What makes a man behave like a man and a woman a woman? The answer may be partly in your genes. Researchers at the University of Virginia Health System have discovered a new twist on the role that estrogens play in the development of behavioral differences between males and females. In laboratory tests on mice, the researchers found evidence that an estrogen receptor in the hypothalamus called ERb regulates defeminization, a process by which males lose the ability to display female-type behavior in adulthood. Defeminization is believed by many experts to be the main neurological process that differentiates males and females before birth. The discovery is detailed in the March 10 edition of the Proceedings of the National Academies of Sciences found at: www.pnas.org. “Our hypothesis is that neonatal males are exposed to the steroid estradiol (a form of natural estrogen) produced by their testes. Estradiol binds to the estrogen receptor (ERb) and this acts to turn on, or turn off, other genes which sculpt the neural architecture required for adult function,” said the study’s main author, Emilie Rissman, PhD, a professor of biochemistry and molecular genetics at U.Va. and a specialist in the genetics of mammalian behavior. “We’d like to find out what the genes are, where precisely they reside in the brain, when in development this happens, and what the cellular targets are of these genes,” Rissman said. Interestingly, male fetuses are exposed to estrogen in their normal development and females are not because ovaries don’t fully develop until puberty. © 1998 – 2005 by the Rector & Visitors of the University of Virginia

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 7016 - Posted: 06.24.2010

Nathan Seppa People who make a particular form of an immune system protein have a heightened risk of developing old-age blindness, three teams of researchers report in an upcoming Science. In a search for the factors underlying age-related macular degeneration—a deterioration of the eye that is the primary cause of vision loss in the elderly—the researchers have implicated one of several variants of the gene that encodes the protein called complement factor H, or CFH. The scientists hypothesize that this version of CFH fails to rein in inflammatory proteins, the protein's normal role. This braking of inflammation is indispensable to the eyes of some elderly people, the new studies suggest. As people age, microscopic damage accumulates in their eye tissues. In many people, this results in formation of drusen, a yellowish combination of fats, proteins, and cellular debris. In people with macular degeneration, large amounts of drusen destroy eye tissue. Using blood samples, the researchers analyzed the genetics of macular degeneration patients and elderly people who didn't have the condition. "We scanned across the genome to see what contrasts there were … and [the CFH gene] came up," says Yale University statistician Josephine Hoh. Copyright ©2005 Science Service.

Keyword: Vision; Genes & Behavior
Link ID: 7015 - Posted: 06.24.2010

by Steven Schultz · Recent studies from the lab of neuroscientist Elizabeth Gould are helping to show how major experiences -- such as early-life traumas -- can have a long-term effect on the structure of the brain. In one study published last year, researchers in Gould’s lab found that baby rats that were separated from a care-giving adult for several hours a day formed fewer new neurons in their brains later in life. Another study showed that adult rats that grew up normally produced elevated numbers of new neurons if they achieved social dominance in a small community of rats. “These are different examples of how life experience changes the brain,” said Gould, a professor of psychology at Princeton. Until the last decade, scientists did not believe that the brain changes that Gould and colleagues study were even possible. The conventional view in neuroscience was that once animals, including humans, reach adulthood, they acquire no new neurons, or nerve cells. Gould is a pioneer in showing that several important areas of the brain continue to create neurons throughout life, a process called adult neurogenesis. In recent years, Gould has investigated factors that influence the rate of adult neurogenesis and the roles played by the new brain cells. © 2005 The Trustees of Princeton University

