By Jacek Krywko edited by Allison Parshall There are only so many colors that the typical human eye can see; estimates put the number just below 10 million. But now, for the first time, scientists say they’ve broken out of that familiar spectrum and into a new world of color. In a paper published on Friday in Science Advances, researchers detail how they used a precise laser setup to stimulate the retinas of five participants, making them the first humans to see a color beyond our visual range: an impossibly saturated bluish green. Our retinas contain three types of cone cells, photoreceptors that detect the wavelengths of light. S cones pick up relatively short wavelengths, which we see as blue. M cones react to medium wavelengths, which we see as green. And L cones are triggered by long wavelengths, which we see as red. These red, green and blue signals travel to the brain, where they’re combined into the full-color vision we experience. But these three cone types handle overlapping ranges of light: the light that activates M cones will also activate either S cones or L cones. “There’s no light in the world that can activate only the M cone cells because, if they are being activated, for sure one or both other types get activated as well,” says Ren Ng, a professor of electrical engineering and computer science at the University of California, Berkeley. Ng and his research team wanted to try getting around that fundamental limitation, so they developed a technicolor technique they call “Oz.” “The name comes from the Wizard of Oz, where there’s a journey to the Emerald City, where things look the most dazzling green you’ve ever seen,” Ng explains. On their own expedition, the researchers used lasers to precisely deliver tiny doses of light to select cone cells in the human eye. First, they mapped a portion of the retina to identify each cone cell as either an S, M or L cone. Then, using the laser, they delivered light only to M cone cells. © 2025 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: 29752 - Posted: 04.19.2025

By Catherine Offord Scientists say they have found a long–sought-after population of stem cells in the retina of human fetuses that could be used to develop therapies for one of the leading causes of blindness. The use of fetal tissue, a source of ethical debate and controversy in some countries, likely wouldn’t be necessary for an eventual therapy: Transplanting similar human cells generated in the lab into the eyes of mice with retinal disease protected the animals’ vision, the team reported this week in Science Translational Medicine. “I see this as potentially a very interesting advancement of this field, where we are really in need of a regenerative treatment for retinal diseases,” says Anders Kvanta, a retinal specialist at the Karolinska Institute who was not involved in the work. He and others note that more evidence is needed to show the therapeutic usefulness of the newly described cells. The retina, a layer of light-sensing tissue at the back of the eye, can degenerate with age or because of an inherited condition such as retinitis pigmentosa, a rare disease that causes gradual breakdown of retinal cells. Hundreds of millions of people worldwide are affected by retinal degeneration, and many suffer vision loss or blindness as a result. Most forms can’t be treated. Scientists have long seen a potential solution in stem cells, which can regenerate and repair injured tissue. Several early-stage clinical trials are already evaluating the safety and efficacy of transplanting stem cells derived from cell lines established from human embryos, for example, or adult human cells that have been reprogrammed to a stem-like state. Other approaches include transplanting so-called retinal progenitor cells (RPCs)—immature cells that give rise to photoreceptors and other sorts of retinal cells—from aborted human fetuses. Some researchers have argued that another type of cell, sometimes referred to as retinal stem cells (RSCs), could also treat retinal degeneration. These cells’ long lifespans and ability to undergo numerous cells divisions could make them better candidates to regenerate damaged tissue than RPCs. RSCs have been found in the eyes of zebrafish and some other vertebrates, but evidence for their existence in mammals has been controversial. Reports announcing their discovery in adult mice in the early 2000s were later discounted.

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: 29719 - Posted: 03.27.2025

