By SARA REISTAD-LONG When older people can no longer remember names at a cocktail party, they tend to think that their brainpower is declining. But a growing number of studies suggest that this assumption is often wrong. Instead, the research finds, the aging brain is simply taking in more data and trying to sift through a clutter of information, often to its long-term benefit. The studies are analyzed in a new edition of a neurology book, “Progress in Brain Research.” Some brains do deteriorate with age. Alzheimer’s disease, for example, strikes 13 percent of Americans 65 and older. But for most aging adults, the authors say, much of what occurs is a gradually widening focus of attention that makes it more difficult to latch onto just one fact, like a name or a telephone number. Although that can be frustrating, it is often useful. “It may be that distractibility is not, in fact, a bad thing,” said Shelley H. Carson, a psychology researcher at Harvard whose work was cited in the book. “It may increase the amount of information available to the conscious mind.” For example, in studies where subjects are asked to read passages that are interrupted with unexpected words or phrases, adults 60 and older work much more slowly than college students. Although the students plow through the texts at a consistent speed regardless of what the out-of-place words mean, older people slow down even more when the words are related to the topic at hand. That indicates that they are not just stumbling over the extra information, but are taking it in and processing it. Copyright 2008 The New York Times Company

Keyword: Alzheimers; Learning & Memory
Link ID: 11648 - Posted: 06.24.2010

By DAVID DOBBS IN TUNE Dr. Conrad, a pianist and surgeon, says that he works better when he listens to music and that music is helpful to patients. “If I don’t play for a couple of days,” said Dr. Conrad, a third-year surgical resident at Harvard Medical School who also holds doctorates in stem cell biology and music philosophy, “I cannot feel things as well in surgery. My hands are not as tender with the tissue. They are not as sensitive to the feedback that the tissue gives you.” Like many surgeons, Dr. Conrad says he works better when he listens to music. And he cites studies, including some of his own, showing that music is helpful to patients as well — bringing relaxation and reducing blood pressure, heart rate, stress hormones, pain and the need for pain medication. But to the extent that music heals, how does it heal? The physiological pathways responsible have remained obscure, and the search for an underlying mechanism has moved slowly. Now Dr. Conrad is trying to change that. He recently published a provocative paper suggesting that music may exert healing and sedative effects partly through a paradoxical stimulation of a growth hormone generally associated with stress rather than healing. Copyright 2008 The New York Times Company

Keyword: Hearing; Hormones & Behavior
Link ID: 11647 - Posted: 06.24.2010

By JOHN TIERNEY The ladies who lunch do not obsess about their weight in the rhesus monkey compound at the Yerkes National Primate Research Center in Atlanta. Food is freely available, and the high-status females do not pride themselves on passing it up. They don’t seem to stigmatize obesity — there is no equivalent of a Kirstie Alley joke — and they certainly don’t turn themselves into Social X-Rays. In fact, the dominant females ordinarily eat a little more than the subordinates. The lower status monkeys can get as much food as they want but seem to have less of a desire to eat, perhaps because of the higher level of stress hormones in their brain. The anxiety of constantly toadying to their social superiors seems to curb their appetite, researchers suspect, at least when their regular high-fiber, low-fat chow is on the menu. But suppose you tempted them with the equivalent of chocolate and potato chips and ice cream? Mark Wilson, a neuroscientist at Emory University, and a team tried that experiment at Yerkes by installing feeders with a constant supply of banana-flavored pellets — not exactly Dove bars, but they had enough sugar and fat to appeal even to human palates. (In the interest of science, I sampled a few pellets.) Once these foods were available, the low-status monkeys promptly developed an appetite. They began eating significantly more calories than their social superiors. While the dominant monkeys dabbled in the sweet, fatty pellets just during the daytime, the subordinate monkeys kept scarfing them down after dark. Copyright 2008 The New York Times Company

