Daniel Cressey The full structure of a fiendishly complicated and important brain protein has been determined by researchers, potentially enabling the development of new treatments for a wealth of neurological disorders. Eric Gouaux and his colleagues undertook the difficult task of mapping the structure of a glutamate receptor, a protein that mediates signalling between neurons in the brain and elsewhere in the nervous system. The receptor is also thought to be crucial to processes such as memory and learning. The resulting picture "tells us things about the organization of the receptor that were just completely unanticipated" says Gouaux, a protein crystallographer at Oregon Health and Science University in Portland. The work appears online today in Nature1. The researchers studied a rat glutamate receptor known as GluA2. They grew a crystal of many such proteins, then exposed this to a beam of X-rays. By watching how X-rays scattered from the crystal, they were able to produce an atomic-level picture of a single protein. In humans, these receptors work as relays for the central nervous system. When the neurotransmitter glutamate binds to the receptor, this opens an 'ion channel' in the neuronal membrane, allowing ions to flow across the membrane. This results in the transmission of an electrical pulse down the nerve. © 2009 Nature Publishing Group

Keyword: Miscellaneous
Link ID: 13521 - Posted: 06.24.2010

By ANAHAD O’CONNOR THE FACTS It has long been said that regular physical activity and better sleep go hand in hand. Burn more energy during the day, the thinking goes, and you will be more tired at night. But only recently have scientists sought to find out precisely to what extent. One extensive study published this year looked for answers by having healthy children wear actigraphs — devices that measure movement — and then seeing whether more movement and activity during the day meant improved sleep at night. The results should be particularly enlightening to parents. The study found that sleep onset latency — the time it takes to fall asleep once in bed — ranged from as little as roughly 10 minutes for some children to more than 40 minutes for others. But physical activity during the day and sleep onset at night were closely linked: every hour of sedentary activity during the day resulted in an additional three minutes in the time it took to fall asleep at night. And the children who fell asleep faster ultimately slept longer, getting an extra hour of sleep for every 10-minute reduction in the time it took them to drift off. Studies on adults have reached generally similar results, showing that an increase in physical activity improves sleep onset and increases sleep duration, particularly in people who have trouble sleeping. THE BOTTOM LINE Studies suggest that being more physically active can lead to better sleep. Copyright 2009 The New York Times Company

Keyword: Sleep
Link ID: 13520 - Posted: 06.24.2010

By TARA PARKER-POPE When Cami Walker of Los Angeles learned three years ago that she had multiple sclerosis, her health and her spirits plummeted — until she got an unusual prescription from a holistic health educator. Ms. Walker, now 36, scribbled the idea in her journal. And though she dismissed it at first, after weeks of fatigue, insomnia, pain and preoccupation with her symptoms, she decided to give it a try. The treatment and her experience with it are summed up in the title of her new book, “29 Gifts: How a Month of Giving Can Change Your Life” (Da Capo Press). Ms. Walker gave a gift a day for 29 days — things like making supportive phone calls or saving a piece of chocolate cake for her husband. The giving didn’t cure her multiple sclerosis, of course. But it seems to have had a startling effect on her ability to cope with it. She is more mobile and less dependent on pain medication. The flare-ups that routinely sent her to the emergency room have stopped, and scans show that her disease has stopped progressing. “My first reaction was that I thought it was an insane idea,” Ms. Walker said. “But it has given me a more positive outlook on life. It’s about stepping outside of your own story long enough to make a connection with someone else.” And science appears to back her up. “There’s no question that it gives life a greater meaning when we make this kind of shift in the direction of others and get away from our own self-preoccupation and problems,” said Stephen G. Post, director of the Center for Medical Humanities, Compassionate Care and Bioethics at Stony Brook University on Long Island and a co-author of “Why Good Things Happen to Good People” (Broadway, 2007). “But it also seems to be the case that there is an underlying biology involved in all this.” Copyright 2009 The New York Times Company

