Chapter 7. Vision: From Eye to Brain
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|By Stephen L. Macknik and Susana Martinez-Conde The Best Illusion of the Year Contest brings scientific and popular attention to perceptual oddities. Anyone can submit an illusion to next year's contest at http://illusionoftheyear.com/submission-instructions for the rules Decked out in a mask, cape and black spandex, a fit young man leaps onto the stage, one hand raised high, and bellows, “I am Japaneeeese Bat-Maaaaaan!” in a thick accent. The performer is neither actor nor acrobat. He is a mathematician named Jun Ono, hailing from Meiji University in Japan. Ono's single bound, front and center, at the Philharmonic Center for the Arts in Naples, Fla. (now called Artis-Naples), was the opening act of the ninth Best Illusion of the Year Contest, held May 13, 2013. Four words into the event, we knew Ono had won. Aside from showcasing new science, the contest celebrates our brain's wonderful and mistaken sense that we can accurately see, smell, hear, taste and touch the world around us. In reality, accuracy is not the brain's forte, as the illusion creators competing each year will attest. Yes, there is a real world out there, and you do perceive (some of) the events that occur around you, but you have never actually lived in reality. Instead your brain gathers pieces of data from your sensory systems—some of which are quite subjective or frankly wrong—and builds a simulation of the world. This simulation, which some call consciousness, becomes the universe in which you live. It is the only thing you have ever perceived. Your brain uses incomplete and flawed information to build this mental model and relies on quirky neural algorithms to often—but not always—obviate the flaws. Let us take a spin through some of the world's top illusions and their contributions to the science of perception. (To see videos of these illusions, see ScientificAmerican.com/may2014/illusions.) © 2014 Scientific American
Mégevand P et al., Journal of Neuroscience (2014) Close your eyes and imagine home. Sharp details—such as the shape of the front doorknob, the height of the windows, or the paint color—assemble in your mind with a richness that seems touchable. A new study has found where this mental projection lives in the brain by inducing hallucinations in an epilepsy patient. A 22-year-old male was receiving deep brain stimulation to isolate where his daily seizures originated. His disorder appeared after he caught West Nile virus at the age of 10 and subsequently suffered from brain inflammation. His episodes were always preceded by intense déjà vu, suggesting a visual component of his disease, but he had no history of hallucinations. Brain scans revealed a shrunken spot near his hippocampus—the brain’s memory center. Studies had shown that this region—known as the parahippocampal place area (PPA)—was involved with recognizing of scenes and places. Doctors reconfirmed this by showing the patient pictures of a house and seeing the PPA light up on brain scans with functional magnetic resonance imaging (images above show brain activity; yellow indicates stronger activation than red). Thin wire electrodes—less than 2 mm thick—placed in the PPA (yellow dots in right panel) recorded similar brain activity after viewing these pictures. To assess if the PPA was ground zero for seizures, the doctors used a routine procedure that involves shooting soft jolts of electricity into the region and seeing if the patient senses an oncoming seizure. Rather than have déjà vu, the patient’s surroundings suddenly changed as he hallucinated places familiar to him. In one instance, the doctors morphed into the Italians from his local pizza place. Zapping a nearby cluster of neurons produced a vision of his subway station. The findings, published on 16 April in The Journal of Neuroscience, confirm that this small corner of the brain is not only responsible for recognizing places, but is also crucial to recalling a mental vision of that place. © 2014 American Association for the Advancement of Science
Link ID: 19499 - Posted: 04.17.2014
By Ariel Van Brummelen The presence of light may do more for us than merely allow for sight. A study by Gilles Vandewalle and his colleagues at the University of Montreal suggests that light affects important brain functions—even in the absence of vision. Previous studies have found that certain photoreceptor cells located in the retina can detect light even in people who do not have the ability to see. Yet most studies suggested that at least 30 minutes of light exposure is needed to significantly affect cognition via these nonvisual pathways. Vandewalle's study, which involved three completely blind participants, found that just a few seconds of light altered brain activity, as long as the brain was engaged in active processing rather than at rest. First the experimenters asked their blind subjects whether a blue light was on or off, and the subjects answered correctly at a rate significantly higher than random chance—even though they confirmed they had no conscious perception of the light. Using functional MRI, the researchers then determined that less than a minute of blue light exposure triggered changes in activity in regions of their brain associated with alertness and executive function. Finally, the scientists found that if the subjects received simultaneous auditory stimulation, a mere two seconds of blue light was enough to modify brain activity. The researchers think the noise engaged active sensory processing, which allowed the brain to respond to the light much more quickly than in previous studies when subjects rested while being exposed to light. The results confirm that the brain can detect light in the absence of working vision. They also suggest that light can quickly alter brain activity through pathways unrelated to sight. The researchers posit that this nonvisual light sensing may aid in regulating many aspects of human brain function, including sleep/wake cycles and threat detection. © 2014 Scientific American