Keyword: Neurogenesis; Stress
Link ID: 7014 - Posted: 06.24.2010

Anthropologists have constructed the world's first complete articulated Neanderthal skeleton to expand public and scientific understanding of the group, as well as of the differences between Neanderthals and modern humans. Their research will be published online March 11, 2005 in The Anatomical Record Part B: The New Anatomist, and will be available via Wiley InterScience (http://www.interscience.wiley.com/journal/ar). Questions about Neanderthals have persisted for nearly 150 years, many based upon an early erroneous stereotype of a slouched, bent-kneed biped with primitive mental capacity. Over the years, many artists have put forth images of Neanderthals, yet no one had ever constructed a complete skeleton using authentic fossil skeletal material. Anthropologists G.J. Sawyer of the American Museum of Natural History in New York and Blaine Maley of Washington University in St. Louis, MO set out to be the first, in an attempt to contribute to a more objective understanding of Neanderthals. "The primary purpose was to provide a more scientific understanding of Neanderthal skeletal anatomy based on the totality of available evidence, and to help us get a better estimation of stature differences between modern humans and our Neanderthal cousins," said the authors. "Our results would be used to educate the scientific community and the public on these differences, as well as give us a potential vehicle for undertaking more accurate biomechanical studies on Neanderthal positional and locomotor behaviors."

Keyword: Evolution
Link ID: 7013 - Posted: 03.11.2005

Fascination with oral hygiene is nothing new. Babylonians chewed twigs until the ends frayed enough to provide a good brushing. Chinese ancients crafted the first bristle toothbrush from wild boar. And Greeks of old introduced rough linen cloth to Alexander the Great who, egged on by Aristotle, used it to buff his bicuspids. Today's dental care smorgasbord offers flavored floss, bubble gum toothpaste, whitening mouthwashes and space-age looking toothbrushes angled to get at oral gunk. Now, fresh evidence shows that our long fixation with clean mouths may be doing more than keeping cavities away; it might actually reduce the risk of stroke and heart attack. Infectious disease researcher Moïse Desvarieux, of the Mailman School of Public Health , neurologist Ralph Sacco of the College of Physicians and Surgeons, and Panos Papapanou, of Columbia University's School of Dental & Oral Surgery, reported in the journal Circulation that thickening of the carotid artery, at work in stroke and heart attack, is associated with high levels of harmful oral bacteria found in gum disease. "The relationship that we have between gum disease, the bacteria, and the thicker carotid was only present in the bad bacteria and not in the others," says Desvarieux, the study's principal investigator. The team spent five years tracking 657 people over age 55 of mixed race and income, all with no stroke history. In a three part process, they screened patients for diabetes, hypertension, and smoking, stroke and heart disease risks factors, sampled eleven types of oral bacteria, four thought to cause gum disease and seven that are believed to have no role in gum disease, and took ultrasounds to examine carotid artery thickening. © ScienCentral, 2000-2005.

Keyword: Stroke
Link ID: 7012 - Posted: 06.24.2010

A research group based at the University of Chicago has found that an enriched environment -- in this case more chances to exercise, explore and interact with others – can dramatically reduce the biological hallmarks of Alzheimer's disease in mice that are genetically predisposed to the disorder. In the 11 March 2005 issue of Cell, the researchers show that mice raised in a deluxe setting – large cages filled with running wheels, colored tunnels and multiple toys -- had much less of the beta-amyloid peptides that are characteristic of Alzheimer's disease deposited in their brains and far lower levels of these damaging peptides in their blood than genetically similar mice raised in a standard environment. Mice from enriched settings also had more of an enzyme that breaks down amyloid as well as increased activity of several genes involved in learning and memory, brain cell survival and the growth of new blood vessels. "We have plenty of epidemiological evidence connecting activity, exercise and education with later onset of Alzheimer's, but it has never been clear which came first," said study-author Sangram Sisodia, Ph.D., professor of neurobiology, pharmacology and physiology at the University of Chicago. "Did the active lifestyle delay disease, or was there something inherent in a disease-resistant brain that led to a mentally and physically active lifestyle?"

