In Huntington's disease, a mutated protein in the body becomes toxic to brain cells. Recent studies have demonstrated that a small region adjacent to the mutated segment plays a major role in the toxicity. Two new studies supported by the National Institutes of Health show that very slight changes to this region can eliminate signs of Huntington's disease in mice. Researchers do not fully understand why the protein (called mutant huntingtin) is toxic, but one clue is that it accumulates in ordered clumps of fibrils, perhaps clogging up the cells' internal machinery. "These studies shed light on the structure and biochemistry of the mutant huntingtin protein and on potentially modifiable factors that affect its toxicity," said Margaret Sutherland, Ph.D., a program director at NIH's National Institute of Neurological Disorders and Stroke (NINDS). "They reveal sites within the huntingtin protein and within broader disease pathways that could serve as targets for drug therapy." Both studies were published online this week. One study, published in the Journal of Cell Biology, was led by Leslie Thompson, Ph.D., and Joan Steffan, Ph.D., of the University of California, Irvine. The other study, in Neuron, was led by X. William Yang, M.D., Ph.D., of the University of California, Los Angeles in collaboration with Ron Wetzel, Ph.D., of the University of Pittsburgh School of Medicine. The normal huntingtin protein consists of about 3,150 amino acids (which are the building blocks for all proteins). In individuals with Huntington’s disease, the mutated protein contains an abnormally long string of a single amino acid repeat; lengthier chains are associated with worse symptoms and earlier onset of the disease.

Keyword: Huntingtons
Link ID: 13627 - Posted: 06.24.2010

By ALISON GOPNIK At this very moment, you are actually moving your eyes over a white page dotted with black marks. Yet you feel that you are simply lost in the universe of The New York Times Book Review, alert to the seductive perfume of a promising new novel and the acrid bite of a vicious critical attack. That transformation from arbitrary marks to vivid experience is one of the great mysteries of the human mind. It’s especially mysterious because reading is a relatively recent invention, dating to some 5,000 to 10,000 years ago. Our brains didn’t evolve to read. Stanislas Dehaene, a distinguished French cognitive scientist, has helped unravel that mystery. His gifts, on display in “Reading in the Brain,” include an aptitude for complex experiments and an appetite for detail. This makes for excellent science but not, paradoxically, easy reading. Still, his book will repay careful study, even if it doesn’t inspire blissful absorption. Dehaene begins by describing the remarkably complicated neural circuitry devoted to getting from marks to thoughts. He then explains how reading developed historically (from Sumerian inscriptions and Egyptian hieroglyphics to the Greek and Roman alphabets and Chinese characters), how we learn to read as children and why dyslexia makes reading so hard. Every time you complete a word recognition security test on a Web site, you are paying unconscious homage to the sophistication and subtlety of the reading brain. The most advanced spambots can’t even recognize letters as well as we can, let alone recover the meaning that lurks behind them. Cognitive science has shown that the simplest experiences — talking, seeing, remembering — are the result of fiendishly complex computations. Dehaene’s work, along with that of others, adds reading to the list. Copyright 2010 The New York Times Company

Keyword: Language
Link ID: 13626 - Posted: 06.24.2010

By BARBARA STRAUCH I LOVE reading history, and the shelves in my living room are lined with fat, fact-filled books. There’s “The Hemingses of Monticello,” about the family of Thomas Jefferson’s slave mistress; there’s “House of Cards,” about the fall of Bear Stearns; there’s “Titan,” about John D. Rockefeller Sr. The problem is, as much as I’ve enjoyed these books, I don’t really remember reading any of them. Certainly I know the main points. But didn’t I, after underlining all those interesting parts, retain anything else? It’s maddening and, sorry to say, not all that unusual for a brain at middle age: I don’t just forget whole books, but movies I just saw, breakfasts I just ate, and the names, oh, the names are awful. Who are you? Brains in middle age, which, with increased life spans, now stretches from the 40s to late 60s, also get more easily distracted. Start boiling water for pasta, go answer the doorbell and — whoosh — all thoughts of boiling water disappear. Indeed, aging brains, even in the middle years, fall into what’s called the default mode, during which the mind wanders off and begin daydreaming. Given all this, the question arises, can an old brain learn, and then remember what it learns? Put another way, is this a brain that should be in school? As it happens, yes. While it’s tempting to focus on the flaws in older brains, that inducement overlooks how capable they’ve become. Over the past several years, scientists have looked deeper into how brains age and confirmed that they continue to develop through and beyond middle age. Copyright 2010 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 13625 - Posted: 06.24.2010

