Chapter 10. Vision: From Eye to Brain

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By Marlene Cimons Ruth Obadal, 72, a retired firefighter in Eugene, Ore., was tired of having to constantly switch glasses, one major reason she decided to have cataract surgery. “I needed progressive lenses for reading up close and for distance such as driving,” she says. Moreover, as a volunteer track-and-field official working outdoors, “I also needed the sunglasses version,” she says. “I also had separate glasses for computer and piano, as I needed to see up close and straight ahead, not just down.” U.S. coronavirus cases tracker and map In addition to the inconvenience, she found it increasingly difficult to get crisp vision, even when fine-tuning her prescriptions. So she had the procedure in both eyes — each two weeks apart — in May. She is happy with the results. “Now, I don’t use glasses for anything,” she says. Everyone who ages is vulnerable to developing a cataract in one or both eyes, a cloudy area in the eye’s natural lens that can cause vision to become blurry, hazy and less colorful. Cataracts result from normal changes in the eyes as people get older. At about age 40, the proteins in the lens begin to break down and clump together, causing the cloudiness. Over time, it worsens. Sunlight during the day and nighttime glare from streetlights and cars can be uncomfortable, even painful, interfering with the daily tasks of life, such as driving a vehicle, especially after dark. “I tell my patients that the time for surgery is when you can’t see what you need to do, whether it’s driving, reading the sports scores on bottom of your TV screen or seeing your mobile device,” says Amir Khan, an ophthalmologist at the Mayo Clinic. “We let the patient decide.”

Keyword: Vision
Link ID: 28067 - Posted: 11.09.2021

Bill Chappell A former science teacher who's been blind for 16 years became able to see letters, discern objects' edges — and even play a Maggie Simpson video game — thanks to a visual prosthesis that includes a camera and a brain implant, according to American and Spanish researchers who collaborated on the project. The test subject had the implant for six months and experienced no disruptions to her brain activity or other health complications, according to an abstract of the study that was published this week in The Journal of Clinical Investigation. The study furthers what it calls a "long-held dream of scientists," to impart a rudimentary form of sight to blind people by sending information directly to the brain's visual cortex. "These results are very exciting because they demonstrate both safety and efficacy," said one of the lead researchers, Eduardo Fernández of Miguel Hernández University, in a statement. "We have taken a significant step forward, showing the potential of these types of devices to restore functional vision for people who have lost their vision." In the experiment, a neurosurgeon implanted a microelectrode array into the visual cortex of Berna Gómez, a former teacher who has been blind for more than 16 years. The implant was then paired with a video camera mounted in the center of a pair of glasses. After a training period, Gómez was able to decipher visual information that was fed from the camera directly to her brain. The training included a video game that helped Gómez learn how to interpret the signals coming from the electrodes. In the game, a screen suddenly shows an image of Maggie Simpson holding a gun, in either her left or right hand. The player must correctly select which hand holds the weapon; using input from the array, Gómez learned how to succeed in that task. At the time of the study, Gómez was 57 years old. Because of her participation, including her ability to give clinically precise feedback to the scientists, Gómez was named as a co-author of the study. © 2021 npr

Keyword: Vision; Robotics
Link ID: 28052 - Posted: 10.27.2021

Andrew Gregory Health editor Millions of people with eye conditions including age-related macular degeneration, cataracts and diabetes-related eye disease have an increased risk of developing dementia, new research shows. Vision impairment can be one of the first signs of the disease, which is predicted to affect more than 130 million people worldwide by 2050. Previous research has suggested there could be a link between eye conditions that cause vision impairment, and cognitive impairment. However, the incidence of these conditions increases with age, as do systemic conditions such as diabetes, high blood pressure, heart disease, depression and stroke, which are all accepted risk factors for dementia. That meant it was unclear whether eye conditions were linked with a higher incidence of dementia independently of systemic conditions. Now researchers have found that age-related macular degeneration, cataracts and diabetes-related eye disease are independently associated with increased risk of dementia, according to a new study published in the British Journal of Ophthalmology. The research examined data from 12,364 British adults aged 55 to 73, who were taking part in the UK Biobank study. They were assessed in 2006 and again in 2010 with their health information tracked until early 2021. More than 2,300 cases of dementia were documented, according to the international team of experts led by academics from the Guangdong Eye Institute in China. After assessing health data, researchers found those with age-related macular degeneration had a 26% increased risk of developing dementia. Those with cataracts had an 11% increased risk and people with diabetes-related eye disease had a 61% heightened risk. Glaucoma was not linked to a significant increase in risk. © 2021 Guardian News & Media Limited