Keyword: Alzheimers
Link ID: 7011 - Posted: 06.24.2010

Michael Hopkin Geneticists have pinpointed a mutation that increases the chances of age-related blindness. The discovery, made by three separate research groups, could help to identify people who are most vulnerable to the condition. Age-related macular degeneration (AMD) is the chief cause of blindness among the elderly in the developed world, affecting more than 10 million people in the United States alone. The condition involves the deterioration of the central part of the retina, the 'macula', leading to problems distinguishing colours and seeing motion. It ultimately blots out central vision completely. Spotting those most at risk would help to ensure they receive preventative treatment. Although there is no cure, the condition can be slowed by using lasers or drugs to stop damaged, leaky blood vessels from proliferating. The causes of AMD are complicated with experts suspecting the involvement of many factors, both genetic and environmental. Smoking and obesity, for example, are both risk factors. But this picture may not be quite as complex as many had feared, says Albert Edwards of the University of Texas Southwestern Medical Center in Dallas, who led one of the three studies. His team and two other teams have independently pinned down a simple genetic change that could explain around 50% of the variation between people who develop AMD and those who don't. ©2005 Nature Publishing Group

Keyword: Vision; Genes & Behavior
Link ID: 7010 - Posted: 06.24.2010

Just how do antidepressant drugs work? The answer you get (and the confidence with which it's delivered) will vary according to the experience of the person giving it: the more experienced and knowledgeable they are, the more tentative and uncertain the answer. I worked on central nervous system drugs for eight years, and I can confidently state that we know just slightly more than jack. Well, the more, um, standard answer is that antidepressants act by changing the concentrations of key neurotransmitters like serotonin or noradrenaline. That's certainly what they're designed to do, by shutting off metabolic and clearance pathways and allowing serotonin, say, to build up. Underlying all this is a larger hypothesis, one so large that we usually don't even think about it: that depressio is indeed a disorder of those neurotransmitters, a chemical imbalance that could in theory be righted if we just studied the relevant pathways hard enough. There's been a feeling, though, that we've been a bit too reductionist about this. This view is well stated in a new article in Nature Reviews Neuroscience (6, 241) by Eero Castren. "This new hypothesis, the network hypothesis, proposes that problems in activity-dependent neuronal communication might underlie depression, and that antidepressants might work by improving information processing in the affected neural networks. A key aspect of the network view is the recognition that the principal role of the nervous system is not to handle chemicals but to store and process information. . .Although chemical neurotransmitters are crucial for the transfer of information between neurons, information in the brain is not stored in a chemical form but is thought to be processed by the complex interactions of neurons in neural networks. These networks develop through interactions with the environment, and the neuronal structure of, and neurotransmission in these networks are constantly being refined. . ." © Copyright 2004 Corante.

Keyword: Depression
Link ID: 7009 - Posted: 06.24.2010

By Laura A. Sessions and Steven D. Johnson The meganosed fly (Moegistorhynchus longirostris) of southern Africa, like its literary counterpart, Pinocchio, has a bizarre appearance that reveals an underlying truth. Its proboscis, which looks like a nose but is actually the longest mouthpart of any known fly, protrudes as much as four inches from its head—five times the length of its bee-size body. In flight the ungainly appendage dangles between the insect’s legs and trails far behind its body. To an airborne fly, an elongated proboscis might seem a severe handicap (imagine walking down the street with a twenty-seven-foot straw dangling from your mouth). Apparently, though, the handicap can be well worth its aerodynamic cost. The outlandish proboscis gives the meganosed fly access to nectar pools in long, deep flowers that are simply out of reach to insects with shorter mouthparts. But that poses a conundrum: why would natural selection favor such a deep tube in a flower? After all, nectar itself has evolved because it attracts animals that carry pollen, the sperm of the floral world, from one plant to another. And since pollinators perform such an essential service for the flower, shouldn’t evolution have favored floral geometries that make nectar readily accessible to the pollinators? Copyright © Natural History Magazine, Inc., 2005

Keyword: Evolution
Link ID: 7008 - Posted: 06.24.2010

St. Paul, Minn. – Warning signs of an ischemic stroke may be evident as early as seven days before an attack and require urgent treatment to prevent serious damage to the brain, according to a study of stroke patients published in the March 8, 2005 issue of Neurology, the scientific journal of the American Academy of Neurology. Eighty percent of strokes are ischemic, caused by the narrowing of the large or small arteries of the brain, or by clots that block blood flow to the brain. They are often preceded by a transient ischemic attack (TIA), a “warning stroke” or “mini-stroke” that shows symptoms similar to a stroke, typically lasts less than five minutes, and does not injure the brain. The study examined 2,416 people who had experienced an ischemic stroke. In 549 patients, TIAs were experienced prior to the ischemic stroke and in most cases occurred within the preceding seven days: 17 percent occurring on the day of the stroke, 9 percent on the previous day, and 43 percent at some point during the seven days prior to the stroke.

