Microscopic nematode worms are among the most-studied organisms in biology and genetics-- revealing the role of genes in addiction, obesity, and even longevity. Now researchers at the University of Utah have demonstrated they can make them behave like the opposite sex by activating a gene in their brains. "A female avoids other females and males are attracted to females. And so what we can do is swap those behaviors," says Howard Hughes Medical Institute investigator Erik Jorgensen. "But what's really important is that we can identify the circuits in the brain that underlie that behavior. So we have a group of cells that we can now manipulate and demonstrate how this whole process works-- how does the brain work." While the worm, C. elegans, only has 302 nerve cells, "The nerve cell in a worm is exactly how a nerve cell in the human brain works," Jorgensen says. "So if we can understand it in a worm we'll be able to understand how the brain works in the human and that is our goal." As Jorgensen, Jamie White and their colleagues wrote in the journal, Current Biology, the study showed that in worms, sexuality is hard-wired in the brain and is not affected by the body or hormones. © ScienCentral, 2000-2007.

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 10890 - Posted: 06.24.2010

A component of cannabis in small doses can act as a powerful antidepressant, but too much of the drug can cause the polar opposite effect, finds a study released Wednesday. The study, published in the Oct. 24 issue of the Journal of Neuroscience, was conducted jointly by McGill University and a research institute affiliated with the University of Montreal. It finds that a form of THC, the active ingredient in cannabis or marijuana, increased serotonin levels in the brains of laboratory rats when given in low doses. The depletion of serotonin, a neurotransmitter that controls moods, leads to depression and in some cases psychosis. Anti-depression medications work by increasing the amount of serotonin in the brain. However, when the doses were increased in the rats, the effect was described as completely reversed. McGill researcher Francis Bambico said the study seems to support anecdotal evidence that human smokers of marijuana experience positive effects, but they also experience unwanted effects like anxiety and agitation. © The Canadian Press, 2007

Keyword: Drug Abuse; Depression
Link ID: 10889 - Posted: 06.24.2010

NEW YORK - Cigarette smoking and a family history of alcoholism both alter how women perceive sweet foods and what foods they crave, according to studies conducted by two researchers from the Monell Chemical Senses Center in Philadelphia. Marta Yanina Pepino and Julie A. Mennella found that women who smoked were less sensitive to sweet taste than women who never smoked. Women who smoked needed higher concentrations of sugar to detect a sweet taste, and the more years a woman smoked, the less she was able to perceive a sweet taste. “Smoking dulls sweet taste sensitivity,” Pepino and Mennella noted in a joint email to Reuters Health. “Whether this reduced sensitivity for sweets helps smokers control their weight is an important question that is not addressed in the current study.” The researchers also found that cigarette smoking leads to increased food cravings, particularly for starchy carbohydrates and high-fat foods. “We found that food cravings were associated with nicotine dependence ... the more intense the cravings for cigarettes, the more frequent the cravings for foods high in fat and carbohydrates,” Pepino explained. Copyright 2007 Reuters.

Keyword: Drug Abuse; Chemical Senses (Smell & Taste)
Link ID: 10888 - Posted: 06.24.2010

By SCOTT HAIG She was worried about the lump and worried about the children who were worrying about her. She was, however, most worried about the anesthesia. "What if I don't wake up?" just wasn't a question I could answer sufficiently for her. Some people take no solace in statistics (that, for example, there are two or three deaths per 1 million patients anesthetized) — these patients are the medical cousins of the folks still crossing the country by train or bus rather than "risking the airplane." So I warned her that there might be a little pain and agreed to do her biopsy under a local anesthetic — but only if she would allow an anesthesiologist in the room, just in case. The lump was growing near — maybe on — the inner end of Ellen's collarbone, meaning that during the biopsy I might have to use a tool that goes "crunch." It's pretty hard to numb up bone with a local anesthetic so I was glad to have Frank, the anesthesiologist, there at the head of the table with some IV sedatives, in case Ellen got panicky or was in too much pain. She was adamant about not going under, but agreed to "some sedation" if we thought it was necessary. I can understand not wanting to lose consciousness. It's arguably the most precious thing we have. And although serious complications from anesthesia are truly rare these days, so are bone tumors — and she clearly had one of those. Ellen had a history of cancer too — it had not been a cancer that was likely to spread to the bone and there hadn't been any sign of it for years, but it had been a malignancy. © 2007 Time Inc.

