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A brain protein switches from 'Jekyll to Hyde' - building memories, but also playing a role in killing brain cells in conditions such as dementia. Harvard Medical School researchers say the switch is caused by the brain trying to compensate for the damage done by such conditions. Writing in Neuron, they said their study of mice could offer clues about what happens in human brains. Dementia researchers agreed the work could further understanding. The researchers focused on enzymes in the brain which control its biochemistry. Abnormal patterns had already been seen in the brains of patients with Alzheimer's disease. The researchers looked at the influence of a protein called p25 which appears to play a role in triggering these abnormal patterns - in certain circumstances. In the study, the researchers "switched on" p25 at will in the brain's learning and memory centre, the hippocampus. In these mice, they found that switching on p25 for only two weeks boosted learning and memory compared to normal mice. But if the p25 was switched on for six weeks, mice displayed impaired learning and memory in tests. Physiological studies showed that these mice showed significant brain damage and lost nerve cells in the hippocampus. But those who had elevated p25 levels for just two weeks had no such effects. (C)BBC

Keyword: Alzheimers; Learning & Memory
Link ID: 8295 - Posted: 12.10.2005

By Shankar Vedantam Washington Post Staff Writer The 48-year-old man turned down a job because he feared that a co-worker would be gay. He was upset that gay culture was becoming mainstream and blamed most of his personal, professional and emotional problems on the gay and lesbian movement. These fixations preoccupied him every day. Articles in magazines about gays made him agitated. He confessed that his fears had left him socially isolated and unemployed for years: A recovering alcoholic, the man even avoided 12-step meetings out of fear he might encounter a gay person. "He had a fixed delusion about the world," said Sondra E. Solomon, a psychologist at the University of Vermont who treated the man for two years. "He felt under attack, he felt threatened." Mental health practitioners say they regularly confront extreme forms of racism, homophobia and other prejudice in the course of therapy, and that some patients are disabled by these beliefs. As doctors increasingly weigh the effects of race and culture on mental illness, some are asking whether pathological bias ought to be an official psychiatric diagnosis. © 2005 The Washington Post Company

Keyword: Emotions
Link ID: 8294 - Posted: 06.24.2010

At the end of the day, what makes you you? Author Shannon Moffett attempts to answer that question, among others, in The Three-Pound Enigma: The Human Brain and the Quest to Unlock Its Mysteries. In an age when we are becoming immune to the wonders of medicine due simply to the frequency of new discoveries and breakthroughs, it is both humbling and inspiring to find how very much there still is to learn about the three-pound organ at the top of our spinal column that we call home. Moffett opens her book with a bang, literally, introducing the reader to neurosurgeon Roberta Glick, whose main case of the day involves removing a precariously located bullet in a patient’s brain. Between describing the complex physical and neurological processes that Glick must not impair while removing the bullet, Moffett provides a compelling character portrait of the doctor herself, including her self-described “geriatric motherhood” (due to the demands of her profession, Glick waited to have children until she was almost forty), as well as a technically competent introduction to the physical structure of the brain. The author’s skillful combination of character description with straightforward medical and scientific description of the brain and our mental processes is in evidence throughout the entire book. Although many science books are not lauded for their attention to character or story details, Moffett’s succeeds as both a highly readable and surprisingly suspenseful book, as well as a comprehensively detailed one. In subsequent chapters she interviews various brain and consciousness specialists, including John Gabrielli (an authority on memory), Christof Koch and Francis Crick (Crick is more well-known as the co-discoverer, along with James Watson, of DNA), who are busily engaged trying to chart the future of research on consciousness, and various sleep, psychiatry, and meditation specialists who are looking for their own ways to unlock the secrets of our mental beings.

