by Colin Barras What a nerve! Skin cells taken from people with bipolar disorder have been turned into brain cells. These in turn are offering up clues about the changes in the brain that drive the disorder, and may also provide a way to test new treatments. About three in every 100 people develop bipolar disorder – a mental illness characterised by episodes of depression and euphoria. But the condition remains poorly understood. That's because it would be too invasive to obtain and study viable nerve cells from the brains of people with the condition. There are also no good animal models, because bipolar disorder – although highly heritable – has, for the most part, not been linked to any specific genes that can be studied using animals. "People say the condition is probably the result of a lot of small contributions by multiple genes," says Sue O'Shea at the University of Michigan in Ann Arbor. Now O'Shea and her colleagues may have found an ethical way to make a genetic model of the condition. First, they took skin samples from 22 people with bipolar disorder and 10 healthy volunteers. They induced these adult skin cells to return to a stem-cell-like state, creating what are called induced pluripotent stem cells (iPSCs) and then encouraged these cells to mature into neurons. O'Shea was surprised to find that neurons derived from people with bipolar disorder grew differently from those from people without the condition. "I was expecting it would take decades of careful science before we would find any real differences," she says. © Copyright Reed Business Information Ltd.

Keyword: Schizophrenia; Aggression
Link ID: 19412 - Posted: 03.26.2014

James Hamblin Forty-one million IQ points. That’s what Dr. David Bellinger determined Americans have collectively forfeited as a result of exposure to lead, mercury, and organophosphate pesticides. In a 2012 paper published by the National Institutes of Health, Bellinger, a professor of neurology at Harvard Medical School, compared intelligence quotients among children whose mothers had been exposed to these neurotoxins while pregnant to those who had not. Bellinger calculates a total loss of 16.9 million IQ points due to exposure to organophosphates, the most common pesticides used in agriculture. Last month, more research brought concerns about chemical exposure and brain health to a heightened pitch. Philippe Grandjean, Bellinger’s Harvard colleague, and Philip Landrigan, dean for global health at Mount Sinai School of Medicine in Manhattan, announced to some controversy in the pages of a prestigious medical journal that a “silent pandemic” of toxins has been damaging the brains of unborn children. The experts named 12 chemicals—substances found in both the environment and everyday items like furniture and clothing—that they believed to be causing not just lower IQs but ADHD and autism spectrum disorder. Pesticides were among the toxins they identified. “So you recommend that pregnant women eat organic produce?” I asked Grandjean, a Danish-born researcher who travels around the world studying delayed effects of chemical exposure on children. “That’s what I advise people who ask me, yes. It’s the best way of preventing exposure to pesticides.” Grandjean estimates that there are about 45 organophosphate pesticides on the market, and “most have the potential to damage a developing nervous system.” © 2014 by The Atlantic Monthly Group.

Keyword: Neurotoxins; Aggression
Link ID: 19411 - Posted: 03.26.2014

By RICHARD A. FRIEDMAN FEELING down? Smile. Cheer up. Put on a happy face. No doubt you’ve dismissed these bromides from friends and loved ones because everyone knows that you can’t feel better just by aping a happy look. Or perhaps you can. New research suggests that it is possible to treat depression by paralyzing key facial muscles with Botox, which prevents patients from frowning and having unhappy-looking faces. In a study forthcoming in the Journal of Psychiatric Research, Eric Finzi, a cosmetic dermatologist, and Norman Rosenthal, a professor of psychiatry at Georgetown Medical School, randomly assigned a group of 74 patients with major depression to receive either Botox or saline injections in the forehead muscles whose contraction makes it possible to frown. Six weeks after the injection, 52 percent of the subjects who got Botox showed relief from depression, compared with only 15 percent of those who received the saline placebo. (You might think that patients would easily be able to tell whether they got the placebo or Botox. Actually, it wasn’t so obvious: Only about half of the subjects getting Botox guessed correctly. More important, knowing which treatment was received had no significant effect on treatment response.) Other studies over the past several years have found similar effects of Botox on mood. Michael Lewis at Cardiff University reported that nondepressed patients at a cosmetic dermatology clinic receiving Botox injection above the eyes frowned less and felt better than those who did not receive this injection. And M. Axel Wollmer at the University of Basel found that Botox injection was superior to a placebo in a group of depressed patients. © 2014 The New York Times Company

