Michael Reilly A note to the forgetful: be thankful you don’t remember everything. It means your brain is working properly. According to a new study, the brain only chooses to remember memories it thinks are most relevant, and actively suppresses those that are similar but less used, helping to lessen the cognitive load and prevent confusion. Brice Kuhl at Stanford University in California, US, and colleagues used functional magnetic resonance imaging (fMRI) to measure the brain activity of 20 healthy adults while they performed a simple memory test. Participants were given three words pairs to memorise, including two pairs that were closely associated, as follows: ATTIC dust ATTIC junk MOVIE reel After studying "ATTIC dust" a second time, subjects were asked to recall all three pairs using the first words as cues. On average, people were 15% worse at recalling "ATTIC junk" than they were at recalling the unrelated pair, "MOVIE reel". Comparing these findings to the fMRI data taken during the test, the team found participants’ brains were highly active in a region known for handling competing memories, and also in an area believed to induce memory suppression. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory
Link ID: 10371 - Posted: 06.24.2010

Katharine Sanderson Pairs of Australian magpie-larks (Grallina cyanoleuca) that sing in tune and in tempo are more threatening to rivals whose territory they move in on than pairs that can't quite get their twittering coordinated. Michelle Hall from the Max Planck Institute for Ornithology, working at the Australian National University in Canberra with Robert Magrath, listened closely to the shared songs of breeding pairs of the birds. The most coordinated magpie-lark pairs sang alternating notes of the song in a way that, to an untrained ear, gave the impression of being a single voice. Uncoordinated pairs don't get the alternation quite right and produce overlapping notes. Hall then played recordings of coordinated and uncoordinated songs within the territory of 12 magpie-lark pairs. The most closely coordinated songs provoked the most aggressive territorial defence response from the male birds being 'invaded'. These birds who thought their territory was under threat responded by singing more in return. The research raises a number of questions, not least what is so intimidating about a coordinated song, says Peter Slater, an expert in bird duetting at the University of St Andrews, Scotland. "They're producing a song that might as well be produced by an individual," says Slater. "High coordination might be an indication that these are rivals not to be messed with," he suggests. ©2007 Nature Publishing Group

Keyword: Sexual Behavior; Animal Communication
Link ID: 10370 - Posted: 06.24.2010

Scientists have shown how having a stroke - or even snoring heavily - can increase the risk of developing Alzheimer's disease. A Leeds team found a lack of oxygen in the brain, which occurs during strokes or even in heavy snorers, can affect brain cells called astrocytes. The changes to the cells let glutamate, a neurotransmitter, build up - which could contribute to Alzheimer's. The Journal of Neuroscience study may help scientists prevent Alzheimer's. Under normal circumstances astrocytes mop up glutamate in the brain. However, the Leeds team found a lack of oxygen decreased the expression of proteins required by the cells to carry out this task. Glutamate is toxic if allowed to build up in high levels, so the accumulation could lead to brain cell death, and eventually to the onset of Alzheimer's. Lead researcher Professor Chris Peers said the study was important as it suggested why beta amyloid, the protein that builds up in the brains of Alzheimer's patients, is key to the process of triggering disease. It is already known that low oxygen can cause astrocytes to increase their production of beta amyloid. The latest research suggests it may be this increased production of beta amyloid that blocks expression of the proteins needed for astrocytes to mop up excess glutamate. Professor Peers said: "This is an important factor in what's going on in hypoxic brains. Even though the patient may outwardly recover, the hidden cell damage may be irreversible." (C)BBC

