by Jessica Griggs PLINY the Elder recounts the story of two legendary painters, Zeuxis and Parrhasius, who were trying to decide which of them was the more accomplished artist. They brought two covered canvases to show each other. First Zeuxis revealed his - a bunch of grapes so lusciously lifelike that birds swooped down to peck at the canvas. Confident of victory, Zeuxis leaned over to pull the cover off Parrhasius's offering, only to find that the covering itself was the painting. Having been fooled by his rival's handiwork, Zeuxis admitted defeat. Examples of this "trick of the eye" art, or trompe l'oeil as it commonly known, date back to Graeco-Roman times, but it wasn't until the Renaissance, when painters mastered the art of perspective drawing, that the genre flourished. Examples include the image of a little boy climbing out of a painting's frame, called Escaping Criticism, and the work above, known as the Cabinet of Curiosities, thought to have been painted by the Flemish artist Domenico Remps in the 1690s. Trompe l'oeil didn't flourish until the Renaissance, when painters mastered the art of perspective This painting works because the objects are life-size and depicted in hyper-realistic detail, and also because Remps laid a set of decoys that hoodwink our visual system into perceiving depth, says Priscilla Heard, a neuropsychologist at the University of the West of England in Bristol, UK. Misleading cues include the way the wood grain shrinks the further into the cabinet you look, and the way shadows fall on the sill and the paper drawing. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 14482 - Posted: 09.23.2010

David Hirschman Memory is one of the cornerstones of what it means to be human. Recording aspects of the world around us and storing them in our brains for future recall is vital to nearly all advanced human functions. It makes us who we are, and helps us to make sense of reality. But what is really happening in our brains when we are experiencing events and then saving them for later? Dr. Antonio Damasio, a behavioral neurobiologist at the University of Southern California who has studied the neural systems behind memory for years, says that memory is actually a complex process where the brain scatters information across its neurons and then reconnects it using sequential cues. Our brains are not at all like video cameras, he says; they don't have the capacity to keep exact film-like representations of everything that happens in our lives. Instead, the brain records conjunctions of details and events in what Damasio calls "convergence/divergence zones." When we experience something, our neurons create a code to represent a series of disparate facts about the scene or idea that live in different areas of our brains. Recalling specific events or "memories" is actually a process of pulling together these details to essentially reconstruct a version of reality. "When you are asked to remember a certain experience that you had today in which you’re talking with person A, listening to the person’s voice, but you also are in a certain context, B, which is the context of a certain room in a certain building," says Damasio, as an example. "You are going to have the separate recordings of the voice of the person, the sight of the person, the place—but those recordings are going to be reactivated only if another recording of the simultaneity of the event has been made in a convergence/divergence zone." Original content is for Non-commercial use under Creative Commons.

Keyword: Learning & Memory
Link ID: 14481 - Posted: 09.23.2010

by Jessica Hamzelou A FEW years ago, 17-year-old Christopher Simmons was convicted of breaking into Shirley Crook's house in St Louis, Missouri, tying her up and throwing her off a bridge. The evidence was overwhelming and Simmons confessed to the murder. When the jury recommended a death sentence, Simmons's defence referred to scientific papers that suggested a the brain of a typical 17-year-old was not yet fully mature. Not only did Simmons escape the death penalty, the US Supreme Court changed the law so that only those over 18 can face death row. Now neuroscientists claim we are closer to being able to estimate brain maturity using brain scans, which might prompt lawyers to offer a defence of immaturity based on an accused individual's own brain scan. Nico Dosenbach's team at Washington University School of Medicine in St Louis reckon they can predict how old a person is using a 5-minute brain scan. The idea is based on the fact that brain structure changes as we age. For example, the brain's grey matter peaks in childhood and is then pruned throughout adolescence. White matter, which forms the connections between brain regions, steadily increases, eventually levelling off (see diagram). As we age, parts of the brain that are further apart are better connected and better able to communicate. "The short connections get weaker and the longer ones get stronger," says Dosenbach. © Copyright Reed Business Information Ltd.