Keyword: Emotions
Link ID: 19410 - Posted: 03.26.2014

By Jennifer Richler A few days ago, an old friend sent me a panicked email. She had just finished reading Ron Suskind’s beautiful essay in the New York Times Magazine about raising a son with autism: “Reaching My Autistic Son Through Disney.” Suskind describes how, at almost 3 years of age, his son Owen “disappeared.” The child was once “engaged, chatty, full of typical speech,” but then he stopped talking, lost eye contact, even struggled to use a sippy cup. Owen was eventually diagnosed with a regressive form of autism, which Suskind says affects about a third of children with the disorder. “Unlike the kids born with it,” he continues, “this group seems typical until somewhere between 18 and 36 months—then they vanish.” That was the line that alarmed my friend, whose son is nearing his third birthday. “What is this ‘regressive autism?’ ” she asked me, the resident autism expert in her peer group. (I conducted research on autism and regression in autism before becoming a freelance writer.) “I thought we were out of the woods!” I’m sure many parents of young children who read the piece had the same reaction, and it’s completely understandable. It’s also unwarranted. The claim that many kids with autism develop typically for almost three years and then experience a near-complete loss of language, social skills, and motor ability—a claim I’ve read many times before—simply isn’t true. It’s time to set the record straight. © 2014 The Slate Group LLC.

Keyword: Autism
Link ID: 19409 - Posted: 03.26.2014

Andreas von Bubnoff People who are unable to recognize faces can still learn to distinguish between other types of very similar objects, researchers report. The finding provides fresh support for the idea that the brain mechanisms that process face images are specialized for that task. It also offers evidence against an 'expertise' hypothesis, in which the same mechanisms are responsible for recognition of faces and other highly similar objects we have learned to tell apart — the way bird watchers can recognize birds after years of training. Constantin Rezlescu, a psychologist at Harvard University in Cambridge, Massachusetts, and his colleagues worked with two volunteers nicknamed Florence and Herschel, who had acquired prosopagnosia, or face blindness, following brain damage. The condition renders people unable to recognize and distinguish between faces — in some cases, even those of their own family members. The team trained Florence and Herschel to recognize greebles, computer-generated objects that differ from one another in similar ways to faces. The two volunteers spent eight training sessions of up to one hour learning to recognize 20 different greebles. The objects belonged to five different ‘families’ that were easier to distinguish between than were the individual greebles, and initially the participants took longer to discriminate individual greebles within the same family than they did the different families. But by the end of the training, they could tell individual greebles apart just as quickly — a sign that they had become experts in recognizing them, just as dog trainers can recognize individual dogs as easily as different breeds of dog. The study appears in Proceedings of the National Academy of Sciences1. © 2014 Nature Publishing Group

Keyword: Attention
Link ID: 19408 - Posted: 03.25.2014

By CATHERINE SAINT LOUIS ALEXANDRIA, N.H. — For most of his life, Kevin Ramsey has lived with epileptic seizures that drugs cannot control. At least once a month, he would collapse, unconscious and shaking violently, sometimes injuring himself. Nighttime seizures left him exhausted at dawn, his tongue a bloody mess. After episodes at work, he struggled to stay employed. Driving became too risky. At 28, he sold his truck and moved into his mother’s spare bedroom. Cases of intractable epilepsy rarely have happy endings, but today Mr. Ramsey is seizure-free. A novel battery-powered device implanted in his skull, its wires threaded into his brain, tracks its electrical activity and quells impending seizures. At night, he holds a sort of wand to his head and downloads brain data from the device to a laptop for his doctors to review. “I’m still having seizures on the inside, but my stimulator is stopping all of them,” said Mr. Ramsey, 36, whose hands shake because of one of the three anti-seizure drugs he still must take. “I can do things on my own I couldn’t do before. I can go to the store on my own, and get my groceries. Before, I wouldn’t have been able to drive.” Just approved by the Food and Drug Administration, the long-awaited device, called the RNS System, aims to reduce seizures and to improve the lives of an estimated 400,000 Americans whose epilepsy cannot be treated with drugs or brain surgery. “This is the first in what I believe is a new generation of therapy for epilepsy,” said Dr. Dileep R. Nair, head of adult epilepsy at the Cleveland Clinic and an investigator in the pivotal trial for NeuroPace’s RNS. “It’s delivering local therapy. It’s not taking tissue out; the brain is left intact. And it’s unlike a drug, which is a shotgun approach.” © 2014 The New York Times Company