Keyword: Emotions; Neuroimmunology
Link ID: 13519 - Posted: 06.24.2010

Researchers at the University of British Columbia are shining a new light on a condition that affects children's ability to print, tie their shoes or play sports. Called developmental co-ordination disorder (DCD), it affects about six per cent of school-aged children. For the first time, researchers have shown that the brains of children with DCD are different from other kids. According to researcher Jill Zwicker, a PhD candidate in rehabilitation sciences at UBC, DCD often leads to struggles in school, partly because the kids find it physically difficult to print or write. Researchers performed scans to see how the brains of children with DCD were functioning while trying to trace objects on a piece of paper. "We can see that the children with developmental co-ordination disorder are not activating the same brain areas as typically developing children," Zwicker told CBC News. "We need to do more research to flesh that out a bit more, but it's the first evidence to show that these kids are different at this level as far as their brain activity." Zwicker says the research may help lessen the stigma around the condition, which people often believe is just a lack of co-ordination. "Many people just think that it's clumsy kids and there's nothing wrong with them and they'll outgrow it," she said. But cumulative research has shown that these children are struggling and this is the first evidence to show that they are neurobiologically different." © CBC 2009

Keyword: Development of the Brain; Movement Disorders
Link ID: 13518 - Posted: 06.24.2010

By Carolyn Y. Johnson Research into an unusual sleep disorder is unraveling what goes awry in the brains of people who fall prey to daytime sleep attacks - and shedding light on everything from addiction to appetite. Work that began in sleepy dogs and mice has led to a significant advance in understanding narcolepsy, providing new insight into the ways in which sleep and wakefulness, eating, and addictive behaviors are linked. The work is pointing to potential therapies not only for people who are chronically sleepy, but also for the much larger numbers who have trouble sleeping at all. At the root of this work is a fundamental brain chemical called orexin. Research over the past decade has shown that narcolepsy is caused by the loss of a type of brain cell that produces orexin. Scientists have found that the chemical also helps determine when we are asleep and awake and plays a role in regulating appetite and addiction. Orexin “was only discovered in 1998,’’ said Dr. Tom Scammell, a neurologist at Beth Israel Deaconess Medical Center. “A lot of the work is related to sleep, but it’s also opened up these other areas.’’ His lab teases out the nuances of narcolepsy with some unconventional techniques - including tickling sleepy mice to keep them awake and feeding them Froot Loops. The anticipation of the sugary cereal triggers one of the most striking symptoms of the disease: a temporary loss of muscle control called cataplexy, causing mice to drop in their tracks. Using gene therapy, he restored orexin to the brains of mice who lacked it and found that it improves their ability to stay awake and reduces cataplexy. © 2009 NY Times Co.

Keyword: Narcolepsy; Sleep
Link ID: 13517 - Posted: 06.24.2010

By BENEDICT CAREY If a friend is someone who laughs at our stories, then a good friend is one who enjoys them even the second time around. But anyone who gasps with delight on hearing a story for the third time is faking it. Or, it’s a relative: some poor nephew Will or aunt Emily, sitting captive at the holiday table, being polite, perhaps covering a shudder of dread that life is caught in some endless loop where the punch lines never change. It is not an entirely irrational fear, either, according to new research published in the journal Psychological Science. “You hear people of all ages, not just elderly people, say, ‘Stop me if I’ve told you this before,’ ” said Nigel Gopie, a postdoctoral fellow at the Rotman Research Institute, in Toronto, who has a paper in the current issue of the journal on these memory lapses. “We often have a hard time remembering who we told things to, and clearly it starts early.” In their long study of memory, psychologists have made important distinctions between the short-term and long-term varieties. They have documented crucial differences between explicit memories, like for faces and vocabulary, and the implicit kind, like for driving skills. They have published hundreds of studies on autobiographical memory, false memories and so-called source memory — the ability to recall where a fact was learned, whether from the radio or a book, from a work colleague or the neighborhood gossip. Copyright 2009 The New York Times Company

Keyword: Learning & Memory
Link ID: 13516 - Posted: 06.24.2010

By NICHOLAS WADE What is the essence of human nature? Flawed, say many theologians. Vicious and addicted to warfare, wrote Hobbes. Selfish and in need of considerable improvement, think many parents. But biologists are beginning to form a generally sunnier view of humankind. Their conclusions are derived in part from testing very young children, and partly from comparing human children with those of chimpanzees, hoping that the differences will point to what is distinctively human. The somewhat surprising answer at which some biologists have arrived is that babies are innately sociable and helpful to others. Of course every animal must to some extent be selfish to survive. But the biologists also see in humans a natural willingness to help. When infants 18 months old see an unrelated adult whose hands are full and who needs assistance opening a door or picking up a dropped clothespin, they will immediately help, Michael Tomasello writes in “Why We Cooperate,” a book published in October. Dr. Tomasello, a developmental psychologist, is co-director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The helping behavior seems to be innate because it appears so early and before many parents start teaching children the rules of polite behavior. “It’s probably safe to assume that they haven’t been explicitly and directly taught to do this,” said Elizabeth Spelke, a developmental psychologist at Harvard. “On the other hand, they’ve had lots of opportunities to experience acts of helping by others. I think the jury is out on the innateness question.” Copyright 2009 The New York Times Company