Keyword: Stress; Obesity
Link ID: 11646 - Posted: 06.24.2010

By Marco Iacoboni WHAT DO PEOPLE REALLY DO all day, every day? We “read” the world. And much of the world consists of other people. When a tennis player raises his racquet, for example, you know instantly whether he’s going to take a practice swing or throw his racket across the court in anger. We all make dozens—hundreds—of such distinctions every day. It is, quite literally, what we do, usually without a second thought. It all seems so ordinary. In fact, it’s extraordinary—and even more extraordinary that it feels ordinary! We achieve our very subtle understanding of other people thanks to certain collections of special cells in the brain called mirror neurons. They are at the core of how we navigate through our lives. They bind us with each other, mentally and emotionally. Mirror neurons are incredibly powerful; “vicarious” would not be a strong enough word to describe their effects. When we watch movie stars kiss onscreen, some of the cells firing in our brains are the same ones that fire when we kiss our lovers. And when we see someone else suffering or experiencing pain, mirror neurons help us to read her or his facial expression and make us viscerally feel the suffering or the pain of the other person. Those moments, I will argue, are the foundation of empathy (and possibly of morality). Research on mirror neurons gives anyone interested in how we understand one another some remarkable food for thought. © Natural History Magazine, Inc., 2008

Keyword: Vision; Autism
Link ID: 11645 - Posted: 06.24.2010

Max Blake was 7 the first time he tried to kill himself. He wrote a four-page will bequeathing his toys to his friends and jumped out his ground-floor bedroom window, falling six feet into his backyard, bruised but in one piece. Children don't really know what death is, as the last page of Max's will made clear: "If I'm still alive when I have grandchildren," it began. But they know what unhappiness is and what it means to suffer. On a recent Monday afternoon, Max, now 10, was supposed to come home on the schoolbus, but a counselor summoned his mother at 2:15. When Amy Blake arrived at school, her son gave her the note that had prompted the call. "Dear Mommy & Daddy," it read, "I am really feeling sad and depressed and lousy about myself. I love you but I still feel like I want to kill myself. I am really sad but I just want help to feel happy again. The reason I feel so bad is because I can't sleep at night. And dad yells at me to just sleep at night. But, I can't control it. It is not me that does control it. I don't know what controls it, but it is not me. I really really need some help, love Max!!!!! I Love you Mommy I Love you Daddy." This is the story of a family: a mother, a father and a son. It is, in many ways, a horror story. Terrible things happen. People scream and cry and hurt each other; they say and do things that they later wish they hadn't. The source of their pain is bipolar disorder, a mental illness that results in recurring bouts of mania and depression. It is an elusive disease that no parent fully understands, that some doctors do not believe exists in children, that almost everyone stigmatizes. But this is also a love story. Good things happen. A couple sticks together, a child tries to do better, teachers and doctors and friends help out. Max Blake and his parents may not have much in common with other families. They are a family nonetheless. That is what has mattered most to Amy and Richie Blake since Oct. 31, 1997, the day their son took his first ragged breath. © 2008 Newsweek, Inc

Keyword: Schizophrenia; Development of the Brain
Link ID: 11644 - Posted: 06.24.2010

A mutated gene has been discovered as the key behind epilepsy and mental retardation specific to women, thanks to new research at Adelaide’s Women’s & Children’s Hospital and the University of Adelaide, Australia. The world-first discovery, published today in Nature Genetics, shows that although men carry the ‘bad’ gene, only women are affected. The research has been led by Dr Leanne Dibbens and Associate Professor Jozef Gecz from the Department of Genetic Medicine, Women’s & Children’s Hospital, and the Discipline of Paediatrics at the University of Adelaide. The discovery is a result of a major international collaboration involving the Sanger Institute in Cambridge (UK), Wellcome Trust (UK) and many other collaborators in Australia, the United States, Ireland and Israel. Their work has linked, for the first time, a large family of genes known as protocadherins with a condition known as “epilepsy and mental retardation limited to females” (EFMR). Although a relatively uncommon disorder, the condition is hereditary, with successive generations of women affected. In just one of seven families studied across the world, 23 women were affected by the disorder across five generations. This discovery will now enable such families to benefit from genetic counselling, including screening for the genetic mutation at pregnancy. © 2008 Eureka! Science News