Keyword: Alzheimers; Stroke
Link ID: 10369 - Posted: 06.04.2007

Susan Endersbe, a schizophrenic who lived in Minneapolis, battled depression all her life. When her illness worsened, she usually checked into a hospital, which she did for the last time on May 7, 1994. On that occasion, doctors gave her an antidepressant, and three weeks later she said she felt ready to leave soon, according to nurses’ notes. The next day, she was referred to Dr. Faruk Abuzzahab and agreed to participate in a drug study he was being paid to conduct, although her suicidal tendencies should have excluded her. Dr. Abuzzahab stopped giving her the antidepressant, and she was forced to wait nearly two weeks before receiving either an experimental drug or a placebo. Throughout those weeks, Dr. Abuzzahab recorded Ms. Endersbe’s adverse effects as “0,” but nurses documented a steady decline. Ms. Endersbe expressed reservations about being part of a study. “I guess I didn’t understand that I would be going off all my other medications,” she told a hospital worker, according to records. She spoke repeatedly of killing herself, even telling a nurse in a late-night talk on June 8 that she planned to jump off the Franklin Avenue Bridge, “but says she is safe in the hospital,” a hospital worker wrote. On June 10, Dr. Abuzzahab wrote in her chart that Ms. Endersbe was “medically improving.” He gave her permission to visit her apartment alone, although leaving the hospital violated the study’s rules and she had spoken of suicide only the night before. Copyright 2007 The New York Times Company

Keyword: Schizophrenia; Depression
Link ID: 10368 - Posted: 06.24.2010

By Susan DeFord Randy and Lynn Gaston received the distressing diagnosis not once but three times. Their sons, Zachary, Hunter and Nicholas, are triplets, and as the brown-haired boys grew into toddlers, Lynn noticed how oddly they played, how little they babbled, how they cried inconsolably at doctor's offices and family gatherings. Two years ago, when the boys were 4, specialists confirmed the Gastons' suspicions: The boys have varying degrees of autism, a neurological disorder that hampers communication and social interactions and can include obsessive-compulsive behavior. "It was shocking," Lynn said, "but in my heart, I knew, yes, somebody finally sees it." The diagnosis launched a transformation of the Gastons' lives. Now even mundane details of the daily routine are carefully orchestrated, driven by the boys' need for sameness: identical sheets on their beds, baths in the same order every night, the same kind of pizza from the same kind of box. The Gastons rarely go out as a couple; it's difficult to find babysitters. The family has never eaten in a restaurant together, because crowded, unfamiliar environments sometimes make the boys anxious and upset. And the couple never get a full night's rest. Like many autistic children, the boys don't sleep well, going to bed at 8 p.m. and often waking for the day between 2 a.m. and 3 a.m. © 2007 The Washington Post Company

Keyword: Autism
Link ID: 10367 - Posted: 06.24.2010

Alison Abbott You've walked your normal route home a thousand times. Twice, a lurking gang of teenagers jeered as you went by. Most people would see the threat of attack on any day for what it is — minimal. But a few would be too scared to risk the journey alone ever again. Such over-anxious people tend to interpret a potentially dangerous situation as intolerably threatening, even when the risk is tiny. Researchers have now uncovered the neural circuits behind this inappropriate behaviour — at least in mice. Humans probably have a similar system, say the researchers who made the discovery. Knowing the actual cells involved in one manifestation of anxiety might help those developing new therapies. If normal mice are given an electric shock every time they are exposed to a flash of light, they will quickly learn to freeze with fear every time the light flashes. If they get the shock only occasionally, they will show less fear after the cue. But mice lacking a particular receptor for the neurotransmitter serotonin, called 5-Htr1a, show the same level of fear in both cases. Such mice are anxious, and cannot evaluate the true threat of an ambiguous situation. ©2007 Nature Publishing Group

Keyword: Emotions; Genes & Behavior
Link ID: 10366 - Posted: 06.24.2010

Bob Holmes Rhesus monkeys turn out to be pretty good statisticians, a study reveals. They can accurately assess which of two behaviours is more likely to bring them a reward by summing together a series of probabilistic clues. And their reasoning is reflected in the firing rate of individual neurons in their brain. Tianming Yang and Michael Shadlen at the Howard Hughes Medical Institute and the University of Washington in Seattle, US, tested the reasoning of two rhesus macaques by showing them a series of abstract shapes on a video screen. Each shape corresponded to a different probability that a drink reward would be associated with a red instead of a green target. In each trial, the monkey saw a sequence of 4 of 10 possible shapes then, had to choose which target to look at. The probability that the red target would give the reward was the sum of the probabilities for each of the four shapes; otherwise, the green target yielded the drink. After several weeks of training on thousands of trials per day - clearly, the monkeys are no Einsteins - both macaques learned to match their choices closely to the actual probabilities revealed by the shapes they saw, choosing the correct target more than 75% of the time. © Copyright Reed Business Information Ltd.