By Bill Newsome What paper changed your life?: Activity of superior colliculus in behaving monkey. II. Effect of attention on neuronal responses. M.E. Goldberg and R.H. Wurtz Journal of Neurophysiology (1972) In 1972, Mickey Goldberg and Bob Wurtz published a quadrilogy of papers in the Journal of Neurophysiology—yes, you could do that in those days—on the physiological activity of single superior colliculus neurons in alert monkeys trained to perform simple eye fixation and eye movement tasks. The experiments revealed a rich variety of sensory and motor signals: Some neurons fired at the onset of a visual stimulus; others showed bursts of activity immediately prior to the eye movement. The researchers found that visually evoked activity differed depending on whether the monkey ultimately used the stimulus as a target for a saccadic eye movement. The neural response to the visual stimulus was stronger and continued until the time of the eye movement, forming a sort of temporal bridge between stimulus and evoked behavioral response. This bridge was alluring because it hinted at intermediate processes—perhaps the stuff of cognition—between sensory input and behavioral output. But it was also mysterious, in that no models existed for how such activity might be initiated and maintained until the behavioral response. These papers were revelatory to me because they pointed toward a mechanistic physiological understanding of such complex cognitive functions as attention. I was particularly fascinated by the second paper in the series of four, which dug into that mystery. Goldberg and Wurtz explicitly made a suggestive leap from physiology to psychology: “[Because] we can infer that the monkey attended to the stimulus when he made a saccade to it, the enhancement can be viewed as a neurophysiological event related to the psychological phenomenon of attention.” They also issued appropriate caveats, noting that “the unitary behavioral concept” of attention “may not have a single physiological mechanism.” h. © 2025 Simons Foundation

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 14: Attention and Higher Cognition
Link ID: 29679 - Posted: 02.22.2025

By Phil Plait I remember watching the full moon rise one early evening a while back. It was when I still lived in Colorado, and I was standing outside in my yard. I first noticed a glow to the east lighting up the flat horizon in the darkening sky, and within moments the moon was cresting above it, yellow and swollen—like, really swollen As it cleared the horizon, the moon looked huge! It also seemed so close that I could reach out and touch it; it was so “in my face” that I felt I could fall in. I gawped at it for a moment and then smiled. I knew what I was actually seeing: the moon illusion. Anyone who is capable of seeing the moon (or the sun) near the horizon has experienced this effect. The moon looks enormous there, far larger than it does when it’s overhead. I’m an astronomer, and I know the moon is no bigger on the horizon than at the zenith, yet I can’t not see it that way. It’s an overwhelming effect. But it’s not real. Simple measurements of the moon show it’s essentially the same size on the horizon as when it’s overhead. This really is an illusion. It’s been around awhile, too: the illusion is shown in cuneiform on a clay tablet from the ancient Assyrian city Nineveh that has been dated to the seventh century B.C.E. Attempts to explain it are as old as the illusion itself, and most come up short. Aristotle wrote about it, for example, attributing it to the effects of mist. This isn’t correct, obviously; the illusion manifests even in perfectly clear weather. A related idea, still common today, is that Earth’s air acts like a lens, refracting (bending) the light from the moon and magnifying it. But we know that’s not right because the moon is measurably the same size no matter where it is in the sky. Also, examining the physics of that explanation shows that it falls short as well. In fact, while the air near the horizon does indeed act like a lens, its actual effect is to make the sun and moon look squished, like flat ovals, not to simply magnify them. So that can’t be the cause either.

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 14: Attention and Higher Cognition
Link ID: 29522 - Posted: 10.19.2024

By Abdullahi Tsanni Time takes its toll on the eyes. Now a funky, Hitchcockian video of 64 eyeballs, all rolling and blinking in different directions, is providing a novel visual of one way in which eyes age. A video display of 64 eyeballs, captured using eye trackers, helped researchers compare the size of younger and older study participants’ pupils under differing light conditions, confirming aging affects our eyes. Lab studies have previously shown that the eye’s pupil size shrinks as people get older, making the pupil less responsive to light. A new study that rigged volunteers up with eye-trackers and GoPro videos and sent them traipsing around a university campus has confirmed what happens in the lab happens in real life, too. While pupils remain sensitive to changing light conditions, pupil size can decrease up to about 0.4 millimeters per decade, researchers report June 19 in Royal Society Open Science. “We see a big age effect,” says Manuel Spitschan, a neuroscientist at Max Planck Institute for Biological Cybernetics in Tubingen, Germany. The change helps explain why it can be increasingly harder for people to see in dim light as they age. Light travels through the dark pupil in the center of the eye to the retina, a layer of cells in the back of the eyes that converts the light into images. The pupil’s size can vary from 2 to 8 millimeters in diameter depending on light conditions, getting smaller in bright light and larger in dim light. “With a small pupil, less light enters the eye,” Spitschan says. © Society for Science & the Public 2000–2024.