Keyword: Development of the Brain; Emotions
Link ID: 13515 - Posted: 06.24.2010

There is a tiny period of time between the registration of a visual stimulus by the unconscious mind and our conscious recognition of it — between the time we see an apple and the time we recognize it as an apple. Our minds lag behind our eyes, but by how long? And how does this affect our reactions to the world around us? Some estimates say the time delay lasts only 100 milliseconds, others say 500 milliseconds. A new study by Tel Aviv University psychologists says that the answer is somewhere close to the latter, but can vary depending on the complexity of the stimulus. Researcher Moti Salti and his supervisors Dominique Lamy and Prof. Yair Bar-Haim of TAU's Department of Psychology reported their findings in the Journal of Cognitive Neuroscience. "We are hunting for the brain activity associated with conscious perception," says Salti. "When you wander through this world, you see and hear things that may reveal themselves to your conscious mind — and others that don't. We are interested in what cues the brain gives us to open that unconscious perception to the conscious mind — what makes our conscious mind tick." This basic science, Salti says, won't immediately provide marketers with the basis for a new and advanced kind of subliminal advertising. But it may answer long-debated questions about the mysterious nexus between our conscious and unconscious minds. © 2002-2009 redOrbit.com.

Keyword: Vision; Attention
Link ID: 13514 - Posted: 06.24.2010

by Jessica Hamzelou DEPRESSION really does change the way you see the world. People with the condition find it easy to interpret large images or scenes, but struggle to "spot the difference" in fine detail. The finding hints at visual training as a possible treatment. Depressed people have a shortage of a neurotransmitter called GABA; this has also been linked to a visual skill called spatial suppression, which helps us suppress details surrounding the object our eyes are focused on - enabling us to pick out a snake in fallen leaves, for instance. Now Julie Golomb and colleagues at Yale University are trying to link this ability with major depressive disorder (MDD). Golomb asked 32 people to watch a brief computer animation of white bars drifting over a grey and black background, and say which way they were moving. A quicker response gave a higher score. Half of the group had good mental health, while the rest had recently recovered from depression. The latter were chosen so that medication would not interfere with the results, but Golomb thinks results from people with MDD would be similar because the condition is thought to have genetic factors. When the image was large, the recovered volunteers found the task easier, which means they would do better in the forest scenario. But they performed less well than the other group when looking at a small image. "Their ability to discriminate fine details was impaired, which is the sort of perception that we tend to use on a daily basis," says Golomb (Journal of Neuroscience, DOI: 10.1523/jneurosci.1003-09.2009). © Copyright Reed Business Information Ltd

Keyword: Depression; Attention
Link ID: 13513 - Posted: 06.24.2010

By Lindsey Tanner CHICAGO - The first rigorous study of behavior treatment in autistic children as young as 18 months found two years of therapy can vastly improve symptoms, often resulting in a milder diagnosis. The study was small - just 48 children evaluated at the University of Washington - but the results were so encouraging it has been expanded to several other sites, said Geraldine Dawson, chief science officer of the advocacy group Autism Speaks. Dawson, a former University of Washington professor, led the research team. Early autism treatment has been getting more attention, but it remains controversial because there’s scant rigorous evidence showing it really works. The study is thus “a landmark of great import,’’ said Tony Charman, an autism education specialist at the Institute of Education in London. There’s also a growing emphasis on diagnosing autism at the earliest possible age, and the study shows that can pay off with early, effective treatment, said Laura Schreibman, an autism researcher at the University of California at San Diego. The National Institute of Mental Health funded the study, which was published online today in Pediatrics. Children age 18 months to 30 months were randomly assigned to receive behavior treatment called the Early Start Denver model from therapists and parents, or they were referred to others for less comprehensive care. © 2009 NY Times Co.

