Howard Hughes Medical Institute researchers have discovered that pheromones essential for mating behavior in mice are recognized by the nose and not by the vomeronasal system, as researchers had long suspected. The new studies demonstrate that the main olfactory epithelium, which was presumed to be mostly involved with the sense of smell, plays a critical role in pheromone detection. Howard Hughes Medical Institute investigator Catherine Dulac and colleagues Hayan Yoon, an HHMI predoctoral fellow, and Lynn W. Enquist published their findings in an immediate early publication on November 10, 2005, in the journal Cell. Yoon and Dulac are at Harvard University, and Enquist is at Princeton University. Related studies by HHMI investigator Linda B. Buck are published in the same issue. The pheromone communication system, which is found in a wide range of mammals, involves detection of chemical odorants released by animals. Pheromones are chemicals that are involved in changing behavior or hormone secretion. According to most biology textbooks, detection of pheromones takes place in a specialized structure, called the vomeronasal organ (VNO). Although the VNO resides in the nasal cavity, the pheromone sensory system is distinct from the sense of smell, as are the chemical receptors involved. In animals possessing a pheromone sensory system — including mice, dogs, cats, and elephants — the system governs a range of genetically preprogrammed mating, social ranking, maternal, and territorial defense behaviors. © 2005 Howard Hughes Medical Institute.

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 8154 - Posted: 06.24.2010

Howard Hughes Medical Institute researchers have discovered a vast network of neurons in the brain of mice that governs reproduction and controls the effects of reproductive status on other brain functions. In their studies, the researchers found neural circuits that coordinate a complex interplay between neurons that control reproduction and brain areas that carry the neural signals triggered by odorant molecules and those triggered by pheromones, chemical signals produced by animals. The researchers characterize their findings as an initial step in understanding the far-reaching influence that odors and pheromones may have on reproduction and other behaviors. The research team, which was led by HHMI investigator Linda B. Buck at the Fred Hutchinson Cancer Research Center, included first author Ulrich Boehm and Zhihua Zou, who did the work as postdoctoral fellows while in Buck's lab. The researchers published their studies in an immediate early publication on November 10, 2005, in the journal Cell. Related studies by HHMI investigator Catherine Dulac are published in the same issue. The scientists began their studies by focusing on tracing the neural pathways leading to and from neurons that produce gonadotropin releasing hormone (GnRH), which is also known as luteinizing hormone releasing hormone (LHRH). These neurons regulate sexual physiology — including onset of puberty, ovulation, and the menstrual cycle in females and testosterone production in males — by regulating the release of hormones from the pituitary gland. Interestingly, GnRH neurons also appear to be involved in the control of sexual behaviors. © 2005 Howard Hughes Medical Institute

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 8153 - Posted: 06.24.2010

By Rob Stein Washington Post Staff Writer A first-trimester screening test can reliably identify fetuses likely to be born with Down syndrome, providing expectant women with that information much earlier in a pregnancy than current testing allows, according to a major study being released today. The eagerly awaited study of more than 38,000 U.S. women -- the largest ever conducted -- found that the screening method, which combines a blood test with an ultrasound exam, can pinpoint many fetuses with the common genetic disorder 11 weeks after conception. That allows women to decide sooner whether to undergo the riskier follow-up testing needed to confirm the diagnosis. "This is a big deal for women. It's going to have a big impact on care for women, not just in the United States but throughout the world," said Fergal D. Malone of the Royal College of Surgeons in Dublin, who led the study published in today's issue of the New England Journal of Medicine. Screening women before the second trimester allows those who might opt to terminate a pregnancy to make that decision when doctors say an abortion is safer and less traumatic. It also gives those who want to continue the pregnancy more time to prepare emotionally for their child's condition, and provides earlier reassurance to those whose babies are healthy, avoiding weeks of anxiety, Malone and others said. © 2005 The Washington Post Company

Keyword: Development of the Brain; Genes & Behavior
Link ID: 8152 - Posted: 06.24.2010