Keyword: Alzheimers; Vision
Link ID: 27990 - Posted: 09.15.2021

Jon Hamilton The visual impairment known as "lazy eye" can be treated in kids by covering their other eye with a patch. Scientists may have found a way to treat adults with the condition using a pufferfish toxin. MARY LOUISE KELLY, HOST: Children who develop the visual impairment often called lazy eye can be treated by covering their other eye with a patch. Now researchers think they have found a way to treat adults using a toxin found in deadly puffer fish. The approach has only been tried in animals so far, but NPR's Jon Hamilton reports the results are encouraging. JON HAMILTON, BYLINE: A lazy eye isn't really lazy. The term refers to amblyopia, a medical condition that occurs when the brain starts ignoring the signals from one eye. Existing treatments restrict use of the strong eye in order to force the brain to pay attention to the weak one. But Mark Bear, a neuroscientist at MIT, says that approach has limits. MARK BEAR: There are a very significant number of adults with amblyopia where the treatment either didn't work or it was initiated too late. HAMILTON: After a critical period that ends at about age 10, the connections between eye and brain become less malleable. They lose what scientists call plasticity. So for several decades, Bear and a team of researchers have been trying to answer a question. BEAR: How can we rejuvenate these connections? How can they be brought back online? HAMILTON: To find out, Bear's team studied adults with amblyopia who lost their strong eye to a disease or an injury. © 2021 npr

Keyword: Vision; Development of the Brain
Link ID: 27989 - Posted: 09.15.2021

By Talia Ogliore New research from Washington University in St. Louis reveals that neurons in the visual cortex — the part of the brain that processes visual stimuli — change their responses to the same stimulus over time. Although other studies have documented “representational drift” in neurons in the parts of the brain associated with odor and spatial memory, this result is surprising because neural activity in the primary visual cortex is thought to be relatively stable. Xia The study published Aug. 27 in Nature Communications was led by Ji Xia, a recent PhD graduate of the laboratory of Ralf Wessel, professor of physics in Arts & Sciences. Xia is now a postdoctoral fellow at Columbia University. “We know that the brain is a flexible structure because we expect the neural activity in the brain to change over days when we learn, or when we gain experience — even as adults,” Xia said. “What is somewhat unexpected is that even when there is no learning, or no experience changes, neural activity still changes across days in different brain areas.” Researchers in Wessel’s group explore sensory information processing in the brain. Working with collaborators, they use novel data analysis to address questions of dynamics and computation in neural circuits of the visual cortex of the brain. Study co-senior author Michael J. Goard, from the Neuroscience Research Institute at the University of California, Santa Barbara, showed mice a single, short movie clip on a loop. (They used a section of the opening from a classic Orson Welles black-and-white film, de rigueur for today’s mouse vision studies.) While a mouse watched the movie, researchers simultaneously recorded activity in several hundred neurons in the primary visual cortex, using two-photon calcium imaging. ©2021 Washington University in St. Louis

Keyword: Vision
Link ID: 27972 - Posted: 09.01.2021

By Carolyn Wilke Frog and toad pupils come in quite the array, from slits to circles. But overall, there are seven main shapes of these animals’ peepholes, researchers report in the Aug. 25 Proceedings of the Royal Society B. Eyes are “among the most charismatic features of frogs and toads,” says herpetologist Julián Faivovich of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” in Buenos Aires. People have long marveled at the animals’ many iris colors and pupil shapes. Yet “there’s almost nothing known about the anatomical basis of that diversity.” Faivovich and colleagues catalogued pupil shapes from photos of 3,261 species, representing 44 percent of known frogs and toads. The team identified seven main shapes: vertical slits, horizontal slits, diamonds, circles, triangles, fans and inverted fans. The most common shape, horizontal slits, appeared in 78 percent of studied species. Mapping pupil shapes onto a tree of evolutionary relationships allowed the scientists to infer how these seven shapes emerged. Though uncommon in other vertebrates, horizontal pupils seem to have given rise to most of the other shapes in frogs and toads. All together, these seven shapes have evolved at least 116 times, the researchers say. Pupil shape affects the amount of light that reaches the retina and its light-receiving cells, says Nadia Cervino, a herpetologist also at the Argentine museum. But how the shape influences what animals actually see isn’t well-known. © Society for Science & the Public 2000–2021.