Keyword: Attention; Brain imaging
Link ID: 14480 - Posted: 09.23.2010

by Carl Zimmer The great philosopher Immanuel Kant believed that nothing matters more to our existence than space. Every experience we have—from the thoughts in our heads to the stars we see wheeling through the sky—makes sense only if we can assign it a location. “We never can imagine or make a representation to ourselves of the non­-existence of space,” he wrote in 1781. The nonexistence of space may certainly be hard to imagine. But for some people it is part of everyday life. Strokes can rob us of space. So can brain injuries and tumors. In 1941, neurologists Andrew Paterson and O. L. Zangwill, working in Edinburgh, Scotland, published an account of a 34-year-old patient who had been hit in the head by a mortar fragment. The injury wiped out his sense of the left half of his world. Paterson and Zangwill described how the man “consistently failed to appreciate doors and turnings on his left-hand side even when he was aware of their presence.” He also “neglected the left-hand side of a picture or the left-hand page of a book despite the fact that his attention was constantly being drawn to the oversight.” The patient could play checkers but ignored the pieces on the left side of the board. “And when his attention was drawn to the pieces on this side,” the doctors wrote, “he recognized them but immediately thereafter forgot them.” This condition, called spatial neglect, challenges our intuitive notions of how we understand the world. But by mapping how people lose some of their sense of space, neuroscientists are gaining new insights into how we build that sense in the first place. © 2010, Kalmbach Publishing Co.

Keyword: Attention
Link ID: 14479 - Posted: 09.23.2010

By Ferris Jabr Where are you right now? Maybe you are at home, the office or a coffee shop—but such responses provide only a partial answer to the question at hand. Asked another way, what is the location of your "self" as you read this sentence? Like most people, you probably have a strong sense that your conscious self is housed within your physical body, regardless of your surroundings. But sometimes this spatial self-location goes awry. During a so-called out-of-body experience, for example, one's self seems to be transported outside the physical body into a surreal perspective—some people even believe they are viewing their bodies from above, as though their true selves were floating. In a related experience, people with a delusion known as somatoparaphrenia disown one of their limbs or confuse another person's limb for their own. Such warped perceptions help researchers understand the neuroscience of selfhood. A new paper offers examples of rare bodily illusions that are not confined to a single limb, nor are they complete out-of-body experiences—they are somewhere in between. These illusory body perceptions, described in the September issue of Consciousness and Cognition, could offer novel clues about how the brain maintains a link between the physical and conscious selves, or what the researchers call "bodily self-consciousness." "These reports could be interesting for us to better understand how the brain produces ownership of the entire body—a sense that we have a body in the first place," says Henrik Ehrsson, a neuroscientist at the Karolinska Institute in Sweden who was not involved in the new study. © 2010 Scientific American, a Division of Nature America, Inc.

Keyword: Attention
Link ID: 14478 - Posted: 09.23.2010

Got a few pounds to lose? Cancel the gym membership. An increasing body of research reveals that exercise does next to nothing for you when it comes to losing weight. A result for couch potatoes, yes, but also one that could have serious implications for the government's long-term health strategy My mum used to complain that she couldn't lose weight. A size 18 and a couple of stone heavier than ideal, she tried in vain for years to shed the extra. Every week she headed to the gym, where she pounded the treadmill like a paratrooper, often three times a week. Most days she took the dog for a brisk, hour-long walk. She didn't eat unhealthily – the rest of the family ate exactly the same meals, and did a fraction of the exercise she did. She ought to have been the slimmest of the bunch: that she remained overweight was a frustration to her, and a mystery to all of us. From StairMasters to kettlebells, Rosemary Conley to Natalie Cassidy, we understand and expect that getting in shape is going to require serious effort on our part – and the reverse is true, too, that we expect exercise to pay back the hours of boring, sweaty graft with a leaner, lighter body. Since the days of the Green Goddess, we've known that the healthiest way to lose weight is through exercise. It's science, isn't it? Well, science has some bad news for you. More and more research in both the UK and the US is emerging to show that exercise has a negligible impact on weight loss. That tri-weekly commitment to aerobics class? Almost worthless, as far as fitting into your bikini is concerned. The Mayo Clinic, a not-for-profit medical research establishment in the US, reports that, in general, studies "have demonstrated no or modest weight loss with exercise alone" and that "an exercise regimen… is unlikely to result in short-term weight loss beyond what is achieved with dietary change." © Guardian News and Media Limited 2010

