By Laura Sanders Exposure to cigarette smoke in the womb may dampen a baby’s fight-or-flight responses, leaving the newborn vulnerable to sudden infant death syndrome, a study in rats suggests. It has been known that babies exposed to the smoke have a higher risk of the syndrome, in which seemingly healthy infants inexplicably die. The new study, appearing June 3 in The Journal of Neuroscience, may explain why, the researchers report. “SIDS is a complicated disease, and this is why you need these kinds of studies,” comments Ernest Cutz, a pediatric pathologist at The Hospital for Sick Children in Toronto. Researchers led by Colin Nurse, a neurobiologist at McMaster University in Hamilton, Canada, studied chromaffin cells, which are located in the adrenal gland of both rats and humans. In alarming situations — like when a baby is, for any number of reasons, not getting enough oxygen — these cells flood the body with chemical signals called catecholamines. These signals, which include adrenaline, stimulate the fight-or-flight response. “Catecholamines are very important alarm mechanisms that wake a baby up,” Nurse says. The chromaffin cells of newborn rats that were exposed to nicotine while in their mothers’ womb produced more of a protein that dampens the cells’ responses. This protein, called a potassium ATP channel, normally acts as a brake by preventing the cells from releasing the fight-or-flight signals in nonthreatening situations, Nurse says. For the rats that have been exposed to nicotine, he says, “the brake has become too strong.” Fetal nicotine exposure prevented the cells from later sounding the alarm and releasing catecholamines when the researchers deprived the rats of oxygen, Nurse and his colleagues found. © Society for Science & the Public 2000 - 2009

Keyword: Sleep; Development of the Brain
Link ID: 12908 - Posted: 06.24.2010

By Tina Hesman Saey A new strain of fruit flies bred to have trouble getting shut-eye may open researchers eyes to the genetic causes of insomnia. Not so long after scientists discovered that fruit flies sleep, Paul Shaw of Washington University in St. Louis and his colleagues bred a strain of Drosophila melanogaster to have many of the characteristics, and complications, of insomnia in people. Shaw’s team bred 60 generations of fruit flies, selecting for flies that slept the shortest amount of time. The resulting insomniac fruit flies may help scientists find genetic roots of the sleep disorder, the team reports in the June 3 Journal of Neuroscience. There is a fine line between insomnia and sleep deprivation, says Thomas Roth, a sleep researcher at the Henry Ford Hospital in Detroit. Insomniacs lack the ability to fall asleep and sleep well (though Shaw and his colleagues think such people may be protected from many of the negative effects of sleeplessness). Sleep deprived people, however, simply stay up too late, not getting the sleep they need to function properly. Most attempts to mimic insomnia in animals fail to match some hallmarks of the disorder in humans, especially hypersensitivity to light, sound and other stresses. “Was I ready to blow this paper off before I read it? Yeah. I thought it was just another guy doing sleep deprivation and calling it insomnia,” Roth says. But the fruit flies “show real characteristics of insomnia.… They aren’t just short sleepers.” © Society for Science & the Public 2000 - 2009

Keyword: Sleep; Genes & Behavior
Link ID: 12907 - Posted: 06.24.2010

CHICAGO - A persistent decline in the rate of Americans, especially children, newly diagnosed with depression followed the first federal warning on risks connected with antidepressant drugs, a study suggests. In 2003, the Food and Drug Administration first warned about the risk of suicidal thoughts and behavior in young people taking the drugs. That action may have helped reverse a five-year trend of rising rates of diagnosis for depression, the researchers found. The findings, published Monday in the Archives of General Psychiatry, are based on an analysis of eight years of data from nearly 100 managed care plans and more than 55 million patients. It was already known that antidepressant use among young people had fallen since the drugs began carrying a so-called “black box” warning about risks. But the data showing an extended decline in the level of depression diagnoses are new. In some cases, untreated depression can be more dangerous than suicidal feelings when starting antidepressants and a spike in teenage suicides in 2004 worried some experts that could be another unintended result of the FDA warnings. Then, teen suicides fell slightly the following year, offering hope that the suicide increase was just a blip. The new research can’t explain why diagnosis rates have declined, said lead author Anne Libby of the University of Colorado Denver. Diagnosis rates for anxiety and bipolar disorder, also sometimes treated with antidepressants, also fell. © 2009 The Associated Press.

