Chapter 10. Vision: From Eye to Brain


Links 41 - 60 of 1115


Keyword: Consciousness; Vision
Link ID: 21347 - Posted: 08.27.2015

By Jessica Schmerler In the modern age of technology it is not uncommon to come home after a long day at work or school and blow off steam by reading an e-book or watching television. Lately, however, scientists have been cautioning against using light-emitting devices before bed. Why? The light from our devices is “short-wavelength-enriched,” meaning it has a higher concentration of blue light than natural light—and blue light affects levels of the sleep-inducing hormone melatonin more than any other wavelength. Changes in sleep patterns can in turn shift the body’s natural clock, known as its circadian rhythm. Recent studies have shown that shifts in this clock can have devastating health effects because it controls not only our wakefulness but also individual clocks that dictate function in the body’s organs. In other words, stressors that affect our circadian clocks, such as blue-light exposure, can have much more serious consequences than originally thought. How did you become interested in the effects of light on sleep? Brainard: I was interested in the effects of light on animals as a teenager. I never planned to be a scientist—I wanted to be a writer! So I learned more about the topic out of pure curiosity. When I began my career as a journalist, I interviewed researchers on the topic who encouraged me to pursue a career in science. So I returned to school to get my doctorate and studied the effects of different wavelengths and intensities of light on rodents. I have exclusively studied the effects of light on humans for the past 30 years. © 2015 Scientific American

Keyword: Sleep; Biological Rhythms
Link ID: 21337 - Posted: 08.26.2015


Keyword: Vision; Obesity
Link ID: 21317 - Posted: 08.19.2015


Keyword: Vision
Link ID: 21303 - Posted: 08.17.2015


Keyword: Vision
Link ID: 21298 - Posted: 08.15.2015

Despite virtual reality’s recent renaissance, the technology still has some obvious problems. One, you look like a dumbass using it. Two, the stomach-churning mismatch between what you see and what you feel contributes to “virtual reality sickness.” But there’s another, less obvious flaw that could add to that off-kilter sensation: an eye-focusing problem called vergence-accommodation conflict. It’s only less obvious because, well, you rarely experience it outside of virtual reality. At SIGGRAPH in Los Angeles this week, Stanford professor Gordon Wetzstein and his colleagues are presenting a new head-mounted display that minimizes the vergence-accommodation conflict. This isn’t just some esoteric academic problem. Leading VR companies like Oculus and Microsoft know all too well their headsets are off, and Magic Leap, the super secret augmented reality company in Florida, is betting the house on finding a solution first. “It’s an exciting area of research,” says Martin Banks, a vision scientist at the University of California, Berkeley. “I think it’s going to be the next big thing in displays.” Okay okay, so what’s the big deal with the vergence-accommodation conflict? Two things happen when you simply “look” at an object. First, you point your eyeballs. If an object is close, your eyes naturally converge on it; if it’s far, they diverge. Hence, vergence. If your eyes don’t line up correctly, you end up seeing double. The second thing that happens is the lenses inside your eyes focus on the object, aka accommodation. Normally, vergence and accommodation are coupled. “The visual system has developed a circuit where the two response talk to each other,” says Banks. “That makes perfect sense in the natural environment. They’re both trying to get to the same distance, so why wouldn’t they talk to one another?” In other words, your meat brain has figured out a handy shortcut for the real world.

Keyword: Vision
Link ID: 21287 - Posted: 08.12.2015

Nell Greenfieldboyce Take a close look at a house cat's eyes and you'll see pupils that look like vertical slits. But a tiger has round pupils — like humans do. And the eyes of other animals, like goats and horses, have slits that are horizontal. Scientists have now done the first comprehensive study of these three kinds of pupils. The shape of the animal's pupil, it turns out, is closely related to the animal's size and whether it's a predator or prey. The pupil is the hole that lets light in, and it comes in lots of different shapes. "There are some weird ones out there," says Martin Banks, a vision scientist at the University of California, Berkeley. Cuttlefish have pupils that look like the letter "W," and dolphins have pupils shaped like crescents. Some frogs have heart-shaped pupils, while geckos have pupils that look like pinholes arranged in a vertical line. Needless to say, scientists want to know why all these different shapes evolved. "It's been an active point of debate for quite some time," says Banks, "because it's something you obviously observe. It's the first thing you see about an animal — where their eye is located and what the pupil shape is." For their recent study, Banks and his colleagues decided to keep things simple. They looked at just land animals, and just three kinds of pupils. "We restricted ourselves to just pupils that are elongated or not," Banks explains. "So they're either vertical, horizontal or round." © 2015 NPR

