The compelling urge to satisfy one's hunger enlists structures throughout the brain, as might be expected in a process so necessary for survival. But until now, studies of those structures and of the feeding cycle have been only fragmentary--measuring brain regions only at specific times in the feeding cycle. Now, however, Ivan de Araujo, Duke University Medical Center, and colleagues report they have mapped the activity of whole ensembles of neurons in multiple feeding-related brain areas across a full cycle of hunger-satiety-hunger. Their findings, reported in the August 17, 2006, issue of the journal Neuron, published by Cell Press, open the way to understanding how these ensembles of neurons integrate to form a sort of distributed "code" that governs the motivation that drives organisms to satisfy their hunger. In their paper, Ivan de Araujo and colleagues implanted bundles of infinitesimal recording electrodes in areas of rat brain known to be involved in feeding, motivation, and behavior. Those areas include the lateral hypothalamus, orbitofrontal cortex, insular cortex, and amygdala. The researchers then recorded neuronal activity in those regions through a feeding cycle, in which the rats became hungry, fed on sugar water to satisfy that hunger, and then grew hungry again. "This allowed us to measure both the ability of single neurons to encode for specific phases of a feeding cycle and how neuronal populations integrate information conveyed by these phase-specific neurons in order to reflect the animal's motivational state," wrote the researchers.

Keyword: Obesity
Link ID: 9246 - Posted: 08.19.2006

By Kelli Whitlock Burton Three independent research groups have identified a large genetic deletion that causes mental retardation. "They've broken open a bubble of something that's going to lead to a lot of follow up," comments William Dobyns, a developmental neurogeneticist at the University of Chicago, who was not affiliated with any of the studies. Mental retardation comes in a baffling diversity of conditions and could be caused by hundreds of underlying genetic triggers, only a few of which have been identified. One glimmer of hope is the advent of detailed scans of individuals' genomes, which are powerful tools in the search for mutations. However, they yield a deluge of data. Focusing in, researchers in the Netherlands, the United Kingdom, and at the University of Washington (UW) in Seattle decided to take aim at "hot spots" on the genome. These regions are flanked by duplicated genetic sequences prone to rearrangement, which can lead to the accidental loss of genes. Each team examined a different population of people, ranging in size from 50 to 1200, with various kinds of mental retardation. They found that a small number were missing the same six genes on chromosome 17. Two of these genes, when deleted, are thought to be involved with mental retardation. The data suggest that the deletion could be involved in about 1% of all cases of mental retardation, the researchers report online 13 August in a trio of papers in Nature Genetics. © 2006 American Association for the Advancement of Science.

Keyword: Development of the Brain; Genes & Behavior
Link ID: 9245 - Posted: 06.24.2010

The same brain machinery that responds to the active substance in marijuana provides a central "on-demand" protection against seizures, researchers have found. They said their discoveries suggest that the "endocannabinoid" system might constitute a prime target for drugs against seizures of epilepsy and other neurodegenerative diseases. The findings were published by Beat Lutz and Giovanni Marsicano, of Max Planck Institute of Psychiatry and Johannes Gutenberg University in Mainz, and colleagues in the August 17, 2006, issue of the journal Neuron, published by Cell Press. The endocannabinoid system--which includes the receptors, the natural cannabinoid compounds that trigger them, as well as the machinery for regulating the process--was already known to modulate the excitation of neuronal transmission, noted the researchers. However, it had not been established that such modulation might affect neurons in the hippocampus responsible for the "excitotoxicity" that underlies the uncontrolled activity of seizures. Thus, Lutz, Marsicano, and his colleagues used genetic techniques to pinpoint the role of the endocannabinoid system on these neurons and on seizure activity. They used mice as their animal model and induced seizures in these mice with the chemical kainic acid (KA).