Keyword: Epilepsy; Genes & Behavior
Link ID: 11643 - Posted: 06.24.2010

Ewen Callaway Monkeys genetically engineered to get the deadly neurological disease Huntington's could provide a unique way to test potential treatments because of their cognitive and genetic similarities to humans. "Monkey models may have a privilege over other animal models," says Anthony Chan, a biologist at Yerkes National Primate Center in Atlanta, Georgia, whose team engineered five rhesus macaque monkeys to churn out the mutant protein that causes Huntington's. Researchers routinely splice human genes in and out of mice to give them diabetes, cancer, and heart disease. But mice are of limited use when investigating brain diseases such as Huntington's: people who have it can't control their movement, speech or swallowing and their cognitive abilities deteriorate. But mice engineered to express the Huntington's protein don't jerk their muscles like humans do and it can be tough to gauge their cognitive decline. To see if primates might offer more insight, Chan's team used a virus to insert the Huntingon's gene into the DNA of 130 macaque eggs, along with a gene that makes a fluorescent green jellyfish protein. The researchers then fertilised the eggs and implanted them into eight mothers. All the monkeys born expressed the green protein, indicating that gene transfer was successful, and some already appear to have the monkey equivalent of Huntington's. The brains of one set of twins, who died a day after birth, were littered with clumps of a mutant protein found in humans with Huntington's, while the lone animal, who died a month after birth, jerked involuntarily. © Copyright Reed Business Information Ltd.

Keyword: Huntingtons; Genes & Behavior
Link ID: 11642 - Posted: 06.24.2010

A small molecule may have a big role in making the body clock tick, say Cambridge University researchers. Studies in mice have shown cAMP - a common signalling molecule - is involved in keeping the body clock "rhythms" going. The team hope to develop drugs that target cAMP to help shift workers, frequent flyers or those with sleep disorders reset their body clocks. But the research, published in Science, is still a long way from the clinic. The body's internal clock is a highly sensitive mechanism able to anticipate changes in the environment and regulate a host of body functions, from sleep patterns to metabolism and behaviour. Disruption of these "circadian" rhythms have been shown to be linked with insomnia, depression, heart disease, cancer and neurodegenerative disorders. At the beginning of the circadian day, genes are switched on which then produce proteins which in turn go on to switch off the same genes at the end of the day. The proteins are broken down over the circadian night and the process starts all over again in the morning. Researchers at the Medical Research Council Laboratory of Molecular Biology discovered that cAMP not only helps regulate the production of these proteins but that its own rhythm is also regulated by this "loop". In laboratory experiments in cells the proteins were engineered to light up so the researchers could easily monitor the circadian rhythms depending on how much protein was present dependent on the activity of cAMP. Study leader Dr Michael Hastings said in mice who by a quirk of genetics had a 20-hr body clock, they were able to reset the clock to 24 hours by using known compounds that are known to slow down the action of cAMP. "What's neat about cAMP is that it is very easily controlled by different medicines and compounds." (C)BBC

Keyword: Biological Rhythms
Link ID: 11641 - Posted: 05.17.2008

We humans have the ability to learn, to reason and solve problems. We're self-aware, and we’re also conscious of the presence, thoughts and feelings of others. We make tools and practice the art of deception. We're creative. We think abstractly. We have language and use it to express complex ideas. All of these are arguably signs of intelligence. Scientists may not agree on the best and fullest definition of intelligence – but they generally agree that humans are highly intelligent. Other members of the animal kingdom exhibit signs of intelligence as well, and some scientists might say the definition of animal vs. human intelligence is merely a matter of degree – a point that was brought home in 2005 when the London Zoo put “Homo sapiens” on display in the exhibit pictured here. Click the "Next" arrow above to learn about nine other species that stand out for their smarts. © 2008 MicrosoftMSN