by Geoffrey Miller PEOPLE have radically diverse responses to the very idea of conspicuous consumption. Some folks consider it blindingly obvious that most economic behaviour is driven by status seeking, social signalling and sexual solicitation. These include most Marxists, marketers, working-class fundamentalists and divorced women. Other folks consider this an outrageously cynical view, and argue that most consumption is for individual pleasure ("utility") and family prosperity ("security"). Those folks include most capitalists, economists, upper-class fundamentalists, and soon-to-be-divorced men. Such differences of opinion can rarely be resolved by trading examples or anecdotes, or arguing from first principles. It more often helps to apply some psychology. With this in mind, some colleagues and I devised a series of experiments inspired by "costly signalling theory" - the idea that animals, including humans, use costly, intricate and hard-to-fake signals to flaunt their biological fitness to potential mates and social partners. Our goal was to see how thinking about mating influences people's decisions about spending and giving (Journal of Personality and Social Psychology, vol 93, p 85). In the first experiment the team, led by Vladas Griskevicius from Arizona State University in Tempe and Josh Tybur from the University of New Mexico in Albuquerque, invited college students to the lab in small groups. Each was randomly assigned to one of two conditions: "mating" or "non-mating". The mating subjects looked at three photographs of people of the opposite-sex on a computer screen, picked which one they thought most desirable, and spent a few minutes writing about an ideal first date with that person. The non-mating subjects looked at a street scene photograph and spent the same amount of time writing about the ideal weather for walking around and looking at the buildings it featured. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Emotions
Link ID: 13624 - Posted: 06.24.2010

Mosquitoes can impress potential mates by harmonizing the high-pitched whine of their tiny wings. Now, scientists have discovered how this musical matchmaking helps the insects to pick their perfect partner. Research on one of the main malaria carriers in Africa, Anopheles gambiae, shows that the insects use subtle differences in tone to distinguish between forms of mosquito that appear to be physically identical. The preference for harmony is so strong that it seems to be causing two forms of mosquito living in the same region to become separate species. This strict mating policy may be a key factor in maintaining the genetic diversity that makes the insect so adaptable to different environments, and could point to other ways to disrupt mosquito reproduction in malaria-ridden countries. A. gambiae is actually a complex of seven species that are physically indistinguishable but with slightly different behavioural traits. In Burkina Faso, one of these species includes two forms — Mopti (M) and Savannah (S) — and additional forms exist in other parts of Africa. The sheer diversity of the mosquito has puzzled scientists. "People studying this mosquito have wondered how it manages to speciate so quickly," says sensory physiologist Gabriella Gibson at the University of Greenwich, UK. Also unclear is how two forms that swarm together can avoid mating with one another, thereby preventing their genetic diversity from being diluted. © 2010 Nature Publishing Group,

