Jean Bennett Gene therapy is a set of techniques that harness DNA or RNA to treat or prevent disease. Gene therapy treats disease in three primary ways: by substituting a disease-causing gene with a healthy new or modified copy of that gene; turning genes on or off; and injecting a new or modified gene into the body. Get facts about the coronavirus pandemic and the latest research How has gene therapy changed how doctors treat genetic eye diseases and blindness? In the past, many doctors did not think it necessary to identify the genetic basis of eye disease because treatment was not yet available. However, a few specialists, including me and my collaborators, identified these defects in our research, convinced that someday treatment would be made possible. Over time, we were able to create a treatment designed for individuals with particular gene defects that lead to congenital blindness. This development of gene therapy for inherited disease has inspired other groups around the world to initiate clinical trials targeting other genetic forms of blindness, such as choroideremia, achromatopsia, retinitis pigmentosa and even age-related macular degeneration, all of which lead to vision loss. There are at least 40 clinical trials enrolling patients with other genetic forms of blinding disease. Gene therapy is even being used to restore vision to people whose photoreceptors – the cells in the retina that respond to light – have completely degenerated. This approach uses optogenetic therapy, which aims to revive those degenerated photoreceptors by adding light-sensing molecules to cells, thereby drastically improving a person’s vision. © 2010–2023, 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: 28781 - Posted: 05.13.2023

A National Institutes of Health team has identified a compound already approved by the U.S. Food and Drug Administration that keeps light-sensitive photoreceptors alive in three models of Leber congenital amaurosis type 10 (LCA 10), an inherited retinal ciliopathy disease that often results in severe visual impairment or blindness in early childhood. LCA 10 is caused by mutations of the cilia-centrosomal gene (CEP290). Such mutations account for 20% to 25% of all LCA – more than any other gene. In addition to LCA, CEP290 mutations can cause multiple syndromic diseases involving a range of organ systems. Using a mouse model of LCA10 and two types of lab-created tissues from stem cells known as organoids, the team screened more than 6,000 FDA-approved compounds to identify ones that promoted survival of photoreceptors, the types of cells that die in LCA, leading to vision loss. The high-throughput screening identified five potential drug candidates, including Reserpine, an old medication previously used to treat high blood pressure. Observation of the LCA models treated with Reserpine shed light on the underlying biology of retinal ciliopathies, suggesting new targets for future exploration. Specifically, the models showed a dysregulation of autophagy, the process by which cells break down old or abnormal proteins, which in this case resulted in abnormal primary cilia, a microtubule organelle that protrudes from the surface of most cell types. In LCA10, CEP290 gene mutations cause dysfunction of the primary cilium in retinal cells. Reserpine appeared to partially restore autophagy, resulting in improved primary cilium assembly.

Related chapters from BN: Chapter 1: Introduction: Scope and Outlook; 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: 28720 - Posted: 03.29.2023

By Jack Tamisiea Even a fisher’s yarn would sell a whale shark short. These fish—the biggest on the planet—stretch up to 18 meters long and weigh as much as two elephants. The superlatives don’t end there: Whale sharks also have one of the longest vertical ranges of any sea creature, filter feeding from the surface of the ocean to nearly 2000 meters down into the inky abyss. Swimming between bright surface waters and the pitch black deep sea should strain the shark’s eyes, making their lifestyle impossible. But researchers have now uncovered the genetic wiring that prevents this from happening. The study, published this week in the Proceedings of the National Academy of Sciences, pinpoints a genetic mutation that makes a visual pigment in the whale shark’s retina more sensitive to temperature changes. As a result, the pigments—which sense blue light in dark environments—are activated in the chilly deep sea and deactivated when the sharks return to the balmy surface to feed, allowing them to prioritize different parts of their vision at different depths. Ironically, the genetic alteration is surprisingly similar to one that degrades pigments in human retinas, causing night blindness. It remains unclear why whale sharks dive so deep. Because prey is scarce at these depths, the behavior may be linked to mating. But whatever they do, the sharks rely on a light-sensing pigment in their retinas called rhodopsin to navigate the dark waters. Although the pigments are less useful in sunny habitats, they help many vertebrates, including humans, detect light in dim environments. In the deep sea, the rhodopsin pigments in whale shark eyes are specifically calibrated to see blue light—the only color that reaches these depths. Previous research has revealed bottom-dwelling cloudy catsharks (Scyliorhinus torazame) have similarly calibrated pigments in their eyes to spot blue light. But these small sharks are content in the deep, making whale sharks the only known sharks to sport these pigments in the shallows. In lighter waters, these blue light–sensing pigments could act as a hindrance to seeing other kinds of light, but whale sharks are still able to maneuver with ease as they vacuum up seafood.

