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Researchers at the National Eye Institute (NEI) have decoded brain maps of human color perception. The findings, published today in Current Biology, open a window into how color processing is organized in the brain, and how the brain recognizes and groups colors in the environment. The study may have implications for the development of machine-brain interfaces for visual prosthetics. NEI is part of the National Institutes of Health. “This is one of the first studies to determine what color a person is seeing based on direct measurements of brain activity,” said Bevil Conway, Ph.D., chief of NEI’s Unit on Sensation, Cognition and Action, who led the study. “The approach lets us get at fundamental questions of how we perceive, categorize, and understand color.” The brain uses light signals detected by the retina’s cone photoreceptors as the building blocks for color perception. Three types of cone photoreceptors detect light over a range of wavelengths. The brain mixes and categorizes these signals to perceive color in a process that is not well understood. To examine this process, Isabelle Rosenthal, Katherine Hermann, and Shridhar Singh, post-baccalaureate fellows in Conway’s lab and co-first authors on the study, used magnetoencephalography or “MEG,” a 50-year-old technology that noninvasively records the tiny magnetic fields that accompany brain activity. The technique provides a direct measurement of brain cell activity using an array of sensors around the head. It reveals the millisecond-by-millisecond changes that happen in the brain to enable vision. The researchers recorded patterns of activity as volunteers viewed specially designed color images and reported the colors they saw.

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 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 27588 - Posted: 11.21.2020

By Elizabeth Pennisi When Ian Ausprey outfitted dozens of birds with photosensor-containing backpacks, the University of Florida graduate student was hoping to learn how light affected their behavior. The unusual study, which tracked 15 species in Peru’s cloud forest, has now found that eye size can help predict where birds breed and feed—the bigger the eye, the smaller the prey or the darker the environment. The study also suggests birds with big eyes are especially at risk as humans convert forests into farmland. The study reveals a “fascinating new area of sensory biology,” says Richard Prum, an evolutionary biologist at Yale University who was not involved in the new work. It also shows the size of a bird’s eye says a lot about its owner, adds Matthew Walsh, an evolutionary ecologist at the University of Texas, Arlington, also not involved with the work. Light matters—not just for plants, but also for animals. Large eyes have long been associated with the need to see in dim conditions, but very little research has looked in depth at light’s impact on behavior. Recently, scientists have shown that the relative size of frogs’ eyes corresponds to where they live, hunt, and breed. And several studies published in the past 3 years suggest the eyes of killifish and water fleas vary in size depending on the presence of predators. With no predators, even slightly larger eyes offer a potential survival advantage. To find out how eye size might matter for birds, Ausprey and his adviser, Scott Robinson, an ecologist at the Florida Museum of Natural History, turned to the 240 species they had identified in one of Peru’s many cloud forests. The study area included a range of habitats—dense stands of trees, farms with fencerows, shrubby areas, and open ground. Because light can vary considerably by height—for example, in the tropics, the forest floor can have just 1% of the light at the tops of the trees—they included species living from the ground to the treetops. © 2020 American Association for the Advancement of Science.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27554 - Posted: 10.28.2020

By Moises Velasquez-Manoff Jack Gallant never set out to create a mind-reading machine. His focus was more prosaic. A computational neuroscientist at the University of California, Berkeley, Dr. Gallant worked for years to improve our understanding of how brains encode information — what regions become active, for example, when a person sees a plane or an apple or a dog — and how that activity represents the object being viewed. By the late 2000s, scientists could determine what kind of thing a person might be looking at from the way the brain lit up — a human face, say, or a cat. But Dr. Gallant and his colleagues went further. They figured out how to use machine learning to decipher not just the class of thing, but which exact image a subject was viewing. (Which photo of a cat, out of three options, for instance.) One day, Dr. Gallant and his postdocs got to talking. In the same way that you can turn a speaker into a microphone by hooking it up backward, they wondered if they could reverse engineer the algorithm they’d developed so they could visualize, solely from brain activity, what a person was seeing. The first phase of the project was to train the AI. For hours, Dr. Gallant and his colleagues showed volunteers in fMRI machines movie clips. By matching patterns of brain activation prompted by the moving images, the AI built a model of how the volunteers’ visual cortex, which parses information from the eyes, worked. Then came the next phase: translation. As they showed the volunteers movie clips, they asked the model what, given everything it now knew about their brains, it thought they might be looking at. The experiment focused just on a subsection of the visual cortex. It didn’t capture what was happening elsewhere in the brain — how a person might feel about what she was seeing, for example, or what she might be fantasizing about as she watched. The endeavor was, in Dr. Gallant’s words, a primitive proof of concept. And yet the results, published in 2011, are remarkable. The reconstructed images move with a dreamlike fluidity. In their imperfection, they evoke expressionist art. (And a few reconstructed images seem downright wrong.) But where they succeed, they represent an astonishing achievement: a machine translating patterns of brain activity into a moving image understandable by other people — a machine that can read the brain. © 2020 The New York Times Company