Keyword: Sexual Behavior; Hearing
Link ID: 13623 - Posted: 06.24.2010

Earlier bedtimes may help protect teens from depression and suicidal thoughts, says a U.S. study published Friday. Researchers analyzed data from 15,659 U.S. students in Grades 7 to 12 and their parents. Participants were surveyed from 1994 to 1996 for the study by James Gangwisch, a professor of psychiatry at Columbia University Medical Center in New York, and his colleagues . On average, the teenagers said they got seven hours and 53 minutes of shut-eye a night, compared with the nine or more hours recommended for adolescents by the American Academy of Sleep Medicine, the team reported in the journal Sleep. Adolescents who reported that they usually slept five or fewer hours a night were 1.71 times more likely to suffer from depression and 1.48 times more likely to think about committing suicide than those who said they got eight hours of sleep a night. These calculations took into account demographic factors such as race and whether the family received public assistance, the study said. "Our findings suggest that later parental-set bedtimes contribute to shorter sleep durations and perceptions of not getting enough sleep, which in turn are associated with depression and [thoughts of suicide]," the study's authors concluded. By setting earlier bedtimes, parents could protect against depression and suicidal thoughts in their children, the authors said. Participants who reported that they "usually get enough sleep" were 0.35 times less likely to suffer from depression and 0.71 times less likely to think of committing suicide, the researchers found. © CBC 2010

Keyword: Depression; Biological Rhythms
Link ID: 13622 - Posted: 06.24.2010

By Carina Storrs When prions are transferred from one species to another—like from sheep and cows to mice in the laboratory or to humans in the case of the fatally neurodegenerative variant Creutzfeldt-Jakob disease—new forms of the infectious proteins can emerge over time that make them deadly to the new host. A new study examines the emergence and persistence of prion mutations, which allow prions to grow in infected cells in the presence of anti-prion compounds. In the classic sense, prions, which are misfolded versions of the brain protein PrP, cannot mutate because they do not contain DNA or RNA. They can, however, give rise to variants with different properties, possibly due to differences in the folding, or shape, of the proteins. In the study, published December 31 in Science Express, researchers estimated the rate at which prion mutants can appear in cultured human nerve cells. In addition, the study suggests that once variants appear, they persist at low levels, giving rise to a heterogeneous prion population. "On the face of it, you have exactly the same process of mutation and adaptive change in prions as you see in viruses," said Dr. Charles Weissmann in a prepared statement. Weissmann, who is the head of the Scripps Florida Department of Infectology in Jupiter, Fla., led the study. To track prion mutation, Weissmann's team mixed one prion-infected human nerve cell with 1,000 uninfected human nerve cells in each petri dish. The infected cell contained a single prion that was susceptible to a drug called swainsonine, or swa. © 1996-2010 Scientific American

Keyword: Prions
Link ID: 13621 - Posted: 06.24.2010

By Tina Hesman Saey Scientists have discovered the true identity of a contagious form of cancer that is killing Tasmanian devils. The cancer, called devil facial tumor disease, stems from cells that normally insulate nerve fibers, a new study shows. Genetic analysis of tumors taken from infected devils in different parts of Tasmania reveals that these insulating cells, known as Schwann cells, became cancerous in a single Tasmanian devil and have since passed to other devils, an international group of researchers reports in the Jan. 1 Science. Previously, scientists had suspected that a virus might be the source of the infection, but the new study confirms that cancer cells themselves are transmitted from devil to devil. Knowing the origin of the contagious tumors could help conservationists diagnose the disease more accurately and may eventually lead to a vaccine that would target tumor proteins, says Katherine Belov, a geneticist at the University of Sydney who was not involved with the project. A vaccine against the facial tumor disease, “while now pie in the sky, in 10 years might not be,” says Gregory Hannon, a Howard Hughes Medical Institute investigator at Cold Spring Harbor Laboratory on Long Island, N.Y. “Ten years might be enough time” to save the devils from extinction, he says. © Society for Science & the Public 2000 - 2010