Keyword: Depression
Link ID: 12906 - Posted: 06.24.2010

By Jackie Christensen When people first meet me, they may not be able to tell that I have Parkinson's disease. I'm 45, and the average age at diagnosis is 55 to 60. (I was 34 when my case was diagnosed.) I don't really have a tremor, and in 2006, I underwent deep brain stimulation, a procedure that controls most of the wriggling and writhing movements that I had been experiencing. But once I open my mouth to speak, it often becomes apparent that there is something going on. It may be that the rigidity of my throat and chest muscles has made my voice soft and lacking inflection. Stiffness in my facial muscles can give me a blank expression or, even worse, make me seem angry or aloof. I may sound like I am trying to talk with a mouthful of marbles. The problem that bothers me the most -- because it seems to be especially disconcerting to others -- is the halting quality that my voice frequently takes on, especially if I'm nervous or upset. It's . . . as . . . if . . . what . . . I . . . want . . . to . . . say . . . has . . . to . . . be . . . squeezed . . . from . . . my . . . brain . . . to . . . come . . . out . . . of . . . my . . . mouth . . . as . . . individual . . . word . . . bubbles. If reading that was annoying to you or made you want to finish the sentence for me, you are not alone. Many of my friends, colleagues and family members feel the same way. I have a theory about what bothers them. © 2009 The Washington Post Company

Keyword: Parkinsons
Link ID: 12905 - Posted: 06.24.2010

By C. CLAIBORNE RAY A. Grinding the teeth while asleep is just one kind of bruxism, a disorder that also includes daytime grinding and clenching of the jaws; it is often called night bruxism. Many explanations have been offered for why night bruxism occurs and who is at risk, without conclusive proof. A 2000 review article in the journal Sleep Medicine Reviews notes that most people will suffer from grinding or clenching at least some time in their lives. Night bruxism becomes a serious problem when it causes pain, damages teeth or disrupts sleep, but many bruxists are sound sleepers, not even aware of the grinding. It seems to be equally prevalent in both sexes, but more common in younger people. Some of the many factors studied for their association with bruxism include teeth that do not meet properly, psychosocial and environmental factors, and problems with neurotransmitters in the brain or malfunction of centers in the brain called basal ganglia. Some studies find sleep apnea, stress and the heavy use of tobacco, alcohol, drugs and caffeine to be associated with higher risks of bruxism, without showing them to be actual causes. Many kinds of treatment for bruxism have been tried as well, with widely varying rates of success, including dental appliances that keep the teeth apart; various kinds of psychotherapy and behavioral therapy; drugs; and even nutritional supplements, on the theory that a mineral or vitamin deficiency may be responsible. Relaxation exercises and warm compresses before sleep are noninvasive steps suggested by some authorities. Copyright 2009 The New York Times Company

Keyword: Sleep
Link ID: 12904 - Posted: 06.02.2009

By JOHN TIERNEY If you own a dog, especially a dog that has anointed your favorite rug, you know that an animal is capable of apologizing. He can whimper and slouch and tuck his tail and look positively mortified — “I don’t know what possessed me.” But is he really feeling sorry? Could any animal feel true pangs of regret? Scientists once scorned this notion as silly anthropomorphism, and I used to side with the skeptics who dismissed these displays of contrition as variations of crocodile tears. Animals seemed too in-the-moment, too busy chasing the next meal, to indulge in much self-recrimination. If old animals had a song, it would be “My Way.” Yet as new reports keep appearing — moping coyotes, rueful monkeys, tigers that cover their eyes in remorse, chimpanzees that second-guess their choices — the more I wonder if animals do indulge in a little paw-wringing. Your dog may not share Hamlet’s dithering melancholia, but he might have something in common with Woody Allen. The latest data comes from brain scans of monkeys trying to win a large prize of juice by guessing where it was hidden. When the monkeys picked wrongly and were shown the location of the prize, the neurons in their brain clearly registered what might have been, according to the Duke University neurobiologists who recently reported the experiment in Science. Copyright 2009 The New York Times Company