Keyword: Drug Abuse; Epilepsy
Link ID: 9244 - Posted: 08.19.2006

A recent study provides evidence that autism affects the functioning of virtually the entire brain, and is not limited to the brain areas involved with social interactions, communication behaviors, and reasoning abilities, as had been previously thought. The study, conducted by scientists in a research network supported by the National Institutes of Health (NIH), found that autism also affects a broad array of skills and abilities, including those involved with sensory perception, movement, and memory. The findings, appearing in the August Child Neuropsychology, strongly suggest that autism is a disorder in which the various parts of the brain have difficulty working together to accomplish complex tasks. The study was conducted by researchers in the Collaborative Program of Excellence in Autism (CPEA), a research network funded by two components of the NIH, the National Institute of Child Health and Human Development and the National Institute on Deafness and Other Communication Disorders. “These findings suggest that further understanding of autism will likely come not from the study of factors affecting one brain area or system, but from studying factors affecting many systems,” said the director of NICHD, Duane Alexander, M.D. People with autism tend to display 3 characteristic behaviors, which are the basis of the diagnosis of autism. Within the last 20 years, however, researchers began studying other aspects of thinking and brain functioning in autism, discovering that people with autism have difficulty in many other areas, including balance, movement, memory, and visual perception skills.

Keyword: Autism
Link ID: 9243 - Posted: 06.24.2010

Jennifer Viegas, Discovery News — Predators prefer to chase smaller-brained prey, which often lack the mental fortitude to escape their brainier hunters, according to a recent study. The findings, published in the Royal Society Journal Biology Letters, suggest brain size evolution may be driven by predator-prey relationships since, like a perpetual "Road Runner" cartoon, each side is forever trying to outwit the other. While there has been a consistent increase in relative brain size, and therefore intelligence, over most mammal groups throughout evolutionary time, predator-prey relationships have led to an intelligence divide, said lead researcher Susanne Shultz. "One could make the argument that there has been an arms race of sorts between prey and their predators, said Shultz, a scientist in the Evolutionary Psychology and Behavioral Ecology Research Group at the University of Liverpool, England. "As prey get better at evading their predators, there is strong selection on predators to adopt counter strategies to better catch prey." Shultz and colleague R.I.M. Dunbar studied data on animals from five forest communities in two continents. The animals came from Taļ National Park in West Africa, the Ituri forest in the Republic of Congo, Mahale National Park in Tanzania, Kibale National Park in Uganda and Manu National Park in Peru. © 2006 Discovery Communications Inc.

Keyword: Intelligence; Evolution
Link ID: 9242 - Posted: 06.24.2010

Seth Borenstein, Associated Press — Sometimes the numbing effect of TV can be helpful. Especially if you're a kid being stuck with a needle at the hospital. Researchers confirmed the distracting power of television — something parents have long known — when they found that children watching cartoons suffered less pain from a hypodermic needle than kids not watching TV. Especially disturbing to the author of the scientific study was that the cartoons were even more comforting than Mom. While it's good to have a powerful distraction for children getting painful medical procedures, it is also troubling "because we have demonstrated the excessive power of television," said chief author, Carlo Bellieni, a father of three and a neonatologist and pediatrician at the University of Siena in Italy. His research at a nearby hospital was reported this week in the British journal Archives of Disease in Childhood. The study involved 69 children, ages 7 to 12, who were separated into three groups and then asked to rate their pain on a numerical scale when they were stuck with needle used to take a blood sample. The children's mothers also rated the kids' pain. © 2006 Discovery Communications Inc.

Keyword: Pain & Touch
Link ID: 9241 - Posted: 06.24.2010

Helen Thomson Adult human brain cells can generate new tissue when implanted into in the brains of mice, new research reveals. The findings could pave the way to new therapies for a host of neurodegenerative diseases, including Alzheimer’s, the researchers say. Furthermore, lab tests show that the mature brain cells have the versatility to divide many times in culture and develop into a wide range of specialised cell types. Researchers at the University of Florida, US, showed for the first time that common human brain cells are adaptable and self-renewing – qualities normally associated with stem cells. Dennis Steindler and his colleagues transplanted adult human brain cells into mice and found that they could successfully generate new neurons and incorporate themselves in a variety of brain regions. The researchers also coaxed a single adult brain cell to divide into millions of new cells in culture. “We can, theoretically, take a single brain cell out of a human being and generate enough brain cells to replace every cell of the donor’s brain,” says Steindler. The new source of human brain cells could be used to repair or replace damaged tissue in degenerative disorders such as Alzheimer’s and Parkinson’s disease, the researchers suggest. © Copyright Reed Business Information Ltd.

