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Gene therapy and CRISPR strategies for curing blindness (Yes, you read that right)

Hemant Khanna In recent months, even as our attention has been focused on the coronavirus outbreak, there have been a slew of scientific breakthroughs in treating diseases that cause blindness. Researchers at U.S.-based Editas Medicine and Ireland-based Allergan have administered CRISPR for the first time to a person with a genetic disease. This landmark treatment uses the CRISPR approach to a specific mutation in a gene linked to childhood blindness. The mutation affects the functioning of the light-sensing compartment of the eye, called the retina, and leads to loss of the light-sensing cells. According to the World Health Organization, at least 2.2 billion people in the world have some form of visual impairment. In the United States, approximately 200,000 people suffer from inherited forms of retinal disease for which there is no cure. But things have started to change for good. We can now see light at the end of the tunnel. I am an ophthalmology and visual sciences researcher, and am particularly interested in these advances because my laboratory is focusing on designing new and improved gene therapy approaches to treat inherited forms of blindness. The eye as a testing ground for CRISPR Gene therapy involves inserting the correct copy of a gene into cells that have a mistake in the genetic sequence of that gene, recovering the normal function of the protein in the cell. The eye is an ideal organ for testing new therapeutic approaches, including CRISPR. That is because the eye is the most exposed part of our brain and thus is easily accessible. © 2010–2020, The Conversation US, Inc.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27327 - Posted: 06.26.2020

“Reality” is constructed by your brain. Here’s what that means, and why it matters.

By Brian Resnick@B_resnickbrian@vox.com Fix your gaze on the black dot on the left side of this image. But wait! Finish reading this paragraph first. As you gaze at the left dot, try to answer this question: In what direction is the object on the right moving? Is it drifting diagonally, or is it moving up and down? Remember, focus on the dot on the left. It appears as though the object on the right is moving diagonally, up to the right and then back down to the left. Right? Right?! Actually, it’s not. It’s moving up and down in a straight, vertical line. See for yourself. Trace it with your finger. This is a visual illusion. That alternating black-white patch inside the object suggests diagonal motion and confuses our senses. Like all misperceptions, it teaches us that our experience of reality is not perfect. But this particular illusion has recently reinforced scientists’ understanding of deeper, almost philosophical truths about the nature of our consciousness. “It’s really important to understand we’re not seeing reality,” says neuroscientist Patrick Cavanagh, a research professor at Dartmouth College and a senior fellow at Glendon College in Canada. “We’re seeing a story that’s being created for us.” Most of the time, the story our brains generate matches the real, physical world — but not always. Our brains also unconsciously bend our perception of reality to meet our desires or expectations. And they fill in gaps using our past experiences. All of this can bias us. Visual illusions present clear and interesting challenges for how we live: How do we know what’s real? And once we know the extent of our brain’s limits, how do we live with more humility — and think with greater care about our perceptions?

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27321 - Posted: 06.24.2020

This shrimp has some of the fastest eyes on the planet

By Elizabeth Pennisi Though not much bigger than a wooden match stick, snapping shrimp (Alpheus heterochaelis, pictured) are already famous for their loud, quick closing claws, the sound of which stuns their prey and rivals. Now, researchers have discovered these marine crustaceans have the eyesight to match this speed. In the new study, scientists stuck a thin conducting wire into the eye of a chilled, live shrimp and recorded electrical impulses from the eye in response to flickering light. The crustaceans refresh their view 160 times a second, the team reports today in Biology Letters. That’s one of the highest refresh rates of any animal on Earth. Pigeons come close, being able to sample their field of view 143 times per second, whereas humans top out at a relatively measly 60 times a second. Only some day-flying insects beat the snapping shrimp, the researchers report. As a result, what people—perhaps even Superman—and all other vertebrates see as a blur, the shrimp detects as discrete images moving across its field of vision. Until a few years ago, most researchers assumed snapping shrimp didn’t see very well because they have a hard hood called a carapace that extends over their eyes. Although the hood seems transparent, with some coloration, it wasn’t clear how well it transmitted light. But it appears to be no impediment to the shrimp detecting fast moving prey or even predators whipping by. This might be important because the shrimp tend to live in cloudy water, so they don’t have much notice when another critter is approaching them. Posted in: © 2020 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: 27318 - Posted: 06.24.2020

