Coffee may cut the risk of dementia by blocking the damage cholesterol can inflict on the body, research suggests. The drink has already been linked to a lower risk of Alzheimer's Disease, and a study by a US team for the Journal of Neuroinflammation may explain why. A vital barrier between the brain and the main blood supply of rabbits fed a fat-rich diet was protected in those given a caffeine supplement. UK experts said it was the "best evidence yet" of coffee's benefits. The "blood brain barrier" is a filter which protects the central nervous system from potentially harmful chemicals carried around in the rest of the bloodstream. Other studies have shown that high levels of cholesterol in the blood can make this barrier "leaky". Alzheimer's researchers suggest this makes the brain vulnerable to damage which can trigger or contribute to the condition. The University of North Dakota study used the equivalent to just one daily cup of coffee in their experiments on rabbits. After 12 weeks of a high-cholesterol diet, the blood brain barrier in those given caffeine was far more intact than in those given no caffeine. "Caffeine appears to block several of the disruptive effects of cholesterol that make the blood-brain barrier leaky," said Dr Jonathan Geiger, who led the study. High levels of cholesterol are a risk factor for Alzheimer's disease, perhaps by compromising the protective nature of the blood brain barrier. Caffeine is a safe and readily available drug and its ability to stabilise the blood brain barrier means it could have an important part to play in therapies against neurological disorders." (C)BBC

Keyword: Drug Abuse; Alzheimers
Link ID: 11504 - Posted: 04.05.2008

Binge drinking teenagers are still at risk of absent-mindedness and forgetfulness days later, a study says. A team from Northumbria and Keele universities compared 26 binge drinkers with 34 non-bingers in memory tests, and found the drinkers fared worse. They told the British Psychological Society conference that binge drinking could be harming developing brains. A spokesman for the charity Addaction said drinking at dangerous levels was putting some young people at risk. Binge drinking is already known to affect people's memories of past events. In this study, the scientists looked at students aged 17 to 19 - a period when the brain is still developing. Binge drinking was defined as at least eight units a session for a man and six for a woman once or twice a week. The researchers said the binge drinkers studied consumed, on average, 30 units in just two sessions. The teenagers were tested three or four days after their last drinking session, so that their bodies would be free of alcohol. They were asked to answer questions about how often they forgot to carry out tasks they intended to do, such as meeting with friends. They were shown a video clip of a shopping trip after being given a couple of minutes to memorise a set of tasks prompted by various cues in the film, such as remembering to text a friend at a certain shop, or to check their bank accounts after seeing a person sitting on a bench. (C)BBC

Keyword: Drug Abuse; Learning & Memory
Link ID: 11503 - Posted: 04.05.2008

Sönke Johnsen and Kenneth J. Lohmann Like the theory of plate tectonics, the idea that animals can detect Earth's magnetic field has traveled the path from ridicule to well-established fact in little more than one generation. Dozens of experiments have now shown that diverse animal species, ranging from bees to salamanders to sea turtles to birds, have internal compasses. Some species use their compasses to navigate entire oceans, others to find better mud just a few inches away. Certain migratory species even appear to use the geographic variations in the strength and inclination of Earth's field to determine their position. But how animals sense magnetic fields remains a hotly contested topic. Whereas the physical basis of nearly all other senses has been determined, and a magnetoreception mechanism has been identified in bacteria, no one knows with certainty how any animal perceives magnetic fields. Finding this mechanism is thus the current grand challenge of sensory biology. The problem is difficult for several reasons. First, humans do not appear to have the ability to sense magnetic fields. Whereas most nonhuman senses, such as polarization detection and UV vision, are relatively straightforward extensions of human abilities, magnetoreception is not. As a result, neither intuitive understanding nor the medical literature on human senses provides much guidance. Another complicating factor is that biological tissue is essentially transparent to magnetic fields, which means that magnetoreceptors, unlike most other sensory receptors, need not be located on an animal's surface and might instead be anywhere in the body. That consideration transforms a routine two-dimensional visual inspection into a three-dimensional search requiring advanced imaging techniques. Another impediment is that large accessory structures for focusing and otherwise manipulating the field—the analogs of eardrums and lenses—are unlikely to exist because few materials of biological origin affect magnetic fields. Indeed, magnetoreception might be accomplished by a small number of microscopic, possibly intracellular structures scattered throughout the body, with no obvious structure devoted to magnetoreception. Finally, the weakness of the interaction between Earth's field and the magnetic moments of electrons and atoms, roughly one five-millionth of the thermal energy kT at body temperature, makes it difficult to even suggest a feasible mechanism. © 2007 by the American Institute of Physics

