By DONALD G. McNEIL Jr. Confirming the fears of Somali immigrants in Minneapolis, the Minnesota Health Department agreed Tuesday that young Somali children there appeared to have higher-than-usual rates of autism. Though health officials emphasized that their report was based on very limited data, they concluded that young Somali children appeared to be two to seven times as likely as other children to be in classes for autistic pupils. Dr. Sanne Magnan, the state health commissioner, said the finding was “consistent with the observations by parents,” who have been saying for more than a year that alarming numbers of Somali children born in this country have severe autism. Somalis began immigrating into the area in the 1990s, fleeing civil war in their homeland. The report made no effort to explain why the children had autism. Its authors did not examine children or their medical records. They accepted the diagnoses — some by doctors, some by school evaluators — that admitted children to special-education classes, and they calculated rates for different ethnic groups. They counted only 3- to 4-year-olds, only children in Minneapolis public schools, and only children born in Minnesota. They drew no comparisons with Somalis in other cities. There have been anecdotal reports of higher autism rates among Somalis in some American cities, and no formal studies. A small study in Sweden reported high rates among Somali schoolchildren in Stockholm. Copyright 2009 The New York Times Company

Keyword: Autism
Link ID: 12732 - Posted: 06.24.2010

Heightened activity in an area of the brain that deals with memory may give a subtle early warning of dementia decades later, UK research suggests. It was known that carrying a rogue version of a gene called ApoE4 raised the risk of Alzheimer's disease. Now researchers have linked the same mutation with raised activity in an area of the brain called the hippocampus in people as young as 20. The study appears in Proceedings of the National Academy of Science. The researchers, from Oxford University and Imperial College London, believe over-activity in the hippocampus may effectively wear it out, raising the risk of dementia in later life. They hope their work could be a first step towards developing a simple method to identify people at increased risk of developing dementia. They could then potentially be offered early treatment and lifestyle advice. Carrying one copy of the rogue ApoE4 gene raises the risk of Alzheimer's by up to four times the normal, two copies by up to 10 times. But not everyone with the rogue gene will develop the condition. The latest study used scans to compare brain activity in 36 volunteers aged 20 to 35. In those who carried the rogue gene activity in the hippocampus was consistently raised, even at rest. Researcher Dr Clare Mackay said: "These are exciting first steps towards a tantalising prospect: a simple test that will be able to distinguish who will go on to develop Alzheimer's." (C)BBC

Keyword: Alzheimers
Link ID: 12731 - Posted: 04.07.2009

by Helen Thomson By the time you retire, there's no doubt about it, your brain isn't what it used to be. By 65 most people will start to notice the signs: you forget people's names and the teapot occasionally turns up in the fridge. There is a good reason why our memories start to let us down. At this stage of life we are steadily losing brain cells in critical areas such as the hippocampus - the area where memories are processed. This is not too much of a problem at first; even in old age the brain is flexible enough to compensate. At some point though, the losses start to make themselves felt. Clearly not everyone ages in the same way, so what's the difference between a jolly, intelligent oldie and a forgetful, grumpy granny? And can we improve our chances of becoming the former? Exercise can certainly help. Numerous studies have shown that gentle exercise three times a week can improve concentration and abstract reasoning in older people, perhaps by stimulating the growth of new brain cells. Exercise also helps steady our blood glucose. As we age, our glucose regulation worsens, which causes spikes in blood sugar. This can affect the dentate gyrus, an area within the hippocampus that helps form memories. Since physical activity helps regulate glucose, getting out and about could reduce these peaks and, potentially, improve your memory (Annals of Neurology, vol 64, p 698). © Copyright Reed Business Information Ltd.

Keyword: Alzheimers; Development of the Brain
Link ID: 12730 - Posted: 06.24.2010

by Anil Ananthaswamy Healthy young adults carrying a gene variant that is a major risk factor for the disease seem to have extra activity in brain regions related to memory, even when their brains are at rest. The gene APOE codes for a protein thought to help create, maintain and repair neuronal connections. One variant, epsilon 4, is considered the biggest risk factor for getting Alzheimer's, increasing your risk by up to 4 times if you have one copy and up to 12 if you have two. It is not known exactly how epsilon 4 ups the risk, but in people who carry it and have developed Alzheimer's, the hippocampus, which is involved in memory functions, is usually smaller. To figure out if epsilon 4 influences brain function earlier on in life, Clare Mackay of the University of Oxford and colleagues at Imperial College London scanned the brains of 18 healthy adults with epsilon 4 and 18 controls who did not have the variant. In the scanner, the volunteers spent time performing memory tests and also doing nothing. During the memory task, the epsilon 4 carriers had more activity in the hippocampus compared with controls, even though there was no difference in their performance on the tests, suggesting that their hippocampuses expend more energy to achieve the same result. © Copyright Reed Business Information Ltd.