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: 28719 - Posted: 03.25.2023

By Allison Parshall Functional magnetic resonance imaging, or fMRI, is one of the most advanced tools for understanding how we think. As a person in an fMRI scanner completes various mental tasks, the machine produces mesmerizing and colorful images of their brain in action. Looking at someone’s brain activity this way can tell neuroscientists which brain areas a person is using but not what that individual is thinking, seeing or feeling. Researchers have been trying to crack that code for decades—and now, using artificial intelligence to crunch the numbers, they’ve been making serious progress. Two scientists in Japan recently combined fMRI data with advanced image-generating AI to translate study participants’ brain activity back into pictures that uncannily resembled the ones they viewed during the scans. The original and re-created images can be seen on the researchers’ website. “We can use these kinds of techniques to build potential brain-machine interfaces,” says Yu Takagi, a neuroscientist at Osaka University in Japan and one of the study’s authors. Such future interfaces could one day help people who currently cannot communicate, such as individuals who outwardly appear unresponsive but may still be conscious. The study was recently accepted to be presented at the 2023 Conference on The study has made waves online since it was posted as a preprint (meaning it has not yet been peer-reviewed or published) in December 2022. Online commentators have even compared the technology to “mind reading.” But that description overstates what this technology is capable of, experts say. “I don’t think we’re mind reading,” says Shailee Jain, a computational neuroscientist at the University of Texas at Austin, who was not involved in the new study. “I don’t think the technology is anywhere near to actually being useful for patients—or to being used for bad things—at the moment. But we are getting better, day by day.”

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: 28708 - Posted: 03.18.2023

By Lisa Mulcahy If you’ve ever had your vision “white out” (or “gray out”), you’ve probably felt a little unnerved by the experience. “You’ll see a bright light, and your vision will go pale,” says Teri K. Geist, an optometrist and trustee of the American Optometry Association. As disconcerting as they are, vision whiteouts are usually benign. Making sure, though, means talking with a physician or optometrist. Before you do, here are some things to consider. If you have recurrent whiteouts, counting their duration in real time can help get you the correct diagnosis. Note any specific details the whiteouts appear to have in common. Do they happen right after you stand up from a chair, for example? Most often, whiteouts occur when a person is ready to pass out because of a sudden drop in blood pressure. About 1 in 3 people will faint at some point in their lives. “Fainting can be benign when it’s related to a sudden stress,” says Sarah Thornton, a neuro-ophthalmologist at Wills Eye Hospital in Philadelphia. “Standing up too fast, overexerting, becoming dehydrated or taking certain medications can also lead to hypotension — low blood pressure — and potentially, a whiteout.” A less common risk: “Whiteouts can occur with changes in G force,” says Geist, for instance, in a car accident or on a roller coaster. A whiteout caused by physical stress or exertion will clear within just a few minutes. Although fainting is usually benign, always tell your doctor if you’ve fainted — occasionally, whiteouts and fainting are tied to something serious. “An underlying heart condition, such as aortic stenosis, could cause fainting symptoms, including whiteout,” says Dean M. Cestari, a neuro-ophthalmologist at Mass General Brigham Mass Eye and Ear in Boston and associate professor of ophthalmology at Harvard Medical School. Other such conditions can include arrhythmias, heart failure and atrial fibrillation.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28568 - Posted: 11.30.2022