Keyword: Miscellaneous
Link ID: 10365 - Posted: 06.24.2010

Tracy Staedter, Discovery News — Stimulating different parts of the brain with implanted electrodes could help treat the nearly two million people in the United States who suffer from severe depression but fail to respond to conventional treatment. "It's a very dangerous disorder. Twenty percent of patients suffering from major depression commit suicide," said Thomas Schlaepfer, professor of psychiatry and psychotherapy at University Hospital in Bonn, Germany and associate professor of psychiatry and mental health at Johns Hopkins University School of Medicine in Baltimore. Schlaepfer and his team are among a handful of researchers using deep brain stimulation — a therapy successfully used to treat tremors associated with Parkinson's disease — to treat depression. The idea is to reset disordered neural activity in the brain in a similar way to how a person might reboot a computer to override a glitch. The system consists of a neurostimulator, a device about the size of a hockey puck, that is implanted in the chest wall. Wires attached to the stimulator run under the skin to two electrodes that are inserted through tiny holes in the skull and glued to the bone. The stimulator, which can be switched on or off by the patient, delivers electrical current to the electrodes. Depending on its intensity and frequency (parameters that are controlled by a medical team member), the current influences brain activity in a particular region. © 2007 Discovery Communications Inc.

Keyword: Depression
Link ID: 10364 - Posted: 06.24.2010

Adding folic acid to their diet can cut a person's stroke risk by a fifth, cumulative evidence suggests. Food advisors have already recommended to ministers that the vitamin should be added to flour or bread. This is to benefit pregnant women and those trying to conceive, by protecting the unborn child against birth defects. The Lancet review of eight studies shows the benefits could be more widespread, but experts warn that this must be balanced against other risks. An increase in folic acid can mask a vitamin B12 deficiency in older people. This type of anaemia can cause serious health problems, like nerve damage. Folate is a water-soluble B vitamin that occurs naturally in food. Folic acid is the synthetic form of folate that is found in supplements and added to fortified foods Both folic acid and vitamin B12 are essential for good health and good levels can be achieved by eating a healthy, balanced diet. Green vegetables are rich in folic acid or folate, while B12 is found in foods such as eggs and meat. Yet 13 million people do not consume enough folate, according to the Food Standards Agency. The current advice is that all adults consume 200 micrograms of folate per day, and that women who are pregnant or thinking of having a baby should take a daily 400 microgram supplement from the time they start trying for a baby until the 12th week of pregnancy. Mandatory fortification of flour with folic acid is already in place in several countries, including the US, to help ensure this. Experts have known for some time that folic acid appears to carry brain benefits. (C)BBC

Keyword: Stroke
Link ID: 10363 - Posted: 06.01.2007

By Betsy Mason Elephants know the difference between good vibrations and bad, according to new research into the big animals' low, rumbling alarm calls. They pay attention to seismic waves made by elephants they know and ignore those of strangers. Behavioral ecologist Caitlin O'Connell-Rodwell of Stanford University in Palo Alto, California, discovered in 2004 that African elephants communicate with each other from kilometers away through ground vibrations. Although they make the calls with their trunks, the sounds also travel several kilometers along the surface of the ground, about as far as airborne sounds. O'Connell-Rodwell witnessed groups of Namibian elephants stopping in their tracks, leaning forward onto their toes, and pressing their trunks to the ground. The animals often adopted this listening posture before the arrival of another group of elephants. O'Connell-Rodwell recorded various elephant calls and found that wild elephants responded to ground vibrations alone. Researchers aren't sure how elephants detect the waves, but they have vibration-sensitive cells in their feet and trunks. In the new study, O'Connell-Rodwell asked whether the elephants can tell who is making the alarm calls. So the team recorded alarm calls made by elephants encountering lions in Kenya and Namibia. Then they converted the sounds into seismic waves and played them back to Namibian elephants visiting a water hole. The elephants responded to the Namibian vibrations by freezing, huddling, and leaving the area sooner. © 2007 American Association for the Advancement of Science.