Keyword: Miscellaneous
Link ID: 8293 - Posted: 06.24.2010

The electric eel generates large electric currents by way of a highly specialized nervous system that has the capacity to synchronize the activity of disc-shaped, electricity-producing cells packed into a specialized electric organ. The nervous system does this through a command nucleus that decides when the electric organ will fire. When the command is given, a complex array of nerves makes sure that the thousands of cells activate at once, no matter how far they are from the command nucleus. Each electrogenic cell carries a negative charge of a little less than 100 microvolts on its outside compared to its inside. When the command signal arrives, the nerve terminal releases a minute puff of acetylcholine, a neurotransmitter. This creates a transient path with low electrical resistance connecting the inside and the outside of one side of the cell. Thus, each cell behaves like a battery with the activated side carrying a negative charge and the opposite side a positive one. Because the cells are oriented inside the electric organ like a series of batteries piled into a flashlight, the current generated by an activated cell "shocks" any inactive neighbor into action, setting off an avalanche of activation that runs its course in just two milliseconds or so. This practically simultaneous start-up creates a short-lived current flowing along the eel's body. If the eel lived in air, the current could be as high as one ampere, turning the creature's body into the equivalent of a 500-volt battery. But eels live in water, which provides additional outlets for the current. They thus generate a larger voltage, but a divided, and therefore diminished, current. © 1996-2005 Scientific American, Inc.

Keyword: Pain & Touch
Link ID: 8292 - Posted: 06.24.2010

Stock market traders are trained to keep a cool head where money is concerned. But what about the rest of us? "I think the people who you see trading on the floor of the exchanges have so much experience that they probably, to a great extent, not completely but to a great extent, learn to control their emotions or work with their emotions," says economist George Loewenstein, from Carnegie Mellon University. "It's the individual investors that are often led astray by their emotions." Loewenstein and his research team have been studying the role of emotion in decision-making. "My collaborators and I are very interested in the role of immediate emotions in human behavior, the idea that people's behavior is determined, not by an assessment of the consequences of decisions, but simply by the immediate emotions that they're experiencing," he explains. "Emotions are clearly very important for human functioning, and people who have damage to emotional parts of the brain exhibit all sorts of different problems. But emotions also have a downside… they can lead people to be very aggressive, they can lead people to be very impatient." In particular, Loewenstein's group is interested in whether it is possible that people with damage to the emotion parts of the brain might make better decisions, economically more advantageous decisions, than normal people in certain circumstances. Research has shown that normal people tend to be pathologically risk averse. © ScienCentral, 2000-2005.

Keyword: Emotions
Link ID: 8291 - Posted: 06.24.2010

By Marc Kaufman and Shankar Vedantam The Food and Drug Administration warned pregnant women and their doctors away from the antidepressant Paxil yesterday because of an increased risk of heart defects in newborns. With the warning, the agency for the first time placed a popular antidepressant -- one in the same drug class as Prozac and Zoloft -- into its second-highest category for risk of birth defects. The agency did not say Paxil could never be used by pregnant women, but it did say the FDA "is advising patients that this drug should usually not be taken during pregnancy." The advisory is based on early results from two studies, which found that women who took Paxil in the first three months of pregnancy were 1 1/2 to two times more likely to give birth to a child with a heart defect than women who took other antidepressants or pregnant women overall. The studies found that Paxil had a risk of birth defects that other common antidepressants did not. "If you're on Paxil and pregnant, our advice is to talk to your physician and consider switching to a different drug," said Robert Temple, the FDA's director of medical policy. "Abrupt withdrawal of Paxil has its own problems, but the clear suggestion here is that you might want to think about a change." © 2005 The Washington Post Company

Keyword: Depression; Development of the Brain
Link ID: 8290 - Posted: 06.24.2010

By BARNABY J. FEDER An unexpected takeover battle between Boston Scientific and Johnson & Johnson for control of Guidant seems bound to send aftershocks through the medical device industry. There is widespread speculation about the effects on prominent competitors like Medtronic and St. Jude Medical in Guidant's main business of electrical implants that regulate heart functioning. Investors and analysts also wonder who will end up with Guidant's business of making stents and other devices used to treat circulatory illnesses. But there are less obvious industry niches that may also be affected by the outcome, like the one occupied by Cyberonics, a Houston-based company in which Boston Scientific has a 15 percent stake. The company and its stock have attracted attention as federal regulators first rejected, then reconsidered and approved Cyberonics' nerve-stimulating device as a treatment for severe depression. Nerve stimulation involves the use of devices that are similar to Guidant's pacemakers and heart defibrillators, but are attached to the brain or other parts of the nervous system to treat conditions like Parkinson's disease, epilepsy and chronic pain. Such devices constitute a $930 million market that is on its way to $2 billion in 2010, according to Lazard Capital Markets. Copyright 2005The New York Times Company