Keyword: Obesity
Link ID: 14477 - Posted: 09.21.2010

By Katherine Harmon The troubled path of diet drugs continues to look challenging, especially after a U.S. Food and Drug Administration (FDA) panel recommended Thursday that the agency not approve a new anti-obesity medication—the second of three to come up for evaluation this year. The new drug, called lorcaserin, acts on the brain's serotonin, a neurotransmitter involved in appetite, digestion, memory, mood and other functions. Serotonin also plays a role in the cardiovascular system, and the diet drug fen-phen (fenfluramine and phentermine) was pulled from the market in the 1990s after it was linked to heart valve problems. When given in high doses, the new medication also gave many rats tumors (though human trials have not been linked to increase cancer risk). "In my opinion the potential risks of the medication outweigh the potential benefits," Heidi Connolly, a panel member and professor of medicine at the Mayo Clinic, told Bloomberg News. Other committee members, however, pointed more to a questionable level of efficacy than concerns over safety in their final vote, which was nine to five against approval. "I really didn't have a lot of issues with the risk," Eric Felner, a panel member and pediatric endocrinologist at Emory University, told The New York Times. "I just didn't see it as being that efficacious." The FDA requires new diet drugs to help people lose at least five percent more of their body weight than a placebo. Those on the lorcaserin lost about 3.3 percent more weight than those on the placebo, according to the Times. But the drug did meet another FDA criteria that at least twice as many people taking the medication (versus those on a placebo) lose five percent or more of their weight. © 2010 Scientific American,

Keyword: Obesity
Link ID: 14476 - Posted: 09.21.2010

By CLAUDIA DREIFUS Q. DID CHILDHOOD VIEWING OF THE “FLIPPER” TELEVISION SERIES MAKE YOU WANT TO BECOME A DOLPHIN RESEARCHER? A. No, it was The New York Times! In the 1970s, I was working as a set designer for an avant-garde theater company in Philadelphia. One Sunday, I read The Times and saw this photograph of a baby whale being killed. Something in me just snapped. “It’s a shame we’re slaughtering these animals when we know so little about them,” I said. I then got a Ph.D. I’ve been devoting myself to studying the abilities and the behaviors of whales and dolphins since. Q. DOLPHINS SPEND MUCH OF THEIR LIVES UNDERWATER. HOW CAN YOU OBSERVE THEIR BEHAVIOR? A. Well, I observe captive dolphins in aquariums. At the moment, my laboratory is an underwater glass booth in the dolphin pool at the National Aquarium in Baltimore. I climb into it with a video camera. The animals are used to me. My goal is to understand their behaviors well enough so that I can find ways to help them tell us about their cognitive capacities. Dolphins, they have these really large, complex brains. The question is: what are they doing with them? These animals look like fish, but the behavior patterns are more like primates and elephants. They are vocal learners, like parrots and humans. What do the sounds they make mean? Copyright 2010 The New York Times Company