Keyword: Glia
Link ID: 13620 - Posted: 06.24.2010

Alzheimer's disease is associated with a reduced risk of cancer and vice versa, a study suggests. US researchers followed 3,020 people aged 65 and above for the study, published in the journal Neurology. Those who had Alzheimer's at the start of the study were 69% less likely to be admitted to hospital with cancer than those free of the disease at the start. And those with cancer at the study's start were 43% less likely to develop Alzheimer's than the cancer free. The researchers followed the subjects for an average of five years to see whether they developed Alzheimer's, and an average of eight years to see whether they developed cancer. At the start of the study, 164 people (5.4%) already had Alzheimer's disease and 522 people (17.3%) already had a cancer diagnosis. During the study, 478 people developed dementia and 376 people developed invasive cancer. The researchers stressed that more work was needed before any firm conclusions could be drawn, and said the findings only seemed fully to apply to white people. They found no association between cancer and another type of dementia, known as vascular dementia, which is thought to be caused by a lack of blood supply to the brain. However, patients with this condition died earlier than people with Alzheimer's. Lead researcher Dr Catherine Roe, of Washington University School of Medicine in St Louis, said this suggested the association between Alzheimer's and cancer was not simply due to people with those conditions dying before they could contract the other ailment. "Discovering the links between these two conditions may help us better understand both diseases and open up avenues for possible treatments," she said. "Alzheimer's disease and cancer are both characterised by abnormal, but opposing, cellular behaviour. (C)BBC

Keyword: Alzheimers
Link ID: 13619 - Posted: 12.31.2009

By Katherine Harmon Having trouble remembering to take your Ginkgo supplement? The pills themselves might not help with that forgetfulness—or any other age-related cognitive decline, according to a new study published online Tuesday in JAMA, The Journal of the American Medical Association. "Compared with placebo, the use of G. biloba, 120 milligrams twice daily, did not result in less cognitive decline in older adults," the authors of the study concluded. The randomized, double-blind, placebo-controlled study is the largest of its kind, having followed 3,069 older adults (72 to 96 years old) who started the trial with no or only mild cognitive impairment. After following the individuals for six years, administering regular testing and interviewing people close to them, the researchers found that those who had been given gingko pills performed the same in memory, language, attention, visuo-spatial judgment and executive function tests as those in the placebo group. The authors, whose research was supported by the National Institutes of Health's National Center for Complementary and Alternative Medicine among other government groups, expected to see at least minor benefits in the ginkgo cohort. "We're a bit surprised [ginkgo is] as ineffective as it turned out to be," says Steven DeKosky, vice president and dean of the University of Virginia School of Medicine in Charlottesville and study co-author. Laboratory tests of the substance have shown "biological effects that give you a pretty good rationale" for expecting it to help shield neural cells, he says. And given the herb's antioxidant properties, many researchers have anticipated positive findings in human subjects. © 1996-2009 Scientific American Inc

Keyword: Alzheimers
Link ID: 13618 - Posted: 06.24.2010

By Jennifer LaRue Huget A few months ago I received a book called "The Two Martini Diet" (Authorhouse, 2008), in which Jerry Sorlucco documents his success at losing more than 100 pounds without forgoing his daily cocktails. He doesn't break new diet-book ground: Sorlucco follows well-established practices such as controlling portion sizes, eating plenty of fruits and vegetables, and managing his calorie intake and expenditure to accommodate those drinks. I've kept the book on my desk because I'm intrigued by the interplay between healthful eating and alcohol consumption. Is it really possible, I've wondered, to incorporate alcoholic beverages into a healthful diet and lifestyle, or are those of us who hope it is possible just fooling ourselves? New Year's Eve seems a perfect time to explore this topic: Tonight we may enjoy a midnight toast; come morning, we might resolve to cut back or quit drinking altogether. Drinking is often considered a vice. But unlike smoking or using recreational drugs, behaviors for which it's hard to claim any health benefits, evidence is mounting that partaking of alcohol can promote not only health but also longevity. I'm aware that my own affection for martinis may skew my opinion about the merits of including cocktails in one's diet. So I turned to some experts -- Walter Willett, chair of the department of nutrition and a professor of epidemiology and nutrition at the Harvard School of Public Health, and Donald Hensrud, a specialist in preventive and internal medicine at the Mayo Clinic and medical editor in chief of "The Mayo Clinic Diet" book, to be released Friday -- to help me put alcohol in its proper place. I hope you'll join me in reviewing their comments and deciding for yourself whether drinking belongs in your life. © 2009 The Washington Post Company