Keyword: Depression; Parkinsons
Link ID: 8289 - Posted: 12.09.2005

It's a scene football fans will see over and over during the bowl and NFL playoff seasons: a player, often the quarterback, being slammed to the ground and hitting the back of his head on the landing. Sure, it hurts, but what happens to the inside of the skull? Researchers and doctors long have relied upon crude approximations made from test dummy crashes or mathematical models that infer – rather loosely – what happens to the brain during traumatic brain injury or concussion. But the truth is that the state of the art in understanding brain deformation after impact is rather crude and uncertain because such methods don't give any true picture of what happens. Now, mechanical engineers at Washington University in St. Louis and collaborators have devised a technique on humans that for the first time shows just what the brain does when the skull accelerates.

Keyword: Brain Injury/Concussion; Brain imaging
Link ID: 8288 - Posted: 06.24.2010

Colleges are becoming more and more like shopping malls. At least, that's what Barry Schwartz, professor of Social Theory and Social Action at Swarthmore and author of The Paradox of Choice: Why More is Less, thinks. Higher education has moved away from educating students in set civic traditions and towards giving people as many options as a J. Crew catalogue. As Schwartz writes, "In some rather prestigious institutions, this shopping-mall view has been carried to an extreme. In the first few weeks of classes, students sample the merchandise. They go to a class, stay ten minutes . . . then walk out . . . to try another class." It might seem that all these new options would ensure that students are happier than ever. Similarly, the opportunity to make more choices anywhere in life would lead to increased satisfaction with life in general. But Schwartz, and myself, would disagree. I hate shopping period. I have perfected my shopping strategy to produce as much agony as possible. First I narrow my possibilities to a mere 30 or 40. Then I hand-write a schedule (the on-line version refuses to display as many classes as I wish), fitting three to four visits in each 50 minute period. When classes finally begin I race from one to the next, my logic changing with every classroom. If I like the class, then I can leave after 15 minutes to visit another just in case there's something better at the same time. If I hate the class, I can leave after 15 minutes, but I am sure to save the syllabus just in case. And if I am unsure about the class then I leave after 15 minutes to compare it with other mediocre classes. The whole process ends with me frantically running from advisor to dean to parents to friends begging them to tell me what to do and to save me from having to make a decision myself. Copyright © 2003 Yale Review of Books

Keyword: Emotions
Link ID: 8287 - Posted: 06.24.2010

by David J. Buller In nearly every newspaper or magazine these days you can find evolutionary explanations for a variety of human behaviors — for what we seek in mates, why we are sometimes unfaithful, why we love our children (but not our stepchildren), why men and women differ, and even why husbands kill their wives. All of these explanations are offered in the name of evolutionary psychology. But what is evolutionary psychology? There are actually two different answers to this question, and it is useful to clearly distinguish them. On the one hand, many behavioral scientists define evolutionary psychology simply as “the evolutionary study of mind and behavior.”1 So conceived, evolutionary psychology is a field of inquiry, akin to mechanics, which is defined not by any specific theories about human psychology, but by the questions it investigates. And these questions cover a broad spectrum. Why do males in some hunter-gatherer populations hunt, which offers highly variable caloric returns, when they could reliably provide their families with equivalent calories by gathering? Why do women in some hunter-gatherer populations wait an average of four years between pregnancies? What evolutionary forces drove cortical expansion in humans? How and why did altruism, or language, evolve? On the other hand, several prominent and influential behavioral scientists — led on the popular front by Steven Pinker (The Blank Slate) and David Buss (The Evolution of Desire and The Murderer Next Door) and on the academic front by Leda Cosmides and John Tooby (The Adapted Mind) — define evolutionary psychology as a specific set of doctrines concerning the evolutionary history and current nature of the human mind. In this sense, evolutionary psychology as a field of inquiry has been elevated by its practitioners to an all encompassing paradigm of Evolutionary Psychology (EP).