Keyword: Epilepsy
Link ID: 19407 - Posted: 03.25.2014

Dragonflies are full of surprises. They have six legs, but most can’t walk. Their giant, 30,000-lens eyes can detect ultraviolet light. And though they lack the brain architecture normally required for a sense of smell, a new study finds that dragonflies may use odors to hunt prey. Smelling, as we humans understand it, requires certain hardware. Our noses are packed with olfactory receptors, each of which is tuned to a precise scent molecule. (Indeed, a recent study suggests we can detect a trillion smells.) When one wafts into our nostrils, these receptors send nerve signals to sensory way stations called glomeruli, which pass them along to the brain for interpretation—“Oh, a rose!” Glomeruli are shared by most terrestrial mammals and insects, and until now, scientists believed they represented the only possible route to a sense of smell. Because dragonflies and their close cousins, damselflies, don’t possess glomeruli or any higher order smell centers in their brains, most scientists believed these insects were unable to smell anything at all. Invertebrate biologist Manuela Rebora at the University of Perugia in Italy was not one of them. When her team took a closer look at dragonfly and damselfly antennae with an electron microscope, they spotted tiny bulbs in pits that resembled olfactory sensilla. Like the insect equivalent of a nose, these sensilla house olfactory neurons. When Rebora’s team exposed the suspected sensilla to scents, they emitted nerve pulses, supporting the idea that damselflies and dragonflies perceive odors. © 2014 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19406 - Posted: 03.25.2014

Daniel Cressey The controversy over electronic cigarettes has been reignited today with the publication of a study claiming that they do not help smokers to quit their habit. Whether or not ‘e-cigarettes’ are an effective aid in the cessation of smoking has become a major issue for the rapidly growing industry that produces the devices, and for the tobacco researchers struggling to assess their impact. There is widespread agreement that inhaling from an e-cigarette, where a heating element vapourizes a liquid containing nicotine, is not as harmful as smoking a conventional cigarette, and proponents say that the products could save millions of lives. But some researchers and tobacco-control activists fear that the devices could make tobacco use seem socially acceptable again and may not assist people in actually reducing their addiction. Pamela Ling, a tobacco researcher at the University of California, San Francisco, and her colleagues followed 949 people who detailed their smoking habits though an online survey, and found that 88 of those who had used e-cigarettes were no more likely to have quit or reduced their smoking after a year than other smokers. “We found that there was no difference in the rate of quitting between smokers who used an e-cigarette and those who did not”, even after controlling for factors such as the user's dependence on tobacco, Ling told Nature in an e-mail. She added: “Advertising suggesting that e-cigarettes are effective for smoking cessation should be prohibited until such claims are supported by scientific evidence.” Her team reports the results today in JAMA Internal Medicine1. © 2014 Nature Publishing Group

Keyword: Drug Abuse
Link ID: 19405 - Posted: 03.25.2014

Claudia Dreifus The biochemist Ricardo E. Dolmetsch has pioneered a major shift in autism research, largely putting aside behavioral questions to focus on cell biology and biochemistry. Dr. Dolmetsch, 45, has done most of his work at Stanford. Since our interviews — a condensed and edited version of which follows — he has taken a leave to join Novartis, where his mission is to organize an international team to develop autism therapies. “Pharmaceutical companies have financial and organizational resources permitting you to do things you might not be able to do as an academic,” he said. “I really want to find a drug.” Q. Did you start out your professional life studying the biochemistry of autism? A. No. In graduate school and as a postdoc, I’d done basic research on the ion channels on the membranes of cells. By my mid-20s, I had my name on some high-profile papers. Then, around 2006, my son who was then 4 was diagnosed with autism. We had suspected it. He didn’t talk much, was hyperactive, very moody. He assembled huge towers based on the color spectrum. He did all sorts of things that were very unusual. Given the signs, why did you wait that long to seek a diagnosis? I’m from Latin America [Cali, Colombia], and my Latin thing was, “This is the way boys are.” But he would just scream for hours and hours, uncontrollable. He didn’t sleep. We didn’t understand it. After a while, his teachers said, “You probably ought to have him seen.” So we went to a psychiatrist and neurologist and ultimately we got differing diagnoses. © 2014 The New York Times Company

