Storing memories in the brain is a physical process that requires some demolition and a lot of construction. Ground zero for this makeover is the synapse - a specialized junction that is the site of chemical chatter between neurons. When new memories are stored, synapses are rapidly reconfigured and rebuilt so neurons are equipped to respond more readily in the future. Researchers are now zeroing in on how single synapses change over time, and one of the key questions facing scientists is how the raw materials are transported to the “construction site” in a timely manner. Now, Howard Hughes Medical Institute researchers have identified the chief motor protein that hauls the building materials to their destinations in the synapse—just when they are needed. Researchers suspect that breakdowns in this transport process may contribute to deficits in learning and memory that accompany certain disorders, such Alzheimer's disease and addiction. Howard Hughes Medical Institute investigator Michael Ehlers and his colleagues at Duke University Medical Center published their findings in the October 31, 2008, issue of the journal Cell. Ehlers's group collaborated on the research with scientists at Brown University, the McLaughlin Research Institute in Montana, and the University of Massachusetts Medical School. © 2008 Howard Hughes Medical Institute.

Keyword: Learning & Memory
Link ID: 12192 - Posted: 06.24.2010

Tennis line judges are more likely to make mistakes when calling balls "out" rather than "in", say researchers. Californian scientists found that of 83 incorrect calls, 70 of the errors were wrong "out" calls. This was down to a time lag of a few hundred milliseconds between an image hitting the retina and the viewer processing it, the team said. This bias, revealed in Current Biology, could enable players to exploit the "challenge" system, they suggested. Decoding information about the position of objects is a complex task, as the brain has to allow not only for the movement of the object, but also for the movement of the eye relative to it. The result is a time lag of a few hundred milliseconds between an image hitting the retina and our becoming aware of it. If the object is moving fast, the brain produces an illusion that the object has moved slightly further than it actually has in order to overcome this lag. The team from the University of California, Davis, says, in tennis terms, this means a ball which bounces on the line could actually be perceived by the line judge or umpire as slightly further away and called "out" as a result. To test this, video clips of 4,000 random Wimbledon points were examined and any incorrect calls logged. If this "bias" did not exist scientists would have expected the number of balls wrongly called "out" to equal the number wrongly judged "in". In fact, of 83 calls, 70 of the errors were wrong "out" calls. (C)BBC

Keyword: Vision
Link ID: 12191 - Posted: 10.30.2008

Parasites may seem merely icky, but some of them have the Halloweenish capacity to take over your brain. Scientists have happened upon a number of neurological nuisances in the animal world, but the scariest of the lot is a tiny critter known as Toxoplasma gondii - which makes rodents, and perhaps even humans, go loco. Stanford neurobiologist Robert Sapolsky provided a status report on the fabled Toxoplasma and other brain snatchers this week on the university's Palo Alto campus, as part of the Council for the Advancement of Science Writing's annual New Horizons in Science seminar. Over the past few years, neuroscientists have used brain imaging and other high-tech tools to track exactly how the one-celled Toxo organism does its nefarious deed. The parasite can reproduce only in cat feces - but once the next generation has been spawned, how does it get into another feline host? That's where zombie rodents play a role: When mice or rats consume the feces, as is their wont, the Toxo protozoans migrate to the brain - specifically, to the amygdala, which is the brain's switchboard for emotional response. There they form encapsulated cysts and proceed to manipulate the wiring of the rodent brain. Studies have shown that the Toxo genome contains what appear to be mammalian versions of two genes that are involved in the production of dopamine, a neurotransmitter that is linked with the brain's reward system. "Toxo has evolved to take over the reward pathway," Sapolsky said. © 2008 msnbc.com

Keyword: Miscellaneous
Link ID: 12190 - Posted: 06.24.2010

Jordan Lite Listen up, ladies: If you're looking to score, break out that red dress. Men were more eager to bed women wearing red than those decked out in other colors, according to five studies involving 149 men and 32 women published today in the Journal of Personality and Social Psychology. The men also judged those women as more attractive than those sans red duds. "I'm not going to let my 16-year-old daughter wear red, let's put it that way," says study author Andrew Elliot, a professor of psychology at the University of Rochester. "I do think a female who's interested in a male and going on a date ought to pull that red shirt out of the closet, because most likely it will make her more attractive to him." There are two explanations for the phenomenon, says Elliot, a visiting professor at the University of Munich this semester. Society's emphasis on red on Valentine's Day as well as in sexy red lingerie may have taught men to link the color with romance, he says. There may also be an evolutionary explanation, based on humans' close genetic relationship with primates: Male primates tend to be especially attracted to female primates who show their red hindquarters, made rosy by increased blood flow when they're most fertile. © 1996-2008 Scientific American Inc.