Keyword: Evolution
Link ID: 8286 - Posted: 06.24.2010

Pacifiers aren't just for soothing colicky babies anymore. A new study has found that use of a pacifier during sleep reduced the chances of a baby suffering from sudden infant death syndrome (SIDS) by 90 percent. Furthermore, pacifiers eliminated the increased risk associated with babies who slept on their stomach or in soft bedding--factors that have been shown to increase the risk of SIDS as much as 10-fold. "A baby who sleeps on his stomach without a pacifier has a 2.5 times greater risk of SIDS," explains De-Kun Li, a reproductive epidemiologist with Kaiser Permanente in Oakland, Calif., who led the research. "If you use a pacifier, that baby's risk disappears." The work draws on interviews with 185 mothers of SIDS babies and 312 mothers of control infants collected between 1997 and 2000. Of course, this doesn't mean that babies should be allowed to sleep on their stomachs, he cautions. Campaigns to promote sleeping on the back have cut the incidence of SIDS significantly. But pacifier use showed benefits no matter the baby's age, how it slept and even if its mother smoked during or after pregnancy, according to the research, which will be published Saturday in the British Medical Journal. © 1996-2005 Scientific American, Inc

Keyword: Sleep
Link ID: 8285 - Posted: 06.24.2010

Roxanne Khamsi When faced with uncertainty, people try to make the most logical decision, given the facts available. But a brain-imaging study has found that, when tackling these tricky decisions, the brain's emotional areas also spring into action. Ming Hsu of the California Institute of Technology in Pasadena and his colleagues compared volunteers' brain activity in two betting games. As the volunteers played, the scientists watched changes in their brain activity using functional magnetic resonance imaging. In one game, researchers gave volunteers the chance to guess the colour of a card drawn from a deck containing equal numbers of red and blue cards, and to bet on whether they were right. In the other game, the ratio of red to blue cards remained unknown. Players in this game were less likely to put money on their guess. And there was a burst of activity in their brain's emotion-processing centres, the amygdala and the orbitofrontal cortex. The study is published in this week's Science1. The volunteers didn't know that the odds of them guessing right were actually the same in both games. Because players in the second game could only say 'red' or 'blue', their chances of betting correctly remained at 50%, whatever the ratio of blue and red cards. ©2005 Nature Publishing Group

Keyword: Emotions
Link ID: 8284 - Posted: 06.24.2010

Rowan Hooper THANKS to research on "mighty mice", the lives of people suffering from muscle-wasting diseases such as muscular dystrophy could be transformed. Two treatments that block a protein called myostatin, which slows muscle growth, are now in the pipeline. The first approach, announced this week, aims to use a drug to mop up myostatin. Meanwhile a second method, which is already in clinical trials in people with muscular dystrophy, uses antibodies to disable the protein. In 1997, researchers led by Se-Jin Lee of Johns Hopkins University School of Medicine in Baltimore, Maryland, engineered mice in which the gene for myostatin had been "knocked out". The animals grew muscles twice as big as normal. A defect in the myostatin gene was what caused a German toddler, whose story was widely publicised last year, to develop prodigious muscles. Now Lee has produced a soluble molecule called activin type IIB receptor (ACVR2B) that binds to myostatin in normal mice, causing their muscles to bulk up. He hopes ACVR2B can be used to treat conditions such as Duchenne muscular dystrophy, a genetic disease that affects 1 in 3000 boys. Their muscles waste away because of a defect in the gene for the protein dystrophin, which is important in organising muscle structure. © Copyright Reed Business Information Ltd