By GRETCHEN REYNOLDS Age-related vision loss is common and devastating. But new research suggests that physical activity might protect our eyes as we age. There have been suggestions that exercise might reduce the risk of macular degeneration, which occurs when neurons in the central part of the retina deteriorate. The disease robs millions of older Americans of clear vision. A 2009 study of more than 40,000 middle-aged distance runners, for instance, found that those covering the most miles had the least likelihood of developing the disease. But the study did not compare runners to non-runners, limiting its usefulness. It also did not try to explain how exercise might affect the incidence of an eye disease. So, more recently, researchers at Emory University in Atlanta and the Atlanta Veterans Administration Medical Center in Decatur, Ga., took up that question for a study published last month in The Journal of Neuroscience. Their interest was motivated in part by animal research at the V.A. medical center. That work had determined that exercise increases the levels of substances known as growth factors in the animals’ bloodstream and brains. These growth factors, especially one called brain-derived neurotrophic factor, or B.D.N.F., are known to contribute to the health and well-being of neurons and consequently, it is thought, to improvements in brain health and cognition after regular exercise. But the brain is not the only body part to contain neurons, as the researchers behind the new study knew. The retina does as well, and the researchers wondered whether exercise might raise levels of B.D.N.F. there, too, potentially affecting retinal health and vision. © 2014 The New York Times Company
Link ID: 19451 - Posted: 04.07.2014
Visual illusions, such as the rabbit-duck (shown above) and café wall (shown below) are fascinating because they remind us of the discrepancy between perception and reality. But our knowledge of such illusions has been largely limited to studying humans. That is now changing. There is mounting evidence that other animals can fall prey to the same illusions. Understanding whether these illusions arise in different brains could help us understand how evolution shapes visual perception. For neuroscientists and psychologists, illusions not only reveal how visual scenes are interpreted and mentally reconstructed, they also highlight constraints in our perception. They can take hundreds of different forms and can affect our perception of size, motion, colour, brightness, 3D form and much more. Artists, architects and designers have used illusions for centuries to distort our perception. Some of the most common types of illusory percepts are those that affect the impression of size, length or distance. For example, Ancient Greek architects designed columns for buildings so that they tapered and narrowed towards the top, creating the impression of a taller building when viewed from the ground. This type of illusion is called forced perspective, commonly used in ornamental gardens and stage design to make scenes appear larger or smaller. As visual processing needs to be both rapid and generally accurate, the brain constantly uses shortcuts and makes assumptions about the world that can, in some cases, be misleading. For example, the brain uses assumptions and the visual information surrounding an object (such as light level and presence of shadows) to adjust the perception of colour accordingly. © 2014 Guardian News and Media Limited
Link ID: 19398 - Posted: 03.22.2014
Neuroscientist Bevil Conway thinks about color for a living. An artist since youth, Conway now spends much of his time studying vision and perception at Wellesley College and Harvard Medical School. His science remains strongly linked to art--in 2004 he and Margaret Livingstone famously reported that Rembrandt may have suffered from flawed vision--and in recent years Conway has focused his research almost entirely on the neural machinery behind color. "I think it's a very powerful system," he tells Co.Design, "and it's completely underexploited." Conway's research into the brain's color systems has clear value for designers and artists like himself. It stands to reason, after all, that someone who understands how the brain processes color will be able to present it to others in a more effective way. But the neuroscience of color carries larger implications for the rest of us. In fact, Conway thinks his insights into color processing may ultimately shed light on some fundamental questions about human cognition. Step back for a moment to one of Conway's biggest findings, which came while examining how monkeys process color. Using a brain scanner, he and some collaborators found "globs" of specialized cells that detect distinct hues--suggesting that some areas of the primate brain are encoded for color. Interestingly, not all colors are given equal glob treatment. The largest neuron cluster was tuned to red, followed by green then blue; a small cell collection also cared about yellow. © 2014 Mansueto Ventures, LLC.