Keyword: Intelligence; Evolution
Link ID: 11640 - Posted: 06.24.2010

By ALIYAH BARUCHIN The first thing you notice about 13-year-old Nora Leitner is the dark circles under her eyes. They stand in stark contrast to the rest of her appearance. At a glance she might be any petite, pretty tween girl, with her blond ponytail, elfin frame and thousand-watt smile, but the circles tell a different story. Nora looks as if she hasn’t slept in a month. In a sense, she hasn’t. Nora has epilepsy, and as with 30 percent of those with the disorder, her seizures are not controlled by existing treatments. She often has more than one seizure a day, mostly at night. Her seizures, called tonic-clonic (what used to be known as grand mal), cause her to lose consciousness for a full minute while her body convulses. While some people feel an “aura” of symptoms before a seizure, Nora’s seizures happen entirely without warning. When she seized at the top of a staircase in her home in Yardley, Pa., it was plain luck that her parents were at the bottom and caught her as she fell. Though she is on the brink of adolescence, she is rarely, if ever, left alone. Epilepsy affects 50 million people worldwide and more than 2.7 million people in the United States; half of all patients are children. Especially in its intractable form, also called refractory epilepsy, the disorder — and the side effects of epilepsy medications — can cause problems in learning, memory and behavior, and indelibly alter development. Epilepsy can also consume families, monopolizing their time, money and energy. Copyright 2008 The New York Times Company

Keyword: Epilepsy
Link ID: 11639 - Posted: 06.24.2010

By Martin Portner She did not often have such strong emotions. But she suddenly felt powerless against her passion and the desire to throw herself into the arms of the cousin whom she saw at a family funeral. “It can only be because of that patch,” said Marianne, a participant in a multinational trial of a testosterone patch designed to treat hypoactive sexual desire disorder, in which a woman is devoid of libido. Testosterone, a hormone ordinarily produced by the ovaries, is linked to female sexual function, and the women in this 2005 study had undergone operations to remove their ovaries. After 12 weeks of the trial, Marianne had felt her sexual desire return. Touching herself unleashed erotic sensations and vivid sexual fantasies. Eventually she could make love to her husband again and experienced an orgasm for the first time in almost three years. But that improvement was not because of testosterone, it turned out. Marianne was among the half of the women who had received a placebo patch—with no testosterone in it at all. Marianne’s experience underlines the complexity of sexual arousal. Far from being a simple issue of hormones, sexual desire and orgasm are subject to various influences on the brain and nervous system, which controls the sex glands and genitals. And many of those influences are environmental. Recent research, for example, shows that visual stimuli spur sexual stirrings in women, as they do in men. Mari­anne’s desire may have been invigorated by conversations or thoughts about sex she had as a result of taking part in the trial. Such stimuli may help relieve inhibitions or simply whet a person’s appetite for sex. © 1996-2008 Scientific American Inc.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 11638 - Posted: 06.24.2010

Last summer, Mark Cheslen noticed that his dog Roxi was having trouble playing fetch at the local lake. Soon, Roxi’s vision deteriorated “to the point where she couldn’t see anything straight ahead, to the point that we’d walk out of the room and she’d still be looking up just to think we were still there,” Chelsen says. The vet’s diagnosis: a degenerative retinal disease with no known cure. That’s a hard answer for any pet owner to hear, and for Chelsen, more bad news was coming. Over the next few months, his nine-year old golden retriever also was found to have a brain tumor and a lung problem that eventually caused her death this past winter. But during Roxi’s last weeks, Chelsen did have a source of comfort: Roxi could see. Under the care of researcher and veterinary ophthalmologist Sinisa Grozdanic at Iowa State University, Roxi was the first dog to receive an experimental treatment for her retinal degeneration disease, a condition which can afflict dogs of any age. Grozdanic says after that the treatment, Roxi “pretty much recovered the vision to the point of a healthy dog.” Mark Chelsen says that as Roxi passed away, she “watched us as if to say good bye. Imagine if she could not see.” Grozdanic cautions that Roxi’s result may not be typical. But in her case at least, the result of the eye treatment was dramatic. “If somebody told me that this is possible, a month ago, I would say that it’s just a pure lie,” says Grozdanic. © ScienCentral, 2000-2008.