Keyword: Hearing; Animal Communication
Link ID: 10362 - Posted: 06.24.2010

Matt Kaplan A study of orangutans walking through the tree-tops suggests that humans' ancestors may also have first stood upright in the trees, say researchers. The apes stand on two legs when moving along narrow branches, using their hands to steady them, say Robin Crompton at the University of Liverpool, UK, and his colleagues. They believe that a similar behaviour is the most plausible precursor of true bipedal walking. The question of how humans came to walk upright has perplexed anthropologists. It is difficult to work out which came first: living on the ground, or walking on two legs. The problem is finding an evolutionary advantage for standing upright. It's been proposed, for example, that standing exposes the body to less sunburn on the savannah, but our ape ancestors might have spent most of their time in shady forest. The new research shows that a tree-dweller can benefit from standing up. "This research makes the strongest case yet that bipedalism could have evolved arboreally," comments Dennis Bramble, who studies animal locomotion at the University of Utah in Salt Lake City. ©2007 Nature Publishing Group

Keyword: Evolution
Link ID: 10361 - Posted: 06.24.2010

Nora Schultz Stress in a pregnant woman may be experienced by her unborn fetus as early as 17 weeks into gestation, researchers say. A new study, which measured levels of a maternally produced stress hormone that are excreted by the fetus, also demonstrates that testing amniotic fluid samples offers a useful alternative to fetal blood sampling, which is a more risky, invasive procedure. Researchers have long suspected that maternal stress can damage a developing fetus, when stress hormones such as cortisol cross the placenta. Now scientists have new evidence that the unborn child's exposure to cortisol following maternal stress is evident earlier in gestation than previously believed. Pampa Sarkar and colleagues at Imperial College, London, UK, analysed blood and amniotic fluid samples from 267 pregnant women, and found a strong correlation in levels of cortisol in the two fluids in each woman. The correlation between the mothers' blood cortisol levels and the amount of cortisol found in her amniotic fluid could be seen from as early as 17 weeks gestation. "Before then, the placenta may allow less cortisol to leak across to the fetus", says Sarkar, who wants to investigate this possibility further in her next study. © Copyright Reed Business Information Ltd

Keyword: Stress; Development of the Brain
Link ID: 10360 - Posted: 06.24.2010

By ALAN SCHWARZ For the past seven years, Mel Renfro, a former star defensive back for the Dallas Cowboys and a member of the National Football League’s Hall of Fame, has wondered why he wakes up most mornings with a malaise that seems only to be getting worse. Last week he got a clearer idea, and reassurance that he is not alone. A study by the University of North Carolina’s Center for the Study of Retired Athletes, to be published today by the journal of the American College of Sports Medicine, claims that the rate of diagnosed clinical depression among retired N.F.L. players is strongly correlated with the number of concussions they had sustained on the football field. Renfro, 65, recalled receiving nine concussions as a football player — three in high school, three at the University of Oregon and three in the N.F.L. — including one in which he regained consciousness at the end of the Cowboys’ bench with no idea of who or where he was. Renfro said he was glad to learn more about this possible factor in his depression, which he said was first diagnosed several years ago. “At least I know,” Renfro said. “At least I have the understanding of what it is. You feel funny all the time, foggy, you’re in and out of depression. Just to know — the unknown is what bothered me more than anything else.” Copyright 2007 The New York Times Company

Keyword: Depression; Brain Injury/Concussion
Link ID: 10359 - Posted: 06.24.2010

A chemical found in chocolate, tea, grapes and blueberries can improve the memory of mice, research suggests. The Salk Institute study could lead to further tests to see if epicatechin also works on humans. The study, published in the Journal of Neuroscience, suggests it improves blood flow in the brain - especially in combination with extra exercise. However, nutritionists warn chocolate is high in fat and sugar, which may undo any potential benefits. This is not the first study to find a link between 'flavanol' chemicals in certain foods and health benefits - other studies claim that cardiovascular health can be improved by including them in the diet. The researchers, led by Dr Henriette van Praag, working with chocolate firm Mars, compared mice fed a typical diet with those fed a diet supplemented with epicatechin. Half the mice in each group were allowed to run on a wheel for two hours each day and then, a month later, were trained to find a platform hidden in a pool of water. Those that both exercised and ate the epicatechin diet remembered the location of the platform longer than the other mice. The epicatechin-fed mice who did not exercise also showed enhanced memory, but to a lesser degree. The mice on the special diet appeared to have greater blood vessel growth in certain parts of their brain, alongside more mature brain nerve cells. Dr van Praag said: "A logical next step will be to study the effects of epicatechin on memory and brain blood flow in aged animals - and then humans, combined with mild exercise." Dr Mark Mattson, from the US National Institute on Ageing, said: "This is an important advance because it identifies a single natural chemical with memory-enhancing effects, suggesting it may be possible to optimise brain function by combining exercise and dietary supplementation." (C)BBC