Keyword: Alzheimers
Link ID: 12729 - Posted: 06.24.2010

By Bruce Bower CHICAGO — Give the chimpanzees living at Uganda’s Toro-Semliki Wildlife Reserve a hand for having the mental moxie to dig water-collection holes along the edge of a river that flows only during rainy months. In fact, give them two hands, because wells dug by these chimps show no evidence of having been fashioned by either right-handers or left-handers, according to anthropologist Linda Marchant of Miami University in Oxford, Ohio. Evidence of ambidexterity in Semliki chimps counters a suggestion from other researchers, based largely on studies of captive animals, that chimps often favor one hand over the other when performing various tasks. If it exists, chimp handedness interests researchers because it may reflect an evolutionary move toward a brain organized more like that of people — with one hemisphere dominating over the other and prompting either right- or left-handedness —than has often been assumed. “We see no signs of handedness among the Semliki chimps, which appears to be the condition in the wild,” said anthropologist and study coauthor William McGrew of the University of Cambridge in England. Marchant presented her team’s new findings on April 3 at the American Association of Physical Anthropologists annual meeting. Rather than excluding hand preferences altogether among wild chimps, findings at Semliki indicate that chimps use both hands equally on physically demanding jobs, such as well digging, remarked Elizabeth Lonsdorf, director of the Lester E. Fisher Center for the Study and Conservation of Apes at Lincoln Park Zoo in Chicago. © Society for Science & the Public 2000 - 2009

Keyword: Laterality; Evolution
Link ID: 12728 - Posted: 06.24.2010

Women given testosterone for a month were no more likely than women not receiving the hormone to engage in risky financial decisions, according to researchers in Sweden. The findings could suggest that women are a safer pair of hands on the stock-market trading floor than men — or throw into doubt earlier findings about the effect of the hormone on men. A spate of recent studies have found correlations between testosterone levels and risky behaviour in men, including one that found that male securities traders with more testosterone in their saliva made riskier financial decisions1. But now a team led by Magnus Johannesson, an economist at the Stockholm School of Economics, has found no such effects in a group of 200 post-menopausal women. The women were administered testosterone, oestrogen or a placebo for four weeks and asked to play a series of economic games that measure the player's propensity to take risks, their trust and their willingness to share resources. In the 'dictator game', for example, a player can decide how much of a pot of money they will share with a charity and how much to keep for themselves. The team thought that the testosterone-taking women would behave more like men, giving less to charity and accepting more risk in an investment game. Yet their results, which are published in the Proceedings of the National Academy of Sciences, revealed no meaningful differences between the women who had taken testosterone or oestrogen and the placebo group2. "My assumptions have changed a lot," Johannesson says. © 2009 Nature Publishing Group

Keyword: Hormones & Behavior; Aggression
Link ID: 12727 - Posted: 06.24.2010

By Claire Thomas How does the brain cope when, several years after having both hands amputated, a person suddenly receives two new hands? Surprisingly well, it seems. In a study out today, researchers provide the most detailed picture yet of how the brain reorganizes itself to accommodate foreign appendages. And in a result that they are still trying to explain, the scientists found that in two such double-hand transplants, the left hand reconnected with the brain more quickly than did the right. A group of French and Australian doctors performed the world's first hand transplant in 1998, and the same team repeated the feat on both hands 2 years later. Studies carried out since then indicate that the brain reorganizes itself in response to these new appendages. However, the work looked only at coarse hand movements that mainly used nontransplanted muscles. Wanting to learn more about how the brain copes with donor hands, cognitive neuroscientist Angela Sirigu of the French National Research Agency in Lyon and colleagues looked at two right-handed men, one age 20 and the other 42, who recently had left and right hand transplants to replace hands amputated following work injuries 3 to 4 years ago. After extensive training, both men are now able to perform a range of complex tasks with the foreign appendages, from dialing a phone number to using tools such as screwdrivers and pliers to rewire an electrical outlet. The researchers found that both men's motor cortexes--the region of the brain responsible for carrying out muscle movement--had reorganized themselves in response to the new hands. After a person loses a hand, the region of the motor cortex that controls hand movement shrinks and rewires itself to control the upper arm, a property called plasticity. But when Sirigu and colleagues used transcranial magnetic stimulation--a technique that employs magnetic fields to excite neurons in the brain--to stimulate specific fragments of the motor cortex, they found that the "hand areas" in the motor cortex of both men had reassumed their original "wiring." © 2009 American Association for the Advancement of Science.