Keyword: Vision; Evolution
Link ID: 27958 - Posted: 08.25.2021

Ruth Williams In the days before a newborn mouse opens its peepers, nerve impulses that have been sweeping randomly across the retina since birth start flowing consistently in one direction, according to a paper published in Science today (July 22). This specific pattern has a critical purpose, the authors say, helping to establish the brain circuitry to be used later in motion detection. “I love this paper. It blew my mind,” says David Berson, who studies the visual system at Brown University and was not involved in the research. “What it implies is that evolution has built a visual system that can simulate the patterns of activity that it will see later when it’s fully mature and the eyes are open, and that [the simulated pattern] in turn shapes the development of the nervous system in a way that makes it better adapted to seeing those patterns. . . . That’s staggering.” The thread of this concept may be looped, but to unravel it, Berson says, it helps to think of the mammalian visual system, or really any neuronal circuitry, as being formed by a combination of evolution and life experiences—in short, nature and nurture. We might expect that life’s visual experiences, the nurture part, would begin when the eyes open. But, much like a human baby in the womb practices breathing and sucking without ever having experienced air or breastfeeding, the eyes of newborn mice appear to practice seeing before they can actually see. Motion detection is important enough to mouse survival that evolution has selected for gene variants that set up this prevision training, says Berson. © 1986–2021 The Scientist.

Keyword: Vision; Development of the Brain
Link ID: 27950 - Posted: 08.18.2021

By Lisa Sanders, M.D. The burning started as soon as the 59-year-old woman put the drops into her eye. She blinked to try to rinse away the medication with her tears. She leaned forward to the mirror. Her left eye was red and angry-looking. She’d been using these eye drops for nearly a year to treat her newly diagnosed glaucoma, adding artificial tears for the dry eyes that appeared a few months later. And while she’d had plenty of problems with her eyes since all this started, this fiery pain was new. The vision in her left eye had been bad for a few years by then, but with an operation nearly two years earlier to remove an abnormal membrane on her retina and more recent cataract surgery, she had hoped she would have her old vision back by now. She was a physician-researcher and spent much of her time reading and writing, so her vision was very important to her livelihood. But despite the efforts of her eye doctors — and at this point she had many — she still couldn’t see well. It was when she was getting ready for the cataract surgery that the patient learned she had glaucoma. After her initial exam, her new eye surgeon told her that the pressure inside her left eye was abnormally high, and she was already showing signs of damage from it. He wanted her to see one of his colleagues, Dr. Amanda Bicket, a glaucoma specialist who was then at the Wilmer Eye Institute at Johns Hopkins. A quick phone call later, she had an appointment to see the doctor that day. It was urgent that this be evaluated and treated before her upcoming surgery. © 2021 The New York Times Company

Keyword: Vision
Link ID: 27938 - Posted: 08.11.2021

By Emily Conover Scientists could be a step closer to understanding how some birds might exploit quantum physics to navigate. Researchers suspect that some songbirds use a “quantum compass” that senses the Earth’s magnetic field, helping them tell north from south during their annual migrations (SN: 4/3/18). New measurements support the idea that a protein in birds’ eyes called cryptochrome 4, or CRY4, could serve as a magnetic sensor. That protein’s magnetic sensitivity is thought to rely on quantum mechanics, the math that describes physical processes on the scale of atoms and electrons (SN: 6/27/16). If the idea is shown to be correct, it would be a step forward for biophysicists who want to understand how and when quantum principles can become important in various biological processes. In laboratory experiments, the type of CRY4 in retinas of European robins (Erithacus rubecula) responded to magnetic fields, researchers report in the June 24 Nature. That’s a crucial property for it to serve as a compass. “This is the first paper that actually shows that birds’ cryptochrome 4 is magnetically sensitive,” says sensory biologist Rachel Muheim of Lund University in Sweden, who was not involved with the research. Scientists think that the magnetic sensing abilities of CRY4 are initiated when blue light hits the protein. That light sets off a series of reactions that shuttle around an electron, resulting in two unpaired electrons in different parts of the protein. Those lone electrons behave like tiny magnets, thanks to a quantum property of the electrons called spin. © Society for Science & the Public 2000–2021.