Keyword: Vision; Evolution
Link ID: 21277 - Posted: 08.08.2015

By Rachel Feltman Ever wondered what the world looks like to nonhuman animals? Scientists do, too. It can actually be a really important question. Sometimes humans can't see things -- like skin markings designed to attract mates or flower colors meant to draw pollinators -- that are incredibly important in the life and behavior of an animal. That's why researchers at the University of Exeter have developed a software that converts photos to "animal vision." The software, which is available for free online, is described in a recent paper in the journal Methods in Ecology and Evolution. Its creators have already used it extensively themselves to perform studies on animals who see light outside the spectrum visible to humans. They've also used it to track imperceptible color changes that occur in women's faces during ovulation. The software works by integrating photos taken using ultraviolet filters with those taken using regular color filters, a process that scientists used to have to dial in manually for whatever species they were studying. By meshing the visible light spectrum with information from a full-spectrum image, the software can replicate the visual experience of animals who see more colors than humans, including light in the ultraviolet range.

Keyword: Vision
Link ID: 21272 - Posted: 08.08.2015

By Hanae Armitage Cataracts cloud the eyes of tens of millions of people around the world and nearly 17.2% of Americans over the age of 40. Currently, the only treatment is surgery—lasers or scalpels cut away the molecular grout that builds in the eye as cataracts develop, and surgeons sometimes replace the lens. But now, a team of scientists and ophthalmologists has tested a solution in dogs that may be able to dissolve the cataract right out of the eye’s lens. And the solution is itself a solution: a steroid-based eye drop. Though scientists don’t fully understand how cataracts form, they do know that the “fog” often seen by patients is a glob of broken proteins, stuck together in a malfunctioning clump. When healthy, these proteins, called crystallins, help the eye’s lens keep its structure and transparency. But as humans and animals alike get older, these crystallin proteins start to come unglued and lose their ability to function. Then they clump together and form a sheathlike obstruction in the lens, causing the signature “steamy glass” vision that accompanies cataracts. Coming up with a solution other than surgery has been tough. Scientists have been hunting for years for mutations in crystallin proteins that might offer new insights and pave the way to an alternate therapy. Now, it looks like a team led by University of California (UC), San Diego, molecular biologist Ling Zhao may have done just that. Her team came up with the eye drop idea after finding that children with a genetically inherited form of cataracts shared a mutation that stopped the production of lanosterol, an important steroid in the body. When their parents did not have the same mutation, the adults produced lanosterol and had no cataracts. © 2015 American Association for the Advancement of Science.

Keyword: Vision
Link ID: 21205 - Posted: 07.23.2015

It’s a good combination. Gene therapy to reverse blindness repairs damaged cells in the eye and also rearranges the brain to help process the new information. Visual pathways in the brain are made up of millions of interconnected neurons. When sensory signals are sent along them, the connections between neurons become strong. If underused – for example, as people lose their sight – the connections become weak and disorganised. Over the past few years, a type of gene therapy – injecting healthy genes into the eye to repair mutations – has emerged as a promising way to treat congenital and degenerative blindness. One of the first successful trials began in 2007. It involved 10 blind volunteers with a hereditary disease called Leber’s congenital amaurosis. The condition causes the retina to degenerate and leaves people completely blind early in life. Mutations in at least 19 genes can cause the disease, but all of the people in the trial had mutations in a gene called RPE65. The participants got an injection of a harmless virus in one of their eyes. The virus inserted healthy copies of RPE65 into their retina. Some of the volunteers went from straining to see a hand waving half a metre from their face to being able to read six lines on a sight chart. Others were able to navigate around an obstacle course in dim light – something that would have been impossible before the therapy. © Copyright Reed Business Information Ltd.