Keyword: Regeneration
Link ID: 12726 - Posted: 06.24.2010

By ANNIE LUBLINER LEHMANN When my husband and I were told that our son Jonah’s autism was “untreatable,” we made up our minds to prove the experts wrong. We were young and energetic, and the developmental gap between 3-year-old Jonah and his peers, while obvious, was not glaring. With no other children to care for at the time, we made helping Jonah the focus of our lives. Every exchange would become a lesson, every experience a tutorial. Jonah cared most about food (and still does), so I’d go to the grocery store with a list and an agenda, hoping to use that passion to teach him essential concepts. I would follow his gaze and point out colors (red apple) and shapes (round cookie). When he turned away from such lessons, despite our most animated efforts, we tried everything else we could think of. Nothing was too difficult or too expensive. We gave him vitamins and restricted his diet. We introduced communication boards and arranged sensory integration therapy. We had him wear headphones to normalize his hearing and tried other snake-oil treatments no thinking person would consider. But each hope was followed by disappointment. We might as well have been chasing butterflies with a torn net. By the time Jonah reached his teens, we were worn out and frustrated, not very far from where we’d started. We faced the specter of hopelessness and a plethora of unanswerable questions. Copyright 2009 The New York Times Company

Keyword: Autism
Link ID: 12725 - Posted: 06.24.2010

By David Dobbs When Helen Mayberg started curing depression by stimulating a previously unknown neural junction box in a brain area called Brod­mann’s area 25—discovered through 20 years of dogged research—people asked her where she was going to look next. Her reaction was, “What do you mean, Where am I going to look next? I’m going to look more closely here!” Her closer look is now paying off. In a series of papers last year, May­berg and several of her colleagues used diffusion tensor imaging (DTI) to reveal the neural circuitry of depression at new levels of precision. This MRI technique illuminates the connective tracts in the brain. For depression, the resulting map may allow a better understanding of what drives the disorder—and much better targeting and patient selection for treatments such as deep-brain stimulation (DBS) that seek to tweak this circuitry. In the early 2000s Mayberg and Wayne C. Drevets, then at Washington University Medical School, separately established that area 25, which appeared to connect several brain regions involved in mood, thought and emotion, is hyperactive in depressed patients. The area’s significance was confirmed when Mayberg and her colleagues at the University of Toronto—neurosurgeon Andres Lazano and psychiatrist Sidney Kennedy—used DBS devices to bring relief to 12 out of 20 intractably depressed patients [see “Turning Off Depression,” by David Dobbs; Scientific American Mind, August/September 2006]. “That confirmed my hypothesis that area 25 is an important crossroads,” Mayberg says. “But exactly what circuits were we affecting?” © 1996-2009 Scientific American Inc.

Keyword: Depression; Brain imaging
Link ID: 12724 - Posted: 06.24.2010

Scientists have shown scratching helps relieve an itch as it blocks activity in some spinal cord nerve cells that transmit the sensation to the brain. However, the effect only seems to occur during itchiness itself - scratching at other times makes no difference. While it is widely-known scratching relieves an itch, the physiological mechanisms for how this works are little understood. The University of Minnesota study appears in Nature Neuroscience. Previous research has suggested that a specific part of the spinal cord - the spinothalamic tract - plays a key role. Nerve cells in this area have been shown to be more active when itchy substances are applied to the skin. The latest work, in primates, found that scratching the skin blocks activity of nerve cells in the spinothalamic tract during itchiness - preventing the spinal cord from transmitting signals from the scratched area of skin to the brain. Researcher Dr Glenn Giesler hopes the work could lead to ways to relieve chronic itch effectively for the first time. However, he said more information was still needed about the chemistry underpinning the effect. Professor Gil Yosipovitch, an expert on itching from Wake Forest University in North Carolina, said the finding was "potentially significant". He said: "Although there is a long way to go, methods that can induce a pleasurable scratch sensation without damaging the skin, via mechanical stimuli or drugs that can inhibit these neurons, could be developed to treat chronic itch." (C)BBC