Hummingbirds Navigate an Ultraviolet World We Never See

By Veronique Greenwood Hummingbirds were already impressive. They move like hurried insects, turn on aerial dimes and extract nectar from flowers with almost surgical precision. But they conceal another talent, too: seeing colors that human eyes can’t perceive. Ultraviolet light from the sun creates colors throughout the natural world that are never seen by people. But researchers working out of the Rocky Mountain Biological Laboratory reported on Monday in Proceedings of the National Academy of Sciences that untrained broad-tailed hummingbirds can use these colors to help them identify sources of food. Testing 19 pairings of colors, the team found that hummingbirds are picking up on multiple colors beyond those we can see. From the bird’s-eye view, numerous plants and feathers have these as well, suggesting that they live in a richer-hued world than we do, full of signs and messages that we never notice. Compared with the color vision of many other animals, that of humans leaves something to be desired. The perception of color relies on cone cells in the retina, each of which responds to different wavelengths of light. Humans have three kinds of cone cells, which, when light reflects off an apple, a leaf or a field of daffodils, send signals that are combined in the brain to generate the perception of red, green or yellow. Birds, however, have four types of cones, including one that is sensitive to ultraviolet light. (And they are far from the most generously endowed — mantis shrimp, for instance, have 16.) In lab experiments, birds readily pick up on UV light and UV yellow, a mixture of UV light and visible yellow wavelengths, says Mary Caswell Stoddard, a professor of evolutionary biology at Princeton University and an author of the new study. Likewise, researchers have long known that UV colors are widespread in the natural world, though we can’t see them. However, experiments to see whether wild birds would use UV colors in their daily lives had not yet been performed. © 2020 The New York Times Company

Eye, robot: Artificial intelligence dramatically improves accuracy of classic eye exam

By Marina Wang The classic eye exam may be about to get an upgrade. Researchers have developed an online vision test—fueled by artificial intelligence (AI)—that produces much more accurate diagnoses than the sheet of capital letters we’ve been staring at since the 19th century. If perfected, the test could also help patients with eye diseases track their vision at home. “It’s an intriguing idea” that reveals just how antiquated the classic eye test is, says Laura Green, an ophthalmologist at the Krieger Eye Institute. Green was not involved with the work, but she studies ways to use technology to improve access to health care. The classic eye exam, known as the Snellen chart, has been around since 1862. The farther down the sheet a person can read, the better their vision. The test is quick and easy to administer, but it has problems, says Chris Piech, a computer scientist at Stanford University. Patients start to guess at letters when they become blurry, he says, which means they can get different scores each time they take the test. Piech is no stranger to the Snellen test. At age 10, doctors diagnosed him with chronic uveitis, an inflammatory eye disease. “I was sitting through all these tests and it was pretty obvious to me that it was terribly inaccurate,” he says. He wanted to find a way to remove human error from the Snellen exam, while improving its accuracy. © 2020 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: 27281 - Posted: 06.04.2020

Blind People Could ‘See’ Letters That Scientists Drew on Their Brains with Electricity