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: 29375 - Posted: 07.03.2024

By Elie Dolgin The COVID-19 pandemic didn’t just reshape how children learn and see the world. It transformed the shape of their eyeballs. As real-life classrooms and playgrounds gave way to virtual meetings and digital devices, the time that children spent focusing on screens and other nearby objects surged — and the time they spent outdoors dropped precipitously. This shift led to a notable change in children’s anatomy: their eyeballs lengthened to better accommodate short-vision tasks. Study after study, in regions ranging from Europe to Asia, documented this change. One analysis from Hong Kong even reported a near doubling in the incidence of pathologically stretched eyeballs among six-year-olds compared with pre-pandemic levels1. This elongation improves the clarity of close-up images on the retina, the light-sensitive layer at the back of the eye. But it also makes far-away objects appear blurry, leading to a condition known as myopia, or short-sightedness. And although corrective eyewear can usually address the issue — allowing children to, for example, see a blackboard or read from a distance — severe myopia can lead to more-serious complications, such as retinal detachment, macular degeneration, glaucoma and even permanent blindness. Rates of myopia were booming well before the COVID-19 pandemic. Widely cited projections in the mid-2010s suggested that myopia would affect half of the world’s population by mid-century (see ‘Rising prevalence’), which would effectively double the incidence rate in less than four decades2 (see ‘Affecting every age’). Now, those alarming predictions seem much too modest, says Neelam Pawar, a paediatric ophthalmologist at the Aravind Eye Hospital in Tirunelveli, India. “I don’t think it will double,” she says. “It will triple.” © 2024 Springer Nature Limited

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 13: Memory and Learning
Link ID: 29329 - Posted: 05.29.2024

By Angie Voyles Askham Each time we blink, it obscures our visual world for 100 to 300 milliseconds. It’s a necessary action that also, researchers long presumed, presents the brain with a problem: how to cobble together a cohesive picture of the before and after. “No one really thought about blinks as an act of looking or vision to begin with,” says Martin Rolfs, professor of experimental psychology at Humboldt University of Berlin. But blinking may be a more important component of vision than previously thought, according to a study published last month in the Proceedings of the National Academy of Sciences. Participants performed better on a visual task when they blinked while looking at the visual stimulus than when they blinked before it appeared. The blink, the team found, caused a change in visual input that improved participants’ perception. The finding suggests that blinking is a feature of seeing rather than a bug, says Rolfs, who was not involved with the study but wrote a commentary about it. And it could explain why adults blink more frequently than is seemingly necessary, the researchers say. “The brain capitalizes on things that are changing in the visual world—whether it’s blinks or eye movements, or any type of ocular-motor dynamics,” says Patrick Mayo, a neuroscientist in the ophthalmology department at the University of Pittsburgh, who was also not involved in the work. “That is … a point that’s still not well appreciated in visual neuroscience, generally.” The researchers started their investigation by simulating a blink. In the computational model they devised, a person staring at black and white stripes would suddenly see a dark, uniform gray before once again viewing the high-contrast pattern. The interruption would cause a brief change in the stimulus input to neurons in the retina, which in turn could increase the cells’ sensitivity to stimuli right after a blink, they hypothesized. © 2024 Simons Foundation

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: 29303 - Posted: 05.14.2024

By Emily Cooke & LiveScience Optical illusions play on the brain's biases, tricking it into perceiving images differently than how they really are. And now, in mice, scientists have harnessed an optical illusion to reveal hidden insights into how the brain processes visual information. The research focused on the neon-color-spreading illusion, which incorporates patterns of thin lines on a solid background. Parts of these lines are a different color — such as lime green, in the example above — and the brain perceives these lines as part of a solid shape with a distinct border — a circle, in this case. The closed shape also appears brighter than the lines surrounding it. It's well established that this illusion causes the human brain to falsely fill in and perceive a nonexistent outline and brightness — but there's been ongoing debate about what's going on in the brain when it happens. Now, for the first time, scientists have demonstrated that the illusion works on mice, and this allowed them to peer into the rodents' brains to see what's going on. Specifically, they zoomed in on part of the brain called the visual cortex. When light hits our eyes, electrical signals are sent via nerves to the visual cortex. This region processes that visual data and sends it on to other areas of the brain, allowing us to perceive the world around us. The visual cortex is made of six layers of neurons that are progressively numbered V1, V2, V3 and so on. Each layer is responsible for processing different features of images that hit the eyes, with V1 neurons handling the first and most basic layer of data, while the other layers belong to the "higher visual areas." These neurons are responsible for more complex visual processing than V1 neurons. © 2024 SCIENTIFIC AMERICAN,

