Biological Psychology Links

by David Robson Can you tell a snake from a pretzel? Some can't – and their experiences are revealing how the brain builds up a coherent picture of the world AFTER her minor stroke, BP started to feel as if her eyes were playing tricks on her. TV shows became confusing: in one film, she was surprised to see a character reel as if punched by an invisible man. Sometimes BP would miss seeing things that were right before her eyes, causing her to bump into furniture or people. BP's stroke had damaged a key part of her visual system, giving rise to a rare disorder called simultanagnosia. This meant that she often saw just one object at a time. When looking at her place setting on the dinner table, for example, BP might see just a spoon, with everything else a blur (Brain, vol 114, p 1523). BP's problems are just one example of a group of disorders known collectively as visual agnosias, usually caused by some kind of brain damage. Another form results in people having trouble recognising and naming objects, as experienced by the agnosic immortalised in the title of Oliver Sacks's 1985 best-seller The Man Who Mistook His Wife for a Hat. Agnosias have become particularly interesting to neuroscientists in the past decade or so, as advances in brain scanning techniques have allowed them to close in on what's going on in the brain. This gives researchers a unique opportunity to work out how the brain normally makes sense of the world. "Humans are naturally so good at this, it's difficult to see our inner workings," says Marlene Behrmann, a psychologist who studies vision at Carnegie Mellon University in Pittsburgh, Pennsylvania. Cases like BP's are even shedding light on how our unconscious informs our conscious mind. "Agnosias allow us to adopt a reverse-engineering approach and infer how [the brain] would normally work," says Behrmann. © Copyright Reed Business Information Ltd

By Vilayanur S. Ramachandran and Diane Rogers-Ramachandran Imagine that you are looking at a dog that is standing behind a picket fence. You do not see several slices of dog; you see a single dog that is partially hidden by a series of opaque vertical slats. The brain’s ability to join these pieces into a perceptual whole demonstrates a fascinating process known as amodal completion. It is clear why such a tendency would have evolved. Animals must be able to spot a mate, predator or prey through dense foliage. The retinal image may contain only fragments, but the brain’s visual system links them, reconstructing the object so the animal can recognize what it sees. The process seems effortless to us, but it has turned out to be one of those things that is horrendously difficult to program computers to do. Nor is it clear how neurons in the brain’s visual pathways manage the trick. In the early 20th century Gestalt psychologists were very interested in this problem. They devised a number of cunningly contrived illusions to investigate how the visual system establishes the continuity of an object and its contours when the object is partially obscured. A striking example of amodal completion is an illusion devised by Italian psychologist Gaetano Kanizsa. In one view, you see a set of “chicken feet” arranged geometrically. But if you merely add a set of opaque diagonal bars, a three-dimensional cube springs into focus seemingly by magic, the chicken feet becoming cube corners. © 2010 Scientific American,

Lauran Neergaard, Associated Press Scientists have created a new kind of artificial cornea, inserting a sliver of collagen into the eye that coaxes corneal cells to regrow and restore vision. It worked in a first-stage study of 10 patients in Sweden, researchers reported Wednesday. While larger studies are needed, it's a step toward developing an alternative to standard cornea transplants, which aren't available in much of the world because of a shortage of donated corneas. "We're trying to regenerate the cornea from within," said Dr. May Griffith, senior scientist at the Ottawa Hospital Research Institute in Canada and a professor of regenerative medicine at Linkoping University in Sweden. Vision depends on a healthy cornea, the filmlike covering of the eye's surface that helps it focus light. Corneas are fragile and easily harmed by injury or infection. About 42,000 people in the United States receive transplanted corneas every year. While that's considered an adequate supply in this country, donated corneas aren't available in many countries for the estimated 10 million people worldwide with corneal blindness. Transplants also bring risk of rejection. The new work, published in the journal Science Translational Medicine, is a bioartificial cornea - an attempt to use the same natural substances that make up a real cornea to induce healing. © 2010 Hearst Communications Inc.