Keyword: Vision; Neuroimmunology
Link ID: 11637 - Posted: 06.24.2010

By Bruce Bower Just because there’s no patent office in the jungle doesn’t mean that its inhabitants are uninventive. Japanese researchers working in a forested region of Guinea, West Africa, have issued a rare description of a chimpanzee creating a new form of tool use and later instituting improvements to the technique. In March 2003, a team led by primatologist Shinya Yamamoto of Kyoto University saw a 5-year-old male chimp known as JJ sitting in a tree, fishing carpenter ants out of a hollow in the trunk with a long stick. During the researchers’ 27 years of studying chimps almost year-round in Guinea’s Bossou community, they had never observed such behavior. Bossou chimps prefer to poke long sticks into nests of driver ants on the ground and then swipe the ant-coated tools across their mouths for a quick snack. This behavior is called ant-dipping. JJ’s initial forays into what’s called ant-fishing, a behavior typical of some chimp communities elsewhere in Africa, achieved limited success. He managed to capture and consume ants on only three of 14 attempts, using roughly 34 centimeter–long sticks. Each attempt lasted 10 to 13 minutes. JJ also received three painful ant bites for his trouble. © Society for Science & the Public 2000 - 2008

Keyword: Evolution; Learning & Memory
Link ID: 11636 - Posted: 06.24.2010

By Susan Levine When Chuck Jackson takes his seat this morning before a U.S. Senate committee, he'll not lack for names or faces as he talks about the devastation that a disease called Alzheimer's has visited upon his family. His grandfather John. A dozen aunts and uncles. His mother, Rachel; a brother, Danny. Plus every year, a growing list of cousins. For decades, he'll say, most of them knew it only as the "family disease." It struck them almost always at young ages. Jackson's mother was 44 when she said, "I'm not right in the head anymore," and her son, barely into his teens, became the default caregiver on their small farm in the Oklahoma Panhandle. He will tell the Special Committee on Aging about the sometimes bizarre symptoms, the inexorable losses. He will also tell the panel how Alzheimer's overshadows his own life. His illness was diagnosed four years ago, when he was 50. His generation is at least the fifth to bear such a burden. "Enough generations," he said. Jackson is speaking out as few of his relatives ever dared to do. He is part of a nascent self-advocacy movement in Washington and other cities, an assertion of courage, even defiance, given the stigma attached to dementia. For most people, Alzheimer's is a synonym for fear and despair. © 2008 The Washington Post Company

