Greg Huang SOME of the most basic organisms are smarter than we thought. Rather than moving about randomly, amoebas and plankton employ sophisticated strategies to look for food and might travel in a way that optimises their foraging. Biophysicists have long tried to explain how creatures of all sizes search for food. However, single-celled organisms such as bacteria seem to move in no particular direction in their search. To investigate, Liang Li and Edward Cox at Princeton University studied the movements of amoebas (Dictyostelium) in a Petri dish, recording the paths travelled by 12 amoebas, including every turn and movement straight ahead, for 8 to 10 hours per amoeba. Immediately after an amoeba turned right, it was twice as likely to turn left as right again, and vice versa, they told a meeting of the American Physical Society meeting in Denver, Colorado, last week. This suggests that the cells have a rudimentary memory, being able to remember the last direction they had just turned in, says Robert Austin, a biophysicist at Princeton who was not involved in the study. Such memories might be laid down because of the way the cell moves. To turn, an amoeba extends part of its body in the preferred direction, which creates a scar made of protein down that side of the cell. The scar might make the cell temporarily more likely to move in the opposite direction. For the amoeba, the pay-off is that it avoids travelling in circles and hence can search a larger area. © Copyright Reed Business Information Ltd

Keyword: Learning & Memory
Link ID: 10091 - Posted: 06.24.2010

Erika Check Researchers have used a new technique to hunt for rare genetic quirks that explain why some people are extremely fat or very thin. The researchers, led by Len Pennacchio of the Lawrence Berkeley National Laboratory in California, studied 757 Canadians from Ottawa. Half of the participants were chosen because they were fatter than 95 of the general population for their height: on average they weighed 125 kilograms. The other half was thinner than 90% of the population, with a mean weight of 57 kilograms. The team examined 58 genes known to be related to obesity, appetite, or the conversion of food into energy, in every participant. They looked for tiny differences between people in the series of chemical building blocks that make up each gene. This technique, called medical sequencing or resequencing, aims to discover rare genetic variations that may subtly influence particular traits — including body size. Most previous genetic trawls have focused on using the HapMap — a catalogue of common genetic variants shared by most people with a certain disease. Resequencing is different, as it looks for genetic quirks that are unique to just a few individuals. Resequencing studies have been used to find variations that may cause cancer1 and differences in cholesterol2, whereas HapMap studies have been used to hunt for more common variations that contribute to a range of conditions, including diabetes (see 'Broad sweep of genome zeroes in on diabetes'). ©2007 Nature Publishing Group

Keyword: Obesity; Genes & Behavior
Link ID: 10090 - Posted: 06.24.2010

A couple of sleepless nights can cloud a person's moral judgement, study findings suggest. Army researchers found soldiers struggled to make snap decisions in emotionally charged situations after being deprived of sleep for two nights. The authors say this could be important for other professions, including doctors, who have broken sleep and need to make quick decisions in a crisis. The US work is published in the latest edition of the journal Sleep. It is well established that poor sleep can impair many functions, including concentration and memory. Some people say they need as little as three hours of sleep in every 24 hours to feel rested, while others need 11 hours. Experts generally advise people get about eight hours of solid sleep per night to be on top form. Lead researcher Dr William Killgore, of the Walter Reed Army Institute of Research, stressed that the findings did not mean that sleep deprivation leads to a decline in "morality" or in the quality of moral beliefs. "Our results simply suggest that when sleep deprived, individuals appear to be selectively slower in their deliberations about moral personal dilemmas relative to other types of dilemmas," he said. (C)BBC