By Nicoletta Lanese, Scientists sent patterns of electricity coursing across people’s brains, coaxing their brains to see letters that weren’t there. The experiment worked in both sighted people and blind participants who had lost their sight in adulthood, according to the study, published today (May 14) in the journal Cell. Although this technology remains in its early days, implanted devices could potentially be used in the future to stimulate the brain and somewhat restore people’s vision. Known as visual prosthetics, the implants were placed on the visual cortex and then stimulated in a pattern to “trace” out shapes that the participants could then “see.” More advanced versions of these implants could work similarly to cochlear implants, which stimulate nerves of the inner ear with electrodes to help enhance the wearer’s hearing ability. “An early iteration [of such a device] could provide detection of the contours of shapes encountered,” study authors neuroscientist Michael Beauchamp and neurosurgeon Dr. Daniel Yoshor, both at the Baylor College of Medicine, told Live Science in an email. (Yoshor will start a new position at the Perelman School of Medicine at the University of Pennsylvania this summer.) “The ability to detect the form of a family member or to allow more independent navigation would be a wonderful advance for many blind patients.” The study authors crafted the letters by stimulating the brain with electrical currents, causing it to generate so-called phosphenes — tiny pinpricks of light that people sometimes perceive without any actual light entering their eyes. © 2020 Scientific American

Researchers restore sight in mice by turning skin cells into light-sensing eye cells

Researchers have discovered a technique for directly reprogramming skin cells into light-sensing rod photoreceptors used for vision. The lab-made rods enabled blind mice to detect light after the cells were transplanted into the animals’ eyes. The work, funded by the National Eye Institute (NEI), published April 15 in Nature. The NEI is part of the National Institutes of Health. Up until now, researchers have replaced dying photoreceptors in animal models by creating stem cells from skin or blood cells, programming those stem cells to become photoreceptors, which are then transplanted into the back of the eye. In the new study, scientists show that it is possible to skip the stem-cell intermediary step and directly reprogram skins cells into photoreceptors for transplantation into the retina. “This is the first study to show that direct, chemical reprogramming can produce retinal-like cells, which gives us a new and faster strategy for developing therapies for age-related macular degeneration and other retinal disorders caused by the loss of photoreceptors,” said Anand Swaroop, Ph.D., senior investigator in the NEI Neurobiology, Neurodegeneration, and Repair Laboratory, which characterized the reprogrammed rod photoreceptor cells by gene expression analysis. “Of immediate benefit will be the ability to quickly develop disease models so we can study mechanisms of disease. The new strategy will also help us design better cell replacement approaches,” he said. Scientists have studied induced pluripotent stem (iPS) cells with intense interest over the past decade. IPSCs are developed in a lab from adult cells —rather than fetal tissue— and can be used to make nearly any type of replacement cell or tissue. But iPS cell reprogramming protocols can take six months before cells or tissues are ready for transplantation. By contrast, the direct reprogramming described in the current study coaxed skin cells into functional photoreceptors ready for transplantation in only 10 days. The researchers demonstrated their technique in mouse eyes, using both mouse- and human-derived skin cells.

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: 27196 - Posted: 04.16.2020

Proteins that sense light also sense taste, at least in fruit flies

By Mitch Leslie Like many animals, you couldn’t see without proteins called opsins, which dwell in the light-sensitive cells of your eyes. A new study reveals for the first time that fruit flies can also use some of these proteins, nestled at the tip of their nose, to taste noxious molecules in their food. Opsins in our bodies could also serve the same function, researchers speculate. The results are “paradigm shifting,” says sensory biologist Phyllis Robinson of the University of Maryland, Baltimore County, who wasn’t connected to the research. The most famous opsin forms the backbone of rhodopsin, the pigment in eye cells known as rods that allow you to see in low light. Your cone cells, which permit vision in bright light, harbor different opsins. Altogether, researchers have uncovered about 1000 other varieties of the proteins in various animals and microbes since rhodopsin was discovered more than 150 years ago. But the opsin molecular family still offers some surprises, notes neuroscientist Craig Montell of the University of California, Santa Barbara. A handful of studies, including one in 2011 by Montell and his team, have implicated opsins in hearing, touch, and temperature detection. Montell and colleagues wanted to determine whether any opsins play a role in taste—specifically, whether flies use them to detect a bitter molecule they are known to dislike. The researchers set up a taste test for unmodified Drosophila melanogaster fruit flies and for seven strains that had been genetically altered to each lack a different opsin. All of the flies had the choice between two sugar solutions, one of which was spiked with the bitter compound. © 2020 American Association for the Advancement of Science