By CHARLES Q. CHOI The infants and toddlers resemble cyborgs as they waddle and crawl around the playroom with backpacks carrying wireless transmitters and cameras strapped to their heads. Each has one camera aimed at the right eye and another at the field of view, and both send video to monitors nearby. When the video feeds are combined, the result is a recording in which red cross hairs mark the target of a child’s gaze. Scientists are using the eye-tracking setup to learn how children look at the world as they figure out how to interact with it. In the lab, children 5 months and older crawl and walk up, down and over an obstacle course of adjustable wooden slopes, cliffs, gaps and steps. And to add to the challenge, the subjects are sometimes outfitted with Teflon-coated shoes or lead-weighted vests. It may seem like the set for a new reality television show, but there are no prizes, except perhaps for the researchers. They hope to understand what prompts one child to respond to another, how infants coordinate their gaze with their hands and feet to navigate around obstructions or handle objects, and how these very young children adapt to changes, like those brought on by slippery footwear. The findings provided by these eye-trackers so far (the first light enough for children to wear) suggest that infants may be more capable of understanding and acting on what they see than had been thought. “Quick gazes at obstacles in front of them or at their mothers’ faces may be all they need to get the information they want. They seem to be surprisingly efficient,” said John Franchak, a doctoral candidate in developmental psychology at New York University. Copyright 2010 The New York Times Company

by Bijal Trivedi CLAIRE CHESKIN used to live in a murky world of grey, her damaged eyes only seeing large objects if they were right next to her. She could detect the outlines of people but not their expressions, and could just about make out the silhouettes of buildings, but no details. Looking into the distance? Forget it. Nowadays things are looking distinctly brighter for Cheskin. Using a device called vOICe, which translates visual images into "soundscapes", she has trained her brain to "see through her ears". When travelling, the device helps her identify points of interest; at home she uses it to find things she has put down, like coffee cups. "I've sailed across the English Channel and across the North Sea, sometimes using the vOICe to spot landmarks," she says. "The lights on the land were faint but the vOICe could pick them up." As if the signposting of objects wasn't impressive and useful enough, some long-term users of the device like Cheskin eventually report complete images somewhat akin to normal sight, thanks to a long-term rewiring of their brains. Sometimes these changes are so profound that it alters their perceptions even when they aren't using the device. As such, the vOICe (the "OIC" standing for "Oh, I See") is now proving invaluable as a research tool, providing insights into the brain's mind-boggling capacity for adaptation. The idea of hijacking another sense to replace lost vision has a long history. One of the first "sensory substitution" devices was developed in 1969 by neuroscientist Paul Bach-y-Rita. He rigged up a television camera to a dentist's chair, on which was a 20-by-20 array of stimulators that translated images into tactile signals by vibrating against the participant's back. Despite the crudeness of the set-up, it allowed blind participants to detect the presence of horizontal, vertical and diagonal lines, while skilled users could even associate the physical sensations with faces and common objects. © Copyright Reed Business Information Ltd.

Q. My husband gets disabling headaches from fluorescent lighting, even the new compact ones that look more like incandescent light. Also from looking directly at LCD monitors. Although he works at home and can avoid this lighting for the most part, it’s very disabling, prevents him from going many places that he’d like to, taking our daughter places, etc. Once he’s affected, the only thing that really helps is sleeping. He’s being treated by a neurologist (who has diagnosed them as migraine), but the one med that seemed to help (I think Topamax) left him with exhaustion as a side effect, so he had to stop taking it. Wearing a baseball cap and sunglasses helps him tolerate the lighting a little better, but not much. The effects are much, much worse earlier in the day; he can tolerate greater exposure if it’s later in the day. Is there anything in the research literature about light-induced migraine and treatment strategies? Ellen, New England Dr. David Dodick responds: Light-induced migraine is common, and light often amplifies the pain after the headache has begun. (Doctors refer to this occurrence as photophobia.) There is exciting new research on the anatomical pathways that account for how and why migraine is worsened by light, and ongoing research to explain how and why light may trigger a migraine attack. Copyright 2010 The New York Times Company