Keyword: Emotions; Evolution
Link ID: 12903 - Posted: 06.24.2010

Citalopram, a medication commonly prescribed to children with autism spectrum disorders (ASD), was no more effective than a placebo at reducing repetitive behaviors, according to researchers funded by the National Institute of Mental Health (NIMH) and other NIH institutes. The study was published in the June 2009 issue of Archives of General Psychiatry. The researchers say their findings do not support using citalopram to treat repetitive behaviors in children with ASD. Also, the greater frequency of side effects from this particular medication compared to placebo illustrates the importance of placebo-controlled trials in evaluating medications currently prescribed to this population. Citalopram is in a class of antidepressant medications called selective serotonin reuptake inhibitors (SSRIs) that is sometimes prescribed for children with ASD to reduce repetitive behaviors. These behaviors, a hallmark of ASD, include stereotypical hand flapping, repetitive complex whole body movements (such as spinning, swaying, or rocking over and over, with no clear purpose), repetitive play, and inflexible daily routines. Past research suggested that some children with ASD have abnormalities in the brain system that makes serotonin, a brain chemical that, among many other functions, plays an important role in early brain development. Children with obsessive compulsive disorder (OCD) may also have serotonin abnormalities and have repetitive or inflexible behaviors. OCD is effectively treated with SSRIs, leading some researchers to wonder whether similar treatment may reduce repetitive behaviors in children with ASD. So far, studies have produced mixed results, but SSRIs remain among the most frequently prescribed medications for children with ASD.

Keyword: Autism
Link ID: 12902 - Posted: 06.02.2009

Eric Bland -- Synthetic fibers can now be embedded with three, and possibly more, drugs or proteins. The new fibers could be woven into a variety of materials that have unique and novel properties -- such as reversing blindness. "The ultimate idea is to implant this material into the eye," said Bin Dong, a scientist from Drexel University who, along with Gary Wnek and Meghan Smith of Case Western University, detailed their work in the journal Small. "One protein will eat the scar tissue away, and the other will help induce the differentiation of retinal progenitor cells," said Dong. Previously scientists were only able to include one drug or protein inside an electrospun fiber because the two would often interact with each other in ways that would negate or modify their effects. To get around this limitation, the Drexel and Case Western scientists put the drugs and proteins inside tiny capsules, which stop the molecules from interacting with each other until they break apart. space station For their first tests, the scientists incorporated both bovine albumin serum (BAS) and epidermal growth factor (EGF) into the same electrospun fiber. Each molecule was also linked to a particular fluorescent dye that appears under special light. Red for BAS, green for EGF. © 2009 Discovery Communications, LLC.

Keyword: Vision; Robotics
Link ID: 12901 - Posted: 06.24.2010

by Joyce Gramza Are men naturally better at math than women or is that just an out-dated stereotype? When former Harvard president Larry Summers said publicly in 2005 that men are innately better at math, many women were outraged. So a couple of women scientists decided to research it. "I would like nothing better than to be proved wrong." That disclaimer didn’t keep then-Harvard president and current National Economics Council director Lawrence Summers from sparking a firestorm of controversy with his 2005 take on the reasons for women’s under representation in math and science leadership. But it did lead some researchers to take up the challenge of proving or disproving Summers’ contention that inherent differences in ability might be more important than discrimination or stereotyping in accounting for the gender gap. University of Wisconsin-Madison psychiatry professor Janet Hyde and her colleague, oncology professor Janet Mertz say their research documenting female ability at the highest levels of mathematical performance was directly "inspired" by Summers. Writing in the Proceedings of the National Academy of Sciences, the researchers specifically targeted the "greater male variability hypothesis" invoked by Summers as evidence of possible innate differences in male and female math ability. ©2009 ScienCentral