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 7: Vision: From Eye to Brain
Link ID: 27166 - Posted: 04.03.2020

The Brain Reshapes Our Malleable Senses to Fit the World

Richard Masland The eye is something like a camera, but there is a whole lot more to vision than that. One profound difference is that our vision, like the rest of our senses, is malleable and modifiable by experience. Take the commonplace observation that people deprived of one sense may have a compensatory increase in others — for example, that blind people have heightened senses of hearing and touch. A skeptic could say that this was just a matter of attention, concentration and practice at the task, rather than a true sensory improvement. Indeed, experiments show that a person’s sensory acuity can achieve major improvement with practice. Yet with modern methodologies, neuroscientists have conclusively proved that the circuits of the brain neurons do physically change. Our senses are malleable because the sensory centers of the brain rewire themselves to strike a useful balance between the capacities of the available neural resources and the demands put on them by incoming sensory impressions. Studies of this phenomenon are revealing that some sensory areas have innate tendencies toward certain functions, but they show just as powerfully the plasticity of the developing brain. Take a rat that has been deprived of vision since birth — let’s say because of damage to both retinas. When the rat grows up, you train that rat to run a maze. Then you damage the visual cortex slightly. You ask the rat to run the maze again and compare its time before the operation and after. In principle, damaging the visual cortex should not do anything to the maze-running ability of that blind rat. But the classic experimental finding made decades ago by Karl Lashley of Yerkes Laboratories of Primate Biology and others is that the rat’s performance gets worse, suggesting that the visual cortex in the blind rat was contributing something, although we do not know what it was. All Rights Reserved © 2020

A tooth-enamel protein is found in eyes with a common form of macular degeneration

By Alex Fox Deposits of a mineral found in tooth enamel at the back of the eye could be hastening the progression of age-related macular degeneration, the leading cause of deteriorating eyesight in people over 50. Now researchers have identified a protein called amelotin that experiments suggest is involved in producing the mineral deposits that are the hallmark of “dry” age-related macular degeneration, the most common of the two forms of the disease. Age-related macular degeneration, or AMD, affects about 3 million people in the United States. But the new finding, if confirmed, could change that. While the “wet” form of AMD, which comprises up to 30 percent of AMD cases, can be treated with injections, there are currently no treatments for dry AMD. “Finding amelotin in these deposits makes it a target to try to slow the progression of mineralization, which, if it’s borne out, could result in new therapies,” says Imre Lengyel, an ophthalmologist at Queen’s University Belfast in Scotland who was not involved in the research. These deposits, first documented in 2015, are made of a type of mineralized calcium called hydroxyapatite and appear beneath the retinal pigment epithelium — a layer of cells just outside the retina that keeps its light-sensing rods and cones happy and healthy. The deposits may worsen vision by blocking the flow of oxygen and nutrients needed to nourish those light-sensitive cells of the retina. By contrast, in wet AMD abnormal blood vessels intrude into the retina and often leak. Both types of AMD distort a person’s central vision — the focused, detailed sight needed for reading and recognizing faces — which can make independent living difficult. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27136 - Posted: 03.24.2020