Keyword: Neurogenesis; Stem Cells
Link ID: 9240 - Posted: 06.24.2010

Gaia Vince The fastest evolving gene in the human genome is one linked to brain development, researchers say. A study of differences between the human and chimp genomes has identified a gene associated with neural growth in the cerebral cortex – the part of the brain involved in processing thoughts and learning – as having undergone “accelerated evolutionary change”. Katherine Pollard and colleagues at the University of California Santa Cruz, US, suggest that the fast-changing gene may help explain the dramatic expansion of this part of the brain during the evolution of humans. They identified the rapidly evolving region of DNA – called human accelerated region 1 (HAR1) – after carrying out an extensive computational comparison between the genomes of humans, chimpanzees and other vertebrates. There are only two changes in the 118 letters of DNA code that make up HAR1 between the genomes of chimps and chickens. But chimps and humans are 18 letter-changes apart. And those mutations occurred in just five million years, as we evolved from our shared ancestor. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Genes & Behavior
Link ID: 9239 - Posted: 06.24.2010

Birds prove wisdom of 'opposites attract' Michael Hopkin Attention henpecked husbands: animal experts have shown that, for cockatiels at least, a one-sided relationship is the best way to ensure harmonious family life. The cockatiel mating game is largely a case of 'opposites attract', says Rebecca Fox of the University of California, Davis, who led the research. She found that cockatiels (Nymphicus hollandicus) actively seek out potential mates with a personality different to their own, and that these unions tend to progress most smoothly. "Cockatiels are similar to us in the way they have relationships," says Fox. "They have long, cooperative partnerships, raise young together, and compatibility is important to them. It's something people can relate to." The most important consideration for the birds is how agreeable or aggressive their partner is, Fox found when studying their mating tactics. Most aggressive cockatiels tend to court only those that are more docile, and vice versa. This might sound like a recipe for disaster. But it avoids conflicts that might damage the welfare of the birds' young, she explains. "The more agreeable partner is likely to back off and let the less agreeable one cool down in the case of conflict," she says. ©2006 Nature Publishing Group

Keyword: Sexual Behavior
Link ID: 9238 - Posted: 06.24.2010

NEW YORK (Reuters Health) - Elderly diabetics with poor blood sugar control have a high prevalence of undiagnosed cognitive dysfunction, depression and functional disabilities, according to a study by researchers in Boston. Dr. Medha Munshi, of the Joslin Diabetes Center, and colleagues examined the association between cognitive dysfunction and blood sugar control in 60 diabetics older than age 70. These individuals had diabetes for an average of about 14 years and elevated hemoglobin A1C levels -- an indicator of poor blood sugar control. The mean HbA1C level was 7.9 percent. The American Diabetes Association recommends a target A1C level of 7.0 or lower. Several common tests were used to screen for cognitive dysfunction such as the Mini Mental State Examination and standard drawing tests. The subjects were also screened for depression and functional disability. Overall, the Mini Mental State Examination scores correlated with drawing test scores. More than a third had low scores on the drawing tests and these scores were inversely correlated with cognitive function. This suggests an association between cognitive dysfunction and poor blood sugar control, the researchers report in Diabetes Care. © 1996-2006 Scientific American, Inc.