Keyword: Vision; Genes & Behavior
Link ID: 21185 - Posted: 07.18.2015

By Chris Foxx Technology reporter Twitter has responded to an epilepsy charity that said two of its online adverts were "irresponsible". The social media giant had uploaded two short videos on Vine that featured a looping, rapid succession of flashing colours. "Twitter's ads were dangerous to people living with photo-sensitive epilepsy," said Epilepsy Action's deputy chief executive, Simon Wigglesworth. Twitter told the BBC it had removed the videos on Friday morning. Around one in 3,500 people in the UK has photosensitive epilepsy, according to Epilepsy Action. Seizures can be triggered by flashing lights and bold patterns. An episode of Japanese cartoon Pokemon was famously blamed for triggering convulsions in 1997. "Eighty seven people are diagnosed with epilepsy every day and that first seizure can often come out of nowhere," said Mr Wigglesworth. "For a huge corporation like Twitter to take that risk was irresponsible." The Advertising Standards Authority told the BBC that "marketing communications", even those uploaded on a company's own website, should not include "visual effects or techniques that are likely to adversely affect members of the public with photosensitive epilepsy". It said both online and broadcast adverts in the UK had to adhere to rules made by the Committees of Advertising Practice. "We take very seriously ads in online media that might cause harm to people with photosensitive epilepsy," an ASA spokeswoman told the BBC. Twitter's flashing Vine videos were online for 18 hours before the company removed them. © 2015 BBC

Keyword: Epilepsy; Vision
Link ID: 21157 - Posted: 07.11.2015

Spider-like cells inside the brain, spinal cord and eye hunt for invaders, capturing and then devouring them. These cells, called microglia, often play a beneficial role by helping to clear trash and protect the central nervous system against infection. But a new study by researchers at the National Eye Institute (NEI) shows that they also accelerate damage wrought by blinding eye disorders, such as retinitis pigmentosa. NEI is part of the National Institutes of Health. “These findings are important because they suggest that microglia may provide a target for entirely new therapeutic strategies aimed at halting blinding eye diseases of the retina,” said NEI Director, Paul A. Sieving, M.D. “New targets create untapped opportunities for preventing disease-related damage to the eye, and preserving vision for as long as possible.” The findings were published in the journal EMBO Molecular Medicine. Retinitis pigmentosa, an inherited disorder that affects roughly 1 in 4,000 people, damages the retina, the light-sensitive tissue at the back of the eye. Research has shown links between retinitis pigmentosa and several mutations in genes for photoreceptors, the cells in the retina that convert light into electrical signals that are sent to the brain via the optic nerve. In the early stages of the disease, rod photoreceptors, which enable us to see in low light, are lost, causing night blindness. As the disease progresses, cone photoreceptors, which are needed for sharp vision and seeing colors, can also die off, eventually leading to complete blindness.

Keyword: Vision; Glia
Link ID: 21130 - Posted: 07.04.2015


Keyword: Vision; Evolution
Link ID: 21058 - Posted: 06.16.2015

By Stephen L. Macknik, Susana Martinez-Conde and Bevil Conway This past February a photograph of a dress nearly broke the Internet. It all started when a proud mother-in-law-to-be snapped a picture of the dress she planned to wear to her daughter's wedding. When she shared her picture with her daughter and almost-son-in-law, the couple could not agree on the color: she saw white and gold, but he saw blue and black. A friend of the bride posted the confusing photo on Tumblr. Followers then reposted it to Twitter, and the image went viral. “The Dress” pitted the opinions of superstar celebrities against one another (Kanye and Kim disagreed, for instance) and attracted millions of views on social media. The public at large was split into white-and-gold and blue-and-black camps. So much attention was drawn, you would have thought the garment was conjured by a fairy godmother and accessorized with glass slippers. To sort out the conundrum, the media tapped dozens of neuroscientists and psychologists for comment. Pride in our heightened relevance to society gave way to embarrassment as we realized that our scientific explanations for the color wars were not only diverse but also incomplete. Especially perplexing was the fact that people saw it differently on the same device under the same viewing conditions. This curious inconsistency suggests that The Dress is a new type of perceptual phenomenon, previously unknown to scientists. Although some early explanations for the illusion focused on individual differences in the ocular structure of the eye, such as the patterning and function of rod and cone photoreceptor cells or the light-filtering properties internal to the eye, the most important culprit may be the brain's color-processing mechanisms. These might vary from one person to the next and can depend on prior experiences and beliefs. © 2015 Scientific American