Keyword: Animal Migration
Link ID: 11502 - Posted: 06.24.2010

Dana Small, a neuroscientist at the John B. Pierce Laboratory in New Haven, Conn., and the Yale School of Medicine, sniffs out an answer. In a classic experiment, French researchers colored a white wine red with an odorless dye and asked a panel of wine experts to describe its taste. The connoisseurs described the wine using typical red wine descriptors rather than terms they would use to evaluate white wine, suggesting that the color played a significant role in the way they perceived the drink. Although sight is not technically part of taste, it certainly influences perception. Interestingly, food and drink are identified predominantly by the senses of smell and sight, not taste. Food can be identified by sight alone—we don't have to eat a strawberry to know it is a strawberry. The same goes for smell, in many cases. To our brains, "taste" is actually a fusion of a food's taste, smell and touch into a single sensation. This combination of qualities takes place because during chewing or sipping, all sensory information originates from a common location: whatever it is we're snacking on. Further, "flavor" is a more accurate term for what we commonly refer to as taste; therefore, smell not only influences but is an integral part of flavor. Pure taste sensations include sweet, sour, salty, bitter, savory and, debatably, fat. Cells that recognize these flavors reside in taste buds located on the tongue and the roof of the mouth. When food and drink are placed in the mouth, taste cells are activated and we perceive a flavor. Concurrently, whatever we are eating or sipping invariably contacts and activates sensory cells, located side-by-side with the taste cells, that allow us to perceive qualities such as temperature, spiciness or creaminess. We perceive the act of touch as tasting because the contact "captures" the flavor sensation. © 1996-2008 Scientific American Inc.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 11501 - Posted: 06.24.2010

By KATE MURPHY Modern life is loud. The jolting buzz of an alarm clock awakens the ears to a daily din of trucks idling, sirens blaring, televisions droning, computers pinging and phones ringing — not to mention refrigerators humming and air-conditioners thrumming. But for the 12 million Americans who suffer from severe tinnitus, the phantom tones inside their head are louder than anything else. Often caused by prolonged or sudden exposure to loud noises, tinnitus (pronounced tin-NIGHT-us or TIN-nit-us) is becoming an increasingly common complaint, particularly among soldiers returning from combat, users of portable music players, and aging baby boomers reared on rock ’n’ roll. (Other causes include stress, some kinds of chemotherapy, head and neck trauma, sinus infections, and multiple sclerosis.) Although there is no cure, researchers say they have never had a better understanding of the cascade of physiological and psychological mechanisms responsible for tinnitus. As a result, new treatments under investigation — some of them already on the market — show promise in helping patients manage the ringing, pinging and hissing that otherwise drives them to distraction. The most promising therapies, experts say, are based on discoveries made in the last five years about the brain activity of people with tinnitus. With brain-scanning equipment like functional magnetic resonance imaging, researchers in the United States and Europe have independently discovered that the brain areas responsible for interpreting sound and producing fearful emotions are exceptionally active in people who complain of tinnitus. Copyright 2008 The New York Times Company

Keyword: Hearing
Link ID: 11500 - Posted: 06.24.2010

By NATALIE ANGIER When Jeremy Wolfe of Harvard Medical School, speaking last week at a symposium devoted to the crossover theme of Art and Neuroscience, wanted to illustrate how the brain sees the world and how often it fumbles the job, he naturally turned to a great work of art. He flashed a slide of Ellsworth Kelly’s “Study for Colors for a Large Wall” on the screen, and the audience couldn’t help but perk to attention. The checkerboard painting of 64 black, white and colored squares was so whimsically subtle, so poised and propulsive. We drank it in greedily, we scanned every part of it, we loved it, we owned it, and, whoops, time for a test. Dr. Wolfe flashed another slide of the image, this time with one of the squares highlighted. Was the highlighted square the same color as the original, he asked the audience, or had he altered it? Um, different. No, wait, the same, definitely the same. That square could not now be nor ever have been anything but swimming-pool blue ... could it? The slides flashed by. How about this mustard square here, or that denim one there, or this pink, or that black? We in the audience were at sea and flailed for a strategy. By the end of the series only one thing was clear: We had gazed on Ellsworth Kelly’s masterpiece, but we hadn’t really seen it at all. The phenomenon that Dr. Wolfe’s Pop Art quiz exemplified is known as change blindness: the frequent inability of our visual system to detect alterations to something staring us straight in the face. The changes needn’t be as modest as a switching of paint chips. At the same meeting, held at the Italian Academy for Advanced Studies in America at Columbia University, the audience failed to notice entire stories disappearing from buildings, or the fact that one poor chicken in a field of dancing cartoon hens had suddenly exploded. In an interview, Dr. Wolfe also recalled a series of experiments in which pedestrians giving directions to a Cornell researcher posing as a lost tourist didn’t notice when, midway through the exchange, the sham tourist was replaced by another person altogether. Copyright 2008 The New York Times Company

