Vinci himself did not. As a result, da Vinci may have had intermittent exotropia, present only some of the time and perhaps controllable, Tyler suspects. “The person [with intermittent exotropia] can align their eyes and see in 3-D, but if they’re inattentive or tired, the eye may droop,” he says. If da Vinci could control his exotropia, Tyler speculates that it would have been an artistic advantage. “The artist’s job is to paint on a 2-D surface,” he says. “This can be difficult when you view the world three-dimensionally.” Both eyes need to focus on the same subject for 3-D vision. Many artists shut one eye when viewing their subjects to more easily translate details into two dimensions. But with intermittent exotropia, da Vinci could have switched from 3-D to 2-D and back again with ease. |© Society for Science & the Public 2000 - 201

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25596 - Posted: 10.22.2018

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.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 4: 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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25532 - Posted: 10.05.2018

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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 4: Development of the Brain
Link ID: 25412 - Posted: 09.04.2018

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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 11: Emotions, Aggression, and Stress
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 25174 - Posted: 07.05.2018