Keyword: Sleep; Emotions
Link ID: 10089 - Posted: 03.16.2007

The mineral zinc may play a role in the development of a common cause of blindness, research suggests. Age-related macular degeneration (AMD) is the leading cause of blindness among elderly people in the developed world. Researchers found high zinc levels in deposits in the eye which are a marker for AMD development. The study, published in Experimental Eye Research and led by London's Institute of Ophthalmology, could help the development of new treatments. AMD is a form of macular disease which affects the eye's retina, and causes loss of central vision. An estimated 500,000 people in the UK have it, including 40% of people aged over 75. An early sign of the disease is the formation of microscopic structures called drusen in the eye. Exactly what the effects of these are and why they form is not yet fully understood. The latest research found that drusen in eyes with AMD contain very high levels of zinc. Researcher Dr Imre Lengyel said: "Zinc had previously been shown to contribute to the formation of plaques in the brains of patients with Alzheimer's disease, so it was logical for us to test the idea that zinc might also contribute to the formation of plaque-like drusen in the eye as well. AMD can be considered as the Alzheimer's disease of the eye, in that both involve the build-up of proteins and metals like zinc and copper into microscopic clumps." (C)BBC

Keyword: Vision; Alzheimers
Link ID: 10088 - Posted: 03.16.2007

By Amy Norton NEW YORK (Reuters Health) - The popular herbal supplement ginkgo biloba may not do much for healthy older adults' memory, at least in the short term, a new study suggests. Extracts of ginkgo biloba are among the most widely used dietary supplements. The herb is marketed as a memory enhancer, and some studies have suggested it may help improve memory and other mental functions in people with dementia. Meanwhile, many older adults, while not suffering from dementia, do develop milder problems with memory, concentration and other mental functions -- and so far, studies have come to mixed conclusions as to whether ginkgo can slow such age-related cognitive decline. The new findings, published in the Journal of the American Dietetic Association, suggest that healthy older adults are unlikely to see any quick results from ginkgo. Among the 90 men and women ages 65 to 84 in the study, those who took a ginkgo-containing supplement every day for 4 months performed no better on tests of memory, attention and other cognitive functions than those who took an inactive placebo. Overall, this and other well-designed studies suggest that, in the short term, ginkgo biloba does not benefit healthy older adults' cognitive function, according to lead study author Dr. Joseph J. Carlson of Michigan State University in East Lansing. SOURCE: Journal of the American Dietetic Association, March 2007. © 1996-2007 Scientific American, Inc.

Keyword: Learning & Memory
Link ID: 10087 - Posted: 06.24.2010

By JUSTIN POPE -- Substance abuse on college campuses is nothing new, but it is taking a more extreme and dangerous form, with higher rates of frequent binge drinking and prescription drug abuse, and more negative consequences for students such as arrests and risky sexual behavior. That's the portrait painted by a new, comprehensive report tying together a range of recent research on college substance abuse, supplemented with some of its own new survey data. The report by The National Center on Addiction and Substance Abuse at Columbia University, argues substance abuse isn't an inevitable rite of passage for young adults. Rather, it argues a particular culture of excessive consumption has flourished on college campuses, and calls on educators to take bolder stands against students and alumni to combat it. "If they make this a priority they can do something about it," said Joseph Califano, chairman and president of the center, who among other steps called on colleges and the NCAA to stop allowing alcohol advertising during high-profile events like the NCAA men's basketball tournament. © 2007 The Associated Press

Keyword: Drug Abuse
Link ID: 10086 - Posted: 06.24.2010

NEW YORK (Reuters Health) - A mother whose child has a naturally fearful temperament may act less nurturing toward the child, triggering a vicious cycle of behavior that reinforces the child's fearfulness and shyness, researchers propose. In previous work, Dr. Nathan A. Fox of the University of Maryland, College Park, and colleagues found that children carrying one or two short versions of a gene involved in transport of the neurotransmitter serotonin were more likely to be extremely shy at age 7 if their mothers reported little social support. If their mothers had plenty of social support, kids carrying the so-called "shy gene" were at no greater risk of shyness. But children with two long versions of the serotonin transporter gene -- meaning they were free of the shy gene -- were normally outgoing at age 7 no matter how little social support their mothers received. The team's latest research, reported in the journal Current Directions in Psychological Science, points to a possible mechanism by which a mother's lack of social support might reinforce a child's tendency toward withdrawn behavior. Fox and colleagues observed that people carrying two copies of the "shy gene" are more likely to react poorly to life stresses by becoming depressed or developing other maladaptive behavior, while those who don't carry the gene seem to be somewhat shielded from stress. Individuals with just one copy of the shy gene "fall somewhere in the middle." SOURCE: Current Directions in Psychological Science, February 2007, © 1996-2007 Scientific American, Inc