Keyword: Vision
Link ID: 11499 - Posted: 06.24.2010

Boston University Associate Dean for research, Salomon Amar has found that obese mice are not as effective as lean mice in mounting a counterattack against an infection. In research published in the Proceedings of the National Academy of Sciences, Amar found that the mice's inflammatory response, part of the body's defense against infection, was blunted. Amar fed mice a diet that was many times greater than they needed, and then infected both the now obese mice and a similar group of lean mice that grew up on a normal diet. Amar found that if a lean animal "Would take seven days to eliminate the microorganism…the obese animal would take about 10 days or 12 to 13 days." Amar also found that this reduced response had a second problem. Even though it the obese mice had a blunted inflammatory response, it lasted longer than necessary. He says, "You have to understand that the inflammatory response is very bad for the body when it stays longer. It's there to clean up the damages and then it needs to be removed." As examples, he notes that extended inflammation is an important problem for diabetics and that in some cases extended inflammation can result in fatal septic shock. Amar pointed out that in his experiments, he was able to take diabetes out of the equation by infecting the obese mouse before the onset of diabetes. The experiments were also specific to obesity caused by diet, and not some sort of genetic situation. © ScienCentral, 2000-2008

Keyword: Obesity; Neuroimmunology
Link ID: 11498 - Posted: 06.24.2010

By Elsa Youngsteadt Mice can whistle and chirp like birds--and researchers now say their songs seem to be happy ones. New experiments associate the rodents' ultrasonic chatter with the brain's dopamine-based reward system, and investigators hope that studying the songs may eventually point toward genes behind human emotional disorders such as schizophrenia and autism. Researchers have known for nearly 50 years that rodents produce ultrasonic calls. In 2005, they discovered that mice even sing complex songs (ScienceNOW, 1 November 2005). Their sparrowlike whistles and twitters are a couple of octaves too high for human ears to hear. No one knew exactly why mice sing, but rats make similar calls during sex, pleasant brain stimulation, and drug use, so psychologists thought the songs might be a sign of happiness. If this held true in mice, then powerful genetic tools available only in mouse studies could help researchers discover new genes that affect emotion and pleasure. A team of researchers led by brain scientist John Yeomans at the University of Toronto in Canada used special microphones to eavesdrop on mice during sex. When they let a male mouse into a female's cage, he approached her with a series of whistle calls and then, during intercourse, sang more complex chirp songs until ejaculation. (Females sing during social reunion with other females but only squeak uncomfortably during sex). Even without sex, the male mice sang complex chirps after the researchers injected them with a low dose of amphetamine, which activates the brain's reward circuitry by boosting levels of the neurotransmitter dopamine. © 2008 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Animal Communication
Link ID: 11497 - Posted: 06.24.2010

Bruce Bower Stimulants have long been prescribed to children diagnosed with attention-deficit hyperactivity disorder, or ADHD. Over the past decade, child psychiatrists have debated the long-term potential for these medications to trigger drug abuse. Two new studies indicate that the stimulants do not increase children's risk of abusing cocaine, nicotine, and other drugs as adults. Although these findings come as a relief to child psychiatrists, not all the news is good. The new investigations, already published online and slated to appear in the May American Journal of Psychiatry, underscore earlier evidence that youngsters with ADHD frequently become drug abusers, whether or not they take prescribed stimulants. "It is still critical that young people with ADHD be screened for substance abuse," says Nora D. Volkow, director of the National Institute on Drug Abuse in Bethesda, Md. Boys with ADHD who start stimulant treatment early, at age 6 or 7, face a lower risk of later drug abuse than do those who begin taking medication later, between ages 8 and 12, report psychologist Salvatore Mannuzza of New York University's Child Study Center and his colleagues. ©2008 Society for Science & the Public