Keyword: Sexual Behavior; Intelligence
Link ID: 12900 - Posted: 06.24.2010

A significant number of children with autism and related disorders could be undiagnosed, a study has suggested. A Cambridge University team looked at existing diagnoses - and carried out recognised tests to assess other children. Of the 20,000 studied, 1% had an autistic spectrum disorder, 12 times higher than the rate 30 years ago. Autism experts said it was crucial to have accurate data on how many children were affected by the disorder. The research, published in the British Journal of Psychiatry, was carried out in three parts. The scientists first looked at cases of autism and Asperger syndrome among 8,824 children on the Special Educational Needs registers in 79 schools in East Anglia. A total of 83 cases were reported, giving a prevalence of 94 in 10,000, or 1 in 106 children. The team then sent a diagnosis survey to parents of 11,700 children in the area. From 3,373 completed surveys, 41 cases of autism-spectrum conditions were reported, corresponding to prevalence of 1 in 101. This 1% rate confirms estimates from previous research. They then sent the Childhood Autism Screening Test (CAST) to the same parents to help identify any undiagnosed cases of autism-spectrum conditions. All those with high scores, plus some who had medium and low scores, were called in for further assessment. The team found an additional 11 children who met the criteria for an autism spectrum condition, but had not yet been diagnosed. The researchers say that, if these findings were extrapolated to the wider population, for every three known cases of autism spectrum, there may be a further two cases that are undiagnosed. Professor Baron-Cohen said: "In terms of providing services, if we want to be prepared for the maximum numbers that might come through, these undiagnosed cases might be significant." (C)BBC

Keyword: Autism
Link ID: 12899 - Posted: 05.30.2009

Electrodes inserted into certain parts of the brain — in a technique known as deep brain stimulation — can stimulate the growth of new neurons that are used in memory formation, according to research in mice. The findings show that artificially created neurons can be fully functional — a topic of hot debate in the neuroscience community. Knowing that the cells are functional, rather than just useless growths, is a boost for those seeking to use the treatment against Alzheimer's disease and other memory-degeneration disorders. "I'm hoping to help people who have difficulty remembering things," says Scellig Stone, a neurosurgery resident and PhD candidate at the University of Toronto. One of Stone's supervisors, Paul Frankland of the Hospital for Sick Children in Toronto, presented the results at the annual meeting of the Canadian Association for Neuroscience in Vancouver, Canada, on 25 May. In his study, Stone electrically stimulated part of the limbic system in the brains of mice for an hour. Rodent brains normally produce thousands of new neurons a day; by 3–5 days after the procedure, the electrical stimulation had doubled that. During this time of high neuron growth, the team injected the mice with iododeoxyuridine to label the newly formed cells. Six weeks after the stimulation, the mice were trained to find a platform hidden underwater in a swimming tank. Once the researchers were convinced the mice had learned the task, they examined their brains, looking for a protein called Fos. Fos is produced only by active cells, and takes around 90 minutes to form, so the team could time their examination to pinpoint neurons that had been used explicitly in the memory task. They found that the new neurons had the same level of Fos and were therefore just as active as other, older neurons. "These new neurons aren't just sitting around doing nothing," says Stone. © 2009 Nature Publishing Group,