Keyword: Animal Migration; Vision
Link ID: 27882 - Posted: 06.29.2021

Scientists studied the brain activity of school-aged children during development and found that regions that activated upon seeing limbs (hands, legs, etc.) subsequently activated upon seeing faces or words when the children grew older. The research, by scientists at Stanford University, Palo Alto, California, reveals new insights about vision development in the brain and could help inform prevention and treatment strategies for learning disorders. The study was funded by the National Eye Institute and is published in Nature Human Behaviour. “Our study addresses how experiences, such as learning to read, shape the developing brain,” said Kalanit Grill-Spector, Ph.D., a professor at Stanford University’s Wu Tsai Neurosciences Institute. “Further, it sheds light on the initial functional role of brain regions that later in development process written words, before they support this important skill of reading.” Grill-Spector’s team used functional MRI to study areas in the ventral temporal cortex (VTC) that are stimulated by the recognition of images. About 30 children, ages 5 to 12 at their first MRI, participated in the study. While in the MRI scanner, the children viewed images from 10 different categories, including words, body parts, faces, objects, and places. The researchers mapped areas of VTC that exhibited stimulation and measured how they changed in intensity and volume on the children’s subsequent MRI tests over the next one to five years. Results showed that VTC regions corresponding to face and word recognition increased with age. Compared to the 5-9-year-olds, teenagers had twice the volume of the word-selective region in VTC. Notably, as word-selective VTC volume doubled, limb-selective volume in the same region halved. According to the investigators, the decrease in limb-selectivity is directly linked to the increase in word- and face-selectivity, providing the first evidence for cortical recycling during childhood development.

Keyword: Vision; Development of the Brain
Link ID: 27860 - Posted: 06.19.2021

Dr Rocio Camacho Morales A transparent metallic film allowing a viewer to see in the dark could one day turn regular spectacles into night vision googles. The ultra-thin film, made of a semiconductor called gallium arsenide, could also be used to develop compact and flexible infrared sensors, scientists say. Though still a proof of concept, the researchers believe it could eventually be turned into a cheap and lightweight replacement for bulky night-vision goggles, which are used in military, police and security settings. The film was developed by a team of Australian and European researchers, with details published in the journal Advanced Photonics. It works by converting infrared light – which is normally invisible to humans – into light visible to the human eye. The study’s first author, Dr Rocio Camacho Morales of the Australian National University, said the material was hundreds of times thinner than a strand of human hair. The gallium arsenide is arranged in a crystalline structure only several hundred nanometres thick, which allows visible light to pass through it. The film has certain similarities to night vision goggles. Blind man has sight partly restored after pioneering treatment Read more “The way these night vision goggles work [is] they also pick up infrared light,” said Camacho Morales. “This infrared light is converted to electrons and displayed [digitally]. In our case, we’re not doing this.” Instead, the film, which does not require any power source, changes the energy of photons of light passing through it, in what is known as a nonlinear optical process. One likely advantage of this film over existing technologies is weight: bulky helmet-mounted night vision goggles have previously been associated with neck pain in airforce pilots, for example. Photons of infrared light have very low energy, Camacho Morales said, which means that electronic night vision devices can be affected by random fluctuations in signal. To minimise these fluctuations, many infrared imaging devices use cooling systems, sometimes requiring cryogenic temperatures. © 2021 Guardian News & Media Limited

Keyword: Vision
Link ID: 27854 - Posted: 06.16.2021

By Carl Zimmer Dr. Adam Zeman didn’t give much thought to the mind’s eye until he met someone who didn’t have one. In 2005, the British neurologist saw a patient who said that a minor surgical procedure had taken away his ability to conjure images. Over the 16 years since that first patient, Dr. Zeman and his colleagues have heard from more than 12,000 people who say they don’t have any such mental camera. The scientists estimate that tens of millions of people share the condition, which they’ve named aphantasia, and millions more experience extraordinarily strong mental imagery, called hyperphantasia. In their latest research, Dr. Zeman and his colleagues are gathering clues about how these two conditions arise through changes in the wiring of the brain that join the visual centers to other regions. And they’re beginning to explore how some of that circuitry may conjure other senses, such as sound, in the mind. Eventually, that research might even make it possible to strengthen the mind’s eye — or ear — with magnetic pulses. “This is not a disorder as far as I can see,” said Dr. Zeman, a cognitive scientist at the University of Exeter in Britain. “It’s an intriguing variation in human experience.” The patient who first made Dr. Zeman aware of aphantasia was a retired building surveyor who lost his mind’s eye after minor heart surgery. To protect the patient’s privacy, Dr. Zeman refers to him as M.X. When M.X. thought of people or objects, he did not see them. And yet his visual memories were intact. M.X. could answer factual questions such as whether former Prime Minister Tony Blair has light-colored eyes. (He does.) M.X. could even solve problems that required mentally rotating shapes, even though he could not see them. I came across M.X.’s case study in 2010 and wrote a column about it for Discover magazine. Afterward, I got emails from readers who had the same experience but who differed from M.X. in a remarkable way: They had never had a mind’s eye to begin with. © 2021 The New York Times Company