Link ID: 19390 - Posted: 03.21.2014
|By Nathan Collins A car detects when a driver starts to nod off and gently pulls over. A tablet or laptop senses its user is confused and offers assistance. Such interventions seem futuristic, but in fact they may not require any technological breakthroughs: a recent study suggests that with the aid of a standard camera, a simple computer program can learn to read people's eye movements to determine what they are doing and perhaps how they are feeling. Psychologists at the University of South Carolina were curious if a computer could figure out what a person was up to based on their eye movements. They first had 12 people engage in four tasks, including reading lines of text and searching photographs for a specific printed letter. Each person repeated the tasks 35 to 50 times while a camera recorded how their eyes moved. Using a subset of those data, the team trained a simple computer program, called a naive Bayes classifier, to identify which of the four tasks each person was doing. In the remaining trials, the classifier correctly determined which task the person was working on 75 percent of the time, well above the 25 percent expected by chance. Because the computer program is based on a flexible algorithm that is simple but powerful, this set-up could most likely be used to identify emotions or mental states such as confusion or fatigue, the researchers suggest in the paper, which appeared in September 2013 in PLOS ONE. With only a brief training period, a car's onboard computer—existing models are more than powerful enough—could learn how a driver's gaze changed as he or she became more exhausted. Further work, the authors suggest, could lead to devices capable of identifying and aiding people in need of assistance in a variety of situations. © 2014 Scientific American
by Tania Lombrozo St. Patrick's Day is my excuse to present you with the following illusion in green, courtesy of , a psychology professor at Ritsumeikan University in Japan. In this perceptual illusion, the two spirals appear to be different shades of green. In fact, they are the same. In this perceptual illusion, the two spirals appear to be different shades of green. In fact, they are the same. This image includes two spirals in different shades of green, one a yellowish light green and the other a darker turquoise green. Right? Wrong. At least, that's not what the pixel color values on your monitor will tell you, or what you'd find if you used a photometer to measure the distribution of lightwaves bouncing back from the green-looking regions of either spiral. In fact, the two spirals are the very same shade of green. If you don't believe me, here's a trick to make the illusion go away: replace the yellow and blue surrounding the green segments with a uniform background. Here I've replaced the blue with black: And here the yellow is gone, too: Tada! The very same green. The fact that the illusion disappears when the surrounding colors are replaced with a uniform background illustrates an important feature of color perception. Our experience of color for a given region of space isn't just a consequence of the wavelengths of light reaching our retinas from that region. Instead, the context matters a lot! ©2014 NPR
Link ID: 19375 - Posted: 03.18.2014
By Gary Marcus and Christof Koch What would you give for a retinal chip that let you see in the dark or for a next-generation cochlear implant that let you hear any conversation in a noisy restaurant, no matter how loud? Or for a memory chip, wired directly into your brain's hippocampus, that gave you perfect recall of everything you read? Or for an implanted interface with the Internet that automatically translated a clearly articulated silent thought ("the French sun king") into an online search that digested the relevant Wikipedia page and projected a summary directly into your brain? Science fiction? Perhaps not for very much longer. Brain implants today are where laser eye surgery was several decades ago. They are not risk-free and make sense only for a narrowly defined set of patients—but they are a sign of things to come. Unlike pacemakers, dental crowns or implantable insulin pumps, neuroprosthetics—devices that restore or supplement the mind's capacities with electronics inserted directly into the nervous system—change how we perceive the world and move through it. For better or worse, these devices become part of who we are. Neuroprosthetics aren't new. They have been around commercially for three decades, in the form of the cochlear implants used in the ears (the outer reaches of the nervous system) of more than 300,000 hearing-impaired people around the world. Last year, the Food and Drug Administration approved the first retinal implant, made by the company Second Sight. ©2014 Dow Jones & Company, Inc.