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 7: Vision: From Eye to Brain
Link ID: 27448 - Posted: 09.02.2020

Georgina Ferry The lightning flick of the tongue that secures a frog its next meal depends on a rapid response to a small black object moving through its field of view. During the 1950s the British neuroscientist Horace Barlow established that neurons in the frog’s retina were tuned to produce just such a response, not only detecting but also predicting the future position of a passing fly. This discovery raised the curtain on decades of research by Barlow and others, establishing that individual neurons of the billions that make up the visual system contribute to the efficient processing of movement, colour, position and orientation of objects in the visual world. Barlow, who has died aged 98, combined three approaches to the question of how the brain enables us to see. He looked at how people perceive, for example measuring the smallest and faintest spot of light they could reliably detect; he studied the responses of single neurons in the retina and brain to different visual stimuli; and he developed theories to account for the relationship between what neurons are doing and the corresponding visual experience. All his work started from the principle – apparently obvious but not often stated – that a deep, mathematical understanding of what is involved in the psychological process of seeing is an essential basis for exploring how the physiological elements of the visual system serve that end. In a vivid analogy, he wrote: “A wing would be a most mystifying structure if one did not know that birds flew.” He is best known for demanding answers to the question of how such a complex system could work most efficiently. He was influenced by early computer scientists, and was a pioneer in seeing visual signals as information to be processed. His concept of “efficient coding” predicted that of all the information presented to the eye, the brain would transmit the minimum necessary, wasting no energy on redundant signals. © 2020 Guardian News & 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: 27433 - Posted: 08.26.2020

By Katherine J. Wu Dr. Arianne Pontes Oriá stands firm: She does not make animals cry for a living. Technically, only humans can cry, or weep in response to an emotional state, said Dr. Oriá, a veterinarian at the Federal University of Bahia in Brazil. For humans, crying is a way to physically manifest feelings, which are difficult to study and confirm in other creatures. But Dr. Oriá does collect animal tears — the liquid that keeps eyes clean and nourished. In vertebrates, or animals with backbones, tears are vital for vision, Dr. Oriá said. And yet, these captivating fluids have been paid little to no attention, except in a select few mammals. “A lot of vision, we’re not aware of until it’s a problem,” said Sebastian Echeverri, a biologist who studies animal vision but doesn’t work with Dr. Oriá’s team. “We notice when tears are missing.” That’s a bit of a shame, Dr. Oriá said. Because whether it hails from dogs, parrots or tortoises, the stuff that seeps out of animals’ eyes is simply “fascinating,” she said. As she and her colleagues have reported in a series of recent papers, including one published on Thursday in the journal Frontiers in Veterinary Science, tears can be great equalizers: Across several branches of the tree of life, vertebrates seem to swaddle their eyes with fluid in much the same way. But to help them cope with the challenges of various environments, evolution has tinkered with the tears of the world’s creatures in ways that scientists are only beginning to explore. Research like Dr. Oriá’s could offer a glimpse into the myriad paths that eyes have taken to maximize their health and the well-being of the organisms that use them. © 2020 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: 27418 - Posted: 08.15.2020

Children wearing multifocal contact lenses had slower progression of their myopia, according to results from a clinical trial funded by the National Eye Institute, part of the National Institutes of Health. The findings support an option for controlling the condition, also called nearsightedness, which increases the risk of cataracts, glaucoma and retinal detachment later in life. Investigators of the Bifocal Lenses In Nearsighted Kids (BLINK) Study published the results August 11 in JAMA(link is external). “It is especially good news to know that children as young as 7 achieved optimal visual acuity and got used to wearing multifocal lenses much the way they would a single vision contact lens. It’s not a problem to fit younger kids in contact lenses. It’s a safe practice,” said BLINK study chair, Jeffrey J. Walline, O.D., Ph.D., associate dean for research at the Ohio State University College of Optometry Myopia occurs when a child’s developing eyes grow too long from front to back. Instead of focusing images on the retina—the light-sensitive tissue in the back of the eye—images of distant objects are focused at a point in front of the retina. As a result, people with myopia have good near vision but poor distance vision. Single vision prescription glasses and contact lenses are used to correct myopic vision but fail to treat the underlying problem. Multifocal contact lenses – typically used to improve near vision of people over the age of 40 years – correct myopic vision in children while simultaneously slowing myopia progression by slowing eye growth.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 27415 - Posted: 08.12.2020

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

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

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

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

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: 27313 - Posted: 06.22.2020

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

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

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 27250 - Posted: 05.16.2020

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 13: Memory and Learning
Link ID: 27196 - Posted: 04.16.2020

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

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

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 13: Memory and Learning
Link ID: 27143 - Posted: 03.25.2020

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

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

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

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

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