Keyword: Stroke
Link ID: 7007 - Posted: 06.24.2010

Peter DaSilva VACAVILLE, Calif. - Brenda Marrero came upon her son Efrain surfing the Internet one day last October. When Efrain hid what was on the screen, she asked what he had been looking at. He turned and said he wanted to tell her something: He was using steroids. She called her husband, Frank, and they told Efrain he needed to stop, because steroids are dangerous. "But Barry Bonds does it," his parents remember Efrain saying. "That doesn't make it right," his father responded. To please his parents, Efrain retrieved a dozen pink pills, a vial of liquid and two syringes. His mother flushed the pills and kept the vial. Efrain, who played football, promised to stop using steroids. It was a promise that no one doubts he kept. Three and a half weeks later, Mrs. Marrero found Efrain in a bedroom at home, a bullet in his head, a .22-caliber pistol in his hand. He left no explanation for his suicide. He had no history of depression or mental illness. He was 19. Copyright 2005 The New York Times Company

Keyword: Drug Abuse; Hormones & Behavior
Link ID: 7006 - Posted: 03.10.2005

HANOVER, NH – A group of Dartmouth researchers has learned that the brain's auditory cortex, the part that handles information from your ears, holds on to musical memories. In a study titled "Sound of silence activates auditory cortex" published in the March 10 issue of Nature, the Dartmouth team found that if people are listening to music that is familiar, they mentally call upon auditory imagery, or memories, to fill in the gaps if the music cuts out. Using functional magnetic resonance imaging (fMRI) to measure brain activity, the researchers found that study participants could mentally fill in the blanks if a familiar song was missing short snippets. "We played music in the scanner [fMRI], and then we hit a virtual 'mute' button," says first author David Kraemer, a graduate student in Dartmouth's Psychological and Brain Sciences Department. "We found that people couldn't help continuing the song in their heads, and when they did this, the auditory cortex remained active even though the music had stopped." The researchers say that this finding extends previous work on auditory imagery and parallels work on visual imagery, which both show that sensory-specific memories are stored in the brain regions that created those events. Their study, however, is the first to investigate a kind of auditory imagery typical of everyday experience.

Keyword: Hearing
Link ID: 7005 - Posted: 06.24.2010

By James V. Grimaldi Like all fathers, I thought we had the perfect baby. So when our son, Xavier, was a couple of months old, and my wife asked me, "Does his head look flat in the back?" I rejected the idea. But the question was odd enough that it lingered. Within a week or so, after looking at his head from different angles, I changed my mind: There was a flat surface on his head, on the right rear part of his skull. His forehead also was protruding and his ears were not symmetrical. Thus began our odyssey into a little-known but surprisingly common condition in infants: plagiocephaly -- literally, an oblique or misshapen head. We were relieved that our son's kind would not require surgery. And there was a remedy. Still, we faced some difficult decisions. The treatment is somewhat controversial, unnecessary in many cases, not always paid for by health insurance, inconvenient for parents and annoying for the infant. A specially fitted helmet -- worn 23 1/2 hours a day for as long as six months -- is used to shape the baby's growing skull. The seemingly extreme remedy posed a dilemma: Do we "fix" our son's head by subjecting him to a helmet for six months? Or do we let him grow up with a flattened head? © 2005 The Washington Post Company