Keyword: Obesity
Link ID: 9237 - Posted: 06.24.2010

Calorie-restriction -- consuming 30-percent fewer calories than normal -- is the only scientifically proven way to slow the process of aging in organisms ranging from yeast to mammals. Now a new study in mice shows that through a similar mechanism, calorie restriction may also slow or prevent Alzheimer's disease. "A decrease in amount of calorie intake might have a causal effect in prevention of Alzheimer's disease," says Giulio Pasinetti, professor of psychiatry and neuroscience at Mount Sinai School of Medicine. He and his team conducted the study in a strain of transgenic mice destined to develop Alzheimer's-like symptoms. The mice that were fed a calorie-restricted diet, mainly by a reduction in their carbohydrate intake, over a period of six months, had fewer disease symptoms than their normal-diet counterparts. "With this kind of calorie restriction we were able to improve memory function – I would say five-fold times more efficient," says Pasinetti. The amount of beta-amyloid peptides, molecules that cause the build-up of characteristic Alzheimer's plaques, was also much lower in the brains of the mice on the low-calorie diet. Since calorie restriction has been found to increase the expression of proteins known as sirtuins, Pasinetti and his team tested whether or not one of these proteins could be responsible for the reduction of Alzheimer's symptoms in these mice. As they reported in the Journal of Biological Chemistry, they synthesized a sirtuin called SIRT1 and applied it to brain cells in the laboratory to see whether they'd see similar results to those with calorie restriction. © ScienCentral, 2000-2006.

Keyword: Alzheimers; Obesity
Link ID: 9236 - Posted: 06.24.2010

Janet Raloff Known largely as a component of rocket fuel, perchlorate is a pollutant that often turns up in soil and water. In dozens of studies, it has perturbed thyroid-hormone concentrations, which can affect growth and neurological development. Data from fish now indicate that perchlorate can also disrupt sexual development. Some of the changes were so dramatic that scientists initially mistook female fish for males. Several females displayed male-courtship behavior and produced sperm. Richard R. Bernhardt of the University of Alaska in Anchorage and his colleagues focused on threespine sticklebacks (Gasterosteus aculeatus), a tiny marine species. For 3 weeks, the researchers incubated wild-captured adults in clean water or in water treated with 30, 60, or 100 parts per million (ppm) perchlorate. The adults spawned during that period. Each group's offspring were then raised to sexual maturity in similarly treated or untreated water. At spawning age, 10 apparent males per treatment group were each given their own aquariums. Once a day, each male received a 10-minute visit from an egg-swollen female in the same treatment group. ©2006 Science Service.

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 9235 - Posted: 06.24.2010

Christen Brownlee Prolonged and frequent use of fetal ultrasound might lead to abnormal brain development, a study in mice suggests. The finding sounds a cautionary note for pregnant women getting the commonplace procedure. In that technique, an ultrasound probe sends high-frequency sound waves into the abdomen of a pregnant woman. The waves bounce back to detectors, creating images of the fetus. Doctors use the pictures to check for birth defects and to assess a fetus' size and movements. Many women also undergo ultrasounds to create collections of early baby pictures. Ultrasound has generally been regarded as safe. However, a few studies have suggested that it might cause neurological changes, such as delayed speech or an increase in left-handedness. Researchers hadn't studied how the number or duration of ultrasound procedures affects neurons growing in the fetal brain, says neuroscientist Pasko Rakic of Yale University. Neurons are created in discrete places within the brain as it develops, and they then travel to the brain's outer layers. Rakic and his colleagues study this process, which is known as neural migration. ©2006 Science Service.

Keyword: Development of the Brain; Brain imaging
Link ID: 9234 - Posted: 06.24.2010