By Nicola Jones What color is a tree, or the sky, or a sunset? At first glance, the answers seem obvious. But it turns out there is plenty of variation in how people see the world — both between individuals and between different cultural groups. A lot of factors feed into how people perceive and talk about color, from the biology of our eyes to how our brains process that information, to the words our languages use to talk about color categories. There’s plenty of room for differences, all along the way. For example, most people have three types of cones — light receptors in the eye that are optimized to detect different wavelengths or colors of light. But sometimes, a genetic variation can cause one type of cone to be different, or absent altogether, leading to altered color vision. Some people are color-blind. Others may have color superpowers. Our sex can also play a role in how we perceive color, as well as our age and even the color of our irises. Our perception can change depending on where we live, when we were born and what season it is. To learn more about individual differences in color vision, Knowable Magazine spoke with visual neuroscientist Jenny Bosten of the University of Sussex in England, who wrote about the topic in the 2022 Annual Review of Vision Science. This conversation has been edited for length and clarity. How many colors are there in the rainbow? Physically, the rainbow is a continuous spectrum. The wavelengths of light vary smoothly between two ends within the visible range. There are no lines, no sharp discontinuities. The human eye can discriminate far more than seven colors within that range. But in our culture, we would say that we see seven color categories in the rainbow: red, orange, yellow, green, blue, indigo and violet. That’s historical and cultural. © 2022 Annual Reviews

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28531 - Posted: 10.28.2022

By Betsy Mason 08.05.2022 What is special about humans that sets us apart from other animals? Less than some of us would like to believe. As scientists peer more deeply into the lives of other animals, they’re finding that our fellow creatures are far more emotionally, socially, and cognitively complex than we typically give them credit for. A deluge of innovative research is revealing that behavior we would call intelligent if humans did it can be found in virtually every corner of the animal kingdom. Already this year scientists have shown that Goffin’s cockatoos can use multiple tools at once to solve a problem, Australian Magpies will cooperate to remove tracking devices harnessed to them by scientists, and a small brown songbird can sometimes keep time better than the average professional musician — and that’s just among birds. This pileup of fascinating findings may be at least partly responsible for an increase in people’s interest in the lives of other animals — a trend that’s reflected in an apparent uptick in books and television shows on the topic, as well as in legislation concerning other species. Public sentiment in part pushed the National Institutes of Health to stop supporting biomedical research on chimpanzees in 2015. In Canada, an outcry led to a ban in 2019 on keeping cetaceans like dolphins and orcas in captivity. And earlier this year, the United Kingdom passed an animal welfare bill that officially recognizes that many animals are sentient beings capable of suffering, including invertebrates like octopuses and lobsters. Many of these efforts are motivated by human empathy for animals we’ve come to see as intelligent, feeling beings like us, such as chimpanzees and dolphins. But how can we extend that concern to the millions of other species that share the planet with us?

Related chapters from BN: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 28447 - Posted: 08.27.2022

By Fionna M. D. Samuels, Liz Tormes Experiencing art, whether through melody or oil paint, elicits in us a range of emotions. This speaks to the innate entanglement of art and the brain: Mirror neurons can make people feel like they are physically experiencing a painting. And listening to music can change their brain chemistry. For the past 11 years, the Netherlands Institute for Neuroscience in Amsterdam has hosted the annual Art of Neuroscience Competition and explored this intersection. This year’s competition received more than 100 submissions, some created by artists inspired by neuroscience and others by neuroscientists inspired by art. The top picks explore a breadth of ideas—from the experience of losing consciousness to the importance of animal models in research—but all of them tie back to our uniquely human brain. In the moment between wakefulness and sleep, we may feel like we are losing ourself to the void of unconsciousness. This is the moment Daniela de Paulis explores with her interdisciplinary project Mare Incognito. “I always had a fascination for the moment of falling asleep,” she says. “Since I was a very small child, I always found this moment as quite transformative, also quite frightening in a way.” The winning Art of Neuroscience submission is the culmination of her project: a film that recorded de Paulis falling asleep among the silver, treelike antennas of the Square Kilometer Array at the Mullard Radio Observatory in Cambridge, England, while her brain activity was converted into radio waves and transmitted directly into space. “We combined the scientific interest with my poetic fascination in this idea of losing consciousness,” she says. In the clip above, Tristan Bekinschtein, a neuroscientist at the University of Cambridge, explains the massive change humans and their brain experience when they drift from consciousness into sleep. As someone falls asleep, their brain activity slows down in stages until they are fully out. Then bursts of activity light up their gray matter as their brain switches over to rapid eye movement (REM) sleep, and they begin to dream. © 2022 Scientific American,