Keyword: Muscles; Movement Disorders
Link ID: 8283 - Posted: 06.24.2010

A new study from the Monell Chemical Senses Center may shed light on why some people like salt more than others. The results suggest that a person's liking for salty taste may be related to how much they weighed when they were born. In a paper published in the European Journal of Clinical Nutrition, the Monell researchers report that individual differences in salty taste acceptance by two-month old infants are inversely related to birth weight: lighter birth weight infants show greater acceptance of salt-water solutions than do babies who were heavier at birth. According to lead author Leslie Stein, Ph.D., "The early appearance of this relationship suggests that developmental events occurring in utero may have a lasting influence on an individual's preference for salty taste." A similar relationship was found in a subset of the same children at preschool age, suggesting that the relationship between salty taste preference and birth weight persists at least through early childhood, a critical time for the formation of flavor and food preferences. By studying individual differences in liking for salty taste, scientists hope to obtain needed insights into the underlying factors driving salt preference and intake. Such information could potentially be used in programs designed to reduce salt intake, which is believed by many to contribute to the development and maintenance of high blood pressure.

Keyword: Chemical Senses (Smell & Taste); Development of the Brain
Link ID: 8282 - Posted: 12.08.2005

Playing too many video games has been reported to increase violent tendencies in some people or make some kids slow learners, but they may also create skilled surgeons and have also been used as a virtual distraction helping some kids get through painful medical treatments. Now it seems that playing certain special computer games could help prepare some kids for school. Psychologists at the University of Oregon designed the games to train the network of brain areas involved in attention, which undergoes important development between ages three and seven. "It's important, particularly in child development, for the child's ability to regulate their thoughts and to control their emotions," explains neuro-psychologist Mike Posner. "This executive network, which tends to control the child's emotions, and also allows them to continue to work on a particular task, it's also likely that that network is also deficient in ADHD children." Posner and his research team were interested in seeing whether, with a certain amount of training, they might be able to improve the efficiency of the network in children at the age when the network is developing. © ScienCentral, 2000-2005.

Keyword: ADHD; Attention
Link ID: 8281 - Posted: 06.24.2010

By Susan Brown What's behind the satisfaction we get from a tasty dessert? Researchers have long assumed it has something to do with the neurotransmitter dopamine. But a new study suggests that this so-called "pleasure molecule" isn't necessary for us to enjoy that piece of cake after all. Without the pleasurable kick dopamine is thought to provide, researchers assumed that people would be less inclined to get hooked on gambling or drugs (ScienceNOW, 10 January:). But recent evidence has called this theory into question. For example, mice lacking a type of receptor for dopamine still seek out morphine, suggesting that they find the drug rewarding even without dopamine signaling. To investigate further, neurobiologists Thomas Hnasko, Bethany Sotak, and Richard Palmiter at the University of Washington in Seattle gave morphine to dopamine-deficient mice. Once the morphine wore off, the team let the animals roam freely between two chambers: one where they had received the morphine and another one. Dopamine-deficient mice given moderate to high levels of morphine favored the morphine-associated chamber, just like normal mice did, further evidence that dopamine isn't necessary to experience the rewards of morphine, the team reports 8 December in Nature. © 2005 American Association for the Advancement of Science.

Keyword: Drug Abuse
Link ID: 8280 - Posted: 06.24.2010

Roxanne Khamsi Experiments on immature rats' brains suggest that treating epileptic children with benzodiazepine drugs could do more harm than good, scientists in France have claimed. They have found that the neurotransmitters unlocked by these drugs cause changes in brain chemistry that actually promote epileptic activity. Anticonvulsant benzodiazepines are a last-ditch treatment used to stop seizures in both infants and adults. Some medical experts think that the electrical activity associated with seizures can change brain networks, making them more susceptible to future epileptic activity. So understanding the chemistry of seizures might lead to drugs that can counteract epilepsy's development, says Yehezkel Ben-Ari, a neuroscientist at the Mediterranean Institute of Neurobiology in Marseille. His team studied the electrical and chemical activity of brains removed from baby rats. They were particularly interested in the hippocampus, a part of the brain important in epileptic seizures. The researchers found that the neurotransmitter gamma-aminobutyric acid (GABA) triggers rapid electrical signalling in the immature hippocampus - a hallmark of epileptic seizures. Benzodiazepine drugs enhance the action of this neurotransmitter. ©2005 Nature Publishing Group