EAST LANSING, Mich. – Surveys by a Michigan State University researcher find that about one-third of the American population does not believe in evolution, a figure which is much higher than those found in similar surveys in European nations and Japan. The research of Jon D. Miller, MSU Hannah Professor of Integrative Studies, is published in the Aug. 11 issue of the journal Science. “One in three American adults firmly rejects the concept of evolution, a significantly higher proportion than found in any western European country,” Miller said. For example, in Iceland, Denmark, Sweden and France, 80 percent or more of adults accepted the concept of evolution, as did 78 percent of Japanese adults. Only adults in Turkey, a predominantly Muslim nation, were less likely to accept the concept of evolution than American adults. The data for the 32 European countries were collected by the European Commission using primarily personal interviews. The Japan data were collected in 2001 by personal interview. The U.S. data were collected by Miller using Knowledge Networks, an online national sample of households selected on a probability basis. All of the interview and online data in the 34 countries were weighted to reflect actual population distributions and are comparable across countries. © 2006 Michigan State University Division of University Relations

Keyword: Evolution
Link ID: 9233 - Posted: 06.24.2010

Blacksburg, Va. -- Songbirds use multiple sources of directional cues to guide their seasonal migrations, including the Sun, star patterns, the earth's magnetic field, and sky polarized light patterns. To avoid navigational errors as cue availability changes with time of day and weather conditions, these "compass" systems must be calibrated to a common reference. Experiments over the last 30 years have failed to resolve the fundamental question of how migratory birds integrate multiple sources of directional information into a coherent navigational system. Last autumn, Rachel Muheim, a postdoctoral associate in biology professor John Phillips' lab at Virginia Tech, captured Savannah sparrows in the Yukon before they headed south. She was able to demonstrate that the birds calibrate their magnetic compass based on polarized light patterns at sunset and sunrise. The research appears in the Aug. 11, 2006, issue of Science, in the article, "Polarized Light Cues Underlie Compass Calibration in Migratory Songbirds," by Muheim, Phillips, and Suzanne Akesson. Muheim did her Ph.D. work at Lund University in Sweden with Akesson, who made the Alaska trip possible. Polarized light is light that oscillates in one plane relative to the direction of propagation. At sunrise and sunset, there is a band of intense polarized light 90 degrees from the sun that passes directly overhead through the zenith and intersects the horizon 90 degrees to the right and left of the sun. Just as the sun location changes with latitude and the time of year, so does the alignment of the band of polarized light.

Keyword: Animal Migration; Vision
Link ID: 9232 - Posted: 08.12.2006

Lauran Neergaard, Associated Press — Scientists have discovered molecular janitors that clear away a sticky gunk blamed for Alzheimer's disease — until they get old and quit sweeping up. The finding helps explain why Alzheimer's is a disease of aging. More importantly, it suggests a new weapon: drugs that give nature's cleanup crews a boost. "It's a whole new way of thinking in the Alzheimer's field," said Dr. Andrew Dillin, a biologist at California's Salk Institute for Biological Studies who led the new research. The discovery, published Thursday by the journal Science, was made in a tiny roundworm called C. elegans. What do worms have to do with people? They're commonly used in age-related genetics research, and the new work involves a collection of genes that people harbor, too. Dillin's team from Salk and the neighboring Scripps Research Institute already is on the trail of potential drug candidates. About 4.5 million Americans have Alzheimer's, a toll expected to more than triple by 2050 as the population grays. The creeping brain disease gradually robs sufferers of their memories and ability to care for themselves, eventually killing them. There is no known cure; today's drugs only temporarily alleviate symptoms. Copyright © 2006 Discovery Communications Inc.

Keyword: Alzheimers
Link ID: 9231 - Posted: 06.24.2010

By NATASHA SINGER Tests that indicated high testosterone levels for Floyd Landis during the Tour de France have again raised questions about whether such substances provide an unfair advantage. But does taking testosterone — a controlled substance whose possession is illegal unless prescribed for medical reasons — automatically improve athletic performance? In sports, testosterone shots or creams are supposed to be magic bullets that spur athletes to train harder, run or bicycle more quickly, jump higher, swim faster, hit a baseball farther, recover sooner, and, let’s not forget, increased sex drive and combativeness. Certainly, the idea that taking doses of the hormone gives competitors an unfair advantage is behind the brouhaha over Floyd Landis, the 2006 Tour de France winner who French officials say tested positive for elevated testosterone on the day of his remarkable comeback during Stage 17. Mr. Landis has denied taking any performance-enhancing substances. But some leading experts who study testosterone are not convinced that supplementing the hormone improves endurance or overall athletic performance. Unlike a hyper-caffeinated sports drink, the synthetic hormone does not provide an instant jolt, but works over time to bulk and fortify muscles. What other effects taking testosterone may have on athletes is the subject of heated debate. Copyright 2006 The New York Times Company