Keyword: Autism
Link ID: 19404 - Posted: 03.25.2014

By Gisela Telis, Jodi Corbitt had been battling depression for decades and by 2010 had resigned herself to taking antidepressant medication for the rest of her life. Then she decided to start a dietary experiment. To lose weight, the 47-year-old Catonsville, Md., mother stopped eating gluten, a protein found in wheat and related grains. Within a month she had shed several pounds — and her lifelong depression. “It was like a veil lifted and I could see life more clearly,” she recalled. “It changed everything.” Corbitt had stumbled into an area that scientists have recently begun to investigate: whether food can have as powerful an impact on the mind as it does on the body. Research exploring the link between diet and mental health “is a very new field; the first papers only came out a few years ago,” said Michael Berk, a professor of psychiatry at the Deakin University School of Medicine in Australia. “But the results are unusually consistent, and they show a link between diet quality and mental health.” “Diet quality” refers to the kinds of foods that people eat, how often they eat them and how much of them they eat. In several studies, including a 2011 analysis of more than 5,000 Norwegians, Berk and his collaborators have found lower rates of depression, anxiety and bipolar disorder among those who consumed a traditional diet of meat and vegetables than among people who followed a modern Western diet heavy with processed and fast foods or even a health-food diet of tofu and salads. © 1996-2014 The Washington Post

Keyword: Depression
Link ID: 19403 - Posted: 03.25.2014

By Maggie Fox Medical marijuana pills or an oral spray made from cannabis may help ease some of the painful spasms caused by multiple sclerosis that make day-to-day life hard for patients, according to new guidelines from the American Academy of Neurology. But the synthetic formulations of marijuana don’t change the course of the disease and might cause unpleasant side-effects, the experts at the academy caution. There is not enough evidence to make any recommendation on smoking marijuana for MS patients, stresses Dr. Vijayshree Yadav of Oregon Health & Science University, who led the team writing the guidelines. Synthetic marijuana in pill form, including the Marinol brand, is legal for use in treating nausea and loss of appetite in cancer. An oral spray called Sativex is approved for treating MS symptoms in Britain but not in the U.S. MS patients often seek alternative and complementary therapies because they have so few options for the chronic and incurable condition, caused when the immune system mistakenly attacks the nerves. A review of those therapies found there's no evidence most of them work. The review found that the herb Ginkgo biloba might help fatigue, but not thinking and memory problems. There’s also some evidence that magnetic therapy may help fatigue.

Keyword: Multiple Sclerosis
Link ID: 19402 - Posted: 03.25.2014

By ANNE EISENBERG People who strain to hear conversations in noisy places sometimes shun hearing appliances as telltale signs of aging. But what if those devices looked like wireless phone receivers? Some companies are betting that the high-tech look of a new generation of sound amplifiers will tempt people to try them. The new in-ear amps come with wireless technology and typically cost $300 to $500. The devices include directional microphones and can be fine-tuned by smartphone apps. Whatever you do, don’t call these amplifiers hearing aids. They are not considered medical devices like the ones overseen by the Food and Drug Administration and dispensed by professionals to aid those with impaired hearing. Rather, they are over-the-counter systems cleared by the F.D.A. for occasional use in situations when speech and other sounds are hard to discern — say, in a noisy restaurant or while bird-watching. “The market is proliferating with lots of devices not necessarily made for impaired hearing, but for someone who wants a boost in certain challenging conditions like lectures,” said Neil J. DiSarno, chief staff officer for audiology at the American Speech-Language-Hearing Association. Dr. DiSarno is among the many audiologists who strongly urge people to see a physician first, in order to rule out medical causes of hearing loss, which could vary from earwax to a tumor, rather than self-diagnosing and self-treating a condition. Carole Rogin, president of the Hearing Industries Association, a trade group, said the biggest problem with personal amplification products was that people might use them instead of seeking appropriate medical oversight. “Untreated hearing loss is not a benign condition,” she said. “We want people to do something about it as soon as they notice a problem,” rather than using these devices to mask a potentially dangerous condition. © 2014 The New York Times Company

Keyword: Hearing
Link ID: 19401 - Posted: 03.24.2014

by Clare Wilson It's a vicious circle of the cruellest kind. Stress might be causing infertility in women, according to new research. This could explain some cases in which couples are diagnosed as infertile with no apparent cause. Taking longer than usual to conceive can lead to stress, so the problem could become self-perpetuating. A link between everyday life stresses and infertility has long been suspected, but there has been little hard evidence connecting the two. Women receiving fertility treatment are generally advised to avoid stress, but not so the average person trying to conceive. An estimated one in seven couples in the UK have fertility problems and, in about a quarter of those, there is no known medical explanation, and they are given a diagnosis of "unexplained infertility". To explore the role of stress, Courtney Lynch at Ohio State University in Columbus and her colleagues collected saliva samples from 373 women in the US who had just started trying to conceive naturally and measured levels of an enzyme called alpha-amylase, a marker of stress. After one year of regular unprotected sex, about 13 per cent of the couples had failed to get pregnant, the standard definition of infertility. The third of women who had the highest alpha-amylase levels were twice as likely to be in the infertile group as the third with the lowest levels. In a previous study, Lynch's team found that those with higher levels of the stress enzyme were slightly less likely to conceive in their first month of trying. But this is the first time that alpha-amylase has been linked to clinical infertility. © Copyright Reed Business Information Ltd.