Keyword: Autism; Development of the Brain
Link ID: 13512 - Posted: 06.24.2010

By DANIEL BERGNER At her group therapy sessions for women despairing of low sexual desire, Lori Brotto likes to pass around a plastic tub of raisins. The women, usually six to a group, sit around two pushed-together beige tables in a fluorescently lighted conference room at the British Columbia Center for Sexual Medicine in Vancouver. A little potted tree is jammed randomly in one corner. Ragged holes scar one wall where a painting used to hang. The décor doesn’t speak of sensuality. That is the job of the raisin. Brotto asks each woman to take a single raisin from the small tub. A slender, elegant 34-year-old psychologist, a mother of two with a third child on the way, she began her career studying the libidos of rats. She is now one of the world’s leading specialists in what is known as hypoactive sexual desire disorder in women. She is in charge of defining the condition’s criteria for the next Diagnostic and Statistical Manual of Mental Disorders, commonly called the D.S.M, which the American Psychiatric Association is preparing to publish in 2012 or 2013. The book is the bible of psychiatric diseases, from autism to sleepwalking, relied on by researchers and clinicians throughout the United States and Canada. Studies suggest that around 30 percent of young and middle-aged women go through extended periods of feeling dim desire — or of feeling no wish for sex whatsoever. “Black raisins,” Brotto said, laughing at her own arbitrary preference as she described her methods. “I don’t like brown raisins or green raisins or cooked raisins.” Copyright 2009 The New York Times Company

Keyword: Sexual Behavior
Link ID: 13511 - Posted: 06.24.2010

By Michelle Roberts US scientists are testing a radical new theory that multiple sclerosis (MS) is caused by blockages in the veins that drain the brain. The University of Buffalo team were intrigued by the work of Italian researcher Dr Paolo Zamboni who claims 90% of MS is caused by narrowed veins. He says the restricted drainage, visible on scans, injures the brain leading to MS. He has already widened the blockages in a handful of patients. The US team want to replicate his earlier work before treating patients. Experts welcomed the research saying it was important to confirm the basic science before evaluating any therapy. MS is a long-term inflammatory condition of the central nervous system which affects the transfer of messages from the nervous system to the rest of the body. The Buffalo team, led by Dr Robert Zivadinov, plan to recruit 1,100 patients with MS and 600 other volunteers as controls who are either healthy or have neurological diseases other than MS. Using Doppler ultrasound, they will scan the patients to see if they can find any blockages within the veins of the neck and brain. BBC © MMIX

Keyword: Multiple Sclerosis
Link ID: 13510 - Posted: 06.24.2010

By Jody Bourton Why do hammerhead sharks have such a famously strange-shaped head? One hypothesis is that having eyes on either side of such a wide 'hammer' allows the sharks to see better. But even this idea divides scientific opinion, as researchers argue over whether the hammerhead design makes it more or less difficult to see. The mystery may now be solved by a study showing that a hammerhead gives sharks outstanding binocular vision and an ability to see through 360 degrees. The finding is published in the Journal of Experimental Biology. Debate over why hammerheads are shaped as they are goes back centuries, and arguments over their visual capabilities goes back decades, says Dr Michelle McComb from Florida Atlantic University in Boca Raton, Florida, US. For example, in 1948, zoologist Gordon Walls, a leading authority on vertebrate eye evolution, suggested that the position of a hammerhead shark's eye precluded it from having binocular vision. Yet in 1984, leading shark expert Leonard Campagno countered by suggesting that the distance between a hammerhead's eyes would actually give it excellent binocular vision. Binocular vision occurs when the fields of two eyes overlap, allowing the accurate perception of depth and distance. It is especially important for predators which need to judge the distance to their prey. BBC © MMIX

Keyword: Vision; Evolution
Link ID: 13509 - Posted: 06.24.2010

by Jessica Hamzelou Sounds played as you sleep can reinforce memories, suggest Ken Paller and his colleagues at Northwestern University in Evanston, Illinois. They asked people to memorise which images and their associated sounds – such as a picture of a cat and a miaow – were associated with a certain area on a computer screen and then to take a nap. They played half the group the sounds in their sleep, and these people were better at remembering the associations than the rest when they woke up. Paller hopes sounds can be used to improve all kinds of memory and next he'll be figuring out if we can learn languages while we snooze. But before you nod off, New Scientist helps you get the most out of your shut-eye. How can you boost your sleep learning capacity? As a rule, hit the hay after learning something new – late-night TV and Xbox marathons are a no-no. That is, of course, unless the skill you hope to learn is a computer game: when Sidarta Ribeiro of the Edmond and Lily Safra International Institute of Neuroscience in Natal, Brazil, got people to play shoot-'em-up video game Doom before bed, those who dreamed about the game during their sleep were better players the next day. © Copyright Reed Business Information Ltd.