Keyword: ADHD; Drug Abuse
Link ID: 11496 - Posted: 06.24.2010

Inherited variations in the amount of an innate anxiety-reducing molecule help explain why some people can withstand stress better than others, according to a new study led by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). "Stress response is an important variable in vulnerability to alcohol dependence and other addictions, as well as other psychiatric disorders," noted NIAAA Director Ting-Kai Li, M.D. "This finding could help us understand individuals' initial vulnerability to these disorders." Scientists led by David Goldman, M. D., chief of the NIAAA Laboratory of Neurogenetics, identified gene variants that affect the expression of a signaling molecule called neuropeptide Y (NPY). Found in brain and many other tissues, NPY regulates diverse functions, including appetite, weight, and emotional responses. "NPY is induced by stress and its release reduces anxiety," said Dr. Goldman. "Previous studies have shown that genetic factors play an important role in mood and anxiety disorders. In this study, we sought to determine if genetic variants of NPY might contribute to the maladaptive stress responses that often underlie these disorders." A report of the findings appears online today in Nature. Analyses of human tissue samples led by researchers at NIAAA identified several NPY gene variants.

Keyword: Stress; Genes & Behavior
Link ID: 11495 - Posted: 04.05.2008

Seth Borenstein -- Scientists say they have pinpointed a genetic link that makes people more likely to get hooked on tobacco, causing them to smoke more cigarettes, making it harder to quit, and leading more often to deadly lung cancer. The discovery by three separate teams of scientists makes the strongest case so far for the biological underpinnings of the addiction of smoking and sheds light on how genetics and cigarettes join forces to cause cancer, experts said. The findings also lay the groundwork for more tailored quit-smoking treatments. "This is kind of a double whammy gene," said Christopher Amos, a professor of epidemiology at the M.D. Anderson Cancer Center in Houston and author of one of the studies. "It makes you more likely to be dependent on smoking and less likely to quit smoking." A smoker who inherits this genetic variation from both parents has an 80 percent greater chance of lung cancer than a smoker without the variants, the researchers reported. And that same smoker on average lights up two extra cigarettes a day and has a much harder time quitting than smokers who don't have these genetic differences. The three studies, funded by governments in the United States and Europe, is being published Thursday in the journals Nature and Nature Genetics. © 2008 Discovery Communications, LLC

Keyword: Drug Abuse; Genes & Behavior
Link ID: 11494 - Posted: 06.24.2010

Ewen Callaway It's thought of as a sexual stereotype: boys tend to play with toy cars and diggers, while girls like dolls. But male monkeys, suggests research, are no different. This could mean that males, whether human or monkey, have a biological predisposition to certain toys, says Kim Wallen, a psychologist at Yerkes National Primate Research Center in Atlanta, Georgia. Wallen's team looked at 11 male and 23 female rhesus monkeys. In general the males preferred to play with wheeled toys, such as dumper trucks, over plush dolls, while female monkeys played with both kinds of toys. This conclusion may upset those psychologists who insist that sex differences – for example the tendency of boys to favour toy soldiers and girls to prefer dolls – depend on social factors, not innate differences. "A five-year-old boy whose compatriots discover has a collection of Barbies is likely to take a lot of flak," Wallen says. Social factors undoubtedly influence children's preferences, he says, but in general boys tend to be pickier with toys than girls. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Development of the Brain
Link ID: 11493 - Posted: 06.24.2010

Michael Hopkin Could a gene be partly responsible for the behaviour of some of the worlds most infamous dictators? Selfish dictators may owe their behaviour partly to their genes, according to a study that claims to have found a genetic link to ruthlessness. The study might help to explain the money-grabbing tendencies of those with a Machiavellian streak — from national dictators down to 'little Hitlers' found in workplaces the world over. Researchers at the Hebrew University in Jerusalem found a link between a gene called AVPR1a and ruthless behaviour in an economic exercise called the 'Dictator Game'. The exercise allows players to behave selflessly, or like money-grabbing dictators such as former Zaire President Mobutu, who plundered the mineral wealth of his country to become one of the world's richest men while its citizens suffered in poverty. The researchers don't know the mechanism by which the gene influences behaviour. It may mean that for some, the old adage that "it is better to give than to receive" simply isn't true, says team leader Richard Ebstein. The reward centres in those brains may derive less pleasure from altruistic acts, he suggests, perhaps causing them to behave more selfishly. © 2008 Nature Publishing Group