Keyword: Epilepsy
Link ID: 8279 - Posted: 06.24.2010

The brainier male bats are, the smaller their testicles, according to a new study. Researchers suggest the correlation exists because both organs require a lot of energy to grow and maintain, leading individual species to find the optimum balance. The analysis of 334 species of bat found that in species where the females were promiscuous, the males had evolved larger testes but had relatively small brains. In species, where the females were monogamous, the situation was reversed. Male fidelity appeared to have no influence over testes or brain size. Both brain tissue and sperm cells require a lot of metabolic energy to produce and maintain. The different species appear to have evolved a preference for developing one organ more than the other, presumably determined by which will help them produce more offspring. “An extraordinary range of testes mass was documented across bat species - from 0.12% to 8.4% of body mass. That exceeds the range of any other mammalian order,” says Scott Pitnick, from Syracuse University in New York, US, one of the research team. Primate testes vary between species from 0.02% and 0.75% of body mass. Copyright Reed Business Information Ltd.

Keyword: Evolution; Sexual Behavior
Link ID: 8278 - Posted: 06.24.2010

A brain chemical recently found to boost trust appears to work by reducing activity and weakening connections in fear-processing circuitry, a brain imaging study at the National Institutes of Health’s (NIH) National Institute of Mental Health (NIMH) has discovered. Scans of the hormone oxytocin’s effect on human brain function reveal that it quells the brain’s fear hub, the amygdala, and its brainstem relay stations in response to fearful stimuli. The work at NIMH and a collaborating site in Germany suggests new approaches to treating diseases thought to involve amygdala dysfunction and social fear, such as social phobia, autism, and possibly schizophrenia, report Andreas Meyer-Lindenberg, M.D., Ph.D., NIMH Genes Cognition and Psychosis Program, and colleagues, in the December 7, 2005 issue of the Journal of Neuroscience. “Studies in animals, pioneered by now NIMH director Dr. Thomas Insel, have shown that oxytocin plays a key role in complex emotional and social behaviors, such as attachment, social recognition and aggression” noted NIH Director Elias Zerhouni, M.D.. “Now, for the first time, we can literally see these same mechanisms at work in the human brain.” “The observed changes in the amygdala are exciting as they suggest that a long-acting analogue of oxytocin could have therapeutic value in disorders characterized by social avoidance,” added Insel.

Keyword: Emotions; Hormones & Behavior
Link ID: 8277 - Posted: 06.24.2010

Researchers have found evidence that may partially exonerate a protein known to be a culprit in the progression of Alzheimer's disease. Their new studies show that the protein p25, which wreaks havoc in the brains of patients with Alzheimer's disease, also has a good side in promoting the plasticity of the brain. In studies in mice, the scientists have shown that the enzyme promotes structural changes in the brain associated with learning and memory. The studies indicate that when the concentration of the protein reaches excessive levels, it contributes to the brain cell death associated with Alzheimer's disease (AD). Their discovery of the dual nature of p25 suggests that drugs that partially inhibit p25's target enzyme could protect the neurons of patients with AD. The research team, which was led by Howard Hughes Medical Institute investigator Li-Huei Tsai, reported its findings in the December 8, 2005, issue of the journal Neuron. Tsai and her colleagues at Harvard Medical School collaborated on the studies with researchers from the National Institute of Mental Health. In earlier studies, Tsai and her colleagues discovered that an enzyme called cyclin-dependent kinase 5 (Cdk5) plays a central role in AD pathology. Like other kinases, Cdk5 switches on enzymes by attaching a phosphate group to them. Under tight regulation by a protein called p35, Cdk5 controls the construction and maintenance of neuronal connections in the brain. © 2005 Howard Hughes Medical Institute.

Keyword: Alzheimers
Link ID: 8276 - Posted: 06.24.2010