Keyword: Genes & Behavior; Sexual Behavior
Link ID: 10085 - Posted: 06.24.2010

Millions of people struggle with the activities of daily living because of vision loss from eye diseases such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP), which damage light sensing cells in the eye’s retina. The retina, the lining of the inside of the back of the eye, consists of cells called "rods" and "cones" that detect light and translate it into electrical impulses. These impulses are interpreted by vision areas in the brain as images of the world around us. Diseases that damage the retina are a leading cause of vision loss. "What happens is that the light sensing cells, rods and cones, are no longer there, and therefore when the light goes into the eye, the patient cannot see in these areas," explains Mark Humayun, M.D., Professor of ophthalmology and biomedical engineering at the Doheny Eye Institute, part of the University of Southern California. Now Humayun is developing a device that mimics the function of the retina and which he hopes will one day restore a useful degree of sight in patients affected by retinal diseases. This year, in collaboration with several U.S. research centers and the Department of Energy, Humayun will begin testing an artificial retinal implant that builds on information gleaned from an earlier and simpler device first implanted by his team in 2002. © ScienCentral, 2000-2007.

Keyword: Vision; Robotics
Link ID: 10084 - Posted: 06.24.2010

Michael Hopkin Most people tend to think of the tropics as the hottest scene on the planet when it comes to spawning new life. But Canadian zoologists have found that it is actually the world's temperate zones where new species evolve and become extinct the fastest. The discovery by Jason Weir and Dolph Schluter of the University of British Columbia in Vancouver threatens to overturn the theory that because tropical regions contain the greatest overall species diversity, that they must also have the fastest rates of 'speciation' — the emergence of new species. "Our findings contradict the conventional view by suggesting that temperate zones, and not the tropics, are the hotbeds of speciation," says Weir. The researchers surveyed 309 pairs of 'sister' species — those that are closely related to one another, much like humans and chimpanzees — from throughout the Americas. They compared their DNA sequences to work out how much the sister species had diverged from one another, and therefore how long ago their split had occurred. Those in temperate zones tended to have diverged more recently, implying that new species are being thrown up faster in these regions. Near the Equator, sister species were separated by an average of 3.4 million years, whereas at the most extreme latitudes studied, stretching as far as the northern wilds of Canada, the figure was less than 1 million years, the researchers report in Science1. ©2007 Nature Publishing Group

Keyword: Evolution
Link ID: 10083 - Posted: 06.24.2010

Tiny gene mutations, each individually rare, pose more risk for autism than had been previously thought, suggests a study funded in part by the National Institute of Mental Health, a component of the National Institutes of Health. These spontaneous deletions and duplications of genetic material were found to be ten times more prevalent in sporadic cases of autism spectrum disorders than in healthy control subjects — but only twice as prevalent in autism cases from families with more than one affected member. The results implicate the anomalies as primary, rather than just contributory, causes of the disorder in most cases when they are present, according to the researchers. Although they might share similar symptoms, different cases of autism could thus be traceable to any of 100 or more genes, alone or in combination. Drs. Jonathan Sebat, Michael Wigler, Cold Spring Harbor Laboratory (CSHL), and 30 colleagues from several institutions, report on their discovery online, March 16, 2007 in Science Express. “These structural variations are emerging as a different kind of genetic risk for autism than the more common sequence changes in letters of the genetic code that we’ve been looking for,” explained NIMH director Thomas Insel, M.D. “The best evidence yet that such deletions and duplications are linked to the disorder, these findings certainly complicate the search for genes contributing to autism. These are rare changes, dispersed across the genome, and they tell us that autism may be the final common path for many different genetic abnormalities.”