Keyword: Alzheimers
Link ID: 11635 - Posted: 06.24.2010

By Jerry Adler With eight months left in 2008, it might be premature to choose the weirdest book of the year, but "The Woman Who Can't Forget," the memoir of a 42-year-old California woman named Jill Price, will be hard to beat. It poses a thought-provoking question—what would it be like to recall almost every day of your life since childhood?—and then unintentionally answers: it's like being stuck on an airplane watching an endless loop of security-camera video. Oddly, in this era of luridly factitious memoirs, Price's comes with unimpeachable credentials. She first came to public attention in 2006 as "AJ," the pseudonymous subject of a paper in the journal Neurocase entitled "A Case of Unusual Autobiographical Remembering." The lead author, James L. McGaugh, a professor of neurobiology at the University of California, Irvine, spent five years bombarding Price with psychological, neurological and physiological tests to investigate what was going on inside her otherwise quite ordinary mind. He coined a new term for her condition, "hyperthymestic syndrome." It means "overdeveloped memory," but of a very particular kind. Price has no special aptitude for memorizing lists of words or numbers, or for facts or stories or languages. She was an average student. What Price does remember—obsessively, uncontrollably and with remarkable accuracy—is stuff that happened to her. Price's memory, which she describes as "shockingly complete" beginning in 1974, when she was 8, and "near perfect" from 1980 on, appears to be organized like a diary. Given a date from the last 30 years, she can instantly summon up the day of the week, and usually at least some tidbit of biographical trivia. "On Friday afternoon, October 19, 1979," she writes, "I came home from school and had some soup because it was unusually cold that day." © 2008 Newsweek, Inc.

Keyword: Learning & Memory
Link ID: 11634 - Posted: 06.24.2010

By Rick Hanley and Debi Roberson How do we perceive a rainbow? And does everyone perceive a rainbow in the same way? These seemingly simple questions can reveal some interesting features of the human brain. For instance, is the “striped” appearance of the rainbow—the seven distinct bands of color that we see—a construct of our higher mental processes, or do the mechanics of human color vision determine it at a very early perceptual level? If your language does not have separate words for “blue” and “green” (and many languages, including Welsh, do not), do you perceive these shades as more similar than a speaker of English? Searching for answers to these questions, in recent years many scientists have concluded that speakers of languages that label color in ways distinct from those used in English may see a different rainbow from that of English speakers. Recent studies have claimed that language processing is automatically involved in perceptual decisions about color in the brains of adults, even when hues are visible only briefly (100 milliseconds) or when decisions do not require participants to name colors verbally. Moreover, these effects are language-specific, so speakers of Russian or Korean show a different pattern of responses to color than speakers of English. A recent study in PNAS by researchers at the University of Surrey challenges this view, however. It suggests an intriguing and novel account of color categorization in infants. In this study 18 English-speaking adults and 13 four-month-old infants were shown a colored target on a colored background. Adults were faster to initiate eye-movements toward the target when the target and background colors came from different color categories (for example, blue target, green background) than when both target and background were the same color (such as different shades of blue). © 1996-2008 Scientific American Inc.

Keyword: Vision; Development of the Brain
Link ID: 11633 - Posted: 06.24.2010

Not all fat is created equal. Accumulating most of your fat around your waistline, or having what's often called an "apple shape," is known to be more dangerous than storing fat around your hips and buttocks, known as having a "pear shape." That's because they are actually two different kinds of fat. The fat in your abdomen tends to be visceral fat, which builds up around your organs, as opposed to subcutaneous fat, or fat under the skin. Visceral fat is strongly linked to metabolic syndrome, the insulin resistance that increases our risk of heart disease, cancer, and all sorts of diseases associated with aging. Obesity researcher Daniel Eitzman says that makes it tricky to study the effects of the fat itself. "When we look at obese humans or animal models of obesity, they develop other well-established risk factors such as diabetes or elevated blood cholesterol that can affect heart disease," he explains. "So it's difficult to tease apart the specific role of the belly fat from these other associated risk factors that are triggered by obesity." But in a new study in mice, Eitzman and his team at the University of Michigan were able to control for those factors. © ScienCentral, 2000-2008.