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: 28446 - Posted: 08.27.2022

By Betsy Mason What is special about humans that sets us apart from other animals? Less than some of us would like to believe. As scientists peer more deeply into the lives of other animals, they’re finding that our fellow creatures are far more emotionally, socially, and cognitively complex than we typically give them credit for. A deluge of innovative research is revealing that behavior we would call intelligent if humans did it can be found in virtually every corner of the animal kingdom. Already this year scientists have shown that Goffin’s cockatoos can use multiple tools at once to solve a problem, Australian Magpies will cooperate to remove tracking devices harnessed to them by scientists, and a small brown songbird can sometimes keep time better than the average professional musician — and that’s just among birds. This pileup of fascinating findings may be at least partly responsible for an increase in people’s interest in the lives of other animals — a trend that’s reflected in an apparent uptick in books and television shows on the topic, as well as in legislation concerning other species. Public sentiment in part pushed the National Institutes of Health to stop supporting biomedical research on chimpanzees in 2015. In Canada, an outcry led to a ban in 2019 on keeping cetaceans like dolphins and orcas in captivity. And earlier this year, the United Kingdom passed an animal welfare bill that officially recognizes that many animals are sentient beings capable of suffering, including invertebrates like octopuses and lobsters. Many of these efforts are motivated by human empathy for animals we’ve come to see as intelligent, feeling beings like us, such as chimpanzees and dolphins. But how can we extend that concern to the millions of other species that share the planet with us?

Related chapters from BN: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 28420 - Posted: 08.06.2022

Allison Whitten When our phones and computers run out of power, their glowing screens go dark and they die a sort of digital death. But switch them to low-power mode to conserve energy, and they cut expendable operations to keep basic processes humming along until their batteries can be recharged. Our energy-intensive brain needs to keep its lights on too. Brain cells depend primarily on steady deliveries of the sugar glucose, which they convert to adenosine triphosphate (ATP) to fuel their information processing. When we’re a little hungry, our brain usually doesn’t change its energy consumption much. But given that humans and other animals have historically faced the threat of long periods of starvation, sometimes seasonally, scientists have wondered whether brains might have their own kind of low-power mode for emergencies. Now, in a paper published in Neuron in January, neuroscientists in Nathalie Rochefort’s lab at the University of Edinburgh have revealed an energy-saving strategy in the visual systems of mice. They found that when mice were deprived of sufficient food for weeks at a time — long enough for them to lose 15%-20% of their typical healthy weight — neurons in the visual cortex reduced the amount of ATP used at their synapses by a sizable 29%. But the new mode of processing came with a cost to perception: It impaired how the mice saw details of the world. Because the neurons in low-power mode processed visual signals less precisely, the food-restricted mice performed worse on a challenging visual task. “What you’re getting in this low-power mode is more of a low-resolution image of the world,” said Zahid Padamsey, the first author of the new study. All Rights Reserved © 2022