Keyword: Aggression; Genes & Behavior
Link ID: 11492 - Posted: 06.24.2010

Kenneth C. Catania I’ve been trapping star-nosed moles for two decades to study their behavior and anatomy, so I am used to the disappointment of finding an empty trap. But one trap I set about twelve years ago disappointed me in another way. I had placed it in a wetland to catch a mole, but found that another small mammal had the nerve to get caught. Recognizing that it was a North American water shrew, I released it at the edge of a nearby stream, wondering just how good it could possibly be at swimming (it doesn’t look very different from its landlubber relatives). I was amazed to see it shoot straight down into a deep pool of water, swim across the stream, and disappear into submerged vegetation on the other side. It seemed more like a fish than a mammal. I never forgot the sight. Although my investigations of star-nosed moles continued to occupy me for years, eventually, in collaboration with Kevin L. Campbell and James F. Hare, biologists at the University of Manitoba, I set out to learn more about the North American water shrew, Sorex palustris. It is not only (at little more than half an ounce) the world’s smallest mammalian diver, but also a predator with remarkable abilities to sense and capture prey. To be fair, you’ll never have to worry about one latching onto your foot and dragging you into a lake. But I have come to think of water shrews as the great white sharks of their diminutive domain. Shrews are members of the order Insectivora, which also includes moles and hedgehogs. Although they may look somewhat like mice, they are only distantly related to rodents. There are three subfamilies of shrews; the North American water shrew belongs to the Soricinae subfamily, the so called red-toothed shrews. This group gets its name from iron deposits in the animals’ teeth that are thought to provide added strength to the enamel (tooth wear is a major problem for shrews, because their teeth don’t grow continuously, as those of rodents do). © Natural History Magazine, Inc., 2008

Keyword: Chemical Senses (Smell & Taste)
Link ID: 11491 - Posted: 06.24.2010

There is strong evidence that exposure to pesticides significantly increases the risk of Parkinson's disease, experts believe. It comes as another study, published in the BMC Neurology journal, has made the link to the neurological disease. The US researchers found those exposed to pesticides had a 1.6 times higher risk after studying 600 people. Experts said it was now highly likely pesticides played a key role - albeit in combination with other factors. The disorder, which normally develops later in life and can affect movement and talking, is also influenced by genetic factors. Several gene defects have been identified, but these are thought to be rare and only account for a small proportion of the 120,000 people affected by the disease in the UK. The US team, which involved scientists from Duke University, Miami University and the Udall Parkinson's Disease Research Center of Excellence, quizzed 319 patients about their pesticide use. The answers were compared to over 200 family members and other controls who did not have the disease. Related individuals were chosen as they would share many environmental and genetic backgrounds in a bid to isolate the impact of the pesticides. They found those exposed to pesticides had a 1.6 times greater risk of developing the disease. Heavy use, classed as over 200 days exposure over a lifetime, carried over double the risk. And the study also revealed herbicides and insecticides were the pesticides most likely to increase risk. (C)BBC

Keyword: Parkinsons; Neurotoxins
Link ID: 11490 - Posted: 03.29.2008

Rats are able to learn from experience and apply what they have learned to new situations, similar to the way toddlers learn language, new research from the United Kingdom suggests. In a report in the March 28 edition of the journal Science, researchers at the University of Oxford report that rats were able to learn a simple, three-step audio or visual sequence and connect the pattern, associated with food, to a different setting. New research from scientists in the United Kingdom suggests that rats are capable of abstract thought. "These experiments show that rats can learn simplified rules and apply these rules to novel stimuli," wrote the researchers. "Even if the cognitive mechanism that allows the rats' behaviour is found to be dissimilar to that found in humans, it does seem that both species have evolved means of solving similar information problems, in this case, the transfer of overall sequence relations." Previous studies have suggested that infants, primates and birds are able to identify sequences, the researchers wrote in their report, but the question of whether animals other than humans are able to learn and apply rules has been contested. © CBC 2008