Keyword: Pain & Touch
Link ID: 12723 - Posted: 04.06.2009

By Rob Stein Children raised in poverty suffer many ill effects: They often have health problems and tend to struggle in school, which can create a cycle of poverty across generations. Now, research is providing what could be crucial clues to explain how childhood poverty translates into dimmer chances of success: Chronic stress from growing up poor appears to have a direct impact on the brain, leaving children with impairment in at least one key area -- working memory. "There's been lots of evidence that low-income families are under tremendous amounts of stress, and we know that stress has many implications," said Gary W. Evans, a professor of human ecology at Cornell University in Ithaca, N.Y., who led the research. "What this data raises is the possibility that it's also related to cognitive development." With the economic crisis threatening to plunge more children into poverty, other researchers said the work offers insight into how poverty affects long-term achievement and underscores the potential ramifications of chronic stress early in life. "This is a significant advance," said Bruce S. McEwen, who heads the laboratory of neuroendocrinology at Rockefeller University in New York. "It's part of a growing pattern of understanding how early life experiences can have an influence on the brain and the body." © 2009 The Washington Post Company

Keyword: Stress; Development of the Brain
Link ID: 12722 - Posted: 06.24.2010

by Graham Lawton So you're in your early 20s and your brain has finally reached adulthood. Enjoy it while it lasts. The peak of your brain's powers comes at around age 22 and lasts for just half a decade. From there it's downhill all the way. The peak of your brain's powers comes at age 22 and lasts for just half a decade This long, slow decline begins at about 27 and runs throughout adulthood, although different abilities decline at different rates. Curiously, the ones that start to go first - those involved with executive control, such as planning and task coordination - are the ones that took the longest to appear during your teens. These abilities are associated with the prefrontal and temporal cortices, which are still maturing well into your early 20s. Episodic memory, which is involved in recalling events, also declines rapidly, while the brain's processing speed slows down and working memory is able to store less information. So just how fast is the decline? According to research by Art Kramer, a psychologist at the University of Illinois in Urbana-Champaign, and others, from our mid-20s we lose up to 1 point per decade on a test called the mini mental state examination (see graph). This is a 30-point test of arithmetic, language and basic motor skills that is typically used to assess how fast people with dementia are declining. A 3 to 4 point drop is considered clinically significant. In other words, the decline people typically experience between 25 and 65 has real-world consequences. © Copyright Reed Business Information Ltd

Keyword: Development of the Brain; Learning & Memory
Link ID: 12721 - Posted: 06.24.2010

By Melinda Wenner Neuroscience has long focused on the brain in terms of components: the visual cortex processes what we see, Broca’s area is the center for language, and so on. As our understanding of the brain has improved, however, it has become clear that a more accurate model depends on how these modules are wired together in circuits. A technique called diffusion tensor imaging (DTI) gives us a tool to probe the nature of those connections. A recent study suggests, for instance, that the more a person seeks out new experiences and relies on social approval, the stronger his or her wiring is among brain areas involved in reward, emotion and decision making. Cognitive neuroscientist Michael Cohen and his colleagues at the University of Bonn in Germany asked 20 adults how often they sought out new experiences and relied on social approval. Then they used DTI to look at the subjects’ white matter, which ­connects disparate regions of the brain. Cognition and high-level processing happen in gray matter, found mostly in the outer layer of the brain and made up of the main cell bodies of neurons. White matter, on the other hand, is made up of the long, spindly “arms” of neurons, called axons, along which electrical signals travel. (This interior part of the brain looks white because the axons are sheathed in myelin, a white insulating protein that helps signals travel more quickly.) Cohen’s team found that the more the subjects sought new experiences, the stronger their connections were from the hippocampus and amygdala, brain regions involved in decision making and emotion, to the ventral and mesial striatum, areas that process information related to emotion and reward. The scientists also found that the subjects who were most dependent on social approval had stronger than normal connections between the striatum and the prefrontal cortex, a brain area involved in higher-order decision making. © 1996-2009 Scientific American Inc.