Keyword: Neurogenesis; Learning & Memory
Link ID: 12898 - Posted: 06.24.2010

by Sunita Reed "The depressed person was in terrible and unceasing emotional pain, and the impossibility of sharing or articulating this pain was itself a component of the pain and a contributing factor in its essential horror." -opening line from "The Depressed Person" by David Foster Wallace Though an excerpt from a work of fiction, that sentiment is all too real for people like 69-year-old artist Cynthia Amberg. Like her mother, Amberg experienced her first episode of depression after her second child was born. Normally exuberant, she says in that dark time she could barely get herself out of bed. “It was a hell worse than anything I could ever adequately describe to someone who hasn’t suffered from it,” says Amberg. Depression is a subject many people are reluctant to talk about openly, but Amberg wants people to know that they don’t need to be ashamed that they have it. She got counseling and medication, and is better able to deal with the depression that she learned often runs in families. She now only checks in periodically with Patrick McGrath, a psychiatrist with affiliations at both Columbia University Medical Center and New York State Psychiatric Institute who monitors her health and her medication. Since the ’90s Amberg has rarely been depressed. Now McGrath’s colleague, child psychiatrist Bradley Peterson, has found new clues as to why people with a family history of depression are at high risk for developing it themselves. Together with epidemiologist Myrna Weissman, they led a brain study of people with and without a family history of depression. ©2009 ScienCentral

Keyword: Depression
Link ID: 12897 - Posted: 06.24.2010

By Bruce Bower Chimpanzees living in central Africa’s dense forests have no access to a hardware store, but that doesn’t stop them from assembling their own brand of toolkits. These apes use as many as five homemade tools in set sequences to obtain honey from beehives located at least 20 meters high in the trees, in fallen tree trunks and up to 1 meter underground, according to two new studies. Chimps living in Gabon’s Loango National Park modify tree branches of various lengths and widths to make complex tool sets for removing honey from the hives of different bee species, anthropologist Christophe Boesch of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues report online May 19 in the Journal of Human Evolution. In other parts of Africa, chimps use only one or two tools at a time to obtain honey from hives, crack nuts or hunt small animals. Near Loango, in a forested region of the Congo Basin called the Goualougo Triangle, another group of chimps also makes and uses different types of tools to open beehives and gather honey, say Crickette Sanz, also of the Max Planck Institute for Evolutionary Anthropology, and David Morgan of Lincoln Park Zoo in Chicago. Chimps across Africa have developed regional tool-using traditions in honey gathering, Sanz and Morgan propose in the June International Journal of Primatology. In central African forests, hard-to-reach hives and competition for food with nearby gorillas have elicited complex forms of tool use by chimps, the researchers contend. That proposal challenges the traditional idea that advanced behaviors among human ancestors emerged only after they left the forest for wide-open savannas. Forest-dwelling ancestors could have achieved chimplike advances in tool-making as well, in Sanz and Morgan’s view. © Society for Science & the Public 2000 - 2009

Keyword: Evolution
Link ID: 12896 - Posted: 06.24.2010

by Michael Le Page, Copenhagen For women, it seems, sex is a big turn-off, reveals a brain scanning study. It shows that many areas of the brain switch off during the female orgasm - including those involved with emotion. "At the moment of orgasm, women do not have any emotional feelings," says Gert Holstege of the University of Groningen in the Netherlands. His team recruited 13 healthy heterosexual women and their partners. The women were asked to lie with their heads in a PET scanner while the team compared their brain activity in four states: simply resting, faking an orgasm, having their clitoris stimulated by their partner's fingers, and clitoral stimulation to the point of orgasm. The results of the study are striking. As the women were stimulated, activity rose in one sensory part of the brain, called the primary somatosensory cortex, but fell in the amygdala and hippocampus, areas involved in alertness and anxiety. During orgasm, activity fell in many more areas of the brain, including the prefrontal cortex, compared with the resting state, Holstege told a meeting of the European Society for Human Reproduction and Development in Copenhagen on Monday. In one sense the findings appear to confirm what is already known, that women cannot enjoy sex unless they are relaxed and free from worries and distractions. "Fear and anxiety levels have to go down for orgasm. Everyone knows this but we can see it happening in the brain," he explains. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior
Link ID: 12895 - Posted: 06.24.2010