NIH researchers discover tooth-enamel protein in eyes with dry AMD

A protein that normally deposits mineralized calcium in tooth enamel may also be responsible for calcium deposits in the back of the eye in people with dry age-related macular degeneration (AMD), according to a study from researchers at the National Eye Institute (NEI). This protein, amelotin, may turn out to be a therapeutic target for the blinding disease. The findings were published in the journal Translational Research. NEI is part of the National Institutes of Health. “Using a simple cell culture model of retinal pigment epithelial cells, we were able to show that amelotin gets turned on by a certain kind of stress and causes formation of a particular kind of calcium deposit also seen in bones and teeth. When we looked in human donor eyes with dry AMD, we saw the same thing,” said Graeme Wistow, Ph.D., chief of the NEI Section on Molecular Structure and Functional Genomics, and senior author of the study. There are two forms of AMD – wet and dry. While there are treatments that can slow the progression of wet AMD, there are currently no treatments for dry AMD, also called geographic atrophy. In dry AMD, deposits of cholesterol, lipids, proteins, and minerals accumulate at the back of the eye. Some of these deposits are called soft drusen and have a specific composition, different from deposits found in wet AMD. Drusen form under the retinal pigment epithelium (RPE), a layer of cells that transports nutrients from the blood vessels below to support the light-sensing photoreceptors of the retina above them. As the drusen develop, the RPE and eventually the photoreceptors die, leading to blindness. The photoreceptors cannot grow back, so the blindness is permanent.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27118 - Posted: 03.14.2020

CRISPR treatment inserted directly into the body for first time

Heidi Ledford A person with a genetic condition that causes blindness has become the first to receive a CRISPR–Cas9 gene therapy administered directly into their body. The treatment is part of a landmark clinical trial to test the ability of CRISPR–Cas9 gene-editing techniques to remove mutations that cause a rare condition called Leber’s congenital amaurosis 10 (LCA10). No treatment is currently available for the disease, which is a leading cause of blindness in childhood. For the latest trial, the components of the gene-editing system – encoded in the genome of a virus — are injected directly into the eye, near photoreceptor cells. By contrast, previous CRISPR–Cas9 clinical trials have used the technique to edit the genomes of cells that have been removed from the body. The material is then infused back into the patient. “It’s an exciting time,” says Mark Pennesi, a specialist in inherited retinal diseases at Oregon Health & Science University in Portland. Pennesi is collaborating with the pharmaceutical companies Editas Medicine of Cambridge, Massachusetts, and Allergan of Dublin to conduct the trial, which has been named BRILLIANCE. This is not the first time gene editing has been tried in the body: an older gene-editing system, called zinc-finger nucleases, has already been administered directly into people participating in clinical trials. Sangamo Therapeutics of Brisbane, California, has tested a zinc-finger-based treatment for a metabolic condition called Hunter’s syndrome. The technique inserts a healthy copy of the affected gene into a specific location in the genome of liver cells. Although it seems to be safe, early results suggest it might do little to ease the symptoms of Hunter’s syndrome. © 2020 Springer Nature Limited

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27100 - Posted: 03.06.2020

Do you like weird art? Blame your brain

By Sara Reardon To many people’s eyes, artist Mark Rothko’s enormous paintings are little more than swaths of color. Yet a Rothko can fetch nearly $100 million. Meanwhile, Pablo Picasso’s warped faces fascinate some viewers and terrify others. Why do our perceptions of beauty differ so widely? The answer may lie in our brain networks. Researchers have now developed an algorithm that can predict art preferences by analyzing how a person’s brain breaks down visual information and decides whether a painting is “good.” The findings show for the first time how intrinsic features of a painting combine with human judgment to give art value in our minds. Most people—including researchers—consider art preferences to be all over the map, says Anjan Chatterjee, a neurologist and cognitive neuroscientist at the University of Pennsylvania who was not involved in the study. Many preferences are rooted in biology–sugary foods, for instance, help us survive. And people tend to share similar standards of beauty when it comes to human faces and landscapes. But when it comes to art, “There are relatively arbitrary things we seem to care about and value,” Chatterjee says. To figure out how the brain forms value judgments about art, computational neuroscientist Kiyohito Iigaya and his colleagues at the California Institute of Technology first asked more than 1300 volunteers on the crowdsourcing website Amazon Mechanical Turk to rate a selection of 825 paintings from four Western genres including impressionism, cubism, abstract art, and color field painting. Volunteers were all over the age of 18, but researchers didn’t specify their familiarity with art or their ethnic or national origin. © 2020 American Association for the Advancement of Science