Keyword: Learning & Memory
Link ID: 10887 - Posted: 06.24.2010

Roxanne Khamsi Two regions of the brain linked to optimism have been discovered by researchers. The identification of the sites that signal positive thinking could shed light on the causes of depression, they say. The US team says that the act of imagining a positive future event – such as winning an award or receiving a large sum of cash – activates two brain areas known as the amygdala and the rostral anterior cingulated cortex (rACC). The finding lends weight to earlier studies that suggested these brain regions malfunction in depression and hint at new ways of diagnosing the disorder. Elizabeth Phelps at the New York University, US, and colleagues measured how optimistic 15 volunteers were using a standard questionnaire. The researchers then asked these subjects to lie in a brain scanner and reflect on one of a number of potential scenarios. For example, in one part of the trial, subjects followed specific instructions to recall a negative event in the past, such a funeral attended in the past five years. In another part of the experiment they had to imagine what it would be like to be involved in a car crash in the near future. At other points in the study subjects had to reflect on positive events such as winning an award in the past or receiving a large sum of cash in the future. © Copyright Reed Business Information Ltd

Keyword: Emotions
Link ID: 10886 - Posted: 06.24.2010

Smoking large amounts of cannabis for therapeutic reasons may increase rather than reduce pain, a US study suggests. The pain-relieving qualities of cannabis have long been hailed, and several countries have made it available for medicinal purposes. But quantity is key, according to the study in the journal Anesthesiology. University of California researchers found moderate use had the greatest impact on pain in 15 volunteers, while large doses actually made pain worse. The team recruited 15 healthy volunteers, in whom pain was induced by injecting capsaicin - the "hot" chemical found in chilli peppers - under their skin. They were then given cannabis to smoke. The strength of the dose was determined by the tetrahydrocannabinol content, which is the main active chemical in cannabis. Some of the volunteers were given a placebo. Five minutes after smoking the drug, none of the doses had any effect on the pain felt. But 45 minutes later, those who had smoked the moderate dose said their pain was much better, while those who consumed high doses said it had got worse. They did, however, feel "higher" than counterparts who had taken moderate doses. Dr Mark Wallace, the lead researcher, said the findings could have implications for the way medicinal cannabis was offered, both in pure and drug form. (C)BBC

Keyword: Pain & Touch; Drug Abuse
Link ID: 10885 - Posted: 10.24.2007

By JANE E. BRODY For decades, I assumed I needed to sleep just five to six hours a night. I nearly always awoke before the alarm in the morning. But I also nearly always fell asleep at concerts and plays, on the subway or while reading or riding in a car. Last summer, when I was able to operate completely on my body’s own time clock, I discovered that it preferred seven to seven and a half hours of sleep. I also discovered that when I slept at night for however long my body wanted to, my daytime dozes all but disappeared. Surveys have shown that few of us past infancy and toddlerhood are receiving the amount of sleep our bodies and brains need to restore them to full function for the day ahead. And many of us — children, teenagers and adults of all ages — may pay a hefty price. As noted elsewhere in this issue, crucial brain functions occur in sleep that cannot be reproduced when we are awake. More than intellectual prowess can suffer; though definitive data are still lacking, a chronic shortage of sleep has been linked to serious physical ills, including heart disease, diabetes and obesity. Copyright 2007 The New York Times Company

Keyword: Sleep
Link ID: 10884 - Posted: 06.24.2010

WASHINGTON - Teenagers who smoke are five times more likely to drink and 13 times more likely to use marijuana than those who are not smokers, according to a report issued on Tuesday. The report by Columbia University's National Center on Addiction and Substance Abuse presented further evidence linking youth smoking to other substance abuse and spotlighted research on how nicotine affects the adolescent brain. "Teenage smoking can signal the fire of alcohol and drug abuse or mental illness like depression and anxiety," Joseph Califano, who heads the center and is a former U.S. health secretary, said in a telephone interview. The report analyzed surveys conducted by the U.S. Substance Abuse and Mental Health Services Administration and other data on youth smokers. Most smokers begin smoking before age 18. Smokers ages 12 to 17 are more likely drink alcohol than nonsmokers — 59 percent compared to 11 percent, the report found. Those who become regular smokers by age 12 are more than three times more likely to report binge drinking than those who never smoked — 31 percent compared to 9 percent. Binge drinking was defined as having five drinks or more in a row. © 2007 Microsoft

Keyword: Drug Abuse; Development of the Brain
Link ID: 10883 - Posted: 06.24.2010