By Christof Koch All of us, even postmodern philosophers, are naive realists at heart. We assume that the external world maps perfectly onto our internal view of it—an expectation that is reinforced by daily experience. I see a coffee mug on the table, reach for a sip and, lo and behold, the vessel’s handle is soon in my grasp as I gingerly imbibe the hot liquid. Or I see a chartreuse-yellow tennis ball on the lawn, pick it up and throw it. Reassuringly, my dog appears to share my veridical view of reality: she chases the ball and triumphantly catches it between her jaws. That there should be a match between perception and reality is not surprising, because evolution ruthlessly eliminates the unfit. If you routinely misperceive or even hallucinate and act on those misapprehensions, you won’t survive long in a world filled with dangers whose avoidance requires accurate distance and speed assessments and rapid reactions. Whether you are diving into rocky waters or driving on a narrow, two-lane road with cars whizzing by in the opposite direction, small mistakes can be lethal. You probably believe that your eyes register high-fidelity information about the absolute size, speed and distance of visible objects and that you respond based on these impartial data. But although we build robots in this manner—equipping them with sensors and computers to plumb the metric properties of their environments—evolution has taken a more complex route. © 2010 Scientific American,

By Katherine Harmon The tangled web of autism symptoms and genetic markers has left researchers searching for patterns and trends in unusual places. New work examining the subtle symptoms shared by close relatives has underscored the disease's heritability. Findings published online August 2 in Archives of General Psychiatry add to the growing list of familial clues about the disease: shared eye-movement deficits. Researchers working at the University of Illinois at Chicago's (U.I.C.) Center for Cognitive Medicine have found a striking trend: those with autistic relatives are more likely to show disrupted eye movement similar to their afflicted relation. Large-scale genetic studies have turned up nuanced and conflicting results about the genetic basis of autism and its myriad symptoms. Other research has discovered that many people with an autistic relative or child might themselves have some subtle behavior variant as well, such as obsessive-compulsive tendencies or communication problems. Eye movement is easier to study neurologically than complex social and behavioral patterns—in large part because "we know a lot about what parts of the brain are involved," says Matthew Mosconi, an assistant professor of psychiatry at the U.I.C. and lead author of the new study. And the new findings examine basic deficits unclouded by social tendencies, such as the aversion many people with autism spectrum disorder have to looking at faces. © 2010 Scientific American

by Sujata Gupta WHAT happens when you take blind mice and see how they run? It turns out they can identify objects using receptors in the eye that were previously thought to have no role in forming images. Since humans possess the same receptors, the finding could point the way to giving blind people some ability to see. Mice, and humans, have three types of light-detecting receptor in the eye. Rods and cones detect light, darkness, shape and colour, and make normal sight possible. Receptors of the third type, the melanopsin-containing ganglion cells (MCGCs), were until now thought only to respond to light over longer periods of time, to help moderate patterns of sleep and wakefulness. To investigate their role in vision, Samer Hattar of the Krieger School of Arts and Sciences at Johns Hopkins University in Baltimore, Maryland, and colleagues engineered mice to lack rods and cones. When these mice were placed in a maze, they were able to identify a lever with a visible pattern on it which allowed them to escape. Mice that lacked rods, cones and MCGCs could not find the lever. In another task, the team found that the MCGC mice could follow the movement of a rotating drum (Neuron, DOI: 10.1016/j.neuron.2010.05.023). This suggests MCGCs can form "low-acuity yet measurable images", Hatter says. Tom Cronin at the University of Maryland notes that the mice in the experiment behave like people with "blindsight", who can navigate round objects without consciously perceiving them. "It's mind-boggling but I suspect that the mice are doing something like that," he says. © Copyright Reed Business Information Ltd.