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 28376 - Posted: 06.15.2022

Researchers from the National Eye Institute (NEI) have identified a new disease that affects the macula, a small part of the light-sensing retina needed for sharp, central vision. Scientists report their findings on the novel macular dystrophy, which is yet to be named, in JAMA Ophthalmology. NEI is part of the National Institutes of Health. Macular dystrophies are disorders that usually cause central visual loss because of mutations in several genes, including ABCA4, BEST1, PRPH2, and TIMP3. For example, patients with Sorsby Fundus Dystrophy, a genetic eye disease specifically linked to TIMP3 variants, usually develop symptoms in adulthood. They often have sudden changes in visual acuity due to choroidal neovascularization– new, abnormal blood vessels that grow under the retina, leaking fluid and affecting vision. TIMP3 is a protein that helps regulate retinal blood flow and is secreted from the retinal pigment epithelium (RPE), a layer of tissue that nourishes and supports the retina’s light-sensing photoreceptors. All TIMP3 gene mutations reported are in the mature protein after it has been “cut” from RPE cells in a process called cleavage. “We found it surprising that two patients had TIMP3 variants not in the mature protein, but in the short signal sequence the gene uses to ‘cut’ the protein from the cells. We showed these variants prevent cleavage, causing the protein to be stuck in the cell, likely leading to retinal pigment epithelium toxicity,” said Bin Guan, Ph.D., lead author. The research team followed these findings with clinical evaluations and genetic testing of family members to verify that the two new TIMP3 variants are connected to this atypical maculopathy.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28364 - Posted: 06.11.2022

Smriti Mallapaty Live-cell imaging of the eye’s transparent cornea has revealed a surprising resident — specialized immune cells that circle the tissue, ready to attack pathogens. “We thought that the central cornea was devoid of any immune cells,” says Esen Akpek, a clinician-scientist who works on immunological diseases of the cornea at Johns Hopkins University in Baltimore, Maryland. The study, published in Cell Reports1 on 24 May, could help researchers to better understand diseases that affect the eye and to develop therapies that target infections on the eye’s surface, says Tanima Bose, an immunologist at the pharmaceutical company Novartis in Kundl, Austria. Immune response The cornea has a dampened response to infection, in part because aggressive immune cells could damage the clear layer of tissue and obstruct vision, says co-author Scott Mueller, an immunologist at the University of Melbourne, Australia. For this reason, the immune cells that mount a quick but crude response to an infection, such as dendritic cells and macrophages, largely reside in the outer sections of the cornea and emerge only when needed. But in almost every tissue in the body are long-lived immune cells, known as T cells, that swiftly attack pathogens they have previously encountered — a process called ‘immune memory’. Mueller and his colleagues wondered whether such cells lived in the cornea. Using a powerful multiphoton microscope for studying living tissue, the researchers examined the corneas of mice whose eyes had been infected with herpes simplex virus. They saw that cytotoxic T cells and T-helper cells — precursors for immune memory — had infiltrated the cornea and persisted for up to a month after the infection. Further investigations, including more intrusive microscopy techniques, revealed that the cytotoxic T cells had developed into long-lived memory cells that resided in the cornea. © 2022 Springer Nature 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: 28357 - Posted: 06.07.2022

By Colleen DeGuzman Jessica Oberoi, 13, cannot remember when her eyesight started getting blurry. All she knows is that she had to squint to see the whiteboard at school. It wasn’t until last fall when her eighth-grade class in Bloomington, Ind., got vision screenings that Jessica’s extreme nearsightedness and amblyopia, or lazy eye, were discovered. She has been going through intense treatment since then, and her optometrist, Katie Connolly, said Jessica has made great improvements — but her lazy eye, which causes depth perception problems, may never go away. The chances of it being completely corrected would have been much higher if her condition had been caught earlier, said Connolly, chief of pediatric and binocular vision service at Indiana University’s School of Optometry. Jessica is one of the countless students falling through the cracks of the nation’s fractured efforts to catch and treat vision problems among children. A mobile clinic is helping low-income students to see clearly — one pair of glasses at a time The Centers for Disease Control and Prevention estimates that more than 600,000 children and teens are blind or have a vision disorder. A recent opinion article published on JAMA Network notes that a large number of these children could be helped simply with glasses, but because of high costs and lack of insurance coverage, many are not getting them. Yet the National Survey of Children’s Health, funded by the U.S. Health Resources and Services Administration, found that in 2016-2017 a quarter of children were not regularly screened for vision problems. And a large majority of those vision impairments could be treated or cured if caught early, Connolly said. “Screenings are important for kids because kids don’t realize what’s abnormal,” Connolly said. “They don’t know what their peers around them — or even their parents — are seeing to realize their experience is different.” © 1996-2022 The Washington Post