Link ID: 19371 - Posted: 03.17.2014
by Kat Arney Feeling dopey? Refresh your "circadian eye" with a burst of orange light. Light is a powerful wake-up call, enhancing alertness and activity. Its effect is controlled by a group of photoreceptor cells in the eyeball that make the light-sensing pigment melanopsin. These cells, which work separately to the rods and cones needed for vision, are thought to help reset animals' body clocks - or circadian rhythms. Studies with people who are blind suggest this also happens in humans, although the evidence isn't conclusive. To find out how melanopsin wakes up the brain, Gilles Vandewalle at the University of Liege, Belgium, and his team gave 16 people a 10-minute blast of blue or orange light while they performed a memory test in an fMRI scanner. They were then blindfolded for 70 minutes, before being retested under a green light. People initially exposed to orange light had greater brain activity in several regions related to alertness and cognition when they were retested, compared with those pre-exposed to blue light. Light switch Vandewalle thinks that melanopsin is acting as a kind of switch, sending different signals to the brain depending on its state. Orange light, which has the longer wavelength, is known to make the pigment more light-sensitive, but blue light has the opposite effect. Green light lies somewhere in the middle. The findings suggest that pre-exposure to orange light pushes the balance towards the more light-sensitive form of melanopsin, enhancing the response in the brain. © Copyright Reed Business Information Ltd.
|By Jason G. Goldman Most people don't spend much time pondering the diameter of their pupils. The fact is that we don't have much control over our pupils, the openings in the center of the irises that allow light into the eyes. Short of chemical interventions—such as the eyedrops ophthalmologists use to widen their patients' pupils for eye exams—the only way to dilate or shrink the pupils is by changing the amount of available light. Switch off the lamp, and your pupils will widen to take in more light. Step out into the sun, and your pupils will narrow. Mechanical though they may be, the workings of pupils are allowing researchers to explore the parallels between imagination and perception. In a recent series of experiments, University of Oslo cognitive neuroscientists Bruno Laeng and Unni Sulutvedt began by displaying triangles of varying brightness on a computer screen while monitoring the pupils of the study volunteers. The subjects' pupils widened for dark shapes and narrowed for bright ones, as expected. Next, participants were instructed to simply imagine the same triangles. Remarkably, their pupils constricted or dilated as if they had been staring at the actual shapes. Laeng and Sulutvedt saw the same pattern when they asked subjects to imagine more complex scenes, such as a sunny sky or a dark room. Imagination is usually thought of as “a private and subjective experience, which is not accompanied by strongly felt or visible physiological changes,” Laeng says. But the new findings, published in Psychological Science, challenge that idea. The study suggests that imagination and perception may rely on a similar set of neural processes: when you picture a dimly lit restaurant, your brain and body respond, at least to some degree, as if you were in that restaurant. © 2014 Scientific American
A man blind since birth is taking up a surprising new hobby: photography. His newfound passion is thanks to a system that turns images into sequences of sound. The technology not only gives “sight” to the blind, but also challenges the way neurologists think the brain is organized. In 1992, Dutch engineer Peter Meijer created vOICe, an algorithm that converts simple grayscale images into musical soundscapes. (The capitalized middle letters sound out “Oh, I see!”). The system scans images from left to right, converting shapes in the image into sound as it sweeps, with higher positions in the image corresponding to higher sound frequencies. For instance, a diagonal line stretching upward from left to right becomes