Keyword: Development of the Brain
Link ID: 7004 - Posted: 06.24.2010

Curious female rats, more willing to step out and explore their environment, survive breast and pituitary tumors longer than their more cautious sisters, says a Penn State researcher. Dr. Sonia Cavigelli, assistant professor of biobehavioral health, says that her study of 80 female rats from birth to death shows that the curious ones with tumors lived, on average, an additional six months, or 25 percent longer lives, than the cautious ones. "It's difficult to extrapolate from rats to people,Ó she notes.ÒHowever, there have been studies that show that shy elderly people report more health symptoms than their more outgoing age-mates. Our new results with rats are consistent with those findings and support the notion that personality traits may have a significant impact on health and resilience to disease." Cavigelli, who joined the Penn State faculty in August, detailed the results at the American Psychosomatic Society meeting in Vancouver, Canada, in a paper, Exploratory Tendency During Infancy and Survival in Female Rats with Spontaneous Tumors. She conducted the study while she was a postdoctoral researcher at the University of Chicago. Her co-authors are J. R. Yee, graduate student in human development, and Dr. Martha McClintock, professor of psychology, both at the University of Chicago.

Keyword: Neuroimmunology
Link ID: 7003 - Posted: 03.09.2005

Roger Harris Imagine life without numbers. Science as we know it would be impossible and, indeed, so would modern civilization. Yet, some societies get along just fine without numbers greater than four or five. Two studies of Amazonian rainforest tribes reported simultaneously in the journal Science (October 15) used this paucity to shed light on how people perceive, learn and reason with numbers. In one of the investigations, a French team of cognitive neuroscientists led by Pierre Pica from Paris University studied speakers of Mundurukú in central Brazil. Mundurukú lacks vocabulary for numbers beyond 5, so it's a natural experiment for investigating the process of counting—associating real things with abstract symbols such as words. But how is anyone able to count at all? To answer this question, team member Stanislas Dehaene developed a neuronal-network model of number processing, which is built on behavioral and brain-imaging studies. He hypothesizes that human beings have a "number sense," an evolutionarily ancient cerebral system that enables people to approximate quantities. This system is capable only of simple computations, but humans have tweaked it by inventing cultural "tools" such as number symbols and counting routines. These confer the ability to perform accurate calculations. Because the Mundurukú have so few number words, they're ideal to test this hypothesis. To do so, the French scientists devised a series of simple experiments based on presenting subjects with various numbers of dots on a solar-powered laptop computer screen. © Sigma Xi, The Scientific Research Society

Keyword: Intelligence
Link ID: 7002 - Posted: 06.24.2010

By Robert McHenry Of late there have been a number of stories in the media about happiness, all of them noting with concern that surveys are showing that there isn't enough of it around. Despite historically unprecedented levels of wealth and leisure, citizens of developed countries report that they are no happier than their parents were, or than citizens of less developed countries are, or than someone else is. One of the latest of these reports is "Happiness is Back" by British Labour party advisor Richard Layard, published in Prospect magazine. Layard talks about the surveys, accepts their findings, makes the usual observation about what money does not buy, and then goes on to prescribe a number of mainly government-sponsored actions to improve our general happiness. What is it that we are talking about here? The surveys depend on their respondents' private notions of "happiness," which may differ greatly from person to person and none of which is described for our examination. Layard does not offer a definition or specification for happiness in the individual or in (what interests him most) the collective. He mentions a few examples of experiences that might count toward happiness, but they are mostly instances of momentary pleasure, and he suggests that happiness would consist of a great many of these strung together on the thread of life. © 2005 Tech Central Station

Keyword: Emotions
Link ID: 7001 - Posted: 06.24.2010

DURHAM, N.C. -- Researchers exploring the brain structures involved in recalling an emotional memory a year later have found evidence for a self-reinforcing "memory loop" -- in which the brain's emotional center triggers the memory center, which in turn further enhances activity in the emotional center. The researchers said their findings suggest why people subject to traumatic events may be trapped in a cycle of emotion and recall that aggravates post-traumatic stress disorder (PTSD). They said their findings also suggest why therapies in which people relive such memories and reshape perspective to make it less traumatic can help people cope with such memories. The paper by Florin Dolcos, Kevin LaBar and Roberto Cabeza, was published online February 9, 2005, in the Proceedings of the National Academy of Sciences. The researchers are in Duke University's Center for Cognitive Neuroscience, Department of Psychological and Brain Sciences, and Brain Imaging and Analysis Center. Their work was sponsored by the National Institutes of Health and the National Science Foundation. "This study is the first to really test recall of emotional memories after a long time period," said Cabeza.