Keyword: Sexual Behavior
Link ID: 12189 - Posted: 06.24.2010

by Joyce Gramza Nothing melts manly into mushy like fatherhood. Now a study of marmoset monkeys reveals how the mere scent of his baby turns dad from protector to parent, by ratcheting down levels of the male hormone testosterone. "We have found when they are smelling the infant scent they have hormonal changes which may make them more maternal-like, more interested in bonding with an infant, whereas when their testosterone goes up, they may be more ready to, say, defend their family," says lead researcher Toni Ziegler, a senior scientist at the Wisconsin National Primate Research Center at the University of Wisconsin-Madison. "Testosterone is known for increasing muscle mass in males, and it also has behavioral effects, such as a tendency to make one more aggressive, which might be important if you need to protect your family," Ziegler explains. "It’s also very much involved in mating behavior, and increased testosterone occurs when males are mating, or interested in, or interacting with a female that may be ovulating." "You don’t normally think of someone that’s providing a lot of care for an infant to be aggressive or be interested in mating," she adds. "So this way, a father can respond with lower testosterone at a time when he’s interacting with his infant, but at times when he needs to be more protective of the family his testosterone is able to change and respond to the environment." ©2008 ScienCentral

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 12188 - Posted: 06.24.2010

Erika Check Hayden Genetic testing for Alzheimer's disease tells a cautionary tale about the legal, medical and ethical complications of personal genomics, as the story of a Pennsylvania company shows. Smart Genetics, based in Philadelphia, has stopped offering its controversial 'Alzheimer's Mirror' genetic test just eight months after introducing it. The test checked for variants in a gene, called APOE, that bestow as much as a 15-fold increased risk of developing Alzheimer's. Soon after launching the test, though, Smart Genetics chief executive Julian Awad found himself in a controversy over whether it violated intellectual-property agreements covering APOE testing. Smart Genetics' tests were performed by Athena Diagnostics, based in Worcester, Massachusetts. Athena had, in turn, licensed the patents from Duke University in Durham, North Carolina, where researcher Allen Roses discovered the APOE link to Alzheimer's in the early 1990s. Roses and Duke argue that Athena's licence covers APOE testing only in people who already have symptoms of dementia. "The test was never intended to be used for wholesale screening of non-cognitively impaired individuals," adds Alan Herosian, director of corporate alliances for Duke University. He says he has contacted Athena many times in recent months to press this point. © 2008 Nature Publishing Group

Keyword: Alzheimers; Genes & Behavior
Link ID: 12187 - Posted: 06.24.2010

Linda Geddes TIREDNESS, depression and lack of libido all seem inevitable parts of male ageing, but what if an age-related lack of testosterone is at the root of all these symptoms? Increasingly, doctors say such an "andropause" exists and that its effects may go beyond feeling a bit tired - obesity and diabetes also appear to be linked. The good news is that testosterone supplements might help treat the problem. Though testosterone is sometimes prescribed for ageing men in Europe and the US, until recently even the existence of andropause was considered controversial. Treating it was seen by many as unnecessary and potentially harmful because of concerns that testosterone supplements could contribute to prostate cancer by driving the growth of cancerous cells. Now that attitude is starting to change. While many researchers and doctors still dislike the use of the word andropause - because it implies equivalence with menopause and yet does not affect all men - there is an acceptance that testosterone levels decline with age, resulting in testosterone deficiency - or late-onset hypogonadism (LOH) - in around 20 per cent of men over 65. "Age-related declines in testosterone are real," says Adrian Dobs of Johns Hopkins University in Baltimore, Maryland. "If a man has signs of hypogonadism then treatment should be considered." Meanwhile, a handful of recent studies have linked low testosterone to the development of type 2 diabetes, obesity and cardiovascular disease. Other research indicates that some of the fears about testosterone supplements increasing the risk of prostate cancer may have been unfounded (See "Doesn't testosterone drive cancer?"). © Copyright Reed Business Information Ltd