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28355 - Posted: 06.07.2022

The Age-Related Eye Disease Studies (AREDS and AREDS2) established that dietary supplements can slow progression of age-related macular degeneration (AMD), the most common cause of blindness in older Americans. In a new report, scientists analyzed 10 years of AREDS2 data. They show that the AREDS2 formula, which substituted antioxidants lutein and zeaxanthin for beta-carotene, not only reduces risk of lung cancer due to beta-carotene, but is also more effective at reducing risk of AMD progression, compared to the original formula. A report on the study, funded by the National Institutes of Health, published in JAMA Ophthalmology. “Because beta-carotene increased the risk of lung cancer for current smokers in two NIH-supported studies, our goal with AREDS2 was to create an equally effective supplement formula that could be used by anyone, whether or not they smoke,” said Emily Chew, M.D., director of the Division of Epidemiology and Clinical Application at the National Eye Institute (NEI), and lead author of the study report. “This 10-year data confirms that not only is the new formula safer, it’s actually better at slowing AMD progression.” AMD is a degenerative disease of the retina, the light-sensitive tissue at the back of the eye. Progressive death of retinal cells in the macula, the part of the retina that provides clear central vision, eventually leads to blindness. Treatment can slow or reverse vision loss; however, no cure for AMD exists. The original AREDS study, launched in 1996, showed that a dietary supplement formulation (500 mg vitamin C, 400 international units vitamin E, 2 mg copper, 80 mg zinc, and 15 mg beta-carotene) could significantly slow the progression of AMD from moderate to late disease. However, two concurrent studies also revealed that people who smoked and took beta-carotene had a significantly higher risk of lung cancer than expected.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28348 - Posted: 06.04.2022

Researchers have identified distinct differences among the cells comprising a tissue in the retina that is vital to human visual perception. The scientists from the National Eye Institute (NEI) discovered five subpopulations of retinal pigment epithelium (RPE)—a layer of tissue that nourishes and supports the retina’s light-sensing photoreceptors. Using artificial intelligence, the researchers analyzed images of RPE at single-cell resolution to create a reference map that locates each subpopulation within the eye. A report on the research published in Proceedings of the National Academy of Sciences. “These results provide a first-of-its-kind framework for understanding different RPE cell subpopulations and their vulnerability to retinal diseases, and for developing targeted therapies to treat them,” said Michael F. Chiang, M.D., director of the NEI, part of the National Institutes of Health. “The findings will help us develop more precise cell and gene therapies for specific degenerative eye diseases,” said the study’s lead investigator, Kapil Bharti, Ph.D., who directs the NEI Ocular and Stem Cell Translational Research Section. Vision begins when light hits the rod and cone photoreceptors that line the retina in the back of the eye. Once activated, photoreceptors send signals through a complex network of other retinal neurons that converge at the optic nerve before traveling to various centers in the brain. The RPE sits beneath the photoreceptors as a monolayer, one cell deep. Age and disease can cause metabolic changes in RPE cells that can lead to photoreceptor degeneration. The impact on vision from these RPE changes varies dramatically by severity and where the RPE cells reside within the retina. For example, late-onset retinal degeneration (L-ORD) affects mostly peripheral retina and, therefore, peripheral vision. Age-related macular degeneration (AMD), a leading cause of vision loss, primarily affects RPE cells in the macula, which is crucial for central vision.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28318 - Posted: 05.07.2022