Keyword: Learning & Memory; Emotions
Link ID: 7000 - Posted: 03.09.2005

Cooking shows on TV usually give a Web address where you can find, read, and print out the recipe of the dish created on that day’s show. The reason is obvious: It’s too hard to just follow along with what the chef is doing, let alone remember it all. There are too many directions and ingredients — too many variables and steps in the process to keep track of quickly. New research shows why it doesn’t take much for a new problem or an unfamiliar task to tax our thinking. According to University of Queensland cognitive science researchers Graeme S. Halford, Rosemary Baker, Julie E. McCredden and John D. Bain of Griffith University, the number of individual variables we can mentally handle while trying to solve a problem (like baking a lemon meringue pie) is relatively small: Four variables are difficult; five are nearly impossible. Their report, "How Many Variables Can Humans Process?" is published in the January 2005 issue of Psychological Science, a journal of the American Psychological Society. It’s difficult to measure the limits of processing capacity because most people automatically use problem solving skills to break down large complex problems into small, manageable "chunks." A baker, for example, will treat "cream butter, sugar and egg together" as a single chunk — a single step in the process — rather than thinking of each ingredient separately. Likewise she won’t think, "break egg one into bowl, break egg two into bowl." She’ll just think, "add all of the eggs."

Keyword: Learning & Memory
Link ID: 6999 - Posted: 06.24.2010

By Ronald Kotulak, Tribune science reporter The discovery of an early stage of Alzheimer's disease may drive up the number of Americans thought to have the memory-robbing disorder by 100 percent or more, researchers at Chicago's Rush University reported Monday in the science journal Neurology. Mild cognitive impairment, in which a person has increasing difficulty forming new memories, had been considered a normal part of aging but now appears to be an indicator of Alzheimer's disease, said the study's lead author, Dr. David A. Bennett, director of the Alzheimer's Disease Center at Rush. The researchers emphasized, however, that most people who worry about losing their memory as they age are not suffering from creeping Alzheimer's. The findings emerged from the largest study ever conducted on people diagnosed with mild cognitive impairment. The research, which involved postmortem examinations of the brains of 180 Catholic nuns, priests and brothers, indicates that most of the 2.5 million to 10 million Americans with that condition may already have some degree of Alzheimer's disease. Copyright © 2005, Chicago Tribune

Keyword: Alzheimers
Link ID: 6998 - Posted: 06.24.2010

Firm suggested to writer that link between SIDS, secondhand smoke be downplayed Alex Barnum, Chronicle Staff Writer Researchers at UCSF reviewing once-secret industry documents have detailed an elaborate effort by a leading tobacco company to raise doubts among doctors and public health officials about the well-established link between secondhand smoke and sudden infant death syndrome. The UCSF analysis shows how, in one case, executives at Philip Morris International hired a consultant to write a scientific article on the causes of SIDS, and persuaded him to change his original conclusions so the article called into question the connection to secondhand smoke. The article, published in 2001 in a respected medical journal, has been cited at least 19 times by other scientific papers, which meant it was taken seriously by medical researchers and, ultimately, the UCSF researchers say, was used to mislead doctors and public health officials about the risks of secondhand smoke. The tobacco companies "have this strategy to exert a subtle but very important influence over the research. It is designed to get the whole medical literature off in the wrong direction," said Stanton Glantz, a UCSF professor of medicine and senior author of the analysis. ©2005 San Francisco Chronicle

Keyword: Drug Abuse; Development of the Brain
Link ID: 6997 - Posted: 06.24.2010