By Melody Dye Subject 046M, for male, was seated nervously across from me at the table, his hands clasped tightly together in his lap. He appeared to have caught an incurable case of the squirms. I resisted the urge to laugh, and leaned forward, whispering conspiratorially. “Today, we’re going to play a game with Mr. Moo” —I produced an inviting plush cow from behind my back. “Can you say hi to Mr. Moo?” In the Stanford lab I work in with Professor Michael Ramscar, we study how children go about what is arguably the most vital project in their career as aspiring adults—learning language. Over the last several years, we’ve been particularly taken with the question of how kids learn a small, but telling piece of that vast complex: color words. We want to know how much they know, when they know it, and whether we can help them get there faster. 046M was off to a good start. I arranged three different color swatches in front of him. “Can you show me the red one?” He paused slightly, then pointed to the middle rectangle: red . “Very good!” I said, beaming. “Now, what about the one that’s blue?” The test was not designed to trip kids up. Far from it—we only tested basic color words, and we never made kids pick between confusable shades, like red and pink. To an adult, the test would be laughably easy. Yet, after several months of testing two-year olds, I could count my high scorers on one hand. Most would fail the test outright. 046M, despite his promising start, proved no exception. © 2010 Scientific American,

By ALICIA CHANG LOS ANGELES - Dozens of people who were blinded or otherwise suffered severe eye damage when they were splashed with caustic chemicals had their sight restored with transplants of their own stem cells — a stunning success for the burgeoning cell-therapy field, Italian researchers reported Wednesday. The treatment worked completely in 82 of 107 eyes and partially in 14 others, with benefits lasting up to a decade so far. One man whose eyes were severely damaged more than 60 years ago now has near-normal vision. "This is a roaring success," said ophthalmologist Dr. Ivan Schwab of the University of California, Davis, who had no role in the study — the longest and largest of its kind. Stem cell transplants offer hope to the thousands of people worldwide every year who suffer chemical burns on their corneas from heavy-duty cleansers or other substances at work or at home. The approach would not help people with damage to the optic nerve or macular degeneration, which involves the retina. Nor would it work in people who are completely blind in both eyes, because doctors need at least some healthy tissue that they can transplant. In the study, published online by the New England Journal of Medicine, researchers took a small number of stem cells from a patient's healthy eye, multiplied them in the lab and placed them into the burned eye, where they were able to grow new corneal tissue to replace what had been damaged. Since the stem cells are from their own bodies, the patients do not need to take anti-rejection drugs. Copyright 2010 The Associated Press.

— Researchers have traced the light-sensing circuitry for a type of “second sight” that is distinct from the conventional visual system and seems to interact directly with the body’s internal clock. The researchers speculate that subtle genetic malfunctions of this machinery might underlie some sleep disorders. In an article published in the February 8, 2002, Science, a research team led by Howard Hughes Medical Institute investigator King-Wai Yau described the circuitry, which consists of a subset of nerve cells that carry visual signals from the eye to the brain. The scientists showed that circadian-pacemaker nerve cells almost certainly depend on a different light-sensing pigment, called melanopsin, than the conventional visual system, which relies on rod and cone photoreceptors arrayed across the retina. ©2002 Howard Hughes Medical Institute

St. Louis, – Investigators at Washington University School of Medicine in St. Louis have demonstrated that a particular protein is important for the eye's pupil to respond to light. The discovery may help scientists learn more about the eye's role in non-visual functions such as the synchronization of the body's internal, circadian clock. The team was led by Russell N. Van Gelder, M.D., Ph.D., assistant professor of ophthalmology and visual sciences and of molecular biology and pharmacology. Reporting in the Jan. 10 issue of the journal Science, the researchers say that mice that lack the two main types of photoreceptor cells in the retina -- rods and cones -- as well as proteins in the retina called cryptochromes, lose about 99 percent of their sensitivity to light. "In the past, it was assumed that the eye functioned pretty much like an old-style camera," says Van Gelder.