Keyword: Drug Abuse
Link ID: 13617 - Posted: 06.24.2010

A portable device that uses electrical stimulation is not recommended to treat chronic low-back pain, a new guideline says. Transcutaneous electric nerve stimulation or TENS uses a pocket-sized unit to apply a mild electrical current to the nerves through electrodes. It is used to relieve pain, strengthen muscles and enhance healing of soft tissue injuries, according to the American Academy of Orthopaedic Surgeons. No one knows how TENS works to provide pain relief. It's thought that TENS stimulation may confuse the brain and block pain signals from getting through nerves. The American Academy of Neurology released the guideline Wednesday in its online issue of the medical journal Neurology. "The strongest evidence showed that there is no benefit for people using TENS for chronic low-back pain," said guideline author Dr. Richard Dubinsky of Kansas University Medical Center in Kansas City. "Doctors should use clinical judgment regarding TENS use for chronic low-back pain. People who are currently using TENS for their low-back pain should discuss these findings with their doctors," he added in a release. In drafting the guidelines, the authors reviewed evidence on the use of TENS for chronic low-back pain that has persisted for three months or longer. The chronic back pain studies reviewed excluded people with known causes of low-back pain, such as a pinched nerve or the curving of the spine known as severe scoliosis. © CBC 2009

Keyword: Pain & Touch
Link ID: 13616 - Posted: 06.24.2010

By Elyn R. Saks Elyn Saks is a law professor at the University of Southern California, a Marshall scholar, and a graduate of Yale Law School. She also suffers from schizophrenia -- an illness that many would assume makes her impressive resume an impossibility. In 2007, she published an acclaimed memoir of her struggle with the disease, “The Center Cannot Hold.” Her book is a frank and moving portrait of the experience of schizophrenia, but also a call for higher expectations -- a plea that we allow people with schizophrenia to find their own limits. If anything, she says, her work as a scholar has helped her to cope with the disease. In September, she was awarded a MacArthur Foundation “genius” grant. She chatted with Mind Matters editor Gareth Cook. COOK: Can you describe your first experience with schizophrenia, I think you said that you were just 8 years old? SAKS: I don’t think I would have been diagnosed as someone with childhood schizophrenia, but there were perhaps some early warning signs. For instance, I had periods of disorganization, where it felt like my mind was falling apart: there was no center to take things in, put them together, and make them make sense. Hence, following Yeats, I call my book “The Center Cannot Hold.” The first frank episode of psychosis happened when I was around 16, and I suddenly started walking home from school in the middle of the day. I began to feel the houses were getting weird; they were sending me messages: “You are special. You are especially bad. Now walk. Cries and whispers.” There were also some warning signs in college but I didn’t really “officially” break down until graduate school at Oxford. © 1996-2009 Scientific American Inc.

Keyword: Schizophrenia
Link ID: 13615 - Posted: 06.24.2010

By Katherine Harmon Loud, persistent ringing in the ears, known as tinnitus, can be vexing for its millions of sufferers. This perceived noise can be symptomatic of many different ills—from earwax to aging—but the most common cause is from noise-induced hearing loss, such as extended exposure to construction or loud music, and treating many of its underlying neural causes has proven difficult. But many people with tinnitus might soon be able to find refuge in the very indulgence that often started the ringing in the first place: music. A new music-based therapy has shown promise in helping reduce the ringing's volume in tinnitus sufferers within a year, according to a study published online Monday in the Proceedings of the National Academy of Sciences. "Tinnitus loudness can be significantly diminished by an enjoyable, low-cost, custom-tailored notched music treatment," wrote the researchers, who were led in part by Christo Pantev at the Institute for Biomagnetism and Biosign Alanalysis at Westfalian Wilhelms-University in Munster, Germany. The treatment is based on behavioral training theories that posit that the auditory cortex, which is responsible for perceiving the sound and has been shown to be distorted in the areas where a specific frequency is "heard," might gradually be trained to reorganize, correcting for its maladaptive distortion. © 1996-2009 Scientific American Inc.