Sharon Begley There must be something deep in the human soul that makes us blame fate, birth, our parents and all sorts of other things beyond our control for how we turn out, and scientists are no less guilty of this. Case in point: a study published in the European Journal of Neuroscience this week concludes that something about the way the brain develops from birth (or earlier) leads some of us to be people persons—socially gregarious, enjoying the company of others—and some of us to be more aloof. True, the scientists hedge their bets by making the requisite acknowledgement that people's experience and behavior might act to alter their brain structure, something for which there is ample (and growing) evidence. (My favorites: London taxicab drivers develop a larger hippocampus (that's the site of spatial memory, a good thing to have to navigate London streets) and violin players develop larger somatosensory cortexes in regions devoted to the digits of their fingering hand. But the title of this latest bit of research tells it all: "The brain structural disposition to social interaction." Translation: brain structure comes first, and the result is that you are either a warm, friendly people person who delights in the company of others or a detached, independent, antisocial loner. The study itself was straightforward. Scientists led by Maël Lebreton and Graham Murray of the University of Cambridge had 4,349 men born in Finland in 1966 fill out a questionnaire that assesses sociability. (The men rated themselves on such points as whether such statements as "I make a warm personal connection with most people" and "I like to please other people as much as I can" describe them.) A high score means a high disposition to social relationships, emotional warmth and sociability called social reward dependence—a people person. A low score indicates a tendency to be socially insensitive and aloof. © 2009 Newsweek, Inc.

Keyword: Autism; Emotions
Link ID: 12894 - Posted: 06.24.2010

Joseph LeDoux We're living in the golden age of the brain. Researchers around the world are trying to figure out how Woody Allen's "second favorite organ" works. The US Society for Neuroscience has more than 40,000 members, and the International Brain Research Organization (IBRO) puts up impressive numbers from the rest of the planet. These legions of scientists, and their pioneering predecessors, have produced a tremendous amount of information about the brain, and also information about what goes wrong in the brains of people with neurological and psychiatric disorders. That's not to say we've got it all figured out, but we're making progress. As someone who studies the brain and also tries to disseminate information about the brain in a user-friendly, but scientifically accurate, way, I cringe when I read some pop accounts of brain research. For example, I recently saw this CNN headline: "Will right-brainers rule this century?" Clicking on the link took me to OPRAH.com, which promised, less hesitantly, to explain "Why right-brainers will rule this century." At least CNN considered the possibility that there was some question about the veracity of the statement. Oprah's headline implied it's a done deal. The current right brain craze was triggered by Daniel Pink's best selling book, A Whole New Mind. In the interview with Oprah, Pink, a former speech writer for Al Gore, says "in many professions, what used to matter most were abilities associated with the left side of the brain: linear, sequential, spreadsheet kind of faculties. Those still matter, but they're not enough. What's important now are the characteristics of the brain's right hemisphere: artistry, empathy, inventiveness, big-picture thinking. These skills have become first among equals in a whole range of business fields." Oprah bought 4500 copies. © 2009 HuffingtonPost.com, Inc.

Keyword: Emotions; Laterality
Link ID: 12893 - Posted: 06.24.2010

By Erica Westly Neuroscience textbooks typically portray the five senses as separate entities, but in the real world the senses frequently interact, as anyone who has tried to enjoy dinner with a stuffy nose can attest. Hearing and vision seem similarly connected, the most famous example being the “McGurk effect,” where visual cues, such as moving lips, affect how people hear speech. And now new research shows that touch can influence speech perception, too. David Ostry, a neuroscientist with co-appointments at McGill University and the New Haven, Conn.–based speech center Haskins Laboratories, has been studying for years the relation between speech and the somatosensory system, the network of receptors in skin and muscle that report information on tactile stimuli to the brain. In his most recent study, published in the Proceedings of the National Academy of Sciences USA, he and two Haskins colleagues found that subjects heard words differently when their mouths were stretched into different positions. The results have implications for neuroscientists studying speech and hearing as well as for therapists looking for new ways to treat speech disorders. In the study, a specially designed robotic device stretched the mouths of volunteers slightly up, down or backward while they listened to a computer-generated continuum of speech verbalizations that sounded like “head” or “had,” or something in between. When the subjects’ mouths were stretched upward, closer to the position needed to say “head,” they were more likely to hear the sounds as “head,” especially with the more ambiguous output. If the subjects’ mouths were stretched downward, as if to say “had,” they were more likely to hear “had,” even when the sounds being generated were closer to “head.” Stretching subjects’ mouths backward had no effect, implying a position-specific response. Moreover, the timing of the stretch had to match that of the sounds exactly to get an effect: the stretch altered speech perception only when it mimicked realistic vocalizations. © 1996-2009 Scientific American Inc