Aficionados may not only treat their automobiles as if they are people, but it now appears that they recognize their cars with the special part of the brain that is also used to identify faces. And, when they try to identify cars and faces at the same time, they are likely to experience a kind of perceptual traffic jam. Those are some of the implications of research conducted at Vanderbilt University and the University of Colorado at Boulder. Researchers there compared how the brains of auto experts and novices process pictures of cars and faces. They found that viewing cars elicits signals from the brains of car experts that are just like the signals evoked by viewing faces in other brains. Moreover, the experts' skill interfered with their ability to identify faces when they were forced to process cars and faces simultaneously. The findings, reported online on March 10 in the journal Nature Neuroscience, directly challenge the widely held view that a small, specialized area in the brain is specially hardwired to recognize faces. When confronted with a novel object, people use different parts of the brain to identify it by breaking it down into pieces. By contrast, the special facial recognition area appears to recognize faces holistically, all at one time, and does so more quickly than the piecemeal approach.

It's common knowledge that things aren't always as they appear, but a new study shows our brains are complicit in our vision errors even at the earliest point in the brain's visual processing system. In an article to be featured in an upcoming issue of Nature Neuroscience, David Ress of Stanford University and David Heeger of NYU report that activity in the brain's visual cortex corresponds to what the subjects perceive, rather than what they actually see. The scientists based their findings on experiments using functional magnetic resonance imaging (fMRI) to measure activity in carefully circumscribed regions of the visual cortex of the brain while human subjects performed a challenging visual discrimination task. Subjects attempted to detect the presence of slight contrast increments added to a background pattern. Behavioral responses were recorded so that the corresponding cortical activity could be grouped into four categories: "hits", when subjects correctly identified the image shown as the higher contrast image; "false alarms", when subjects misidentified the lower-contrast image as the higher contrast image; "misses", when subjects presented with the higher contrast image misidentified it as the lower contrast image; and "correct rejects", when subjects correctly identified the lower contrast image. Hits and false alarms produced significantly more cortical activity than misses, indicating that activity in the visual cortex corresponded to the subjects' precepts, rather than to the physically presented stimulus.

Out of sight By Gila Z. Reckess — Pointing at an object may not seem complicated, but even such a simple act requires an intricate network of brain activity. Scientists traditionally thought this network included a one-way "information highway" between the brain's visual system and its motor and sensory systems, but research at Washington University School of Medicine in St. Louis now challenges this long-held theory. The study presents surprising evidence that the brain's visual system is not only responsible for seeing, or perceiving, objects outside the body, but also is involved when individuals sense and manipulate their own bodies. Such insight may help scientists understand puzzling disorders like anosognosia, which is characterized by unusual perceptual experiences. For example, individuals with this disorder may not recognize their arms as part of their own bodies. "Vision apparently is far more complicated and integrated than we suspected," says Maurizio Corbetta, M.D., associate professor of neurology, of radiology and of anatomy and neurobiology. "Areas thought to be exclusively involved in perceiving the world around us apparently also are involved in integrating visual, spatial and sensory-motor signals to help each of us develop an internal representation of our body and its position in space."

Surprising results from a nationwide clinical trial show that many children age 7 through 17 with amblyopia (lazy eye) may benefit from treatments that are more commonly used on younger children. Treatment improved the vision of many of the 507 older children with amblyopia studied at 49 eye centers. Previously, eye care professionals often thought that treating amblyopia in older children would be of little benefit. The study results, funded by the National Eye Institute (NEI), part of the National Institutes of Health (NIH), appear in the April issue of Archives of Ophthalmology. “Doctors can now feel confident that traditional treatments for amblyopia will work for many older children, said Paul A. Sieving, M.D., Ph.D., director of the NEI. “This is important because it is estimated that as many as three percent of children in the United States have some degree of vision impairment due to amblyopia. Many of these children do not receive treatment while they are young,” he said. Amblyopia is a leading cause of vision impairment in children and usually begins in infancy or childhood. It is a condition resulting in poor vision in an otherwise healthy eye due to unequal or abnormal visual input while the brain is developing in infancy and childhood. The most common causes of amblyopia are crossed or wandering eye (strabismus) or significant differences between the eyes in refractive error, such as, astigmatism, farsightedness, or nearsightedness.