Related chapters from BN: Chapter 18: Attention and Higher Cognition; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 14: Attention and Higher Cognition; Chapter 7: Vision: From Eye to Brain
Link ID: 27062 - Posted: 02.21.2020

Gene therapy to halt rare form of sight loss

Fergus Walsh Medical correspondent A new gene therapy has been used to treat patients with a rare inherited eye disorder which causes blindness. It's hoped the NHS treatment will halt sight loss and even improve vision. Matthew Wood, 48, one of the first patients to receive the injection, told the BBC: "I value the remaining sight I have so if I can hold on to that it would be a big thing for me." The treatment costs around £600,000 but NHS England has agreed a discounted price with the manufacturer Novartis. Luxturna (voretigene neparvovec), has been approved by The National Institute for Health and Care Excellence (NICE), which estimates that just under 90 people in England will be eligible for the treatment. The gene therapy is for patients who have retinal dystrophy as a result of inheriting a faulty copy of the RPE65 gene from both parents. The gene is important for providing the pigment that light sensitive cells need to absorb light. Initially this affects night vision but eventually, as the cells die, it can lead to complete blindness. An injection is made into the back of the eye - this delivers working copies of the RPE65 gene. These are contained inside a harmless virus, which enables them to penetrate the retinal cells. Once inside the nucleus, the gene provides the instructions to make the RPE65 protein, which is essential for healthy vision. © 2020 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: 27046 - Posted: 02.18.2020

Killer Neural Wiring That Links Eyes and Wings in 2 Predators

By Veronique Greenwood You might mistake jewel wings for their colorful cousins, dragonflies. New research shows that these two predators share something more profound than their appearance, however. In a paper published this month in Current Biology, Dr. Gonzalez-Bellido and colleagues reveal that the neural systems behind jewel wings’ vision are shared with dragonflies, with whom they have a common ancestor that lived before the dinosaurs. But over the eons, this brain wiring has adapted itself in different ways in each creature, enabling radically different hunting strategies. For flying creatures, instantaneous, highly accurate vision is crucial to survival. Recent research showed that birds of prey that fly faster also see changes in their field of vision more quickly, demonstrating the link between speed on the wing and speed in the brain. But the group of insects that includes jewel wings and dragonflies took to the air long before birds were even on the evolutionary horizon, and their vision is swifter than any vertebrate’s studied thus far, said Dr. Gonzalez-Bellido. Researchers looking to understand how their vision, flight and hunting abilities are connected are thus particularly interested in the neurons that send visual information to the wings. But recordings made in the lab by Dr. Gonzalez-Bellido and her colleagues confirmed that dragonflies rise up in a straight line to seize unsuspecting insects from below, almost like their prey had stepped on a land mine. This eerie climb may contribute to their startling success rate: Dragonflies snag their prey 97 percent of the time. The difference in hunting behavior may be linked to the placement of the insects’ eyes. Jewel wings’ eyes are on either side of the head, facing forward. The eyes of these dragonflies — the species Sympetrum vulgatum, also known as the vagrant darter — encase the top of the insect’s head in an iridescent dome, with a thin line running down the middle the only visible reminder that they may have once been separate. © 2020 The New York Times Company