Keyword: Hormones & Behavior; Sexual Behavior
Link ID: 12186 - Posted: 06.24.2010

By Mitch Leslie Feeling relaxed? Thank your immune system. A new study suggests that mast cells, which lead the charge against microbial invaders, may also be responsible for tamping down anxiety. Mast cells have a split personality. They are often the first cells to attack foreign microbes, and they coordinate and control other immune cells. Yet they can also be traitors. Upon encountering pollen or dust, they release histamines and other chemicals that can trigger allergies and asthma. Mast cells may also incite or abet conditions as diverse as atherosclerosis, rheumatoid arthritis, autism, and migraines. Although researchers know the functions of many mast cells in the body, a subset that inhabits the brain has remained mysterious. To learn more about these cells, neuroscientist Rae Silver of Columbia University and colleagues subjected mice that lack mast cells to a series of behavioral tests. The researchers measured how much the animals moved around and gauged their responses to stimuli such as a puff of air, an odor, or loud sounds. The mice strayed from the rodent norm in only one way: they were particularly anxious. For instance, mice without mast cells hesitated more than 80 seconds longer than did control mice before stepping out into the open. Mast cell–deficient mice were also reluctant to explore unfamiliar sections of a maze, the team reports online today in the Proceedings of the National Academy of Sciences. © 2008 American Association for the Advancement of Science.

Keyword: Emotions; Neuroimmunology
Link ID: 12185 - Posted: 06.24.2010

By Tim Harford Is a stock market bubble a medical condition? You might well have thought so, had you taken a walk around a trading floor and looked at the behaviour of traders at the height of the dotcom bubble in 2000. "They were displaying classic symptoms of mania," says John Coates, recalling his time as the manager of a New York trading floor. "They were overconfident, they had racing thoughts, they had diminished need for sleep and heightened sexual appetite." But Dr Coates no longer works on Wall Street. He is now one of a small but growing number of "neuroeconomists" - researchers who study the brain, hormones and nervous system in search of an explanation of our behaviour as investors and shoppers. Neuroeconomics is a new discipline that fuses economics and neuroscience, and its practitioners are people who think that everyday phrases such as "impulse buy", "business brain" and "bull market" are more than just figures of speech. "A bull market" refers to a long period of rising share prices, but Dr Coates points out that traders behave uncannily like real bulls and other male animals. A rutting stag, for example, enjoys a testosterone surge if he beats off a sexual rival. More testosterone means more confidence and more risk-taking, which tends to lead to more victories and yet more testosterone. Eventually, the cycle comes to an end - often because confidence has turned into recklessness - and reverses itself. After taking a few saliva samples, Dr Coates has discovered not only that such hormone surges happen to human traders too, but also that they are correlated with risk-taking and short-term profitability. (C)BBC

Keyword: Emotions
Link ID: 12184 - Posted: 10.30.2008

By SAM WANG and JOSHUA GOLD AS we enter the final week of a seemingly endless election campaign, opinion polls continue to identify a substantial fraction of voters who consider themselves “undecided.” Although their numbers are dwindling, they could still determine the outcome of the race in some states. Comedians and other commentators have portrayed these people as fools, unable to choose even when confronted with the starkest of contrasts. Recent research in neuroscience and psychology, however, suggests that most undecided voters may be smarter than you think. They’re not indifferent or unable to make clear comparisons between the candidates. They may be more willing than others to take their time — or else just unaware that they have essentially already made a choice. Neuroscientists have begun to tease out the brain systems that make decisions. Even when it takes no more than a second, decision-making is thought to involve two parts, gathering evidence and committing to a choice. In tasks as simple as deciding whether a shifting pattern of dots is moving to the left or to the right, brain activity in the parietal cortex rises as evidence is gathered, eventually reaching a tipping point (though it’s not yet known which brain regions drive the final choice). Inherent to this process is a trade-off between speed and accuracy. Commit early and you can get on with your life. Take more time and you might make a wiser or more accurate decision. Since a commitment to John McCain or Barack Obama is not required until Nov. 4, for the greatest accuracy, one should gather evidence until that date. So then why aren’t there even more undecided voters? Copyright 2008 The New York Times Company