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: 29298 - Posted: 05.09.2024

Linda Geddes Science correspondent If you have wondered why your partner always beats you at tennis or one child always crushes the other at Fortnite, it seems there is more to it than pure physical ability. Some people are effectively able to see more “images per second” than others, research suggests, meaning they’re innately better at spotting or tracking fast-moving objects such as tennis balls. The rate at which our brains can discriminate between different visual signals is known as temporal resolution, and influences the speed at which we are able to respond to changes in our environment. Previous studies have suggested that animals with high visual temporal resolution tend to be species with fast-paced lives, such as predators. Human research has also suggested that this trait tends to decrease as we get older, and dips temporarily after intense exercise. However, it was not clear how much it varies between people of similar ages. One way of measuring this trait is to identify the point at which someone stops perceiving a flickering light to flicker, and sees it as a constant or still light instead. Clinton Haarlem, a PhD candidate at Trinity College Dublin, and his colleagues tested this in 80 men and women between the ages of 18 and 35, and found wide variability in the threshold at which this happened. The research, published in Plos One, found that some people reported a light source as constant when it was in fact flashing about 35 times a second, while others could still detect flashes at rates of greater than 60 times a second. © 2024 Guardian News & Media 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: 29233 - Posted: 04.02.2024

By Viviane Callier Biologists have often wondered what would happen if they could rewind the tape of life’s history and let evolution play out all over again. Would lineages of organisms evolve in radically different ways if given that opportunity? Or would they tend to evolve the same kinds of eyes, wings, and other adaptive traits because their previous evolutionary histories had already sent them down certain developmental pathways? A new paper published in Science this February describes a rare and important test case for that question, which is fundamental to understanding how evolution and development interact. A team of researchers at the University of California, Santa Barbara happened upon it while studying the evolution of vision in an obscure group of mollusks called chitons. In that group of animals, the researchers discovered that two types of eyes—eyespots and shell eyes—each evolved twice independently. A given lineage could evolve one type of eye or the other, but never both. Intriguingly, the type of eye that a lineage had was determined by a seemingly unrelated older feature: the number of slits in the chiton’s shell armor. This represents a real-world example of “path-dependent evolution,” in which a lineage’s history irrevocably shapes its future evolutionary trajectory. Critical junctures in a lineage act like one-way doors, opening up some possibilities while closing off other options for good. “This is one of the first cases [where] we’ve actually been able to see path-dependent evolution,” said Rebecca Varney, a postdoctoral fellow in Todd Oakley’s lab at UCSB and the lead author of the new paper. Although path-dependent evolution has been observed in some bacteria grown in labs, “showing that in a natural system was a really exciting thing to be able to do.” © 2024 NautilusNext Inc.,

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: 29203 - Posted: 03.21.2024

By Saima Sidik Eye diseases long thought to be purely genetic might be caused in part by bacteria that escape the gut and travel to the retina, research suggests1. Eyes are typically thought to be protected by a layer of tissue that bacteria can’t penetrate, so the results are “unexpected”, says Martin Kriegel, a microbiome researcher at the University of Münster in Germany, who was not involved in the work. “It’s going to be a big paradigm shift,” he adds. The study was published on 26 February in Cell. Inherited retinal diseases, such as retinitis pigmentosa, affect about 5.5 million people worldwide. Mutations in the gene Crumbs homolog 1 (CRB1) are a leading cause of these conditions, some of which cause blindness. Previous work2 suggested that bacteria are not as rare in the eyes as ophthalmologists had previously thought, leading the study’s authors to wonder whether bacteria cause retinal disease, says co-author Richard Lee, an ophthalmologist then at the University College London. CRB1 mutations weaken linkages between cells lining the colon in addition to their long-observed role in weakening the protective barrier around the eye, Lee and his colleagues found. This motivated study co-author Lai Wei, an ophthalmologist at Guangzhou Medical University in China, to produce Crb1-mutant mice with depleted levels of bacteria. These mice did not show evidence of distorted cell layers in the retina, unlike their counterparts with typical gut flora. Furthermore, treating the mutant mice with antibiotics reduced the damage to their eyes, suggesting that people with CRB1 mutations could benefit from antibiotics or from anti-inflammatory drugs that reduce the effects of bacteria. “If this is a novel mechanism that is treatable, it will transform the lives of many families,” Lee says. © 2024 Springer Nature Limited