Waltham, Mass.- A Brandeis University study published this week in Nature shows for the first time that a molecular signal maintains coherence among brain clock cells that regulate daily activity of Drosophila melanogaster (fruit flies). The two key groups of neurons control morning and evening activity and are maintained in synch even when the flies are plunged into darkness for extended periods of time. This daily resetting signal flows from the morning to the evening cells and maintains a 12-hour difference between the timing of morning and evening activity, without the need for any environmental cues. The Brandeis researchers came to this conclusion by speeding up only the morning cell clock or only the evening cell clock. The results showed clearly that these two clocks always remained coupled in a network that was governed by the morning cell signal. "We think it very likely that something similar is occurring in the brain of mammals, including humans, because their clock neurons also maintain remarkable coherence," said Professor Michael Rosbash, director of the National Center for Behavioral Genomics at Brandeis, and a Howard Hughes Medical Institute investigator. "However, circadian brain anatomy in mammals is much more complicated and the tools much too primitive to allow a similar network approach at this time. Flies are state-of-the art. Fortunately, their circadian clocks and even neural mechanisms are quite conserved with mammals."

Keyword: Biological Rhythms; Genes & Behavior
Link ID: 8151 - Posted: 11.10.2005

A deep-voiced black-capped chickadee may wonder why other birds ignore it, but there may be a good reason behind the snub, says a University of Alberta study that looked into how the bird responds to calls. Dr. Isabelle Charrier and Dr. Chris Sturdy modified the black- capped chickadee calls, played those sounds back to the bird and observed how they reacted. They found that the chickadee relies on several acoustic features including pitch, order of the notes and rhythm of the call. They also rejected the calls of the control bird, the gray-crowned rosy finch, in favour of their own species. This research is published in the current edition of the journal, "Behavioural Processes." The chickadees two most well-known vocalizations are the "chick-a-dee" call and the "fee-bee" song. The song is produced mainly by males and is used to attract a mate and to defend a territory during the breeding season. The learned call is produced by both sexes throughout the year and is believed to serve a variety of functions such as raising mild alarm, maintaining contact between mates and co-ordinating flock activities. They even go through stages of learning this "language," which explains why juvenile birds can be heard frantically practicing to perfect the call.

Keyword: Sexual Behavior; Language
Link ID: 8150 - Posted: 11.10.2005

People in early stages of Alzheimer's disease have greater difficulty shifting attention back and forth between competing sources of information, a finding that offers new support for theories that contend breakdowns in attention play an important role in the onset of the disease. Routine tasks that require the shifting of attention, such as driving a car while conversing with a passenger, may become more challenging for people in very early stages of Alzheimer's disease, suggests a new study from Washington University in St. Louis. Published in a recent issue of the journal Neuropsychology, the study suggests that subtle breakdowns in attention may offer a reliable clue that a patient is grappling with early symptoms of Alzheimer's-related dementia. The findings are important because they offer clinicians and researchers another tool by which to better predict and understand dementia of the Alzheimer's type early in its history. Psychologists focus on early detection in part because current medications are useful only when given very early in the course of the disease.

Keyword: Alzheimers; Attention
Link ID: 8149 - Posted: 11.10.2005

Infants begin pulling off an amazing feat sometime in the final three months of their first year of life. They learn an important social interaction by following the gaze of an adult, a step that scientists believe gives babies a leg up on understanding language. University of Washington psychologists Rechele Brooks and Andrew Meltzoff have pinpointed this developmental step as beginning somewhere in the 10th or 11th month of life, and have found that infants who are advanced in gaze-following behavior before their first birthday understand nearly twice as many words when they are 18 months old. Writing in the current issue of the journal Developmental Science, Brooks and Meltzoff provide further evidence for the importance of eyes in human social interactions and trace how gaze-following develops in infants. Three years ago they reported that 12- 14- and 18-month-old infants are much more likely to look at an object when a person turns toward it with open eyes rather than closed eyes. "Our work shows that babies can look where an adult is looking but that it isn't easy, particularly at home where there are a lot of distractions," said Brooks, who is a research associate at the UW's Institute for Learning and Brain Sciences.