Keyword: Attention; Vision
Link ID: 27851 - Posted: 06.11.2021

Linda Geddes Science correspondent A blind man has had his sight partly restored after a form of gene therapy that uses pulses of light to control the activity of nerve cells – the first successful demonstration of so-called optogenetic therapy in humans. The 58-year-old man, from Brittany in northern France, was said to be “very excited” after regaining the ability to recognise, count, locate and touch different objects with the treated eye while wearing a pair of light-stimulating goggles, having lost his sight after being diagnosed with retinitis pigmentosa almost 40 years ago. The breakthrough marks an important step towards the more widespread use of optogenetics as a clinical treatment. It involves modifying nerve cells (neurons) so that they fire electrical signals when they’re exposed to certain wavelengths of light, equipping neuroscientists with the power to precisely control neuronal signalling within the brain and elsewhere. Christopher Petkov, a professor of comparative neuropsychology at Newcastle University medical school, said: “This is a tremendous development to restore vision using an innovative approach. The goal now is to see how well this might work in other patients with retinitis pigmentosa.” This group of rare, genetic disorders, which involves the loss of light-sensitive cells in the retina, affects more than 2 million people worldwide, and can lead to complete blindness. © 2021 Guardian News & Media Limited

Keyword: Vision
Link ID: 27831 - Posted: 05.27.2021

Rob Stein Carlene Knight would love to do things that most people take for granted, such as read books, drive a car, ride a bike, gaze at animals in a zoo and watch movies. She also longs to see expressions on people's faces. "To be able to see my granddaughter especially — my granddaughter's face," said Knight, 54, who lives outside Portland, Ore. "It would be huge." Michael Kalberer yearns to be able to read a computer screen so he could get back to work as a social worker. He also hopes to one day watch his nieces and nephews play soccer instead of just listening to them, and move around in the world without help. But that's not all. "Maybe be able to — as romantically poetic as this sounds — see a sunset again, see a smile on somebody's face again. It's the little things that I miss," said Kalberer, 43, who lives on Long Island in New York. Kalberer and Knight are two of the first patients treated in a landmark study designed to try to restore vision to patients such as them, who suffer from a rare genetic disease. The study involves the revolutionary gene-editing technique called CRISPR, which allows scientists to make precise changes in DNA. Doctors think CRISPR could help patients fighting many diseases. It's already showing promise for blood disorders such as sickle cell disease and is being tested for several forms of cancer. But in those experiments, doctors take cells out of the body, edit them in the lab and then infuse the genetically edited cells back into patients. © 2021 npr

Keyword: Vision; Genes & Behavior
Link ID: 27815 - Posted: 05.12.2021

By Jane E. Brody Look and you shall see: A generation of the real-life nearsighted Mr. Magoos is growing up before your eyes. A largely unrecognized epidemic of nearsightedness, or myopia, is afflicting the eyes of children. People with myopia can see close-up objects clearly, like the words on a page. But their distance vision is blurry, and correction with glasses or contact lenses is likely to be needed for activities like seeing the blackboard clearly, cycling, driving or recognizing faces down the block. The growing incidence of myopia is related to changes in children’s behavior, especially how little time they spend outdoors, often staring at screens indoors instead of enjoying activities illuminated by daylight. Gone are the days when most children played outside between the end of the school day and suppertime. And the devastating pandemic of the past year may be making matters worse. Susceptibility to myopia is determined by genetics and environment. Children with one or both nearsighted parents are more likely to become myopic. However, while genes take many centuries to change, the prevalence of myopia in the United States increased from 25 percent in the early 1970s to nearly 42 percent just three decades later. And the rise in myopia is not limited to highly developed countries. The World Health Organization estimates that half the world’s population may be myopic by 2050. Given that genes don’t change that quickly, environmental factors, especially children’s decreased exposure to outdoor light, are the likely cause of this rise in myopia, experts believe. Consider, for example, factors that keep modern children indoors: an emphasis on academic studies and their accompanying homework, the irresistible attraction of electronic devices and safety concerns that demand adult supervision during outdoor play. All of these things drastically limit the time youngsters now spend outside in daylight, to the likely detriment of the clarity of their distance vision. © 2021 The New York Times Company