Keyword: Autism; Genes & Behavior
Link ID: 10082 - Posted: 06.24.2010

Jennifer Viegas, Discovery News — Chimpanzees will do almost anything to capture the attention of a person with a banana, including using Bronx cheers (otherwise known as raspberries), according to new research. The chimp sounds might not be pretty, but they are evidence that at least one nonhuman primate species can invent new sounds, or give novel meaning to existing ones, a trait believed to play a role in language evolution. In the case of chimpanzees, sheer frustration seems to drive their ability to communicate with people. "If a human (holding a banana) is turned away or oriented away from the chimp, it might try a raspberry or extended food grunt to get the person's attention," lead author William Hopkins explained to Discovery News. "If the human does not respond, the chimpanzee might try making some sound again, or it might try another attention-getting behavior," added Hopkins, who is a research associate at Yerkes National Primate Research Center and an associate psychology professor at Berry College. He also said that if the person with the coveted banana is turned toward a chimp, the chimp might try another visual signal, such as pouting with its lips, or it might even offer some leftover food, or another object in its enclosure, to exchange for the fruit. © 2007 Discovery Communications Inc.

Keyword: Language
Link ID: 10081 - Posted: 06.24.2010

A single episode of severe stress can be enough to kill off new nerve cells in the brain, research suggests. Rosalind Franklin University researchers believe their finding may give new insights into the development of depression. Working on rats, they found that cells were lost in the hippocampus, an area of the brain which processes learning, memory and emotion. The study features in the Journal of Neuroscience. The researchers found that in young rats, the stress of encountering aggressive, older rats did not stop the generation of new nerve cells in the hippocampus. However, it did prevent the cells from surviving - leaving fewer new neurons for processing feelings and emotions. The hippocampus is one of two regions of the brain that continues to develop new nerve cells throughout life, in both rats and humans. The researchers believe the loss of cells could be one cause of depression. However, their work also raises hope of possible treatments to stop acute stress from contributing to mood problems. They found that cells tended to die not immediately following a stressful situation, but after a delay of 24 hours or more. In principle, they argue it could eventually be possible to administer treatment during this time to prevent cells being lost. (C)BBC

Keyword: Stress; Apoptosis
Link ID: 10080 - Posted: 03.15.2007

By JESSE McKINLEY SAN FRANCISCO,— Federal appellate judges here ruled Wednesday that a terminally ill woman using marijuana was not immune to federal prosecution simply because of her condition, and in a separate case a federal judge dismissed most of the charges against a prominent advocate for the medicinal use of the drug. The woman, Angel McClary Raich, says she uses marijuana on doctors’ recommendation to treat an inoperable brain tumor and a battery of other serious ailments. Ms. Raich, 41, asserts that the drug effectively keeps her alive, by stimulating appetite and relieving pain, in a way that prescription drugs do not. She wept when she heard the decision. “It’s not every day in this country that someone’s right to life is taken from them,” said Ms. Raich, appearing frail during a news conference in Oakland, where she lives. “Today you are looking at someone who really is walking dead.” In 2002, she and three other plaintiffs sued the government, seeking relief from federal laws outlawing marijuana. The case made its way to the Supreme Court, and in 2005, the court ruled against Ms. Raich, finding that the federal government had the authority to prohibit and prosecute the possession and use of marijuana for medical purposes. But the justices left elements of Ms. Raich’s case to a lower court to consider. Copyright 2007 The New York Times Company

Keyword: Drug Abuse; Pain & Touch
Link ID: 10079 - Posted: 06.24.2010

By STEPHANIE SAUL The most widely prescribed sleeping pills can cause strange behavior like driving and eating while asleep, the Food and Drug Administration said yesterday, announcing that strong new warnings will be placed on the labels of 13 drugs. The agency also ordered the makers of the well-known drugs Ambien and Lunesta and the producers of 11 other commonly used sleeping pills to create patient fliers explaining how to use them safely. The fliers, which the agency says it requires when it sees a significant public health concern, will be handed out at pharmacies when consumers fill their prescriptions. Although the agency says that problems with the drugs are rare, reports of the unusual side effects have grown as use of sleeping pills have increased. Sales in the United States of Ambien and Lunesta alone last year exceeded $3 billion. Use of those medications and other similar drugs has soared by more than 60 percent since 2000, fueled by television, print and other advertising. Last year, makers of sleeping pills spent more than $600 million on advertising aimed at consumers. The review was prompted, in part, by queries to the agency from The New York Times last year, after some users of the most widely prescribed drug, Ambien, started complaining online and to their doctors about unusual reactions ranging from fairly benign sleepwalking episodes to hallucinations, violent outbursts, nocturnal binge eating and — most troubling of all — driving while asleep. Copyright 2007 The New York Times Company