Keyword: Intelligence; Evolution
Link ID: 14475 - Posted: 09.21.2010

By JAMES GORMAN Late summer is chili harvest time, when the entire state of New Mexico savors the perfume of roasting chilies, and across the country the delightful, painful fruit of plants of the genus Capsicum are being turned into salsa, hot sauce and grizzly bear repellant. Festivals abound, often featuring chili pepper-eating contests. “It’s fun,” as one chili pepper expert wrote, “sorta like a night out to watch someone being burned at the stake.” In my kitchen, as I turn my homegrown habaneros into hot sauce while wearing a respirator (I’m not kidding) I have my own small celebration of the evolutionary serendipity that has allowed pain-loving humans to enjoy such tasty pain. Some experts argue that we like chilies because they are good for us. They can help lower blood pressure, may have some antimicrobial effects, and they increase salivation, which is good if you eat a boring diet based on one bland staple crop like corn or rice. The pain of chilies can even kill other pain, a concept supported by recent research. Others, notably Dr. Paul Rozin at the University of Pennsylvania, argue that the beneficial effects are too small to explain the great human love of chili-spiced food. “I don’t think they have anything to with why people eat and like it,” he said in an interview. Dr. Rozin, who studies other human emotions and likes and dislikes (“I am the father of disgust in psychology,” he says) thinks that we’re in it for the pain. “This is a theory,” he emphasizes. “I don’t know that this is true.” Copyright 2010 The New York Times Company

Keyword: Pain & Touch; Emotions
Link ID: 14474 - Posted: 09.21.2010

By CARL ZIMMER One day in 2007, Dr. Giulio Tononi lay on a hospital stretcher as an anesthesiologist prepared him for surgery. For Dr. Tononi, it was a moment of intellectual exhilaration. He is a distinguished chair in consciousness science at the University of Wisconsin, and for much of his life he has been developing a theory of consciousness. Lying in the hospital, Dr. Tononi finally had a chance to become his own experiment. The anesthesiologist was preparing to give Dr. Tononi one drug to render him unconscious, and another one to block muscle movements. Dr. Tononi suggested the anesthesiologist first tie a band around his arm to keep out the muscle-blocking drug. The anesthesiologist could then ask Dr. Tononi to lift his finger from time to time, so they could mark the moment he lost awareness. The anesthesiologist did not share Dr. Tononi’s excitement. “He could not have been less interested,” Dr. Tononi recalled. “He just said, ‘Yes, yes, yes,’ and put me to sleep. He was thinking, ‘This guy must be out of his mind.’ ” Dr. Tononi was not offended. Consciousness has long been the province of philosophers, and most doctors steer clear of their abstract speculations. After all, debating the finer points of what it is like to be a brain floating in a vat does not tell you how much anesthetic to give a patient. But Dr. Tononi’s theory is, potentially, very different. He and his colleagues are translating the poetry of our conscious experiences into the precise language of mathematics. To do so, they are adapting information theory, a branch of science originally applied to computers and telecommunications. If Dr. Tononi is right, he and his colleagues may be able to build a “consciousness meter” that doctors can use to measure consciousness as easily as they measure blood pressure and body temperature. Perhaps then his anesthesiologist will become interested. Copyright 2010 The New York Times Company

Keyword: Attention
Link ID: 14473 - Posted: 09.21.2010

by Evelyn Fox Keller ONE of the most striking features of the nature/nurture debate, the argument over the relative roles of genes and environment in human nature, is the frequency with which we read it has been resolved (the answer is neither nature nor nurture, but both) while at the same time we see the debate refuses to die. So what is it that evokes such contradictory claims, that persists in confounding us? Indeed, what is the debate really about? This turns out to be far from easy to explain because different kinds of questions take refuge under its umbrella. Some express concerns that can be addressed scientifically, others may be legitimate and meaningful but perhaps not answerable, and still others make no sense. One reason for the persistence of the nature/nurture debate, then, is that these questions are knitted together by ambiguity and uncertainty into an indissoluble tangle, making it all but impossible to stay focused on a single, well-defined, meaningful question. Another important issue is that some of that ambiguity and uncertainty comes from the language of genetics itself. For example, we may read that the debate is about sorting contributions of nature from those of nurture, and trying to estimate the relative importance, but what exactly is meant by "nature" and "nurture"? Sometimes the distinction is between what is inborn and what is acquired after birth; more often, it is between genes and environment. But not only does nurture affect prenatal development, we also need to ask what exactly is a gene, and what does it do? What do we mean by environment? Does it refer to factors beyond the organism that affect its development, to the milieu in which the fertilised egg develops, or to everything other than the DNA sequence? © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain; Genes & Behavior
Link ID: 14472 - Posted: 09.21.2010