a series of ascending musical notes. While more complicated images, such as a person sitting on a lawn chair, at first seem like garbled noise, with enough training users can learn to “hear” everyday scenes. In 2007, neuroscientist Amir Amedi and his colleagues at the Hebrew University of Jerusalem began training subjects who were born blind to use vOICe. Despite having no visual reference points, after just 70 hours of training, the individuals went from “hearing” simple dots and lines to “seeing” whole images such as faces and street corners composed of 4500 pixels. (For comparison, Nintendo’s Mario was made up of just 192 pixels in his first video game appearance.) By attaching a head-mounted camera to a computer and headphones, the blind users were even able to navigate around a room by the sound cues alone. Every few steps the system snaps a photo and converts it into sound, giving the users their bearings as they traverse tables and trashcans. One patient even took up photography, using the head-mounted system to frame his snapshots. © 2014 American Association for the Advancement of Science.
by Megan Gannon, Live Science News Editor Never before seen in biology, a state of matter called "disordered hyperuniformity" has been discovered in the eye of a chicken. This arrangement of particles appears disorganized over small distances but has a hidden order that allows material to behave like both a crystal and a liquid. The discovery came as researchers were studying cones, tiny light-sensitive cells that allow for the perception of color, in the eyes of chickens. For chickens and other birds that are most active during the daytime, these photoreceptors come in four different color varieties — violet, blue, green and red — and a fifth type for detecting light levels, researchers say. Each type of cone is a different size. These cells are crammed into a single tissue layer on the retina. Many animals have cones arranged in an obvious pattern. Insect cones, for example, are laid out in a hexagonal scheme. The cones in chicken eyes, meanwhile, appear to be in disarray. But researchers who created a computer model to mimic the arrangement of chicken cones discovered a surprisingly tidy configuration. Around each cone is a so-called exclusion region that bars other cones of the same variety from getting too close. This means each cone type has its own uniform arrangement, but the five different patterns of the five different cone types are layered on top of each other in a disorderly way, the researchers say. © 2014 Discovery Communications, LLC.
A brain-training video game that improved the vision of college baseball players by as much as two lines on an eye chart has been developed by U.S. researchers. "This is something which I think could help almost anybody," said Aaron Seitz, a neuroscientist at the University of California, Riverside, who the led the research. Players on the university's baseball team improved their visual acuity by 31 per cent after training with the app. And that translated into better performance on the baseball field, where better vision improves the odds of hitting a ball travelling well over 100 km/h. "What we found is they had fewer strikeouts, they were able to create more runs," Seitz told CBC's Quirks & Quarks in an interview that airs Saturday. The players had more runs than predicted even after taking into account the natural improvement that would be expected over the course of the season. Further calculations suggest the improved performance helped the team to win four or five additional games. Following 30 sessions of training with the app, players had better vision, fewer strikeouts, more runs and more wins. But Seitz thinks the app has even more potential to help people with eye conditions such as lazy eye, glaucoma, or age-related macular degeneration. There are 100 million people around the world who have such low vision that glasses don't help, he added. "All that they have to gain is the brain training element.… For these people, there's just really big real-world benefits that could be achieved if we're able to improve their vision."