Keyword: Sleep
Link ID: 10078 - Posted: 06.24.2010

There really is something in the way she moves, according to researchers. An hourglass figure has long been perceived to be the ideal figure for a woman to have. But New York University researchers have found that to be found attractive, a woman had to move in a feminine way - swaying her hips. Men, the Proceedings of the National Academy of Sciences paper found, were more attractive if they moved with a "shoulder swagger". The waist-hip ratio has long been thought to be key to Western perceptions of attractiveness, with a small waist and bigger hips the ideal combination. Marilyn Monroe, and now Beyonce and Jennifer Lopez are famous examples of women with that figure. Its popularity may be down to media images, or because Western women do not need to have strong and muscular bodies in order to carry out manual labour, unlike women in developing countries. But the US research, which was also published in the journal Psychological Science, suggests they would never have achieved their sex symbol status if they did not move in the right way. The team carried out a series of studies involving over 700 participants who were shown a variety of animations and videos of people moving. Some showed shadow figures, where it was not possible to see if it was a man or a woman, while others obviously showed a man or a woman. No matter which format was being used, the participants rated women or "female" figures as more attractive if their hips swayed as they walked, while men were more attractive if they had the characteristic shoulder movement. (C)BBC

Keyword: Sexual Behavior
Link ID: 10077 - Posted: 03.15.2007

By David Biello The mammal ear is a very precise system for hearing—enabling everything from human appreciation of music to the echolocation of bats. Three tiny bones known as ossicles—the hammer (malleus), anvil (incus) and stirrup (stapes)—work together to propagate sound from the outside world to the tympanic membrane, otherwise known as the eardrum. From there, the sound is transmitted to the brain and informs the listener about pitch, intensity and even location. But it has been a mystery how this delicate system evolved from the cruder listening organs of our reptilian ancestors. Paleontologists have scoured fossil records in search of signs of how the jawbones of reptiles migrated and became the middle ear of mammals. Now Zhe-Xi Luo of the Carnegie Museum of Natural History in Pittsburgh and his colleagues have found one: Yanoconodon allini, an intermediate between modern mammals and their distant ancestors. "It helps to show a transitional structure in the long process of evolution of mammal ears," Luo says. The Luo team found the new tiny mammal—just five inches (12.7 centimeters) long—in the Yan Mountains of Hebei Province in China. Similar rocks in other formations date to the Mesozoic era 125 million years ago when dinosaurs roamed Earth and early mammals are thought to have been relegated to scurrying through the undergrowth. Yanoconodon sports three cusps on its molars for feeding on insects and worms as well as a long body compared with its stubby limbs, ideal for scrabbling in the dirt for dinner. "This particular mammal has a very long body but relatively short limbs," Luo says. "By looking at the claw structure, hand bones and foot bones, our general interpretation is that it is a mammal that lived on the ground surface or perhaps was capable of digging." © 1996-2007 Scientific American, Inc.

Keyword: Evolution; Hearing
Link ID: 10076 - Posted: 06.24.2010

Many women say their moods follow a monthly cycle. Now brain researchers have scientific evidence that women's hormonal changes affect the reward circuits -- areas of the brain that produce feelings of pleasure. "No one had ever actually imaged the reward system of the brain during the menstrual cycle," says Karen Berman, who led the research at the National Institute of Mental Health. "This is a very fundamental part of our brain that has great evolutionary significance because it helps us to find out what in the environment is important for us to pay attention to for survival," she explains. "We thought this would be a very important brain network to study because people who have mood disorders, women who have menstrually related mood problems likely aren't activating and processing with this system in a normal fashion." Berman and her team used functional MRI to image women's brains at two key points in their cycle -- before ovulation when the hormone estrogen increases, and after ovulation when the hormone progesterone dominates. The volunteers played a slot-machine game to win money, activating the brain's reward systems. © ScienCentral, 2000-2007.