Keyword: Learning & Memory
Link ID: 11489 - Posted: 06.24.2010

Suzy Allman Public health experts generally agree that after clean water and flush toilets, the most important health advances in history have been vaccinations. Shots against measles, diphtheria, whooping cough, tetanus, polio, mumps, rubella, chicken pox, flu, hepatitis and some causes of childhood meningitis, pneumonia and diarrhea have saved more lives than all the “miracle drugs” of the latter half of the 20th century — antibiotics like penicillin, antivirals like drugs to fight AIDS and flu, and so on. In addition, vaccination is one of the leading reasons that many families in the West now feel comfortable having only two or three children: they can be reasonably certain that the children will survive childhood. According to a large historical study by the Centers for Disease Control and Prevention released in November 2007, death rates for 13 diseases that can be prevented by childhood vaccinations were at all-time lows in the United States. The study looked at hospital and death records going back to 1900 and estimated death rates before various vaccines were invented. In nine of the diseases, rates of hospitalization or death had declined more than 90 percent. For three — smallpox, diphtheria and polio — death rates had dropped by 100 percent. Copyright 2008 The New York Times Company

Keyword: Autism; Neuroimmunology
Link ID: 11488 - Posted: 06.24.2010

By Nikhil Swaminathan A new study indicates that the genetic culprits behind schizophrenia may be much less common than previously believed. Researchers report this week in Science that a rare but devastating change in one of several different genes may dramatically increase the risk of developing the debilitating brain disorder affecting 1 percent of the world's population and marked by psychotic behavior, hallucinations and delusions. Until now, most scientists believed that it was likely that a cluster of relatively common genetic mutations was to blame. "We're not saying that our results themselves are irrefutable proof that schizophrenia is all rare mutations," says study co-author Jonathan Sebat, a geneticist at Cold Spring Harbor Laboratory in Long Island, N.Y. "It is simply that in many schizophrenia cases, much of a patient's individual risk can be accounted for by a 'sledgehammer' mutation." Until recently, researchers trying to unravel the mysterious disease searched the genomes of schizophrenia patients for flaws not present in the genes of healthy people. Their probes turned up a few possible genetic suspects, but the findings were contradicted by those from other studies. In addition, candidate mutations typically only showed up in no more than 10 percent of schizophrenia sufferers sampled. The new study identifies more than 20 genes that may trigger the disease. If researchers can positively link any or all of these genes to the disease, it would set the stage for development of new therapies. © 1996-2008 Scientific American Inc.

Keyword: Schizophrenia; Genes & Behavior
Link ID: 11487 - Posted: 06.24.2010

Tina Hesman Saey A genetic quirk could help cheating athletes beat drug tests and could unfairly taint fair players. The genetic variation affects an enzyme that processes testosterone. Testosterone is naturally made in the body by both men and women, although it is primarily known as a male sex hormone. In order to distinguish between naturally present hormone and synthetic testosterone from steroid use, drug tests measure a ratio of two chemicals found in urine. One chemical, epitestosterone glucuronide (EG), is made at a constant level in the body, regardless of testosterone levels. The other chemical, testosterone glucuronide (TG), is a testosterone by-product. Testers measure the ratio of TG to EG. Any amount of TG greater than four times the level of EG is considered a red flag for doping. An enzyme called UGT2B17 adds a chemical to testosterone to prepare it for secretion in the urine. A group of scientists in Sweden found that some people completely lack the gene that produces UGT2B17, and this difference could affect results of doping tests. ©2008 Society for Science & the Public

Keyword: Hormones & Behavior; Genes & Behavior
Link ID: 11486 - Posted: 06.24.2010

By Clara Moskowitz You're at a crowded party with chaos and noise all around but somehow you focus on what your date says. Scientists have long puzzled over how we do this — filter out unimportant noise to concentrate on one voice out of many in a room. At first, researchers suggested the brain distinguishes different sources of sound by analyzing which direction they come from. But people can still focus on a single voice among many over the telephone when they can't tell where the speaker is in relation to other speakers. Now scientists have discovered that the auditory system probably sorts different sources of sound based on their unique pitch and suppresses less important ones. "We think this is the major way the brain can do this cocktail party phenomenon," said Holger Schulze, a neuroscientist at the Leibniz-Institute for Neurobiology in Magdeburg, Germany. He and his colleagues studied gerbils that have a very similar hearing mechanism to humans, so they think the findings likely apply to humans as well. "It has been known for 20 or 30 years that it is possible without directional information to do the job," Schulze said. "But we didn't know how it works, where in the brain this happens. Now we know it's in one small area within the auditory cortex." © 2008 LiveScience.com.

Keyword: Hearing; Attention
Link ID: 11485 - Posted: 06.24.2010