Keyword: Language; Development of the Brain
Link ID: 8148 - Posted: 11.10.2005

Roxanne Khamsi Researchers have finally pinned down a physical difference between male flies that are engineered to behave homosexually and those that are not: the tweaked variety is missing a small cluster of nerve cells in the brain. Genetically altered flies that are designed to court members of their own sex, or no one at all, have made headlines in recent months (see 'Fruitflies tap in to their gay side '). But no one knew exactly what those genes were doing, or how the flies differed physically from heterosexual ones. Now Japanese researchers have pinpointed one difference in the brain. Scientists caution that fly mating behaviour is very different from that of humans, as are our brains, so these results cannot be extrapolated to people. "No homologue of the fruitless gene is found in mammals and humans," points out Ken-Ichi Kimura of the Hokkaido University of Education in Iwamizawa, Japan. But such work does help researchers to work out the complex genetic and environmental factors that help animals to choose their mates. "This finding will provide insight for understanding how a sexual behaviour is constructed in the circuitry of the brain through a function of single gene," adds Kimura. ©2005 Nature Publishing Group

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 8147 - Posted: 06.24.2010

For most people, a whiff of food that made them sick in the past is enough to trigger a wave of nausea - and to prevent them from eating that food again. It's a response that's instantaneous, involuntary, and so fundamental to basic biology that it occurs in a broad range of species. Even worms, researchers have now shown, quickly learn to avoid smells associated with foods that have made them ill. The new study, led by Howard Hughes Medical Institute investigator Cornelia I. Bargmann and Yun Zhang, a postdoctoral fellow in Bargmann's laboratory at The Rockefeller University, demonstrates a clear capacity for learning in the laboratory animal C. elegans, a microscopic worm with only 302 neurons. The work suggests that the cellular mechanisms underlying this type of learning have been maintained through evolution, and opens the way for more in depth studies of how learning occurs. The study will be published in the November 10, 2005, issue of the journal Nature. One of C. elegans' fundamental behaviors is movement toward food based on its sense of smell. In the laboratory, this often means wriggling across a plate full of agar toward a cluster of E. coli. But in its natural environment, the soil, C. elegans encounters an astounding variety of bacteria. As it writhes through its world, the worm might meet up with hundreds of different species of bacteria in as little as five minutes. But while some bacteria make ideal worm food, others are toxic. © 2005 Howard Hughes Medical Institute

Keyword: Chemical Senses (Smell & Taste); Learning & Memory
Link ID: 8146 - Posted: 06.24.2010

Childhood sex abuse increases the risk of women developing eating disorders - and can even impact on their children, a study says. Researchers found girls abused before the age of 16 were twice as likely to develop eating disorders later in life. The University of Bristol team also said these women were likely to have weight concerns while pregnant and that had a knock-on effect on the child. The findings were published in the British Journal of Psychiatry. The team studied 10,000 women - one in five of whom had being abused. Researchers involved in the university's Children of the 90s project found 79% of the women recalled happy childhoods. The report said these women were less likely to worry about their weight or develop conditions such as bulimia and anorexia later in life. But of those who were sexually abused, 15% showed symptoms of an eating disorder and 30% showed concern about their weight during pregnancy. The researchers said this was a cause for concern, as maternal eating problems after childbirth interfered with parenting and child growth. Women with excessive fears about weight and shape are less likely to breast feed. But the report accepted other distressful experiences during childhood could also trigger problems. Previous research has shown that eating disorders may be connected to a wide range of unhappy childhood influences including parental alcohol misuse, physical or emotional cruelty and other family problems. (C)BBC