Keyword: Learning & Memory
Link ID: 10358 - Posted: 05.31.2007

By Elizabeth Pennisi Red is the color of romance, and not just for people. Among South American monkeys called red uakari, females prefer males with fiery faces: the brighter the red, the better. New research indicates such dramatic coloration arose only after primates evolved the ability to see it, and not vice versa, as some researchers have suggested. Primates stand out among placental mammals in that most can view the entire rainbow. About a century ago, researchers proposed that the ability to see red, orange, and yellow became the norm because it allowed primates to spot edible fruit and nutritious young, reddish leaves. But while studying howler monkeys in Costa Rica, graduate student André Fernandez of Ohio University in Athens noticed that these visually blessed creatures didn't always go for the ripe fruit. Puzzled, he began to wonder whether color vision had instead evolved for other reasons, perhaps--as some have suggested--to aid mate choice. Mate choice turned out to be an unlikely reason. To learn that, Fernandez and his adviser Molly Morris first reconstructed the evolutionary history of tricolor vision and skin color. He combed the scientific literature for information about more than 200 primates, noting skin and coat colors; whether each animal lived in groups; and whether each could see reds as well as the usual blues and greens. He then charted when these various traits appeared by looking at them in the context of each species' place on the primate family tree. © 2007 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Evolution
Link ID: 10357 - Posted: 06.24.2010

Roxanne Khamsi Imagine a painkiller that only switches on in injured tissue, leaving the rest of the body unaffected. That is the idea behind a new class of pH-dependent drugs that interfere with nerve signals to the brain and spinal cord - but only where the tissue is slightly acidic due to injury. Normal tissue has a pH of around 7.4, but this drops to around 7.0 in injured tissue, largely because the blood supply is disrupted, resulting in the accumulation of waste products such as carbon dioxide and a switch to anaerobic respiration, which produces lactic acid. The new drugs act by blocking NMDA receptors, which are found on cells throughout the brain and central nervous system and are implicated in a variety of nerve functions, including pain sensitisation. Earlier generations of drugs, such as ketamine, also targeted NMDA receptors, but these often have unwanted side effects such as impaired movement or hallucinations, because they act on undamaged nerve tissue as well. “The drugs act by blocking NMDA receptors, which are found on cells throughout the brain and central nervous system”Ray Dingledine of the Emory University School of Medicine in Atlanta, Georgia, and his colleagues have now developed a compound called NP-A, that binds to the base of NMDA receptors and stops glutamate and a related neurotransmitter called NMDA from binding. A slight drop in pH can cause a significant boost in NP-A's ability to block the receptor - for example, a drop in pH from 7.6 to 6.9 causes the compound's activity to increase 62 fold. © Copyright Reed Business Information Ltd

Keyword: Pain & Touch
Link ID: 10356 - Posted: 06.24.2010

Marlowe Hood, AFP — Why does one sparrow boldly grab crumbs from an outstretched hand while another hops about nervously at a safe distance, afraid to collect a free meal? Baffling differences in behavior within the same species are not just an accident of nature but an expression of animal personality and part of a complex evolutionary strategy, a team of researchers argue in a theoretical study published Thursday in the British journal Nature. Once thought to be the exclusive domain of human beings, personality is increasingly seen by scientists as a trait common in wild animals, ranging from squids and spiders to mice and monkeys. It also serves a purpose, they say. Dozens of observational studies in recent years have shown that otherwise indistinguishable individuals — same size, age, habitat, sex — can consistently behave in very different ways, even when facing the same dangers or opportunities. Whereas one stickleback fish or great tit bird will stand and fight when confronted with a predator or rival, another may be more inclined to cut and run. © 2007 Discovery Communications Inc.