Keyword: Hearing; Language
Link ID: 12892 - Posted: 06.24.2010

A research institute devoted to Alzheimer's and related diseases has teamed up with a major maker of diagnostic tests to speed development of what could be the first test to detect Alzheimer's in its early stages. If all goes well, the first commercial version of the test could be available in 12 to 18 months, possibly enabling patients to try to slow progression of the increasingly common disease, said Dr. Daniel Alkon, scientific director of the Blanchette Rockefeller Neurosciences Institute. "This may be a way of monitoring how effective a treatment is for Alzheimer's disease" as well, through periodic retesting once scientists can develop a medicine to stop the mind-robbing disease, Alkon told The Associated Press in an exclusive interview Tuesday. Alkon's institute, based at West Virginia University and affiliated with Johns Hopkins University, on Wednesday announced a multimillion-dollar contract with Inverness Medical Innovations Inc. of Waltham, Mass. Inverness will fund development of the Alzheimer's test and future improvements, including an eventual home version, for at least three years. The test works by detecting abnormal function of a protein that has been shown to be involved in memory storage, Alkon said. © CBC 2009

Keyword: Alzheimers; Learning & Memory
Link ID: 12891 - Posted: 06.24.2010

By Tina Hesman Saey Even neurons need quiet time. A new study shows the brain cells take time out while you sleep, preventing you from waking up at the drop of a hat or other nonthreatening object. For decades, scientists have been measuring electrical activity in the brain during sleep with electroencephalograms, or EEGs. Researchers easily recognize the hallmark dips and blips of each stage of sleep, but what brain cells are doing to produce the signals hasn’t been apparent. Now, a new study in the May 22 Science shows that a prominent electrical signal of slow-wave sleep, called the K-complex, indicates downtime for neurons. The quiet periods could help people ignore distractions, such as sounds and touches, and stay asleep, the researchers report. K-complexes appear as sharp dips in EEG tracings. The events happen shortly after a person falls asleep, during a period of slow-wave sleep when people are transitioning from light sleep into the heaviest periods of deep sleep. Such dips correspond to a quieting of brain cell activity in animals. Though the traditional electrodes used in EEG measure activity over large areas on the surface of the outer layer of the human brain — the cortex — no one really knew what the signals indicated about fine-scale brain activity in the cortex’s deeper layers. © Society for Science & the Public 2000 - 2009

Keyword: Sleep
Link ID: 12890 - Posted: 06.24.2010

by Priya Shetty Doubt is being cast on the true role of brain neurons that are said to explain empathy, autism and even morality. Mirror neurons fire both when we perform an action and when we see someone else doing it. The theory is that by simulating action even when watching an act, the neurons allow us to recognise and understand other people's actions and intentions. However, Alfonso Caramazza at Harvard University and colleagues say their research suggests this theory is flawed. Neurons that encounter repeated stimulus reduce their successive response, a process called adaptation. If mirror neurons existed in the activated part of the brain, reasoned Caramazza, adaptation should be triggered by both observation and performance. To test the theory, his team asked 12 volunteers to watch videos of hand gestures and, when instructed, to mimic the action. However, fMRI scans of the participants' brains showed that the neurons only adapted when gestures were observed then enacted, but not the other way around. Caramazza says the finding overturns the core theory of mirror neurons that activation is a precursor to recognition and understanding of an action. If after executing an act, "you need to activate the same neurons to recognise the act, then those neurons should have adapted," he says. © Copyright Reed Business Information Ltd.

Keyword: Autism; Vision
Link ID: 12889 - Posted: 06.24.2010