Obsessed with reruns of the TV sitcom Friends? Well then you probably have at least one “Jennifer Aniston cell” in your brain, suggests research on the activity patterns of single neurons in memory-linked areas of the brain. The results point to a decades-old and dismissed theory tying single neurons to individual concepts and could help neuroscientists understand the elusive human memory. “For things that you see over and over again, your family, your boyfriend, or celebrities, your brain wires up and fires very specifically to them. These neurons are very, very specific, much more than people think,” says Christof Koch at the California Institute of Technology in Pasadena, US, one of the researchers. In the 1960s, neuroscientist Jerry Lettvin suggested that people have neurons that respond to a single concept such as, for example, their grandmother. The notion of these hyper-specific neurons, coined “grandmother cells” was quickly rejected by psychologists as laughably simplistic. But Rodrigo Quiroga, at the University of Leicester, UK, who led the new study, and his colleagues have found some very grandmother-like cells. Previous unpublished findings from the team showed tantalising results: a neuron that fired only in response to pictures of former US president Bill Clinton, or another to images of the Beatles. But for such “grandmother cells” to exist, they must invariably respond to the “concept” of Bill Clinton, not just similar pictures. To investigate further, the team turned to eight patients currently undergoing treatment for epilepsy. In an attempt to locate the brain areas responsible for their seizures, each patient had around 100 tiny electrodes implanted in their brain. Many of the wires were placed in the hippocampus - an area of the brain vital to long-term memory formation. © Copyright Reed Business Information Ltd.

As we continue to live longer we are becoming more and more prone to age-related diseases such as the so-called big four: heart disease, cancer, diabetes and Alzheimer's disease or AD. Although an estimated 4.5 million Americans are believed to have AD, the only way to know for sure is with an autopsy. "Alzheimer's disease is a very difficult disorder to diagnose even in the late stages," explains Alzheimer's researcher Lee E. Goldstein from the Brigham and Women's Hospital and Harvard Medical School in Boston. "If were going to intervene early were going to have diagnose it early right now there is no good way to do that." Although we know a great deal about this disease, primarily from what genetics research has told us over the last ten years, what is needed is a biomarker or a "biological fingerprint" to help doctors spot the disease early. "We don't have good biomarkers for Alzheimer's disease: used not only for prediction and diagnosis, but also used for drug testing. If you want a way to screen to see how well the patient's doing beyond cognitive testing, if you want some kind of measure of whether the brain is being helped — using some kind of representative marker — we don't really have much in that way in Alzheimer's disease," says Goldstein's colleague from Massachusetts General Hospital and Harvard, Rudolph Tanzi, who was one of the geneticists to find the first disease-related genes. © ScienCentral, 2000-2005.

Laser light has been used to remotely control gene therapy in rats. This mechanism will help make gene therapy more effective by allowing the precise time and location at which new genes are activated to be controlled, meaning specific tissues can be targeted while healthy tissues are left alone. Lasers have been used in the past to perforate cells for gene therapy in cultured cells. But the new research – activating marker genes in the eyes of rats – is more sophisticated and the first time lasers have been used for gene therapy in live animals. Kazunori Kataoka, at the University of Tokyo, Japan, and colleagues developed a photosensitive molecular complex that could be activated in rats’ eyes by irradiating them with visible light from a low power laser. The synthetic complex is designed to deliver foreign DNA by carrying it past the cell membrane – a process known as transfection. The complex consists of three components: a photosensitive anionic dendrimer, which provides the triggering mechanism, and a cationic peptide which drives the third component, its DNA payload, towards the nucleus of a cell after it has been released. The complex enters the cell by a process known as endocytosis, where the cell's plasma membrane envelops the complex at its surface and draws it into the cell. The membrane around the complex then detaches from the cell's membrane to form a bubble containing the complex within the cell. © Copyright Reed Business Information Ltd.

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