By JAMES GORMAN SEATTLE — When Clay Reid decided to leave his job as a professor at Harvard Medical School to become a senior investigator at the Allen Institute for Brain Science in Seattle in 2012, some of his colleagues congratulated him warmly and understood right away why he was making the move. Others shook their heads. He was, after all, leaving one of the world’s great universities to go to the academic equivalent of an Internet start-up, albeit an extremely well- financed, very ambitious one, created in 2003 by Paul Allen, a founder of Microsoft. Still, “it wasn’t a remotely hard decision,” Dr. Reid said. He wanted to mount an all-out investigation of a part of the mouse brain. And although he was happy at Harvard, the Allen Institute offered not only great colleagues and deep pockets, but also an approach to science different from the classic university environment. The institute was already mapping the mouse brain in fantastic detail, and specialized in the large-scale accumulation of information in atlases and databases available to all of science. Now, it was expanding, and trying to merge its semi-industrial approach to data gathering with more traditional science driven by individual investigators, by hiring scientists like Christof Koch from the California Institute of Technology as chief scientific officer in 2011 and Dr. Reid. As a senior investigator, he would lead a group of about 100, and work with scientists, engineers and technicians in other groups. Without the need to apply regularly for federal grants, Dr. Reid could concentrate on one piece of the puzzle of how the brain works. He would try to decode the workings of one part of the mouse brain, the million neurons in the visual cortex, from, as he puts it, “molecules to behavior.” © 2014 The New York Times Company
Link ID: 19291 - Posted: 02.25.2014
by Colin Barras If it's beyond repair, you find something else to do its job. This could soon apply to rods and cones, the light-sensitive cells in our eyes that can wither with age, causing blindness. A drug has been found that coaxes neighbours of ailing cells to do their work for them. In 2012, Richard Kramer at the University of California, Berkeley, discovered that injecting a certain chemical into the eyes of blind mice made normally light-insensitive ganglion cells respond to light. These cells ferry optical signals from the rods and cones to the brain, so the mice regained some ability to see light. But it only worked with ultraviolet light. Now, Kramer's team has found a different drug that does the same with visible light. Just 6 hours after they were injected, blind mice could learn to respond to light in the same way as sighted mice – although Kramer says he doesn't know whether they regained vision or just light sensitivity. When the researchers studied the drug's impact on retinal cells in more detail, they realised it had had no effect on healthy cells. "That's what's particularly remarkable and hopeful about this," says Kramer. "It's possible that if you put this drug in a partially damaged eye it would restore vision to the damaged regions and leave the healthy areas unaffected – although we haven't done the experiments to test that." Gene therapy and stem cell treatments are also being explored as ways to restore sight, but a drug would be simpler and any side effects should be reversible, says Kramer. © Copyright Reed Business Information Ltd
Link ID: 19273 - Posted: 02.20.2014
James Hamblin Brain training is becoming big business. Everywhere you look, someone is talking about neuroplasticity and trying to train your brain. Soon there will be no wild brains left. At the same time, everyone who spends more than two continuous hours using a computer is, according to the American Optometric Association, ruining their eyes with Computer Vision Syndrome. So, Dr. Aaron Seitz might be onto something with his new brain-training program that promises better vision. UltimEyes is a game-based app that's sold as "fun and rewarding" as it improves your vision and "reverse[s] the effects of aging eyes." It doesn't claim to work on the eyes themselves, but on the brain cortex that processes vision—the part that takes blurry puzzle pieces from the eyes and arranges them into a sweet puzzle. (Brain training for memory, the kind we hear about the most on TV, would be the part that lacquers the finished puzzle, frames it, and hangs it on the wall.) A standard 25-minute session using UltimEyes forces your eyes to work in ways they probably don't in everyday life, and its website warns that after the first use, "just like the first time that you go to the gym, your eyes may feel a bit tired. This experience typically goes away by your third session as your visual system adjusts to its new work-out routine." Seitz is a neuroscientist at the University of California, Riverside. To test out his vision-training game, he had players on the university's baseball team use the app. Half the team trained for 30 sessions. For comparison, the other half did no training. © 2014 by The Atlantic Monthly Group
by Clare Wilson SOMETIMES you find out more about how something works by turning it off. That seems to be true for mirror neurons, the brain cells implicated in traits ranging from empathy and learning to language acquisition. Mirror neurons are said to help us interpret other people's behaviour, but this has yet to be shown convincingly in experiments. Now a study that briefly disabled these cells might give a better idea of what they do. Mirror neurons were discovered in the 1990s when an Italian team was measuring electrical activity in the brains of monkeys. In the region that controls movement, some of the neurons that fire to carry out a particular action – such as grasping an apple – also fired when the monkey saw another animal do the same thing. The tempting conclusion was that these neurons help interpret others' behaviour. Further work suggested that people also have this system, and some researchers claimed that conditions where empathy is lacking, such as autism or psychopathy, could arise from defective mirror neurons. Yet there has been little evidence to back this up and critics argued that mirror neuron activity could just be some sort of side effect of witnessing action. Powerful magnetic fields are known to temporarily disrupt brain cell activity, and a technique called transcranial magnetic stimulation (TMS) is increasingly used in the lab to dampen specific areas of the brain. © Copyright Reed Business Information Ltd.