Keyword: Hearing
Link ID: 13614 - Posted: 06.24.2010

By Eric Bland The scent of a single chemical can turn peaceful, happy fruit flies into flying fists of fury. For the first time, scientists have found a rage-inducing pheromone and the neuron that detects it in fruit flies. The research, detailed in the journal Nature, could help explain everything from bar fights to species-wide population control. "Not only did we identify the pheromone that leads to aggression and its neuron," said David Anderson, a scientist at Cal Tech and co-author of the Nature study, "but we were able to manipulate the ability of the flies to increase aggression." For the most part, fruit flies are a peaceful species. Give a group of flies a piece of food, and they graze peacefully. Give them some land, and they usually share the territory without incident. These idyllic scenes, however, can quickly turn violent. Drop filter paper soaked in artificially produced pheromone, known as 11-cis-vaccenylacetate, into the air around six flies, and they quickly start karate chopping and judo wrestling their opponents, rearing up on their hind legs and snapping down violently, and grappling with their forelegs. Eventually one fly dominates, scaring all other flies away. © 2009 Discovery Channel

Keyword: Aggression; Genes & Behavior
Link ID: 13613 - Posted: 06.24.2010

By Jeff Wise Editor's note: The following is an excerpt from Extreme Fear: The Science of Your Mind in Danger by Jeff Wise, published on December 8 by Palgrave Macmillan (Scientific American is a Macmillan publication). Extreme Fear explores the neural underpinnings of this powerful and primitive emotion by relating instances in which people were forced to act under duress and presenting the latest findings from cognitive science. In the following passage from the chapter entitled "Superhuman" a seemingly ordinary man performs an extraordinary feat of strength to rescue a cyclist who has been run over by a car. Here's how it is: one minute, you're going through your daily routine, only half paying attention. And the next you're sucked into a vivid, intense world, where time seems to move slower, colors are brighter, sounds more perceptible, as though the whole universe has suddenly come into focus. It was about 8:30 P.M. on a warm summer evening in Tucson. Tom Boyle, Jr., was sitting in the passenger's seat of his pickup truck, his wife Elizabeth at the wheel, waiting to pull out into traffic from the shopping mall where they'd just had dinner. The Camaro ahead of them hit the gas, spun his wheels, and jerked out onto the avenue with a squeal of rubber. "Oh my God," Elizabeth said. "Do you see that?" Boyle glanced up to see a shower of red sparks flying up from beneath the chassis of the Camaro. And something else: A bike, folded up from impact. The Camaro had hit a cyclist, and the rider was pinned underneath the car. Boyle threw open the door of the truck and started running after the car.

Keyword: Emotions; Stress
Link ID: 13612 - Posted: 12.29.2009

by Douglas Fox CONTAINS zero calories! Countless soft drinks are emblazoned with that slogan as a come-on for those of us locked in a never-ending battle to rein in a spreading waistline. Calorie-free sweeteners certainly have a lot to offer. Food and drink manufacturers have become so good at blending sugar substitutes into their products that it can be almost impossible to tell them apart from the real thing - sucrose - in taste tests. But while artificial sweeteners may be able to confuse our taste buds, the suspicion is growing that our brain is not so easily fooled. Could it be that our cravings for sugary foods run deeper than a liking for sweetness? If so, a whole bunch of weight-loss strategies may need rethinking. Non-sugar sweeteners have come a long way. One of the first, and perhaps the worst, was lead. Romans boiled grapes in lead pots, leaching the sweet-tasting metal into their food. The practice outlived the Roman empire by many centuries, and is thought to have led to the deaths of a number of notables, including Pope Clement II, who perished in 1047. Indigenous peoples in South America use a herb called stevia, which contains chemicals that taste sweet but aren't metabolised in the human gut. These early experimenters weren't worried about shedding the kilos - just searching for a way to sweeten food in a world where refined sugar was scarce. © Copyright Reed Business Information Ltd.