Keyword: Vision
Link ID: 21053 - Posted: 06.15.2015

by Penny Sarchet Simon Sponberg of Georgia Institute of Technology in Atlanta and his team have figured out the secret to the moths' night vision by testing them with robotic artificial flowers (see above). By varying the speed of a fake flower's horizontal motion and changing brightness levels, the team tested moths' abilities under different conditions. It has been theorised that the moth brain slows down, allowing their visual system to collect light for longer, a bit like lengthening a camera's exposure. But the strategy might also introduce blur, making it hard to detect fast movement. If the moths were using this brain-slowing tactic, they would be expected to react to fast flower movements more slowly in darker conditions. The team found that there was indeed a lag. It helped them see motion in the dark while still allowing them to keep up with flowers swaying at normal speeds. The size of the lags matched the expected behaviour of a slowed nervous system, providing evidence that moths could be slowing down the action of neurons in their visual system. Previously, placing hawkmoths in a virtual obstacle courseMovie Camera revealed that they vary their navigation strategies depending on visibility conditions. Journal reference: Science, DOI: 10.1126/science.aaa3042 © Copyright Reed Business Information Ltd

Keyword: Vision
Link ID: 21041 - Posted: 06.13.2015

Mo Costandi According to the old saying, the eyes are windows into the soul, revealing deep emotions that we might otherwise want to hide. Although modern science precludes the existence of the soul, it does suggest that there is a kernel of truth in this saying: it turns out the eyes not only reflect what is happening in the brain but may also influence how we remember things and make decisions. Our eyes are constantly moving, and while some of those movements are under conscious control, many of them occur subconsciously. When we read, for instance, we make a series of very quick eye movements called saccades that fixate rapidly on one word after another. When we enter a room, we make larger sweeping saccades as we gaze around. Then there are the small, involuntary eye movements we make as we walk, to compensate for the movement of our head and stabilise our view of the world. And, of course, our eyes dart around during the ‘rapid eye movement’ (REM) phase of sleep. What is now becoming clear is that some of our eye movements may actually reveal our thought process. Research published last year shows that pupil dilation is linked to the degree of uncertainty during decision-making: if somebody is less sure about their decision, they feel heightened arousal, which causes the pupils to dilate. This change in the eye may also reveal what a decision-maker is about to say: one group of researchers, for example, found that watching for dilation made it possible to predict when a cautious person used to saying ‘no’ was about to make the tricky decision to say ‘yes’. © 2015 Guardian News and Media Limited

Keyword: Attention; Vision
Link ID: 21011 - Posted: 06.02.2015

Rebecca Hersher Greg O'Brien sees things that he knows aren't there, and these visual disturbances are becoming more frequent. That's not uncommon; up to 50 percent of people who have Alzheimer's disease experience hallucinations, delusions or psychotic symptoms, recent research suggests. At first, he just saw spider-like forms floating in his peripheral vision, O'Brien says. "They move in platoons." But in the last year or so, the hallucinations have been more varied, and often more disturbing. A lion. A bird. Sprays of blood among the spiders. Over the past five months, O'Brien has turned on an audio recorder when the hallucinations start, in hopes of giving NPR listeners insight into what Alzheimer's feels like. For now, he says, "I'm able to function. But I fear the day, which I know will come, when I can't." Interview Highlights [It's] St. Patrick's Day, about 9 o'clock in the morning in my office, and they're coming again. Those hallucinations. Those things that just come into the mind when the mind plays games. And then I see the bird flying in tighter and tighter and tighter circles. And all of a sudden, the bird — beak first — it darted almost in a suicide mission, exploding into my heart. Today I'm just seeing this thing in front of me. It looks like a lion, almost looks like something you'd see in The Lion King, and there are birds above it. It's floating, and it disintegrates ... it disintegrates ... it disintegrates.