by Anna Reisman Your admission is Evelyn Warwick, little old lady in distress.” The emergency room resident motioned toward a curtained area at the far end of the ward. “Completely delirious.” “Got it,” I said. At the time I was a medical resident at a New York City public hospital, supervising an intern and a medical student. I knew that delirium, an acute confusional state, could result from just about any type of acute illness, or it could be a side effect of medication. And yet, I explained to my team, you could often guess the cause simply from the type of patient. We all agreed about Mrs. Warwick’s probable diagnosis. An elderly woman with delirium at a public city hospital was likely to be a nursing home patient with pneumonia or a urinary tract infection. She might be dehydrated, or maybe she’d had a stroke or a heart attack. When I pulled back the curtain, I did a double take. Evelyn Warwick was a handsome woman with a neat gray bob like an elementary school principal, not a typical city hospital patient. Her pink pajamas glowed against the starched white sheets. Mr. Warwick, a silver-haired man in a tweed jacket, stroked her forehead with a damp cloth. I introduced myself and the team and asked how she was feeling. She opened her watery blue eyes and stared far into the distance. “I don’t know where I am!” she murmured in a clipped British accent. “I woke up and my head exploded.” She looked around the room in a panic and started to weep. “Where am I? What’s all this?” © 2010, Kalmbach Publishing Co.

Keyword: Drug Abuse; Learning & Memory
Link ID: 14471 - Posted: 09.21.2010

By Jennifer Viegas Individual insects and bugs may all look alike to human eyes, but each and every one is unique and possesses its own personality, suggests new research that also helps to explain how personality arises in virtually all organisms. Some individual bugs, like humans, turn out to be shy, while others are very forceful, determined the study, published in the latest Proceedings of the Royal Society B. "Boldness, explorativeness, activity and aggressiveness are the main personality traits usually measured because these connect to each other and appear together," lead author Eniko Gyuris told Discovery News. What makes a bug bold or shy? Gyuris explains the traits manifest themselves a bit differently in insects. "Boldness -- whether they are shier or braver -- could be defined, for example, as to how quickly they start after an alarm, or how soon they come out of their refuge," added Gyuris, a member of the Behavioral Ecology Research Group at the University of Debrecen. "Explorativeness could be measured in another context, namely in which they have the opportunity to discover a new environment with novel objects." Gyuris and his team conducted personality tests on short-winged and long-winged firebugs, a common insect that's known for its striking red and black coloration. The researchers collected these bugs from wild populations in Debrecen, Hungary, and put them through a barrage of different situations. © 2010 Discovery Communications, LLC.

Keyword: Emotions; Evolution
Link ID: 14470 - Posted: 09.21.2010

A virus which causes respiratory infections has been linked to childhood obesity, in a study that is likely to reignite a controversial debate. Previous animal research has implicated common viruses in weight gain, but the evidence has been disputed. The latest study, in Pediatrics, found that obese children with antibodies specific to a certain virus weighed 35lbs (15.8kg) more than those without. Nothing has yet been proven on this theory, say UK experts. Previous research has shown that chicken or mice injected with similar types of viruses showed a statistically significant weight gain. A link between the AD36 virus (adenovirus 36) and obesity in human adults has also been written about previously. But how AD36 infects people and why it affects people differently is still not known. In the University of California study of 124 children aged eight to 18, half of the children were considered obese based on their Body Mass Index. The researchers found the AD36 antibodies in 19 of the children, 15 of whom were in the obese group. Within the group of obese children studied, those with evidence of AD36 infection weighed an average of 35lbs more than obese children who were AD36-negative, says the study. Jeffrey Schwimmer, lead researcher and professor of clinical paediatrics at the University of California school of medicine, said he hoped his research would change attitudes to obese people. (C)BBC