Yasemin Saplakoglu A mosquito watches you through a lattice of microscopic lenses. You stare back, fly swatter in hand, closely tracking the bloodsucker with your humble single-lens eyes. But it turns out that the way you see each other — and the world — may have more in common than you might think. A study published last month in Science Advances found that inside mammalian eyes, mitochondria, the organelles that power cells, may serve a second role as microscopic lenses, helping to focus light on the photoreceptor pigments that convert the light into neural signals for the brain to interpret. The findings, which draw a striking parallel between mammalian eyes and the compound eyes of insects and other arthropods, suggest that our own eyes have hidden levels of optical complexity, and that evolution has found new uses for very old parts of our cellular anatomy. Abstractions navigates promising ideas in science and mathematics. Journey with us and join the conversation. The lens at the very front of the eye focuses light from the environment onto a thin layer of tissue called the retina in the back. There, photoreceptor cells — cones that paint our world in color and rods that help us navigate in low light — absorb the light and translate it into nerve signals that propagate into the brain. But light-sensitive pigments sit at the very ends of photoreceptors, right behind a thick bundle of mitochondria. The odd placement of this bundle turns the mitochondria into seemingly unnecessary, light-scattering obstacles. The mitochondria are the “final hurdle” for the light particles, said Wei Li, a senior investigator at the National Eye Institute and senior author on the paper. For years, vision scientists couldn’t make sense of this odd placement of these organelles — after all, most cells have their mitochondria hugging their center organelle, the nucleus. All Rights Reserved © 2022

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28272 - Posted: 04.06.2022

Terry Gross One morning in 2017, New York Times columnist Frank Bruni woke up to find that everything looked blurry and smeared. "There was a fog, a dappled fog over the right side of my field of vision," Bruni says. "And I thought for hours that there must be some gunk in my eye, or maybe I'd had too much to drink the night before. Then I thought, Oh, no, it's my eyeglasses. I just have to clean them. And on and on, until deep into the day, I realized there was something wrong beyond all of that." Bruni, then 52, soon learned that he'd experienced a rare kind of stroke that had irreparably damaged his optic nerve. The prognosis: His vision in that eye would never return. What's more, there was a 20 to 40% chance that another stroke would impact his good eye. The news was devastating. "I had some emotional, psychological and really spiritual work to do to accept this and figure out how to go on in the most productive and constructive fashion," he says. But after going through a period of shock and terror, Bruni saw himself at a decision point: He could fixate on what had been lost, or he could focus on what remained. He chose to do the latter. "I feel like once you've recognized what's happened, ... it is so important and so constructive and so right to focus instead on all the things you can still do, all the blessings that remain," he says. "I ended up determined — determined to show myself that I could adapt to whatever was going to happen." In the memoir, The Beauty of Dusk, Bruni chronicles the changes to his vision and the adaptations he's had to make in his work, personal life and attitude. The book also profiles a number of other people who've survived and thrived in ways that Bruni says are profoundly instructive. © 2022 npr

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 7: Vision: From Eye to Brain
Link ID: 28248 - Posted: 03.23.2022

By Lisa Sanders, M.D. “You can’t see the ceiling, can you?” the man asked his 31-year-old wife. She grimaced, then shook her head. She was lying in bed looking toward the familiar shadows and shapes cast by the wintry morning sun. But she couldn’t see them. It was as if a dense white fog lay between her and those daily shifting patterns. Squinting didn’t help. Opening her eyes as wide as she could didn’t, either. All her life she had perfect vision. It was a secret source of pride. She’d never even seen an eye doctor. But that morning changed everything. She first noticed the trouble in her eyes six months earlier. She is a professional violinist and a teacher and that summer took her students to Italy to experience the sacred music and art. As she gazed up at the frescos decorating the ceiling of a favorite cathedral, a shimmering shape with jagged, irregular edges appeared out of nowhere. The points seemed to twinkle as the starlike image slowly enlarged. Inside the glittering outline, the colors were jumbled, like the crystals in a kaleidoscope. It was beautiful and terrifying. She dropped her head, closed her eyes and rubbed her aching neck. When she opened her eyes, the star burst, with its glimmering edges, was still there, distorting all that lay beyond it. It grew so large that it was almost all she could see. Then slowly it began to fade; after nearly a half-hour, the world started to resume its familiar look and shape. There had been similar, if less severe, experiences: Every now and then, when she would get up quickly after sitting or lying down, she would feel an intense pressure inside her head, and when it released, everything briefly looked faded and pale before returning to normal hues. These spells only lasted a few seconds and happened only a handful of times over the past few years. She wrote it off to fatigue or stress. After that day in Italy, those glistening star bursts appeared weekly, then daily. Stranger still, straight lines developed weird lumps and bumps when she looked at them out of the corner of her eye. Doorways, curbs and table edges seemed to waver, growing bulges and divots. When she looked at the object full on, it would obediently straighten out but resumed its aberration once it was on the sidelines again. © 2022 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: 28242 - Posted: 03.19.2022