Keyword: Hormones & Behavior
Link ID: 10075 - Posted: 06.24.2010

By Greg Miller To make a memory that lasts, neurons need to regulate the activity of genes. One way to do this is with proteins that latch onto DNA and inhibit or enhance the expression of specific genes. But that's not the only trick neurons have at their disposal. A new study finds that neurons can also regulate gene expression by chemically modifying the genes themselves. During development, the brain uses "epigenetic" mechanisms to make long-term changes in gene expression. One example involves enzymes that work on histones--proteins that act like spools to keep DNA tightly packaged--in a way that makes certain genes more or less accessible. Another example is DNA methylation, in which enzymes add a chemical modification called a methyl group that silences a gene (ScienceNOW, 12 April 2006). Until recently, however, there was little evidence that such epigenetic changes played a role in the fully developed nervous system. In the new study, neurobiologists Courtney Miller and David Sweatt of the University of Alabama, Birmingham, injected rats with a drug that inhibited DNA methylation immediately after the rats had received three mild electrical shocks. Normally, rats remember such an unpleasant experience and freeze up when returned to the same enclosure the following day. Not so for the injected rats: They showed about one-fourth the freezing behavior of uninjected rats, indicating a much weaker memory, Miller and Sweatt report online today in Neuron. © 2007 American Association for the Advancement of Science.

Keyword: Learning & Memory
Link ID: 10074 - Posted: 06.24.2010

Teenage mood swings are known to be down to hormones, but scientists claim they have identified the specific one that makes adolescents so volatile. A team from the State University of New York identified a hormone which normally acts to calm anxiety, but the effect is reversed in adolescence. Writing in Nature Neuroscience, the researchers say it may be possible to reverse the puberty effect. And they add the study should help parents and teachers understand teens. A hormone called THP is normally released in response to stress. It usually behaves like a tranquiliser, acting at sites in the brain that calm brain activity and, in adults and pre-pubescent children, helps someone cope with stress. But a mouse study by the New York team shows THP actually increases anxiety at puberty. They found that the target for the hormone, a specific receptor, is more prevalent in the part of the brain which regulates emotion during puberty. This appears to reverse the normal calming effect. Dr Sheryl Smith, who led the study says it is so far unclear why this happens, but she suggests it is because of the action of all the other hormones which come into play at puberty. (C)BBC

Keyword: Emotions; Hormones & Behavior
Link ID: 10073 - Posted: 03.14.2007

By ALAN SCHWARZ ANNAPOLIS, Md.,— The night that Sylvia Mackey and Eleanor Perfetto first met, back in October at a Baltimore Ravens reception for former National Football League players and their families, their connection was immediate. As she sat on a couch with her husband, Mrs. Mackey watched Dr. Perfetto cradle the hand of her husband as he blankly shuffled across the floor toward the Mackeys. “Your husband has dementia,” Mrs. Mackey said. “Yours does, too,” Dr. Perfetto replied. “We both just knew,” Dr. Perfetto recalled on Friday, when the two visited the assisted-living facility where Dr. Perfetto’s husband, Ralph Wenzel, resides. Mrs. Mackey quickly added, “You can see it in the wives’ faces just like the husbands’.” On that evening last October, Mrs. Mackey added another N.F.L. wife to her growing network of women who seek her guidance and support as their husbands deteriorate mentally. Her husband, John, was a Hall of Fame tight end for the Baltimore Colts in the late 1960s and early ’70s, and is probably the most notable victim of dementia among former football players. Mrs. Mackey said that she regularly communicates with about 10 women like Dr. Perfetto as they learn to handle their husbands’ dementia, which often begins as early as their 50s. “I know about 20 in all,” Mrs. Mackey said. “And if I know 20, there are probably 60 or 80 out there.” Copyright 2007 The New York Times Company

Keyword: Brain Injury/Concussion
Link ID: 10072 - Posted: 06.24.2010