Keyword: Obesity; Development of the Brain
Link ID: 14469 - Posted: 09.20.2010

An IQ comparison shows that Canadian regulations on manganese in drinking water should be updated to protect children, Quebec researchers say. Manganese is a naturally occurring metal found in groundwater. It is an essential nutrient but, in excessive amounts, it can damage the nervous system. National and international guidelines for safe manganese levels in water should be revised, Quebec researchers say.National and international guidelines for safe manganese levels in water should be revised, Quebec researchers say. (CBC) Manganese occurs in naturally high levels in several parts of Quebec, New Brunswick and other regions, researchers say. Their study, published in Monday's online issue of the journal Environmental Health Perspectives, focused on manganese levels in drinking water in eight communities along the St. Lawrence River between Montreal and Quebec City. The water came from municipal wells and wasn't specially treated for manganese. "We found significant deficits in the intelligence quotient (IQ) of children exposed to higher concentration of manganese in drinking water," said the study's lead author, Maryse Bouchard of the University of Quebec at Montreal's Centre for Interdisciplinary Studies in Biology, Health, Society and Environment. © CBC 2010

Keyword: Development of the Brain; Neurotoxins
Link ID: 14468 - Posted: 09.20.2010

by Michael Le Page No one would believe that bacteria caused stomach ulcers – until Barry Marshall swallowed some BACK in 1984, a young Australian doctor called Barry Marshall swallowed a nasty-tasting solution of bacteria. This was no accident. He did it to convince his peers that his suspicions about a highly prevalent disease were not as far-fetched as they thought. In 1981, Marshall had met pathologist Robin Warren, who had found curved bacteria in inflamed stomach tissue. In further studies, they found that this bacterium, later named Helicobacter pylori, was present in most people who had inflammation or ulcers of the stomach or gut. Like two long-forgotten German researchers in 1875, they concluded that these bacteria were to blame. "I was met with constant criticism that my conclusions were premature," Marshall later wrote. "My results were disputed and disbelieved, not on the basis of science but because they simply could not be true." It is often claimed that doctors were wedded to the idea that ulcers were caused by excess stomach acid, or that they didn't believe that bacteria could grow in the stomach. In fact, the main reason for the scepticism, says Richard Harvey of the Frenchay Hospital in Bristol, UK, was that four-fifths of ulcers were not in the stomach but further down the digestive tract. © Copyright Reed Business Information Ltd.

Keyword: Stress
Link ID: 14467 - Posted: 09.20.2010

By Steve Connor The scourge of premenstrual tension, which affects more than half of women and causes physical as well as emotional trauma, could soon be eradicated by a safe, low-dose pill, scientists said yesterday. A laboratory-based study has found that very low doses of the anti-depression drug Prozac can eliminate the symptoms of premenstrual syndrome, which include mood swings, tiredness, irritability, headaches and joint pains. The scientist leading the research said the findings, which have so far been observed in laboratory rats, are strong enough to warrant a full-scale clinical trial with Prozac given that the drug has already undergone the necessary safety tests at the higher doses needed to treat depression. A clinical trial could begin within six months, and if the results are favourable, women could be taking the drug to treat premenstrual syndrome within two years, said Thelma Lovick, a neuroscientist at the University of Birmingham, who led the study. Not all women have the monthly symptoms associated with their menstrual cycle, but it is estimated that 75 per cent have experienced them at some time and that between 30 and 40 per cent have more severe symptoms that badly affect their work and family lives. The three-year study, funded by the Medical Research Council, has shown that Prozac taken in doses of about a tenth of that needed to treat depression can stop premenstrual symptoms in rats, animals which show physical and emotional changes, such as increased anxiety and sensitivity to pain, similar to those seen in women. Higher doses of Prozac have been prescribed to women suffering from premenstrual syndrome in the past, especially by doctors in the US, but usually for the treatment of more severe symptoms such as depression. ©independent.co.uk