Keyword: Brain imaging
Link ID: 12720 - Posted: 06.24.2010

By BENEDICT CAREY Suppose scientists could erase certain memories by tinkering with a single substance in the brain. Could make you forget a chronic fear, a traumatic loss, even a bad habit. Researchers in Brooklyn have recently accomplished comparable feats, with a single dose of an experimental drug delivered to areas of the brain critical for holding specific types of memory, like emotional associations, spatial knowledge or motor skills. The drug blocks the activity of a substance that the brain apparently needs to retain much of its learned information. And if enhanced, the substance could help ward off dementias and other memory problems. So far, the research has been done only on animals. But scientists say this memory system is likely to work almost identically in people. The discovery of such an apparently critical memory molecule, and its many potential uses, are part of the buzz surrounding a field that, in just the past few years, has made the seemingly impossible suddenly probable: neuroscience, the study of the brain. “If this molecule is as important as it appears to be, you can see the possible implications,” said Dr. Todd C. Sacktor, a 52-year-old neuroscientist who leads the team at the SUNY Downstate Medical Center, in Brooklyn, which demonstrated its effect on memory. “For trauma. For addiction, which is a learned behavior. Ultimately for improving memory and learning.” Copyright 2009 The New York Times Company

Keyword: Learning & Memory; Emotions
Link ID: 12719 - Posted: 06.24.2010

By Andy Greenberg, Forbes.com The Force, it seems, is not so strong with this one. In the virtual world of a game called Neuroboy, I'm staring out over a lagoon at an exact digital replica of a Star Wars X-wing spaceship submerged in blue water. My task: to lift that virtual object out of its murky depths using not my mouse or keyboard, but instead — ą la Luke Skywalker — my thoughts. Back in the real world, I'm wearing a bluetooth headset that touches my forehead with a single metal sensor. The more I relax, according to the headset's manufacturer, Neurosky, the more that small metal point will pick up my brain's alpha waves, triggering the ship to rise. I relax. The spaceship doesn't budge. I close my eyes to slits and let myself slip into a half-trance daze. The ship wiggles ever so slightly, and I respond with a bit of hopeful excitement that immediately sends it sinking back into the water. After a minute or so of frustration, I retreat to my keyboard to switch the game from "lift" to "pull" mode. Suddenly, and without a single Jedi mind trick, the X-wing leaps toward me and fills the entire screen, only coming to rest when I pull off the headset to break the sensor's connection with my forehead. Either my mental powers aren't yet ready for Neurosky's gadgetry, or vice versa. Ready or not, telekinesis gadgets like Neurosky's so-called "Mindset" are coming to market, along with those built by competitors like OCZ Technology and Emotiv Systems. Neurosky plans to announce Thursday at the Game Developers Conference in San Francisco that it's partnering with Toshiba to release the $199 US consumer headsets this summer, along with a software platform for third-party developers to create games and other applications for the device. © CBC 2009

Keyword: Robotics
Link ID: 12718 - Posted: 06.24.2010

By Bruce Bower CHICAGO — In the strange and contentious world of fossil hobbits, a chimp-sized brain may boast humanlike powers. An analysis of the inner surface of an 18,000-year–old skull assigned to Homo floresiensis, a species also known as hobbits, indicates that this tiny individual possessed a brain blessed with souped-up intellectual capacities needed for activities such as making stone tools, says anthropologist Dean Falk of Florida State University in Tallahassee. Even as H. floresiensis evolved a relatively diminutive brain, the species underwent substantial neural reorganization that allowed its members to think much like people do, Falk contended on April 2 in a presentation at the American Association of Physical Anthropologists annual meeting. She also reported the findings in a paper published online February 28 in the Journal of Human Evolution. Falk compared a cast of the cranium’s inner surface, or endocast, obtained from the partial hobbit skeleton LB1 to endocasts from both modern humans and from other fossil skulls in the human evolutionary family, called hominids for short. These casts bring into relief impressions made by various anatomical landmarks on the brain’s surface. “LB1 reveals that significant cortical reorganization was sustained in ape-sized brains of at least one hominid species,” Falk said. © Society for Science & the Public 2000 - 2009

Keyword: Evolution
Link ID: 12717 - Posted: 06.24.2010

Prions, the mis-folded proteins best known for causing diseases such as bovine spongiform encephalopathy in cows, scrapie in sheep and Creutzfeldt–Jakob disease in humans, could also help yeast survival, according to a study in the journal Cell1. "We think prions are really important," says co-author Simon Alberti of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. "When environmental conditions are harsh, they might allow a species to survive." The work, led by Susan Lindquist of the Whitehead Institute, bolsters the theory that prions might confer an evolutionary advantage, says Alberti. Lindquist first broached that idea nine years ago, after finding that a prion called PSI+ in the yeast Saccharomyces cerevisiae triggered heritable changes that could provide a way of adapting to fluctuating environments2. More recent work also suggests prions might play a role in memory in sea slugs and smell in mice. In the new work, a scan of the S. cerevisiae genome yielded 24 potential prion-forming proteins. Only five prions were known to exist in yeast before this study. The team focused on a protein called Mot3 and found that it can twist into a prion form. When in its normal shape, Mot3 suppresses yeast genes involved in building the cellular wall. But when Mot3 kinks into a prion, it loses this function and the wall-building genes activate. Hence, yeast carrying the Mot3 prions grew thicker, more robust cell walls. © 2009 Nature Publishing Group,