Keyword: Emotions; Evolution
Link ID: 10355 - Posted: 06.24.2010

By Mary Carmichael, Newsweek - Late into the night of May 2, 1863, a few hours after Thomas (Stonewall) Jackson took two bullets in his left arm at the Battle of Chancellorsville, surgeon Hunter Holmes McGuire sawed off the bleeding limb, trying to save the general's life. With the knife came another medical tool, one fairly new to the battlefield—a rag soaked in chloroform. As he awaited amputation, Jackson, who would die a week later, was as stoic as his nickname suggested. But as he slipped into unconsciousness, it's said, he betrayed his vulnerability in the face of pain just once, mumbling that the anesthesia was "an infinite blessing." For most of the 144 years since then, the military has stuck with similarly crude techniques for treating its soldiers' pain. Morphine, also given to Jackson and many others in the Civil War, is still the Army's most commonly used painkilling drug. It works, but compared with more-modern options, it's one step above chloroform and two above biting the bullet. Now, though, with casualties mounting in Iraq and Afghanistan, the military is being forced to change its strategy. More than 90 percent of wounded soldiers have made it off the battlefield—the highest survival rate in American history—only to overwhelm chronic-pain clinics when they come home. "We're seeing the tip of a tidal wave of pain," says Lt. Col. Chester (Trip) Buckenmaier, an anesthesiologist at Walter Reed Army Medical Center, who has emerged as a sort of pain czar for the Army. After decades of "sucking it up," the military has finally started to respond in new and innovative ways to this escalating pain crisis. Even as the VA hospital system has come under fire for poor care, Army doctors haven't just joined up in medicine's larger war against pain—they're leading the charge.

Keyword: Pain & Touch
Link ID: 10354 - Posted: 06.24.2010

Heidi Ledford As an ice cream melts in your mouth this summer, take a moment to contemplate the protein that may be bringing you that sense of cool relief — and numbing your tongue. Researchers have pinned down that particular protein in mice, and think that a similar one in humans does the same job. Three papers, two published recently in Neuron and the third in this week's issue of Nature, have shown that mice rely on a single protein, called TRPM8, to sense both cold temperatures and menthol, the compound that gives mints their cool sensation. The sensor also controls the pain-relieving effect of cool temperatures, but does not seem to play an important role in the response to painfully cold temperatures below 10 °C. TRPM8 is in the same family as the protein that detects heat and capsaicin, the compound that makes peppers hot. These proteins lie in the cell membranes of select neurons, and form channels that open and close in response to external signals. Both cold temperatures and menthol trigger TRPM8 to open, allowing small, positively charged molecules, such as calcium ions, to pour into the cell. Mice and humans each contain the gene that codes for TRPM8. In the lab dish, both versions open their channel when temperatures dip below 27 °C. Now, three teams have independently created mutant mice that cannot produce the TRPM8 protein. ©2007 Nature Publishing Group

Keyword: Pain & Touch
Link ID: 10353 - Posted: 06.24.2010

While most people need peace and quiet to cram for a test, the brain itself may need noise to learn, a recent study suggests. In experiments with monkeys, the researchers found that neural activities in the brain gradually change, even when nothing new is being learned. Challenging the monkeys to adjust their task triggered systematic changes in their neural activities on top of this background “noise.” The researchers said their findings suggest a new theory of how the brain learns. Traditional views held that learning occurs by rewiring neural circuitry that is normally stable. In contrast, the new theory proposes that neural circuitry is continually being rewired, even during behavior that does not change. According to the theory, this neural rewiring normally remains invisible at the behavioral level because the brain's motor cortex is redundant; many wiring configurations can accomplish the same behavior. “What surprised us most was that the neural representation of movement seems to change even when behavior doesn't seem to change at all,” said Howard Hughes Medical Institute investigator Sebastian Seung, one of the scientists who led the study. “This was a surprising degree of instability in the brain's representation of the world.” © 2007 Howard Hughes Medical Institute

Keyword: Learning & Memory
Link ID: 10352 - Posted: 06.24.2010