Dinsa Sachan Could being visually impaired have had a role in the musical genius of Stevie Wonder and Ray Charles? A study provides some clues by showing that adult mice kept in the dark quickly develop sharper hearing and become better at distinguishing pitch and frequency. The improvements were correlated with adaptations in the brain — such as strengthening of connections between neurons — that normally happen only early in life. For their study, published today in Neuron1, Hey-Kyoung Lee, a neuroscientist at Johns Hopkins University in Baltimore, Maryland, and her collaborators selected two sets of healthy adult mice. They kept the first group in a darkened environment for a week, while the other was exposed to natural light. The team used electrodes to measure activity in neurons in the animals' primary auditory cortex — the part of the brain that processes what a sound is, how loud it is and where it comes from. The researchers played sounds of different frequencies and intensities to the mice, and watched how their brain cells reacted. The results “showed that neurons in visually deprived animals can 'hear' much softer sounds” than in control animals, says Lee. “They also have much finer discrimination ability as far as identifying pitch goes.” Previous studies have found that changes in the auditory cortex take a long time, and that people who become blind early in life adapt better than those who lose their sight later. The team's findings, however, show that some modifications can occur rapidly in the adult brain, she says. “Moreover,” she adds, “the changes in the auditory cortex were achieved by changes in the strength of synaptic connections. These were believed to be unchangeable in adults.” © 2014 Nature Publishing Group
By Molly Sharlach Reader, be proud. You’re a perceptual expert. As you read, your eyes alternately focus and move along each line of text in a seamless sequence honed over years of practice. Reading, recognizing faces and distinguishing colors or musical tones are all forms of perceptual expertise. To appreciate the visual skill involved in reading, turn a text upside down. You’ll stumble along in fits and starts, your eyes pausing longer and more often, each movement bringing less information to your brain. To assess how such neuro-ocular blundering might be improved, researchers at the University of British Columbia asked seven volunteers to practice reading novels upside down. After 30 half-hour sessions over a period of 10 weeks, they gained an average of 35 words per minute in reading speed on inverted text. This could be promising news for people with right hemianopia (hemi-uh-NOH-pee-uh), a condition that erases part of the right field of vision in both eyes. Any damage to the left occipital lobe of the brain, or the pathways connecting it to the eyes, can cause this disorder. Hemianopia, from the Greek for “half sight,” most often results from a stroke, but can also befall patients with multiple sclerosis, brain tumors or traumatic injuries. When we read, we see only three or four letters to the left of our eyes’ fixation point, but we pick up information 10 to 15 letters to the right. So in a society that reads from left to right, left hemianopia has little effect on reading ability, but right hemianopia can be devastating. Brain injury patients rank the inability to read among the most significant effects on their quality of life. © 2014 Scientific America