Keyword: Emotions
Link ID: 12183 - Posted: 06.24.2010

WASHINGTON - Your 9-year-old's eyes hurt during homework? Your teen's a slow reader plagued with headaches? They may have a common yet often missed vision problem: Eyes that don't turn together properly to read. As many as one of every 20 students have some degree of what eye doctors call "convergence insufficiency," or CI, where eye muscles must work harder to focus up-close. And those standard vision screenings administered by schools and pediatricians won't catch it — they stress distance vision. When symptoms such as eye strain, headaches, double vision or reading problems trigger the right diagnosis, doctors prescribe any of a hodgepodge of exercises designed to strengthen eye coordination. Now a major government study finally offers evidence for the best approach: Eye training performed in a doctor's office for 12 weeks. The right treatment can make a profound difference, says Adele Andrews of Rydal, Pa., whose son Thomas participated in the study when he was 10 — and improved enough to at last start reading for fun. His mother knew something wasn't right early on: Reading seemed to require a physical struggle of Thomas that his three older siblings never experienced. Copyright 2008 The Associated Press.

Keyword: Vision
Link ID: 12182 - Posted: 06.24.2010

By Nelson Hernandez On her back in a dark tube, Blair Smith held still as a scanner combed her brain with magnetic waves. Words flashed by her eyes: tack, vase, hope, glow, vague, cade. The 11-year-old had been told to press the button in her right hand if the word was real, the button in her left if it was nonsense. The answer itself was less important than the map the scanner would make of which areas of Blair's brain lighted up when she struggled with a word. The aim of the study, said Laurie E. Cutting, director of the Education and Brain Research Program at the Kennedy Krieger Institute in Baltimore, is to understand the neurological differences among students who are skilled readers, those who have difficulties and those with diagnosed learning disabilities. If neuroscientists can pinpoint which parts of the brain are activated when a reader puzzles over an unknown word, they may eventually help teachers tailor reading instruction for individuals. That is only the beginning. Many educators hunger for scientific data to help them structure their lessons, and neuroscience is beginning to offer them broad guidance about what works best. One of the most startling recent revelations in neuroscience has been that the brain's structure is much more flexible (a concept called neuroplasticity) than was previously thought; this understanding may help teachers find ways to train the brain to better solve math problems or understand a book. © Copyright 1996-2008 The Washington Post Company

Keyword: Learning & Memory
Link ID: 12181 - Posted: 06.24.2010

By C. CLAIBORNE RAY A. “In both humans and other mammals, as the body became more complex and reacted to environmental stressors, the brain developed in response to that,” said Dr. Philip E. Stieg, chief of neurosurgery at NewYork-Presbyterian Hospital/Weill Cornell. “We do not know what specific stimulus changed or caused a species that has a single brain lobe to evolve to have two hemispheres. It was probably a series of stimuli.” All animals that show complex responses have two hemispheres, Dr. Stieg said. A worm, for example, reacts to simple sensory input with a simple set of motor responses, he said. But the human brain deals with not just complex sensory input, but more diverse and complex motor responses mixed with an array of emotional and cognitive interplays. The result, he said, is that parts of the different hemispheres of the cerebral cortex, the top part of the brain, developed specialties. For just a few examples, he said, “the dominant side of the temporal lobes (the left in 97 percent of us) have speech and visual pathways; the parietal lobes, straight up from the ear, are intermixed on the dominant side, with the left handling speech; and the sensory function of one side of the body is handled by the other side, so that if the brain is bruised on the right side of the parietal lobe, and I hit you on the left side of the body, you might not pay attention to it.” Patients can have half their brain cut out to treat severe seizures and still function, but not at the same cognitive level, Dr. Stieg said. Copyright 2008 The New York Times Company