Keyword: Anorexia & Bulimia; Sexual Behavior
Link ID: 8145 - Posted: 11.09.2005

Diana Lutz The Velocity of Honey's 24 chapters are short meditations on questions that are probably never going to make the cover of Science or Nature, such as why toast falls butter side down and why time seems to speed up as we grow older. You might call them crossword puzzles for the scientifically minded—they offer a mental workout for its own sake but also soothe and amuse. In fact, author Jay Ingram calls The Velocity of Honey "a self-help book." Its essays "reduce stress," he says, and offer "a brief interruption in the ridiculous rush of life." Ingram, who hosts the Discovery Channel's science program Daily Planet, says he picked the topics for their appeal—adding with characteristic self-irony that this means their appeal to him. Somehow, he says, that turned out to mean there is a lot of physics and psychology and not much in between. (Ingram himself has a master's degree in microbiology from the University of Toronto.) The physics chapters include, in addition to tumbling toast, essays on the way paper crumples and crackles when it is squeezed, the aerodynamics of the maple key (the thin fibrous "wing" that encases the maple seed), the tricky behavior of stones thrown slantwise across water or sand, and the motion across ice of the 20-kilo granite "rocks" used in the sport of curling. © Sigma Xi, The Scientific Research Society

Keyword: Biological Rhythms; Attention
Link ID: 8144 - Posted: 06.24.2010

Thomas H. Maugh, Los Angeles Times Lovastatin, a widely used cholesterol-lowering drug, reverses common learning disabilities in mice, offering the first hope for a treatment of the problem in humans, UCLA researchers reported Monday. Three separate human trials in both children and adults will begin at UCLA and other U.S. and European locations within weeks, said Dr. Alcino Silva, a neurobiologist at UCLA and the lead author of a paper appearing in the journal Current Biology. "Currently, there are no treatment options for these people," Silva said. "That's why our findings are so exciting from a clinical perspective." Lovastatin, trade-named Mevacor, is one of a family of drugs known collectively as statins that have revolutionized the treatment of high cholesterol. The drugs, first introduced in the 1990s and taken daily by millions of people at risk for heart disease and other problems, have been widely recognized as safe. The learning problems studied by the researchers were caused by a genetic defect called neurofibromatosis 1, the most common genetic cause of learning disabilities. It affects 1 in every 3,000 to 4,000 people. The learning disabilities include poor attention spans, difficulties in carrying out tasks involving spatial abilities and problems learning new tasks. ©2005 San Francisco Chronicle

Keyword: Learning & Memory; Genes & Behavior
Link ID: 8143 - Posted: 06.24.2010

Every sight, sound, smell, and touch sends a barrage of electrical signals zipping to the brain. But how the subjective experience of, say, a redolent pink rose emerges from this flurry of neural activity is mysterious. Now researchers say they've found an important piece of the puzzle, identifying monkey neurons that appear to convey the perception of a simple touch. The first relay station for incoming touch signals in the cerebral cortex is called the primary somatosensory cortex, or S1 for short. Neurons here rev up whenever something brushes or pokes the body, and many researchers have thought that this neural activity is responsible for the subjective experience of touch, says Ranulfo Romo, a neuroscientist at the Universidad Nacional Autónoma de México in Mexico City. But when Romo and colleague Victor de Lafuente took a closer look at neural activity in S1, they began to doubt this assumption. The pair trained monkeys to press one of two buttons to indicate whether or not they'd felt a vibration applied to one finger. Correct responses earned a reward. Neurons in S1 scale their activity according to the strength of the vibration, the researchers found, but don't necessarily reflect what the monkeys perceive. For example, when the researchers made the task difficult by delivering a barely detectable vibration, monkeys reported catching the vibe only some of the time. But S1 neurons responded similarly to such weak vibrations regardless of which button the monkeys pushed. © 2005 by the American Association for the Advancement of Science.