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: 29167 - Posted: 02.27.2024

By Angie Voyles Askham The primary visual cortex carries, well, visual information — or so scientists thought until early 2010. That’s when a team at the University of California, San Francisco first described vagabond activity in the brain area, called V1, in mice. When the animals started to run on a treadmill, some neurons more than doubled their firing rate. The finding “was kind of mysterious,” because V1 was thought to represent only visual signals transmitted from the retina, says Anne Churchland, professor of neurobiology at the University of California, Los Angeles, who was not involved in that work. “The idea that running modulated neural activity suggested that maybe those visual signals were corrupted in a way that, at the time, felt like it would be really problematic.” The mystery grew over the next decade, as a flurry of mouse studies from Churchland and others built on the 2010 results. Both arousal and locomotion could shape the firing of primary visual neurons, those newer findings showed, and even subtle movements such as nose scratches contribute to variance in population activity, all without compromising the sensory information. A consensus started to form around the idea that sensory cortical regions encode broader information about an animal’s physiological state than previously thought. At least until last year, when two studies threw a wrench into that storyline: Neither marmosets nor macaque monkeys show any movement-related increase in V1 signaling. Instead, running seems to slightly suppress V1 activity in marmosets, and spontaneous movements have no effect on the same cells in macaques. The apparent differences across species raise new questions about whether mice are a suitable model to study the primate visual system, says Michael Stryker, professor of physiology at the University of California, San Francisco, who led the 2010 work. “Maybe the primate’s V1 is not working the same as in the mouse,” he says. “As I see it, it’s still a big unanswered question.” © 2024 Simons Foundation

Related chapters from BN: Chapter 10: Vision: From Eye to Brain; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 5: The Sensorimotor System
Link ID: 29153 - Posted: 02.20.2024

By Shruti Ravindran When preparing to become a butterfly, the Eastern Black Swallowtail caterpillar wraps its bright striped body within a leaf. This leaf is its sanctuary, where it will weave its chrysalis. So when the leaf is disturbed by a would-be predator—a bird or insect—the caterpillar stirs into motion, briefly darting out a pair of fleshy, smelly horns. To humans, these horns might appear yellow—a color known to attract birds and many insects—but from a predator’s-eye-view, they appear a livid, almost neon violet, a color of warning and poison for some birds and insects. “It’s like a jump scare,” says Daniel Hanley, an assistant professor of biology at George Mason University. “Startle them enough, and all you need is a second to get away.” Hanley is part of a team that has developed a new technique to depict on video how the natural world looks to non-human species. The method is meant to capture how animals use color in unique—and often fleeting—behaviors like the caterpillar’s anti-predator display. Most animals, birds, and insects possess their own ways of seeing, shaped by the light receptors in their eyes. Human retinas, for example, are sensitive to three wavelengths of light—blue, green, and red—which enables us to see approximately 1 million different hues in our environment. By contrast, many mammals, including dogs, cats, and cows, sense only two wavelengths. But birds, fish, amphibians, and some insects and reptiles typically can sense four—including ultraviolet light. Their worlds are drenched in a kaleidoscope of color—they can often see 100 times as many shades as humans do. Hanley’s team, which includes not just biologists but multiple mathematicians, a physicist, an engineer, and a filmmaker, claims that their method can translate the colors and gradations of light perceived by hundreds of animals to a range of frequencies that human eyes can comprehend with an accuracy of roughly 90 percent. That is, they can simulate the way a scene in a natural environment might look to a particular species of animal, what shifting shapes and objects might stand out most. The team uses commercially available cameras to record video in four color channels—blue, green, red, and ultraviolet—and then applies open source software to translate the picture according to the mix of light receptor sensitivities a given animal may have. © 2024 NautilusNext Inc.,

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: 29133 - Posted: 02.06.2024

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