Keyword: Chemical Senses (Smell & Taste); Obesity
Link ID: 13611 - Posted: 06.24.2010

A "molecular switch" that can prevent Huntington's disease from developing has been found in mice. A US study concluded the mutated huntingtin protein, which causes the disease, could be stopped in its tracks by a subtle chemical modification. It is hoped the work could lead to much-needed treatments for the inherited disorder. The study, by the University of California, Los Angeles, is published in the journal Neuron. It is thought between 6,000 and 8,500 people in the UK have Huntington's disease - a neurological condition that starts to show in mid-life and slowly impairs a person's ability to walk, talk and reason. Children who have one parent with the condition have a 50% chance of developing it themselves and often it is passed on before people are aware that they have it. There is no cure for the illness and treatment focuses on managing the symptoms. Although it is known that a protein mutation underpins the disease, it is not exactly clear how that mutation causes the damage seen in those with the condition. In the latest study, researchers found a small section of the mutated protein that can be modified by phosphorylation - a chemical process in the body that alters how proteins function. In mice they found blocking this phosphorylation caused the animals to develop disease symptoms. But when they tried to mimic the process the disorder did not develop. BBC © MMIX

Keyword: Huntingtons
Link ID: 13610 - Posted: 06.24.2010

Minute organs hidden deep within the ear appear to directly alter blood flow to the brain, scientists have revealed. Until now, experts thought the inner ear's job was to control balance alone. But the Harvard Medical School team, working with Nasa, found the balance organs also affect brain blood flow in their study involving 24 people. They told BMC Neuroscience journal that the connection probably evolved to enable man to stand upright and still get enough blood up to the brain. The organs of balance are deep within the ear, inside a maze of bony chambers. Two sacs, called the utricle and saccule, make up the inner ear's vestibule and three fluid-filled loops, known as the semi-circular canals, detect the rotation and tilting movements of the head. Dr Jorge Serrador and his team from Harvard Medical School asked 24 healthy people to undergo a range of tests normally used on astronauts. These included a tilt test where the individual sits strapped to a chair that is then tilted to different angles, plus a ride inside a giant, spinning centrifuge. In this way, the researchers were able to stimulate the different parts of the balance organs and monitor the effects on blood flow around the body. This revealed that the utricle and saccule, also known as the otoliths, directly affected brain blood flow regulation, independent of other factors, such as blood pressure. BBC © MMIX

Keyword: Hearing
Link ID: 13609 - Posted: 06.24.2010

By Victoria Gill In Africa and in the tropics, armies of tiny creatures make the twisting stems of acacia plants their homes. Aggressive, stinging ants feed on the sugary nectar the plant provides and live in nests protected by its thick bark. This is the world of "ant guards". The acacias might appear overrun by them, but the plants have the ants wrapped around their little stems. These same plants that provide shelter and produce nourishing nectar to feed the insects also make chemicals that send them into a defensive frenzy, forcing them into retreat. Nigel Raine, a scientist working at Royal Holloway, University of London in the UK has studied this plant-ant relationship. Dr Raine and his colleagues from the universities of St Andrews, Edinburgh and Reading in the UK and Lund University in Sweden have been trying to work out some of the ways in which the insects and the acacias might have co-evolved. "They guard the plants they live on," said Dr Raine. "If other animals try to come and feed on the rich, sugary nectar, they will attack them. In Africa, one type of ant-guard, known as Crematogaster , will even attack large herbivores that attempt to eat the plant. If a giraffe starts to eat the leaves of an acacia that is inhabited by ants, the ants will come out and swarm on to its face, biting and stinging," says Dr Raine. BBC © MMIX

Keyword: Evolution
Link ID: 13608 - Posted: 06.24.2010