Keyword: Sleep
Link ID: 13508 - Posted: 06.24.2010

By BENEDICT CAREY One was a middle-aged man who refused to get into the shower. The other was a teenager who was afraid to get out. Before Ross, 21, had brain surgery two years ago, his obsessive-compulsive disorder kept him from leaving the house. “It saved my life,” he said. The man, Leonard, a writer living outside Chicago, found himself completely unable to wash himself or brush his teeth. The teenager, Ross, growing up in a suburb of New York, had become so terrified of germs that he would regularly shower for seven hours. Each received a diagnosis of severe obsessive-compulsive disorder, or O.C.D., and for years neither felt comfortable enough to leave the house. But leave they eventually did, traveling in desperation to a hospital in Rhode Island for an experimental brain operation in which four raisin-sized holes were burned deep in their brains. Today, two years after surgery, Ross is 21 and in college. “It saved my life,” he said. “I really believe that.” The same cannot be said for Leonard, 67, who had surgery in 1995. “There was no change at all,” he said. “I still don’t leave the house.” Both men asked that their last names not be used to protect their privacy. The great promise of neuroscience at the end of the last century was that it would revolutionize the treatment of psychiatric problems. But the first real application of advanced brain science is not novel at all. It is a precise, sophisticated version of an old and controversial approach: psychosurgery, in which doctors operate directly on the brain. Copyright 2009 The New York Times Company

Keyword: OCD - Obsessive Compulsive Disorder; Depression
Link ID: 13507 - Posted: 06.24.2010

by Linda Geddes A man strangles his wife while dreaming about fighting off intruders in his sleep. Does that make him mad, bad or innocent? Recent research is helping to unpick these issues, and may help reveal who, if anyone, bears responsibility in such cases. Last week, British man Brian Thomas appeared in court on a murder charge after strangling his wife as they slept in their camper van. The prosecution withdrew the charges after three psychiatrists testified that locking him up would serve no useful purpose. The judge said that Thomas bore no responsibility for his actions. The case has cast a spotlight on the use of such sleepwalking defences in court. "If you look at the media reports there appears to be an upsurge in the use of the sleepwalking defence," says Michel Cramer-Bornemann of the Minnesota Regional Sleep Disorders Center in Minneapolis. Thomas had a genuine sleep disorder, but Cramer-Bornemann is concerned that in many other cases, the sleepwalking and other sleep-related defences are misused. Studies on the causes of sleepwalking may eventually make it easier to identify who has a genuine sleep disorder that could occasionally result in violence, and who is making it up. Last month, Ursula Voss of Bonn University in Germany and colleagues reported that even during lucid dreaming – a state in which some people claim to be able to control their dreams – some areas of the brain associated with intent stayed offline, while other areas associated with consciousness were active. "As long as you are in a dream, you have no free rein on your actions and emotions," says Voss (Sleep, vol 32, p 1191). © Copyright Reed Business Information Ltd.

Keyword: Sleep; Aggression
Link ID: 13506 - Posted: 06.24.2010

By R. Douglas Fields Practice makes perfect, but how? Two groups of neuroscientists using MRI brain imaging announced last month that they were able to see changes inside the brains of people after mastering a new skill. The big surprise is that the part of the brain that changed has no neurons or synapses in it! The cerebral remodeling during learning was seen in the mysterious and still largely unexplored “white matter” region of the brain. “Grey matter” is synonymous with smarts, but in fact only half of the human brain is grey matter. White matter, the “other brain tissue”, is rarely mentioned. Neurons in the cerebral cortex are packed into in the top layers of the brain, where they are connected together through synapses. Learning takes place in the grey matter by linking neurons together into new circuits by strengthening synapses or forming new ones. But beneath the topsoil of the brain lies a dense network of fibers packed into a spaghetti-like snarl that is so complicated it is difficult to study or comprehend. These fibers are the wire-like axons projecting out from neurons in grey matter that transmit electrical impulses. Like buried telephone lines, these tightly bundled cables transmit information over long distances to communicate between distant regions of the cerebral cortex that are specialized to carry out different aspects of a complex cognitive function. © 1996-2009 Scientific American Inc.