Keyword: Laterality
Link ID: 12180 - Posted: 06.24.2010

By Larry Lindner "For the first time in my life I felt like a normal person," says Josh Thayer, who dropped from 367 pounds to 230 within a year of undergoing gastric bypass surgery in 1998. No longer did he always have to buy the aisle seat at the theater because "you feel guilty hanging over the person sitting next to you." No longer did he have to endure humiliations such as breaking a chair at his brother's wedding. The best part, says Thayer, a Boston area professor, was not having to "think about food for the first time in my life. It was fantastic. I ate when I was hungry, stopped when I was full. I didn't feel like I was fighting an uphill battle." Until five years later, when the weight started creeping back on. When the 6-foot Thayer edged up to 310 earlier this year at age 45, he decided to go for a second operation: adjustable banding, more commonly known as lap-band surgery, which allows for repeated stomach-tightening and thereby offers a new opportunity for reining in appetite. Reactions to his decision vary, he says. While some people close to him worry about his going under the knife again, others have asked, "What the hell did you do wrong?" Second surgeries to combat obesity are on the rise. The American Society for Metabolic and Bariatric Surgery doesn't keep statistics on repeat customers, but obesity surgeons are reporting upticks. Dennis Halmi, a member of the Bluepoint Surgical Group in Woodbridge, says that in 2002 "we did a handful" of second operations on obesity patients, "maybe five, six. This year we are doing probably 30." Scott Shikora of Tufts Medical Center in Boston says that until recently he hadn't performed a second obesity operation on anybody but is already up to about a half-dozen patients. Thayer was one of them. © Copyright 1996-2008 The Washington Post Company

Keyword: Obesity
Link ID: 12179 - Posted: 06.24.2010

By AP / MARIA CHENG (LONDON) — Want to lose weight? Try eating. That's one of the strategies being developed by scientists experimenting with foods that trick the body into feeling full. At the Institute of Food Research in Norwich, England, food expert Peter Wilde and colleagues are developing foods that slow down the digestive system, which then triggers a signal to the brain that suppresses appetite. "That fools you into thinking you've eaten far too much when you really haven't," said Wilde. From his studies on fat digestion, he said it should be possible to make foods, from bread to yogurts, that make it easier to diet. While the research is preliminary, Wilde's approach to curbing appetite is one that some doctors say could be key in combating the obesity epidemic. "Being able to switch off appetite would be a big help for people having trouble losing weight," said Steve Bloom, a professor of investigative medicine at London's Imperial College, who is not connected to Wilde's research. Scientists in North America and elsewhere in Europe are also trying to control appetite, including through chemical injections or implantable devices that interfere with the digestive system. © 2008 Time Inc. All rights reserved

Keyword: Obesity
Link ID: 12178 - Posted: 06.24.2010

By NATALIE ANGIER If you want to glimpse the handiwork of one of your body’s unsung sensory heroes, try this little experiment. Hold your index finger a few inches in front of your face and sweep it back and forth at a rate of maybe once or twice a second. What do you see? A blurry finger. Now hold your finger steady and instead shake your head back and forth at the same half-second pace. This time, no blur, no Marcel Duchamp’s “Nude Descending a Staircase” effect. The finger stays in focus even as your head vigorously pantomimes its denial. And it’s a good thing, too. If the brain couldn’t distinguish between movements of the viewer and movements of the view, if every time you turned around or walked across the room the scenery appeared to smear or the walls to lurch your way, you soon might cease to move at all, uncertain of external threats, unaided by any internal compass marked You. Essential to a fully embodied sense of self is the vestibular system, a paired set of tiny sensory organs tucked deep into the temporal bone on either side of the head, right near the cochlea of the inner ear. The vestibular system isn’t a high-profile, elitist sense like the famed five of vision, hearing, touch, taste and smell. It’s more of a Joe Sixth-Sense, laboring in anonymity and frequently misunderstood. Even its name is a blooper encapsulated, the result of early anatomists thinking the organ merely served as an entrance, or vestibule, to the inner ear. Copyright 2008 The New York Times Company

Keyword: Miscellaneous
Link ID: 12177 - Posted: 06.24.2010

By Lou Dzierzak What's scarier, a deadly snake slithering across your path during a hike or watching a 1,000-point drop in the stock market? Although both may instill fear, researchers disagree over the nature and cause of this very powerful emotion. "When you see the stock market fall 1,000 points, that's the same as seeing a snake," says Joseph LeDoux, professor of neuroscience and psychology the Center for the Neuroscience of Fear and Anxiety based at New York University. "Fear is the response to the immediate stimuli. The empty feeling in your gut, the racing of your heart, palms sweating, the nervousness—that's your brain responding in a preprogrammed way to a very specific threat." LeDoux adds: "Since our brains are programmed to be similar in structure, we can assume that what I experience when I'm threatened is something similar to what you experience." Fear even affects different species in similar ways. "We come into the world knowing how to be afraid, because our brains have evolved to deal with nature," LeDoux says, noting that the brains of rats and humans respond in similar ways to threats, even though the threat itself might be completely different. Other researchers find fear to be a vastly personal experience. Whereas some people become terrified watching a scary film, others may be more afraid to walk back to their cars in a dark parking lot after the movie ends. © 1996-2008 Scientific American Inc.