Twenty-Eight Shades of Shoes

By Stephen L. Macknik The year 2015 will go down in the annals of vision research history as a watershed moment. in which the internet discovered an entirely new visual phenomenon—a dress that half of the world saw as black/blue and the other half as white/gold. Had it not been for social media and its particular way of framing conversations around shared crowd-sourced images, this peculiar visual puzzle might have remained unknown. The idea that an object could look one color under one set of lighting conditions, and another color under another set of lighting conditions, was not new. What was unique about The Dress was that the same image, under the same exact viewing conditions, looked very different to different people. The color ambiguity only became evident when half of the viewers disagreed with the other half, which is probably why social media was so pivotal in its discovery. Vision scientists went bananas. Was it an artifact of different device screens? Did it have to do with gender, culture, education, or some other categorization of brain and persona? How many people—exactly—saw the image one way or the other? This was a dress that sailed a thousand ships. The vision science field eventually verified that the phenomenon was definitely real and not an artifact of viewing conditions. Though the precise underlying mechanisms remain unknown, even now. Similarly ambiguous color images followed the dress, but a main obstacle to figuring out how and why such effects existed was that all of the images were flukes. They were accidental happy snaps created by internet picture-posters. Scientists could not intentionally create new and carefully controlled examples for deep study in the lab. Until now. © 2020 Scientific American

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 26996 - Posted: 01.27.2020

Yes, This Cuttlefish Is Wearing 3-D Glasses

By Veronique Greenwood The cuttlefish hovers in the aquarium, its fins rippling and large, limpid eyes glistening. When a scientist drops a shrimp in, this cousin of the squid and octopus pauses, aims and shoots its tentacles around the prize. There’s just one unusual detail: The diminutive cephalopod is wearing snazzy 3-D glasses. Putting 3-D glasses on a cuttlefish is not the simplest task ever performed in the service of science. “Some individuals will not wear them no matter how much I try,” said Trevor Wardill, a sensory neuroscientist at the University of Minnesota, who with other colleagues managed to gently lift the cephalopods from an aquarium, dab them between the eyes with a bit of glue and some Velcro and fit the creatures with blue-and-red specs. The whimsical eyewear was part of an attempt to tell whether cuttlefish see in 3-D, using the distance between their two eyes to generate depth perception like humans do. It was inspired by research in which praying mantises in 3-D glasses helped answer a similar question. The team’s results, published Wednesday in the journal Science Advances, suggest that, contrary to what scientists believed in the past, cuttlefish really can see in three dimensions. Octopuses and squid, despite being savvy hunters, don’t seem to have 3-D vision like ours. Previous work, more than 50 years ago, had found that one-eyed cuttlefish could still catch prey, suggesting they might be similar. But cuttlefish eyes often focus in concert when they’re hunting, and there is significant overlap in what each eye sees, a promising combination for generating 3-D vision. Dr. Wardill, Rachael Feord, a graduate student at the University of Cambridge, and the team decided to give the glasses a try during visits to the Marine Biological Lab in Woods Hole, Mass. The logic went like this: With each eye covered by a different colored lens, two different-colored versions of a scene, just slightly offset from each other, should pop out into a three-dimensional image. By playing a video on the tank wall of a scuttling pair of shrimp silhouettes, each a different color and separated from each other by varying amounts, the researchers could make a shrimp seem closer to the cuttlefish or farther away. If, that is, the cuttlefish experienced 3-D vision like ours. © 2020 The New York Times Company

This starfish cousin has no eyes, but can still see. Here's how

A cousin of the starfish that resides in the coral reefs of the Caribbean and Gulf of Mexico lacks eyes but can still see, according to scientists who studied the creature. Researchers said on Thursday that the red brittle star, called Ophiocoma wendtii, joins a species of sea urchin as the only creatures known to be able to see without having eyes — known as extraocular vision. The red brittle star possesses this exotic capability thanks to light-sensing cells, called photoreceptors, covering its body and pigment cells, called chromatophores, that move during the day to facilitate the animal's dramatic colour change from a deep reddish-brown in daytime to a striped beige at night. Brittle stars, with five radiating arms extending from a central disk, are related to starfish (also called sea stars), sea cucumbers, sea urchins and others in a group of marine invertebrates called echinoderms. They have a nervous system but no brain. Looking for a safe hiding place The red brittle star — which measure up to about 35 centimetres (14 inches) from arm tip to arm tip — lives in bright and complex habitats, with high predation threats from reef fish. It stays hidden during daytime — making the ability to spot a safe place to hide critical — and comes out at night to feed on detritus. Its photoreceptors are surrounded during daytime by chromatophores that narrow the field of the light being detected, making each photoreceptor like the pixel of a computer image that, when combined with other pixels, makes a whole image. The visual system does not work at night, when the chromatophores contract. "If our conclusions about the chromatophores are correct, this is a beautiful example of innovation in evolution," said Lauren Sumner-Rooney, a research fellow at Oxford University Museum of Natural History, who led the study published in the journal Current Biology. ©2020 CBC/Radio-Canada.