Keyword: Learning & Memory; Brain imaging
Link ID: 13505 - Posted: 06.24.2010

By Carina Storrs The act of hearing is a group effort for the human body's organs, involving the ears, the eyes and also, according to the results of a new study, the skin. In 1976 scientists discovered the importance of the eyes to our sense of hearing by demonstrating that the eyes could fool the ears in a peculiar phenomenon named the McGurk effect. When participants watched a video in which a person was saying "ga" but the audio was playing "ba," people thought they heard a completely different sound—"da." Now, by mixing audio with the tactile sense of airflow, researchers have found that our perception of certain sounds relies, in part, on being able to feel these sounds. The study was published November 26 in Nature. Normally when we say words with the letters "p," "t" and "k," we produce a puff of air. This puff helps the listener distinguish words with these letters from those with the similar sounding "b," "d" and "g," respectively, even though the puff is so subtle that most of us do not even notice feeling it. "Unless you're a microphone manufacturer or a radio jockey or a phonetician, this isn't something that you're aware of," says Bryan Gick, an associate professor of linguistics at the University of British Columbia in Vancouver, and lead author of the study. Donald Derrick, a graduate student in the University's Department of Linguistics, is the other author on the study. Gick and Derrick set out to determine if these puffs of air help us to perceive "p" and "t" sounds. The pair had 66 participants listen to sessions of recorded sounds through headphones. In one session, the participants heard a combination of "pa" and "ba," and, in the other, "ta" and "da." © 1996-2009 Scientific American Inc

Keyword: Hearing; Language
Link ID: 13504 - Posted: 06.24.2010

By Steven Hyman Beauty may be only skin deep, but hot goes to the bone. Proteins involved in breaking down bones are also part of the body’s thermostat, a new study shows. The proteins — a receptor called RANK and the protein that binds to it, called RANKL — turn up the heat to cause fever during infections and also help regulate daily temperature rhythms in female rodents, a study published in the Nov. 26 Nature shows. And the proteins, which are involved in osteoporosis, may also be a source of the hot flashes that post-menopausal women experience. Scientists already knew that RANK and RANKL team up to help tear down bones. That demolition is part of the normal maintenance of bones in the body and in pregnant women, it also helps free up calcium that in turn is used to solidify the baby’s bones. The proteins are also part of the signaling pathway that prompts lactation. After menopause, the bone remodeling system may take tearing down too seriously, resulting in osteoporosis. Large-scale clinical trials have recently shown that denosumab, an antibody directed against RANKL, can help protect bones. But the skeleton isn’t the only place the protein pair works. Researchers had been surprised to find it in the brain, says Josef Penninger, an immunologist at the Institute of Molecular Biotechnology at the Austrian Academy of Sciences in Vienna. No one had a clue what bone proteins were doing in the brain, but it was important to find out before potentially giving RANK blockers such as denosumab to millions of women as an osteoporosis therapy, Penninger says. © Society for Science & the Public 2000 - 2009

Keyword: Miscellaneous
Link ID: 13503 - Posted: 06.24.2010

By Greg Miller Breathe too much carbon dioxide (CO2), and you'll suffocate. That's why people begin to panic if they breathe air enriched with the gas. One reason this happens, according to a new study in mice, is because breathing CO2 triggers chemical sensors in a crucial part of the brain's fear circuitry. The findings could point the way to new treatments for anxiety disorders. Neuroscientist John Wemmie and colleagues at the University of Iowa in Iowa City focused on a protein found in particular abundance in the amygdala, the brain's fear center. They'd shown previously that mice lacking the gene for this protein, known as acid-sensing ion channel-1a (ASIC1a), have impaired fear behavior. In their new study, reported today in Cell, the researchers show that mice lacking this gene don't freeze in place--a commonly used indicator of rodent fear--to the extent that normal mice do when the team pumped CO2 into their enclosure. But when Wemmie and colleagues injected a virus containing the ASIC1a gene into the amygdala of the mice, they acted like normal mice, freezing up when exposed to elevated CO2. In additional experiments, the team found that breathing CO2 slightly lowers the pH in the amygdala, meaning that the tissue becomes more acidic. Exposing cultured mouse amygdala neurons to a similar dip in pH elicited an electrical current, but not in neurons from mice lacking ASIC1a. When the researchers injected normal mice with bicarbonate--a buffer that prevents the pH dip--in the amygdala, the mice froze less in response to CO2. Taken together, the findings point to the following scenario, Wemmie says: Inhaling CO2 raises the acid level in the amygdala, thereby activating ASIC1a and altering the electrical signaling of amygdala neurons to produce a fear response. CO2 also increases the breathing rate in mice and humans, and the findings don't rule out the possibility that this change also contributes to fear responses as some researchers have proposed, Wemmie says. © 2009 American Association for the Advancement of Science

Keyword: Emotions
Link ID: 13502 - Posted: 06.24.2010