Researchers at the National Eye Institute (NEI) have discovered that power-producing organelles in the eye’s photoreceptor cells, called mitochondria, function as microlenses that help channel light to these cells’ outer segments where it’s converted into nerve signals. The discovery in ground squirrels provides a more precise picture of the retina’s optical properties and could help detect eye disease earlier. The findings, published today in Science Advances, also shed light on the evolution of vision. NEI is part of the National Institutes of Health. “We were surprised by this fascinating phenomenon that mitochondria appear to have a dual purpose: their well-established metabolic role producing energy, as well as this optical effect,” said the study’s lead investigator, Wei Li, Ph.D./B.M., who leads the NEI Retinal Neurophysiology Section. Using a modified confocal microscope, the researchers observed the optical properties of living cone mitochondria exposed to light. The path of light became concentrated with transmission from the inner to the outer segments of cone photoreceptors. Credit: John Ball, Ph.D., NEI The findings also address a long-standing mystery about the mammalian retina. Despite evolutionary pressure for light to be translated into signals and pass instantly from the retina to the brain, the trip is hardly direct. Once light reaches the retina, it must pass through multiple neural layers before reaching the outer segment of photoreceptors, where phototransduction (the conversion of light’s physical energy into cellular signals) occurs. Photoreceptors are long, tube-like structures divided into inner and outer segments. The last obstacle a photon must traverse before moving from the inner to the outer segment is an unusually dense bundle of mitochondria. Those bundles of mitochondria would seem to work against the process of vision either by scattering light or absorbing it. So, Li’s team set out to investigate their purpose by studying cone photoreceptors from the 13-lined ground squirrel.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 28228 - Posted: 03.02.2022

By David A. Kaplan Our cross-country drive last winter from New York to Lake Tahoe was going to be eventful enough, with a pandemic, blizzards and the cancellation of salads at McDonald’s. But by Omaha, when the lanes on Interstate 80 seemed to be bouncing around before my very eyes, we entered unexpected territory. “Are you practicing your slalom turns at 80 miles an hour?” my wife asked. Road conditions were normal. Our S.U.V. had new tires. But the lanes often seemed to blur together. Sometimes the melding of lanes occurred late in the day, sometimes early. Sometimes in blinding sun, sometimes in fog. If I closed one eye, the lanes became separate again. What was happening? I’d worn glasses for nearsightedness since fifth grade; I’d seen my eye doctor within the year; my prescription was current. When we reached Tahoe, I went to an optometrist before even unpacking my skis. She said my eyes were fine, but advised an M.R.I. to rule out a brain bleed or a tumor. Days later, it did. She also told me to see a neuro-ophthalmologist, an increasingly rare subspecialty. Nationally, there are only about 600 of them, and because many do academic research or have general ophthalmic practices, just 250 of them are full-time clinicians. In six states, there are none practicing, according to a paper in the Journal of Neuro-Ophthalmology last year. The Tahoe optometrist warned it could take months to obtain an appointment with one of the few practitioners in the area. But my brother, a surgeon at Stanford, helped me get an appointment at Stanford Medical Center, four hours away, in Palo Alto, Ca., the following week. Dr. Heather Moss conducted the 90-minute examination, taking measurements that included the degree to which my eyes were properly centered. © 2022 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: 28220 - Posted: 02.26.2022