Keyword: Obesity
Link ID: 11632 - Posted: 06.24.2010

By Jocelyn Kaiser A daring attempt to use gene therapy to treat a rare, devastating disorder that destroys the brains of children has shown signs of slowing the disease's progression, according to a new paper. However, some experts aren't convinced that the treatment, which involved dripping a virus into young patients' brains, actually worked. The children all have late infantile neuronal ceroid lipofuscinosis (LINCL), a form of the neurodegenerative disorder Batten disease. They were born without a working copy of CLN2, a gene whose protein helps lysosomes--the cell's garbage-disposing structures--break down a waste product called lipofuscin. As a result, lipofuscin builds up and eventually destroy neurons, causing the brain to shrink. Children with LINCL seem normal at birth but by age 2 to 4 show signs of developmental problems and often have seizures. Eventually blind and confined to a wheelchair, they usually die by 8 to 12 years of age. A few years ago, gene therapy researcher Ronald Crystal and colleagues at Weill Cornell Medical College in New York City successfully slowed LINCL in mice using gene therapy in the brain. To test the safety of the approach in humans, the team treated 10 LINCL patients ranging in age from 3 to 10 years, starting in 2004. After anesthetizing the children, the researchers drilled six 2-mm-wide holes in their skulls. They then dripped in a solution of a harmless virus that had been modified to carry a good copy of the CLN2 gene. Four children had an immune response, but it was mild. One patient developed seizures 2 weeks later and died 49 days after the surgery. However, she did not have brain inflammation, and Crystal says it was not clear whether her death had anything to do with the gene therapy. © 2008 American Association for the Advancement of Science

Keyword: Genes & Behavior; Development of the Brain
Link ID: 11631 - Posted: 06.24.2010

Jim Schnabel Blindness leaves its hallmark on the brain even after sight returns.GettyTwo people have been found to retain a mark of blindness years after their sight was partially restored. A part of their visual cortex that normally responds to visual motion now also responds to auditory motion. Researchers who have studied the pair suspect that the subjects have an enhanced ability to track moving sounds, although they have yet to test this. The brains of people who lose their sight at a young age have long been known to turn parts of the visual cortex to non-visual tasks, making use of its spare capacity to handle the processing of auditory and tactile inputs. But it is hard to study exactly how this happens or which subregions are involved, says Melissa Saenz, a neuroscientist at the California Institute of Technology in Pasadena who led the team that conducted the study. “There’s a lot of variability in the brain from one person to another, and in this large region [the visual cortex] particularly. And obviously if a subject is blind, you can’t use visual stimuli to make a functional map of his or her visual cortex.” Saenz found two very rare patients who had lost their sight at an early age but partly recovered it in their 40s: one following a cataract operation, the other after an experimental stem-cell therapy and a corneal transplant. The latter individual, Mike May, now 54, has had his sight-recovery experience portrayed in a book and a television documentary. © 2008 Nature Publishing Group

Keyword: Vision; Hearing
Link ID: 11630 - Posted: 06.24.2010

By Elsa Youngsteadt It's time to retract those disparaging comments about sloths: They actually don't sleep all the time. Sloths are certainly not insomniacs, but a new miniature brain-recording device shows that, in nature, the animals snooze a respectable 9.6 hours per day. Researchers previously believed that sloths slept nearly 16 hours per day. That figure was based on studies of captive sloths using electroencephalograms (EEGs), which detect brain activity associated with slumber. The animals might sleep differently in nature, but good luck keeping a wild sloth wired to the usual heavy EEG equipment. Enter the portable EEG recorder. Developed in part by neurophysiologist Alexei Vyssotski of the University of Zürich, Switzerland, the apparatus is housed in a cap that fits on top of an animal's head. Small wires placed just under the skin of the scalp detect brain waves and send the numbers to a data logger hidden inside the device. A team led by Niels Rattenborg, a sleep researcher at the Max Planck Institute for Ornithology in Starnberg, Germany, caught three brown-throated three-toed sloths (Bradypus variegates) in Panama and installed the mini EEG recorders, a process that took about 1 hour per animal. After 5 days, the researchers tracked down the sloths and retrieved the data loggers. "The thing that really astonished us," Rattenborg says, "was that they slept just nine and a half hours per day." © 2008 American Association for the Advancement of Science.

Keyword: Sleep
Link ID: 11629 - Posted: 06.24.2010