Keyword: Vision; Development of the Brain
Link ID: 27802 - Posted: 05.05.2021

: Peter Campochiaro, M.D. A 72-year-old lawyer who is pursuing his passion for photography in retirement was suddenly unable to take sharp, well-focused photographs. An examination of each eye revealed yellow spots in the macula, the central area of the retina responsible for sharp vision. The macula in the right eye was thickened and raised in height, substantially reducing and distorting his vision. A test called a fluorescein angiogram, in which fluorescent dye is injected into an arm vein that travels to blood vessels in the retina for imaging, revealed a spot of intense fluorescence that enlarged over time, indicating the presence of abnormal blood vessels leaking plasma into surrounding tissue. An optical coherence tomography scan provided a two-dimensional optical cross section showing fluid beneath and within the right eye’s macula. The patient had a condition known as age-related macular degeneration (AMD), common to about 200 million individuals globally and referred to as “age-related” because it is rarely seen in individuals younger than 60 years old. With people living longer and longer, it is estimated that by 2040, there will be 300 million individuals with AMD throughout the world. And besides the blurred vision that this patient was experiencing, other patients often complain about difficulty recognizing familiar faces; straight lines that appear wavy; dark, empty areas or blind spots; and a general loss of central vision, which is necessary for driving, reading, and recognizing faces. Besides age, smoking is a universally agreed upon risk factor for AMD; hypertension and high blood lipids have been identified in some studies but not others. © 2021 The Dana Foundation.

Keyword: Vision
Link ID: 27774 - Posted: 04.17.2021

By Meagan Cantwell In order to see the world as clearly as we do, we process vision from each eyeball on both sides of our brain—a capability known as bilateral visual projection. For a long time, researchers thought this feature developed after fish transitioned to land, more than 375 million years ago. But does this theory hold water today? In a new study, scientists injected fluorescent tracers into the eyes of 11 fish species to illuminate their visual systems. After examining their brains under a specialized 3D fluorescence microscope, they found ancient fish with genomes more similar to mammals can project vision on both the same and opposite side of their brain (see video, above). This suggests bilateral vision did not coincide with the transition from water to land, researchers report this week in Science. In the future, scientists plan to uncover the genes that drive same-sided visual projection to better understand how vision evolved. © 2021 American Association for the Advancement of Science.

Keyword: Vision; Evolution
Link ID: 27764 - Posted: 04.10.2021

By Veronique Greenwood Sign up for Science Times: Get stories that capture the wonders of nature, the cosmos and the human body. In the warm, fetid environs of a compost heap, tiny roundworms feast on bacteria. But some of these microbes produce toxins, and the worms avoid them. In the lab, scientists curious about how the roundworms can tell what’s dinner and what’s dangerous often put them on top of mats of various bacteria to see if they wriggle away. One microbe species, Pseudomonas aeruginosa, reliably sends them scurrying. But how do the worms, common lab animals of the species Caenorhabditis elegans, know to do this? Dipon Ghosh, then a graduate student in cellular and molecular physiology at Yale University, wondered if it was because they could sense the toxins produced by the bacteria. Or might it have something to do with the fact that mats of P. aeruginosa are a brilliant shade of blue? Given that roundworms do not have eyes, cells that obviously detect light or even any of the known genes for light-sensitive proteins, this seemed a bit far-fetched. It wasn’t difficult to set up an experiment to test the hypothesis, though: Dr. Ghosh, who is now a postdoctoral researcher at the Massachusetts Institute of Technology, put some worms on patches of P. aeruginosa. Then he turned the lights off. To the surprise of his adviser, Michael Nitabach, the worms’ flight from the bacteria was significantly slower in the dark, as though not being able to see kept the roundworms from realizing they were in danger. “When he showed me the results of the first experiments, I was shocked,” said Dr. Nitabach, who studies the molecular basis of neural circuits that guide behavior at Yale School of Medicine. In a series of follow-up experiments detailed in a paper published Thursday in Science, Dr. Ghosh, Dr. Nitabach and their colleagues establish that some roundworms respond clearly to that distinctive pigment, perceiving it — and fleeing from it — without the benefit of any known visual system. © 2021 The New York Times Company