Keyword: Hormones & Behavior; Aggression
Link ID: 9230 - Posted: 06.24.2010

Kerri Smith It might not seem inevitable that overweight mothers will have fatter babies. But this is exactly what's happening in the United States, say researchers who have documented how the 'obesity epidemic' is being passed on to the next generation. The team, based at Harvard Medical School in Boston, Massachusetts, has found that the proportion of overweight babies has risen by almost two-thirds over the past two decades, so that 10% of babies now fall into this category. And the proportion of babies at the upper end of the weight scale — termed 'at risk of becoming overweight' — has risen by a third to 14%. The group, led by Matt Gillman, followed more than 120,000 children between birth and 6 years of age, monitoring their weight and height. Infants from birth to 6 months old showed a particularly large increase in obesity from the 1980s to the 2000s, they add. A mother who gains a lot of weight during pregnancy can predispose her child to being overweight for life, says Gillman, who reports the work in the journal Obesity1. In extreme cases, putting on excessive weight when pregnant can lead to a condition called gestational diabetes in the mother. Studies of the disorder in rats show that it increases levels of the hormone insulin in pups. High insulin levels then boost appetite by acting on the hypothalamus, a part of the brain responsible for regulating food intake, he says. It seems the same thing can happen with people too. ©2006 Nature Publishing Group

Keyword: Obesity
Link ID: 9229 - Posted: 06.24.2010

Pictures of brain waves that reveal our ability to see colour could provide a new objective way to diagnose and monitor diseases that affect human colour perception. The research finding by a Universiy of New South Wales PhD student, Ms Mei Ying Boon, has earned her a nomination in this year's Fresh Science Awards. "Eye diseases such as glaucoma can alter people's ability to accurately see colour," says Ms Boon. "Therefore, studying brain activity could be a useful way to diagnose and monitor diseases and conditions that affect colour vision pathways in the brain." Ms Boon and her UNSW colleagues measured the brain waves of 22 adult volunteers while the volunteers viewed computer patterns composed of two different shades. The two colours ranged from very different (red and green) to very similar. If the viewer couldn't distinguish the colours, then the pattern was invisible to them. When the volunteers could see the pattern, their brain waves included a distinctively patterned wave. The researchers measured this signal three different ways and found it could be used to reveal the finest colour discriminations that individuals can make. The result: a potential visual health test.

Keyword: Vision
Link ID: 9228 - Posted: 08.10.2006

Doctors have completed the first step of a unique medical research study, evaluating 1,001 individuals at risk of developing Huntington's disease who do not know – nor do they want to know – whether they carry the genetic defect that causes the condition. An international team led by neurologist Ira Shoulson, M.D., of the University of Rochester Medical Center is trying to identify the earliest signs of the onset of the disease. The information will help clinicians design better studies of new drugs aimed at alleviating or postponing illness. It also helps researchers understand how patients evaluate potentially life-changing knowledge now available to patients through means such as genetic testing. Shoulson and colleagues from the Huntington Study Group reported their progress on the study known as PHAROS, or Prospective Huntington At Risk Observational Study, in the July issue of the Archives of Neurology. While the gene that causes the disease is known and can be identified through a blood test, fewer than one in 10 adults at risk for developing the disease have chosen to be tested. People at risk but who have not taken the test have a 50/50 chance of developing the disease. This at-risk group offers physicians a unique opportunity to witness the earliest signs of the disease, before anyone knows whether a person actually has the gene for Huntington's or not.

Keyword: Huntingtons
Link ID: 9227 - Posted: 06.24.2010