Keyword: Stress; Aggression
Link ID: 19400 - Posted: 03.24.2014

By MATT RICHTEL A dangerous new form of a powerful stimulant is hitting markets nationwide, for sale by the vial, the gallon and even the barrel. The drug is nicotine, in its potent, liquid form — extracted from tobacco and tinctured with a cocktail of flavorings, colorings and assorted chemicals to feed the fast-growing electronic cigarette industry. These “e-liquids,” the key ingredients in e-cigarettes, are powerful neurotoxins. Tiny amounts, whether ingested or absorbed through the skin, can cause vomiting and seizures and even be lethal. A teaspoon of even highly diluted e-liquid can kill a small child. But, like e-cigarettes, e-liquids are not regulated by federal authorities. They are mixed on factory floors and in the back rooms of shops, and sold legally in stores and online in small bottles that are kept casually around the house for regular refilling of e-cigarettes. Evidence of the potential dangers is already emerging. Toxicologists warn that e-liquids pose a significant risk to public health, particularly to children, who may be drawn to their bright colors and fragrant flavorings like cherry, chocolate and bubble gum. “It’s not a matter of if a child will be seriously poisoned or killed,” said Lee Cantrell, director of the San Diego division of the California Poison Control System and a professor of pharmacy at the University of California, San Francisco. “It’s a matter of when.” © 2014 The New York Times Company

Keyword: Drug Abuse; Aggression
Link ID: 19399 - Posted: 03.24.2014

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

Keyword: Vision
Link ID: 19398 - Posted: 03.22.2014

By BENOIT DENIZET-LEWISy The traffic was bad, even by the warped standards of a Southern California commute. We were headed south from Los Angeles to San Diego on an overcast morning last spring, but we hadn’t moved in 10 minutes. I was sandwiched in the back seat of the car between John Sylla and Denise Penn, two board members of the Los Angeles-based American Institute of Bisexuality (A.I.B.), a deep-pocketed group partly responsible for a surge of academic and scientific research across the country about bisexuality. We were on our way to an A.I.B. board meeting, where members would decide which studies to fund and also brainstorm ways to increase bisexual visibility “in a world that still isn’t convinced that bisexuality — particularly male bisexuality — exists,” as Allen Rosenthal, a sex researcher at Northwestern University, told me. When someone suggested that we try another route, Sylla, A.I.B.’s friendly and unassuming 55-year-old president, opened the maps app on his iPhone. I met Sylla the previous day at A.I.B. headquarters, a modest two-room office on the first floor of a quiet courtyard in West Hollywood that’s also home to film-production companies and a therapist’s office. Tall and pale, with an easy smile, Sylla offered me books from A.I.B.’s bisexual-themed bookshelf and marveled at the unlikelihood of his bisexual activism. “For the longest time, I didn’t even realize I was bi,” Sylla said. “When I did, I assumed I’d probably just live a supposedly straight life in the suburbs somewhere.” In the back seat, Sylla lifted his eyes from his phone and suggested an alternate course. Then he shrugged his shoulders. “We could go either way, really,” he told us. He smiled at me. “Get it? Either way?” © 2014 The New York Times Company

Keyword: Sexual Behavior; Aggression
Link ID: 19397 - Posted: 03.22.2014

By Ariana Eunjung Cha, Millions of ordinary Americans are now able to walk into a marijuana dispensary and purchase bags of pot on the spot for a variety of medical ailments. But if you’re a researcher like Sue Sisley, a psychiatrist who studies post- traumatic stress disorder, getting access to the drug isn’t nearly so easy. That’s because the federal government has a virtual monopoly on growing and cultivating marijuana for scientific research, and getting access to the drug requires three separate levels of approval. Marijuana offers hope for 6-year-old girl with rare condition: In marijuana, Lydia Schaeffer’s family members think they might have found a treatment that works. Now, they are trying to help legalize the drug. Sisley’s fight to get samples for her study — now in its fourth month — illuminates the complex politics of marijuana in the United States. While 20 states and the District have made medical marijuana legal — in Colorado and Washington state the drug is also legal for recreational use — it remains among the most tightly controlled substances under federal law. For scientists, that means extra steps to obtain, transport and secure the drug — delays they say can slow down their research by months or even years. © 1996-2014 The Washington Post