Scientists show mice an Orson Welles movie, then disprove dogma about how vision works

By Sharon Begley @sxbegle The filmgoers didn’t flinch at the scene of the dapper man planting a time bomb in the trunk of the convertible, or tense up as the unsuspecting driver and his beautiful blonde companion drove slowly through the town teeming with pedestrians, or jump out of their seats when the bomb exploded in fiery carnage. And they sure as heck weren’t wowed by the technical artistry of this famous opening shot of Orson Welles’ 1958 noir masterpiece, “Touch of Evil,” a single three-minute take that ratchets up the suspense to 11 on a scale of 1 to 10. In fairness, lab mice aren’t cineastes. But where the rodents fell short as film critics they more than delivered as portals into the brain. As the mice watched the film clip, scientists eavesdropped on each one’s visual cortex. By the end of the study, the textbook understanding of how the brain “sees” had been as badly damaged as the “Touch of Evil” convertible, scientists reported on Monday. The new insights into the workings of the visual cortex, they said, could improve technologies as diverse as self-driving cars and brain prostheses to let the blind see. “Neuroscience lets us make better object recognition systems” for, say, self-driving cars and artificial intelligence-based diagnostics, said Joel Zylberberg of York University, an expert on machine learning and neuroscience who was not involved in the new research. “But computer vision has been hampered by an insufficient understanding of visual processing in the brain.” The “unprecedented” findings in the new study, he said, promise to change that. The textbook understanding of how the brain sees, starting with streams of photons landing on the retina, reflects research from the 1960s that won two of its pioneers a Nobel prize in medicine in 1981. It basically holds that neurons in the primary visual cortex, where the signals go first, respond to edges: vertical edges, horizontal edges, and every edge orientation in between, moving and static. We see a laptop screen because of how its edges abut what’s behind it, sidewalks because of where their edges touch the curb’s. Higher-order brain systems take these rudimentary perceptions and process them into the perception of a scene or object. © 2019 STAT

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 26910 - Posted: 12.21.2019

Lions See These Illusions the Same Way You Do

By Susana Martinez-Conde The many evils of social media notwithstanding, millions of users agree that some of its most delightful aspects include viral illusions and cute cat videos. The potential for synergy was vast in retrospect—but only realized in 2013, when Rasmus Bååth, a cognitive scientist from Lund University in Sweden, blended both elements in a YouTube video of his kitten attacking a printed version of Akiyoshi Kitaoka’s famous “Rotating Snakes” illusion. The clip, which has been viewed more than 6 million times as of this writing, led to subsequent empirical research and an internet survey of cat owners, where 29% of respondents answered that their pets reacted to the Rotating Snakes. The results, published in the journal Psychology in 2014, indicated—though not conclusively—that cats experience illusory motion when they look at the Rotating Snakes pattern, much as most humans do. Now, a team of researchers from University of Padova, Italy, Queen Mary University of London in the UK, and the Parco Natura Viva—Garda Zoological Park in Bussolengo, Italy, has collected additional evidence that cats—in this case, big cats—find the Rotating Snakes Illusion fascinating. Advertisement Intrigued by the earlier study on house cats, Christian Agrillo of the University of Padova and his collaborators set out to determine whether lions at Parco Natura Viva were similarly susceptible to motion illusions, as well as explore the possibility that such patterns might serve as a source of visual enrichment for zoo animals. Their findings were published last month in Frontiers in Psychology. © 2019 Scientific American,

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