Keyword: Alzheimers; Vision
Link ID: 21003 - Posted: 06.01.2015

by Clare Wilson A new study has discredited the theory that dyslexia is caused by visual problems. So what does cause the condition and how can it be treated? What kind of visual problems are claimed to cause dyslexia? A huge variety. They include difficulties in merging information from both eyes, problems with glare from white pages or the text blurring or "dancing" on the page. A host of products claim to relieve this so-called visual stress, especially products that change the background colour of the page, such as tinted glasses and coloured overlays. Others advise eye exercises that supposedly help people with dyslexia track words on the page. Despite lack of evidence that these approaches work, some people with dyslexia say they help – more than half of university students with dyslexia have used such products. What are the new findings? That there's no evidence visual stress is linked with dyslexia. Nearly 6000 UK children aged between 7 and 9 had their reading abilities tested as well as performing a battery of visual tests. About 3 per cent of them had serious dyslexia, in line with the national average. But in the visual tests, the differences between the students with and without dyslexia were minimal. In two of the 11 tests, about 16 per cent of the children with dyslexia scored poorly, compared with 10 per cent for children with normal reading abilities. But that small difference could be caused by the fact that they read less, says author Alexandra Creavin of the University of Bristol, UK. And more importantly, the 16 per cent figure is so low, it can't be the main explanation for dyslexia. © Copyright Reed Business Information Ltd.

Keyword: Dyslexia; Vision
Link ID: 20976 - Posted: 05.25.2015

Carl Zimmer Octopuses, squid and cuttlefish — a group of mollusks known as cephalopods — are the ocean’s champions of camouflage. Octopuses can mimic the color and texture of a rock or a piece of coral. Squid can give their skin a glittering sheen to match the water they are swimming in. Cuttlefish will even cloak themselves in black and white squares should a devious scientist put a checkerboard in their aquarium. Cephalopods can perform these spectacles thanks to a dense fabric of specialized cells in their skin. But before a cephalopod can take on a new disguise, it needs to perceive the background that it is going to blend into. Cephalopods have large, powerful eyes to take in their surroundings. But two new studies in The Journal Experimental Biology suggest that they have another way to perceive light: their skin. It’s possible that these animals have, in effect, evolved a body-wide eye. When light enters the eye of a cephalopod, it strikes molecules in the retina called opsins. The collision starts a biochemical reaction that sends an electric signal from the cephalopod’s eye to its brain. (We produce a related form of opsins in our eyes as well.) In 2010, Roger T. Hanlon, a biologist at the Marine Biological Laboratory in Woods Hole, Mass., and his colleagues reported that cuttlefish make opsins in their skin, as well. This discovery raised the tantalizing possibility that the animals could use their skin to sense light much as their eyes do. Dr. Hanlon teamed up with Thomas W. Cronin, a visual ecologist at the University of Maryland Baltimore County, and his colleagues to take a closer look. © 2015 The New York Times Company

Keyword: Vision; Evolution
Link ID: 20966 - Posted: 05.21.2015

By Camille Bains, Imagine being able to see three times better than 20/20 vision without wearing glasses or contacts — even at age 100 or more — with the help of bionic lenses implanted in your eyes. Dr. Garth Webb, an optometrist in British Columbia who invented the Ocumetics Bionic Lens, says patients would have perfect vision and that driving glasses, progressive lenses and contact lenses would become a dim memory as the eye-care industry is transformed. Dr. Garth Webb says the bionic lens would allow people to see to infinity and replace the need for eyeglasses and contact lenses. (Darryl Dyck/Canadian Press) Webb says people who have the specialized lenses surgically inserted would never get cataracts because their natural lenses, which decay over time, would have been replaced. Perfect eyesight would result "no matter how crummy your eyes are," Webb says, adding the Bionic Lens would be an option for someone who depends on corrective lenses and is over about age 25, when the eye structures are fully developed. "This is vision enhancement that the world has never seen before," he says, showing a Bionic Lens, which looks like a tiny button. "If you can just barely see the clock at 10 feet, when you get the Bionic Lens you can see the clock at 30 feet away," says Webb, demonstrating how a custom-made lens that folded like a taco in a saline-filled syringe would be placed in an eye, where it would unravel itself within 10 seconds. He says the painless procedure, identical to cataract surgery, would take about eight minutes and a patient's sight would be immediately corrected. ©2015 CBC/Radio-Canada.

Keyword: Vision
Link ID: 20950 - Posted: 05.19.2015