Keyword: Pain & Touch
Link ID: 8142 - Posted: 06.24.2010

A report in the November Cell Metabolism reveals powerful effects of light on the adrenal glands, a finding that might explain the broad benefits of bright light therapy for a variety of conditions, including sleep and depressive disorders, according to researchers. The body's two adrenal glands sit atop each kidney, where they secrete hormones that regulate stress response and metabolism. The researchers found in mice that light sparks a cascade of gene activity in the adrenal gland through its effects on the suprachiasmatic nucleus (SCN). Located in the brain region called the hypothalamus, the SCN is the seat of the circadian clock, the body's internal clock that regulates the roughly 24-hour cycle of biological processes. Moreover, the researchers report, the gene expression changes accompany a massive surge of the steroid hormone corticosterone in the animals' blood and brain. That hormonal response increased with light intensity, they found. Glucocorticoids--including cortisone in humans and corticosterone in mice--play many roles throughout the body, including metabolic response to starvation, antiinflammatory immune response, and the timing of circadian rhythms in peripheral organs. Therefore, light-induced secretion of glucocorticoids may play a key role in physiological changes in the body and the brain evoked by light, reported study author Hitoshi Okamura of Kobe University Graduate School of Medicine in Japan

Keyword: Biological Rhythms
Link ID: 8141 - Posted: 11.09.2005

Roxanne Khamsi There's a new lesson to be learned about statins, a class of widely prescribed drugs that lower cholesterol. A study in mice suggests that this type of medication could reverse a learning disorder known as neurofibromatosis. The disorder, also called NF1, affects about 1 in every 4,000 children and can cause learning disabilities, coordination problems and benign tumours that grow on nerve tissue. Researchers have found that mutations in a single gene are to blame for NF1. The affected gene fails to produce a protein called neurofibromin, which normally keeps another protein, Ras, in check. Evidence from mouse studies suggests that an overabundance of active Ras results in abnormal nerve-cell responses in the brain. Ras also requires cholesterol compounds to function, and this led medical student Steven Kushner to wonder whether cholesterol-busting drugs could keep Ras in check, should neurofibromin not be up to the task. Kushner stumbled on the idea after learning about statins while on a clinical rotation. "He came to my lab at one in the morning and said 'I think I have a solution'," says his supervisor, Alcino Silva of the University of California, Los Angeles. ©2005 Nature Publishing Group

Keyword: Learning & Memory
Link ID: 8140 - Posted: 06.24.2010

Smokers are twice as likely to suffer post-traumatic stress disorder than non-smokers , according to a study of twin soldiers. It is estimated that after experiencing severe trauma, about one-third of people go on to suffer PTSD, a mental illness characterised by anxiety, flashbacks and panic attacks. Nicotine dependence has been associated with PTSD before, but the exact nature of the link has never been clear. The new study establishes smoking as a key risk factor in pre-disposing people to PTSD. Karestan Koenen, at the Harvard School of Public Health in Cambridge, US, and colleagues, looked at the health records of 6744 pairs of male twins who had served in the US military during the Vietnam era, about half of whom were identical twins. Shared genetic factors explained 63% of the overlap between PTSD and nicotine dependence in the twins. “Some of the same genes that influence risk for PTSD may influence risk for nicotine dependence, and vice versa,” Koenen said. But the researchers found that those with a pre-existing nicotine dependence who were then exposed to trauma had twice the risk of developing PTSD, compared to non-smokers who experienced trauma. © Copyright Reed Business Information Ltd.