Keyword: Prions
Link ID: 12716 - Posted: 06.24.2010

New research is shining a light on differences in the brains of soldiers with post-traumatic stress disorder when compared with soldiers who return from combat without the condition. The work could some day lead to the use of brain scans to help diagnose PTSD, to tailor treatment or even identify people who might be at risk of developing the problem if they're exposed to violence in a war zone, experts say. 'This is consistent with the hypervigilance symptoms that are associated with PTSD that might make these people be very sensitive to detecting anything that could be relevant for survival.'— Dr. Florin Dolcos Dr. Florin Dolcos, an assistant professor of psychiatry and neuroscience at the University of Alberta, travelled to Italy to present the research Friday at the World Psychiatric Association congress in Florence. The experiments were conducted in North Carolina by a team led by Dr. Rajendra Morey of Duke University. Morey is also director of the neuroimaging lab at Durham Veterans Administration Medical Center. Forty-two U.S. soldiers who had returned from Iraq and Afghanistan took part in the study, including 22 soldiers who had developed post-traumatic stress disorder and 20 who had not. © CBC 2009

Keyword: Stress; Brain imaging
Link ID: 12715 - Posted: 06.24.2010

By Roberta Friedman Scientists know that small variations in certain genes can predispose people to cancers or heart disease. Now researchers are starting to show a direct, quantifiable effect on learning traceable to these types of genetic influences: single-nucleotide polymorphisms. A difference in just one amino acid in a protein might explain why some people learn new motor skills faster and reach higher levels of performance. The protein, called brain-derived neurotro­phic factor (BDNF), is a key driver of synaptic plasti­city, the ability of the connections between brain cells to change in strength. This plasticity is an important factor in learning, explains neurologist Janine Reis, who led the study at the National Institutes of Health. According to Reis, this finding offers the first evidence that slight variations in BDNF’s structure affect learning ability. Volunteers with one type of BDNF learned faster and performed better at a task in which they had to grip a handle more or less tightly to move a computer cursor through a sequence of targets. Those with a different variant never reached the skill level acquired by the faster learners. (The researchers excluded people who play video games.) Other groups have found that the BDNF version that Reis linked with poorer acquisition of skills is associated with reduced function of the hippocampus, a brain region involved in motor learning. © 1996-2009 Scientific American Inc.

Keyword: Trophic Factors; Movement Disorders
Link ID: 12714 - Posted: 06.24.2010

By Tina Hesman Saey You snooze, you lose connections between brain cells, two new studies suggest. People have known for some time that getting enough sleep is crucial for proper brain function. “If you don’t get enough sleep your ability to acquire, process and recall information is going to be impaired,” says Paul Shaw, a neuroscientist at Washington University in St. Louis and coauthor of one of the new studies. But scientists debate exactly how sleep helps the brain learn and remember. Two studies appearing in the April 3 Science suggest that sleep weakens or severs connections between brain cells to make way for new information. A study by Giorgio Gilestro, Giulio Tononi and Chiara Cirelli of the University of Wisconsin–Madison shows that proteins found in the connections between neurons, called synapses, build up in fruit fly brains while the flies are awake. Depriving flies of sleep leads to ever-greater levels of synaptic proteins, the researchers show. Levels of the proteins decrease as the flies sleep. Scientists usually determine synapse strength by measuring electrical activity of neurons, but fruit fly brains are far too small for electrical measurements, Cirelli says. The proteins, she says, are markers of synaptic strength. If true, the new finding would offer support for the theory of synaptic homeostasis, advanced by Tononi and Cirelli. The theory holds that sleep scales back the strength of connections between neurons, weakening the strongest connections and completely eliminating the weakest synapses. The cutbacks help save resources, the researchers say, and boost the signal of important memories over the noise of unneeded connections (SN: 12/20/08, p. 9). © Society for Science & the Public 2000 - 2009

Keyword: Sleep; Learning & Memory
Link ID: 12713 - Posted: 06.24.2010