Keyword: Depression; Hormones & Behavior
Link ID: 14466 - Posted: 09.18.2010

By Katherine Harmon When answering a question, your accuracy in assessing whether you have gotten the answer right—or wrong—might depend on the volume of gray matter in a certain part of your brain, according to a new study. Introspection—or metacognition, self-awareness about one's thinking—is a high-level mental process. "Accurate introspection requires discriminating correct decisions from incorrect ones, a capacity that varies substantially across individuals," researchers behind the new findings explained in their study. For the study, researchers used simple visual stimuli to test 32 healthy subjects' perception—and how confident they felt about their assessment of a geometric image. The tests were customized to each individual's level of perceptual skill, in order to keep each subject's accuracy score at 71 percent, so that the test was consistently difficult for all subjects. "Someone who has good introspective ability will accurately be able to know" if they were correct in their assessment of an image, explains Steven Fleming, a cognitive neuroscientist at the Wellcome Trust Centre for Neuroimaging at University College London and co-author of the new study. The study team found "considerable variation" in subjects' accuracy in assessing their own evaluations of the images, which was to be expected based on previous research. Fleming and his colleagues used magnetic resonance imaging (MRI) to evaluate the subjects' whole brains for differences in structure and composition in order to look for correlations with introspective ability. © 2010 Scientific American,

Keyword: Attention
Link ID: 14465 - Posted: 09.18.2010

by Roger Highfield Before winning his Nobel prize, Stanley Prusiner was ridiculed for suggesting that something he called a prion caused spongiform brain diseases WHEN the evidence suggested that the baffling "spongiform" brain disorders Creutzfeldt-Jakob disease (CJD), kuru and scrapie could not be transmitted by a virus or bacterium, the neurologist Stanley Prusiner put forward a novel type of infectious agent as the cause: a rogue protein. It was an idea considered so outrageous that Prusiner was ridiculed. Prusiner first began to study these diseases in 1972, after one of his patients at the University of California, San Francisco, died of CJD. A decade later, in the journal Science (vol 216, p 136), he suggested that these diseases were caused by a "proteinaceous infectious particle", or prion. The idea built on the findings of British researchers. In 1967, Tikvah Alper of the Medical Research Council's Radiopathology Unit showed that whatever it was that caused CJD was unscathed by levels of ultraviolet radiation that would destroy any genetic material (Nature, vol 214, p 764). Shortly afterwards, mathematician John Stanley Griffith of Bedford College in London devised a protein-only hypothesis for scrapie propagation. His 1967 Nature paper (vol 215, p 1043) states there was no reason to fear that the idea "would cause the whole theoretical structure of molecular biology to come tumbling down". © Copyright Reed Business Information Ltd.

Keyword: Prions
Link ID: 14464 - Posted: 09.18.2010

By Gwyneth Dickey Scientists have uncovered a new chemical process that may explain how antidepressants like Prozac work. The newly found mechanism also suggests why the drugs take weeks to start helping and may one day point to new therapies for depression. A team from Paris has found that fluoxetine, commonly known as Prozac, increases the amount of a particular microRNA called miR-16 in the brain. A microRNA is a small piece of RNA that prevents the translation of messenger RNA into protein. The miR-16 microRNA slows the formation of a cleaner-upper protein called the serotonin transporter. The protein clears away serotonin, a chemical that helps brain cells communicate and alleviates depression, from the space between brain cells. With less of the cleaner-upper to gobble up serotonin in the brain, there’s more serotonin in the spaces between brain cells, and depression symptoms lessen for some patients. The results are published in the Sept. 17 Science. “It’s an exciting development,” says pharmacologist Alan Frazer of the University of Texas Health Science Center at San Antonio. “As far as I know, it’s the first demonstration of a microRNA able to affect serotonin transporter expression.” Scientists knew that Prozac and other drugs like it, called selective serotonin reuptake inhibitors or SSRIs, somehow blocked the action of the serotonin transporter and left more serotonin in the brain. But exactly how the drugs worked, and why they took so long to have an effect, was a mystery. © Society for Science & the Public 2000 - 2010

Keyword: Depression
Link ID: 14463 - Posted: 09.18.2010