Keyword: Vision; Evolution
Link ID: 27718 - Posted: 03.06.2021

By Richard Sima Sign up for Science Times: Get stories that capture the wonders of nature, the cosmos and the human body. Though it is well-known for its many arms, the octopus does not seem to know where those eight appendages are most of the time. “In the octopus, you have no bones and no joints, and every point in its arm can go to every direction that you can think about,” said Nir Nesher, a senior lecturer in marine sciences at the Ruppin Academic Center in Israel. “So even one arm, it’s something like endless degrees of freedom.” So how does the octopus keep all those wiggly, sucker-covered limbs out of trouble? According to a study published this month in The Journal of Experimental Biology by Dr. Nesher and his colleagues, the octopus’s arms can sense and respond to light — even when the octopus cannot see it with the eyes on its head. This light-sensing ability may help the cephalopods keep their arms concealed from other animals that could mistake the tip of an arm for a marine worm or some other kind of meal. Itamar Katz, one of the study’s authors, first noticed the light-detecting powers while studying a different phenomenon: how light causes the octopus’s skin to change color. With Dr. Nesher and Tal Shomrat, another author, Mr. Katz saw that shining light on an arm caused the octopus to withdraw it, even when the creature was sleeping. Further experiments showed that the arms would avoid the light in situations when the octopus could not see it with its eyes. Even when the octopuses reached an arm out of a small opening on an opaque, covered aquarium for food, the arm would quickly retract when light was shined on it 84 percent of the time. This was a surprise, as though the octopus “can see the light through the arm, it can feel the light through the arm,” Dr. Nesher said. “They don’t need the eye for that.” ImageScientists suspect octopuses keep their arms concealed from other animals that could mistake the tip of an arm for a meal. Scientists suspect octopuses keep their arms concealed from other animals that could © 2021 The New York Times Company

Keyword: Vision; Evolution
Link ID: 27704 - Posted: 02.23.2021

By Valeriya Safronova Jennifer Lopez is wearing them, Kylie Jenner and Rashida Jones are promoting them, and Drew Barrymore is selling them. Blue-light glasses are shaping up to be the accessory of our prolonged screen-mediated moment. But do we need them? Blue-light glasses are fitted with lenses that filter out certain light waves that are emitted by the sun and, to a lesser extent, by digital devices like phones, laptops and tablets. Blue light is not inherently bad; it boosts attention and wakefulness during the day. But it suppresses the natural production of melatonin at night. By limiting exposure to blue light by as little as 20 percent, companies say, a customer could sleep better, experience less eye strain and prevent potential retinal damage. Scientists, however, are not convinced that the glasses are a worthy investment. “Whichever aspect you look at, it’s very hard to justify spending the extra money,” said Dr. John Lawrenson, a professor of clinical visual science at City, University of London. (Prices vary but start at around $20.) After reviewing several studies that tested the effectiveness of blue-light-blocking lenses, he and his colleagues concluded that the glasses are not necessary. Digital eye strain is real, but it’s impossible to say with certainty that the culprit is blue light. “No one has established an independent causal association between blue light coming from the computer and visual symptoms,” Dr. Lawrenson said. He recommended going to an eye doctor for a checkup instead of rushing to buy nonprescription glasses. Regardless, the blue-light category is booming. A quick Google search pulls up several brands that almost exclusively sell “computer glasses” (like Felix Gray, which raised more than $1.7 million in funding in 2020, bringing its total funding to $7.8 million as of September, according to PitchBook), as well as prescription-eyewear companies like Zenni (which sold two million pairs of its Blokz lenses in 2020, according to the company) and Jins (which noted an uptick in online orders last year). If you’ve shopped at Warby Parker recently, you were probably asked if you’d like a blue-light filter added to your lenses. © 2021 The New York Times Company

Keyword: Sleep; Vision
Link ID: 27698 - Posted: 02.19.2021