Keyword: Drug Abuse; Stress
Link ID: 8139 - Posted: 06.24.2010

STANFORD, Calif. - Researchers at the Stanford University School of Medicine have shown for the first time that a sample of children who either have or are at high risk for bipolar disorder score higher on a creativity index than healthy children. The findings add to existing evidence that a link exists between mood disorders and creativity. The small study, published in the November issue of the Journal of Psychiatric Research, compared creativity test scores of children of healthy parents with the scores of children of bipolar parents. Children with the bipolar parents - even those who were not bipolar themselves - scored higher than the healthy children. "I think it's fascinating," said Kiki Chang, MD, assistant professor of psychiatry and behavioral sciences and co-author of the paper. "There is a reason that many people who have bipolar disorder become very successful, and these findings address the positive aspects of having this illness." Many scientists believe that a relationship exists between creativity and bipolar disorder, which was formerly called manic-depressive illness and is marked by dramatic shifts in a person's mood, energy and ability to function. Numerous studies have examined this link; several have shown that artists and writers may have two to three times more incidences of psychosis, mood disorders or suicide when compared with people in less creative professions.

Keyword: Schizophrenia
Link ID: 8138 - Posted: 11.09.2005

Women get more of a buzz out of cartoons, a brain-imaging study has found, with their brains feeling more rewarded by a funny joke than those of men. Women and men are often perceived as having differences in their senses of humour but, until now, there had been no neurological evidence for such suspicions. The new brain scanning study showed that although men and women tended to agree on which of the single-panel cartoons they were shown were funny, they processed the humour differently in their brains. In particular, women appear to have a lower expectation that the cartoon will be funny than men. “Women appear to have less expectation of a reward, which in this case was the punch line of the cartoon. So when they got to the joke’s punch line, they were more pleased about it,” says Allan Reiss, one of the study’s authors, at Stanford University School of Medicine in California, US. The group of 10 women and 10 men were shown a series of black and white cartoons. They rated the cartoons for funniness while functional magnetic resonance imaging (fMRI) identified the active areas of their brains. The level of activity in those areas was measured using a technique that analyses the level of oxygenation in the blood. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Emotions
Link ID: 8137 - Posted: 06.24.2010

By Simon Busch Special to The Washington Post I don't know what was wrong with me: a case of ill fit with the world, I guess. I suddenly kept being confronted by the fact of my own mortality, like a glacier in my path, and seizing up with panic. I told my doctor and, as luck would have it, he was branching into hypnotherapy and wanted to try it out on me. He was quite the evangelist for the treatment. Hypnosis was no mere stage trick, he insisted: A patient of his had recently had major dental surgery -- I imagined pile drivers and a building site -- solely anesthetized by the doctor's suggestion. As for quitting smoking, why, the cigarettes virtually extinguished themselves. My panic attacks should likewise succumb to the powers of his mind. On my next appointment, he led me to a room where he gestured for me to lie down on a very purple, soft leather couch while he took the armchair opposite. He put a CD of New Age mood music on the stereo -- some sort of ode to aquatic life-forms, I noticed by the cover -- and told me to focus on a psychedelic spiral pattern inscribed on a small piece of paper attached to the ceiling, while simultaneously concentrating on the sound of his voice. © 2005 The Washington Post Company

Keyword: Depression
Link ID: 8136 - Posted: 06.24.2010

By KATE MURPHY As an author of several books about thyroid disease who also moderates a Web site on the topic, Mary J. Shomon gets more than 1,000 e-mail messages a week. "I hear from people all the time who are fighting to be treated," said Ms. Shomon, a patient advocate. Most of the postings on her online message board at thyroid.about.com (presented by a division of The New York Times Company) are from women who report weight gain, fatigue, memory problems and depression. Many say they have thinning hair, dry skin and cold hands and feet. These are classic signs of an underactive thyroid, or hypothyroidism. But the patients say their doctors will not prescribe medicine because their blood tests are normal. But just what is "normal" is "an incredibly controversial question," said Dr. David Cooper, director of the endocrinology division at Sinai Hospital in Baltimore and a professor at Johns Hopkins School of Medicine. For two years, endocrinologists have been arguing about where to set the bar for the diagnosis and treatment of a failing thyroid, the gland in the neck responsible for secreting metabolism-regulating hormones. Some say a single, mildly elevated blood test is enough to start drug therapy; others advocate for more compelling evidence. Copyright 2005 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 8135 - Posted: 11.08.2005