Keyword: Drug Abuse; Aggression
Link ID: 19396 - Posted: 03.22.2014

by Barbara J. King Why do little boys tend to behave differently from little girls? Why do boys and girls play differently, for instance, choosing different toys as their favorites? Ask these questions and you invite a firestorm — of more questions. Is the premise behind these queries even accurate? Aren't our sons and daughters really more similar than different, after all? And when behavioral sex differences do occur, aren't parents who inflict sex-stereotypical expectations on their children largely responsible? Seven experts on chimpanzee behavior, led by of Franklin and Marshall College and including the world-famous primatologist , have in Animal Behaviour that speaks, they say, to these issues. Their data on wild chimpanzees from , Tanzania, indicate that human sex differences in childhood are primarily the result of biological, evolutionary mechanisms. The scientists analyzed data on the behavior of 12 male and eight female chimpanzee youngsters, ages 30-36 months. At that age, chimpanzees, who develop quite slowly compared with many other mammals, are still considered infants. As a rule, chimpanzees spend most of their day in close proximity to their mothers clear through their ninth year of life. In the Gombe study, male infants were found to be more gregarious than female chimpanzees; they interacted with significantly more individuals outside the immediate family, including more adult males, than did females. This result held even when the number of the mothers' social partners was controlled. ©2014 NPR

Keyword: Sexual Behavior; Aggression
Link ID: 19395 - Posted: 03.22.2014

Jessica Morrison The human nose has roughly 400 types of scent receptors that can detect at least 1 trillion different odours. The human nose can distinguish at least 1 trillion different odours, a resolution orders of magnitude beyond the previous estimate of just 10,000 scents, researchers report today in Science1. Scientists who study smell have suspected a higher number for some time, but few studies have attempted to explore the limits of the human nose’s sensory capacity. “It has just been sitting there for somebody to do,” says study co-author Andreas Keller, an olfactory researcher at the Rockefeller University in New York. To investigate the limits of humans' sense of smell, Keller and his colleagues prepared scent mixtures with 10, 20 or 30 components selected from a collection of 128 odorous molecules. Then they asked 26 study participants to identify the mixture that smelled differently in a sample set where two of three scents were the same. When the two scents contained components that overlapped by more than about 51%, most participants struggled to discriminate between them. The authors then calculated the number of possible mixtures that overlap by less than 51% to arrive at their estimate of how many smells a human nose can detect: at least 1 trillion. Donald Wilson, an olfactory researcher at the New York University School of Medicine, says the findings are “thrilling.” He hopes that the new estimate will help researchers begin to unravel an enduring mystery: how the nose and brain work together to process smells. © 2014 Nature Publishing Group,

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19394 - Posted: 03.21.2014

by Simon Makin How much can environmental factors explain the apparent rise in autism spectrum disorders? Roughly 1 per cent of children in the US population are affected by autism spectrum disorder (ASD). Rates in many countries, including the US, have risen sharply in recent years but no one is sure why. It is still not clear whether this is prompted by something in the environment, increased awareness of the condition and changes in diagnoses, or a result of people having children later. The environmental case is hotly debated. There is some evidence that maternal infections during pregnancy can increase the risk. Other studies have pointed to a possible link with antidepressants while others have looked at elevated levels of mercury. But determining prenatal exposure to any substance is difficult because it is hard to know what substances people have been exposed to and when. To get around this, Andrey Rzhetsky and colleagues at the University of Chicago analysed US health insurance claims containing over 100 million patient records – a third of the population – dating from 2003 to 2010. They used rates of genital malformations in newborn boys as a proxy of parents' exposure to environmental risk factors. This is based on research linking a proportion of these malformations to toxins in the environment, including pesticides, lead and medicines. Toxic environment? The team compared the rates of these malformations to rates of ASD county by county. After adjusting for gender, income, ethnicity and socio-economic status, they found that a 1 per cent increase in birth defects – their measure for environmental effects - was associated with an average increase of 283 per cent in cases of ASD. © Copyright Reed Business Information Ltd.

Keyword: Autism
Link ID: 19393 - Posted: 03.21.2014