Keyword: Emotions
Link ID: 12176 - Posted: 06.24.2010

By Michael Price People with muscular dystrophy tire after even light exercise. Now a study suggests that the exhaustion is caused by an enzyme that is missing from the muscle cell membrane, and the results point to a possible treatment for the condition: Viagra. Every year, about 500 boys in the United States are born with Duchenne muscular dystrophy, the disease's most common form. All forms of muscular dystrophy, which cause skeletal muscles to gradually weaken, result from mutations that overload the body with the enzyme creatine kinase, which breaks down muscle tissue. Researchers have long known that even in milder types of the disease, such as Becker's muscular dystrophy, and in the early stages of Duchenne muscular dystrophy, patients tend to fatigue after relatively minor activities. The briefest walk can leave them far more worn out than would be expected from just having weak muscles. These effects show up in mouse models of the disease, too. About 3 years ago, Kevin Campbell, a biophysicist at the University of Iowa in Iowa City, showed a video of the tired muscular dystrophy mice in his lab at a conference. A chance comment inspired a possible solution. "One of the physicians in the audience said, 'That looks just like my Becker's [muscular dystrophy] patients,' " Campbell recalls. One of the hallmarks of Becker's muscular dystrophy is the loss of an enzyme, neuronal nitric oxide synthase (nNOS), from muscle cell membranes. Campbell wondered whether the deficiency of nNOS might be the source of fatigue. © 2008 American Association for the Advancement of Science.

Keyword: Movement Disorders; Muscles
Link ID: 12175 - Posted: 06.24.2010

Germany's constitution guarantees its citizens the freedom to conduct research — but local authorities in the northern city of Bremen are forcing a leading neuroscientist to halt his primate experiments. A court will probably now have to decide whether the controversial ruling violates federal law. Andreas Kreiter at the University of Bremen uses 24 macaques to study cognitive processes in the mammalian brain. Germany's largest animal-protection group, the Animal Welfare Association, has for years campaigned against the experiments, claiming that they are intolerably painful and have no short-term therapeutic use. Local politicians have become increasingly sympathetic to that view. Last year, in a move criticized by scientists as a grab for votes, Bremen's parliament called on the state government to ban Kreiter's primate research (see Nature 446, 955; 2007). After regional elections in May 2007, the newly formed Social Democrat–Green coalition government agreed not to reapprove his experiments when his current licence expires later this year. On 15 October, Kreiter was officially informed by the senate of health — the local authority in charge of approving animal experiments — that his licence will not be renewed. Referring to "changed societal values", the authority argued that the experiments were "ethically unjustified" because they address long-term scientific questions rather than help develop specific medical therapies. © 2008 Nature Publishing Group

Keyword: Animal Rights
Link ID: 12174 - Posted: 06.24.2010

Australian researchers have identified a significant link between a gene involved in testosterone action and male-to-female transsexualism. DNA analysis from 112 male-to-female transsexual volunteers showed they were more likely to have a longer version of the androgen receptor gene. The genetic difference may cause weaker testosterone signals, the team reported in Biological Psychiatry. However, other genes are also likely to play a part, they stressed. Increasingly, biological factors are being implicated in gender identity. One study has shown that certain brain structures in male-to-female transsexual people are more "female like". In the latest study, researchers looked for potential differences in three genes known to be involved in sex development - coding for the androgen receptor, the oestrogen receptor and an enzyme which converts testosterone to oestrogen. Comparison of the DNA from the male to female transsexual participants with 258 controls showed a significant link with a long version of the androgen receptor gene and transsexualism. It is known that longer versions of the androgen receptor gene are associated with less efficient testosterone signalling. This reduced action of the male sex hormone may have an effect on gender development in the womb, the researchers speculated. "We think that these genetic differences might reduce testosterone action and under masculinise the brain during foetal development," said researcher Lauren Hare from Prince Henry's Institute of Medical Research. Co-author Professor Vincent Harley added: "There is a social stigma that transsexualism is simply a lifestyle choice, however our findings support a biological basis of how gender identity develops." (C) BBC

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 12173 - Posted: 10.27.2008