By Nikhil Swaminathan Hey, candidates. Want to win an election? Simple. Just appear competent—even if you're not. A new report confirms what may be some politically inclined people's worst nightmare: looks matter. Princeton University researchers asked student volunteers which of two candidates in gubernatorial races appeared more competent. Much to the scientists' surprise, their picks turned out to be the voters' choices. Study participants were shown photos of the winners and losers in 89 political races that took place between 1996 and 2002. The subjects were given either 100 milliseconds, 250 milliseconds or an unlimited amount of time to choose candidate that they perceived as more competent; in all cases they were instructed to go with their gut. The students' selections were also the election winners in 64 percent of the cases. In a second trial, the volunteers were given either 250 milliseconds or two seconds to mull over their decisions. When given longer time to ponder, the students' individual responses became 5 to 7 percent less predictive, but their overall success rate bumped up to an average 69.1 percent. In a third experiment, which involved yet-to-be-held gubernatorial races, the group did similarly well (68.6 percent) when asked to go with their first impulse, but take as much time as they needed to answer, allowing them to deliberate. "All of the action goes on in the first 250 milliseconds of exposure, and then there's not much going on," says Alexander Todorov, an assistant professor of psychology and co-author of the study, which appeared in Proceedings of National Academy of Sciences USA, noting that these 250-millisecond trials yielded the greatest predictive success. "If they deliberate, they get slightly worse. [Though], they are still above chance in picking the winner." © 1996-2007 Scientific American, Inc

Keyword: Attention; Emotions
Link ID: 10882 - Posted: 06.24.2010

Peter F. MacNeilage A dog earns its reputation as best friend in part because it wags its tail in joy at the sight of its owner. But as a team of Italian researchers led by the University of Bari's Antonio Quaranta reveal in a recent article in Current Biology ("Asymmetric tail-wagging responses by dogs to different emotive stimuli," 20 March 2007), the wag of a dog's tail tells a much larger story. Quaranta and colleagues, examining closely the lesser-remarked fact that dogs wag their tails not just in pleasure but also when they are uneasy with an animal they are encountering, found a dog wags its tails differently in these two types of encounters: it wags the tail more to the right while greeting its owner but more to the left when meeting an unfamiliar dominant dog. Because the brain's control of the body is crossed, a bias in one direction means more activation of the brain hemisphere on the opposite side. Thus a dog's tail reveals which half of its brain is responding. This finding ties into a fascinating line of research regarding hemispheric specialization, evolution, specialized tasks versus routine, and how much like monkeys -- or dogs -- we humans might be. This study is important partly because it subjected a single population to a single experimental paradigm. This provides a more powerful demonstration than if the findings came from different paradigms applied to different subject groups; it compares apples to apples. And these tail-wagging biases fit into a general evolutionary perspective -- a sort of division of labor between right and left brain -- that involves not just mammals but also other major vertebrate groups, including fish, reptiles and birds. © 1996-2007 Scientific American, Inc.

Keyword: Animal Communication; Laterality
Link ID: 10881 - Posted: 06.24.2010

By Elie Dolgin Many more genes separate humans from chimpanzees than scientists believed. A new study shows that what sets us apart from our closest primate cousin is the accelerated rate at which we acquire new genes and ditch unnecessary ones. It's often said that there's only 1% to 2% difference between the genomes of chimps and humans, two species that had their most recent common ancestor about 5 million years ago. But that percentage refers to the nucleotide differences in shared genes. Evolution can do more than just tinker with gene sequences; the number of copies of a gene can also vary from one species to the next, even when the gene itself stays the same. Sometimes genes are gained, and sometimes they are lost. Quantifying this turnover has been difficult, however, because it requires the complete genome sequences of many species. Now, with several mammals sequenced and a suite of new statistical methods available, Matthew Hahn and colleagues at Indiana University, Bloomington, have taken a closer look. They measured how quickly genes were duplicated or lost across six mammalian genomes. By looking at about 120,000 genes in 10,000 gene families, they discovered that gene turnover was faster in primates than in dogs or in rodents, and even faster in humans, who swapped genes 1.6 times faster than monkeys and 2.8 times quicker than nonprimates. Thanks to this rapid change, 6.4% of the 22,000-odd human genes aren't present in chimps, making the gap between the two suddenly seem much wider.

Keyword: Evolution; Genes & Behavior
Link ID: 10880 - Posted: 10.24.2007

WASHINGTON - Having more years of formal education delays the memory loss linked to Alzheimer's disease, but once the condition begins to take hold, better-educated people decline more rapidly, researchers said on Monday. Their study, published in the journal Neurology, tracked memory loss in a group of elderly people from New York City's Bronx borough before they were diagnosed with Alzheimer's or another form of old-age dementia. Every year of education delayed the accelerated memory decline that precedes dementia by about 2-1/2 months, according to the researchers at Yeshiva University's Albert Einstein College of Medicine in New York. But once this memory loss began, the rate of decline unfolded 4 percent more quickly for each additional year of education, the researchers said. Someone with 16 years of schooling might experience memory decline 50 percent more quickly than another person with just four years education, based on the findings. Alzheimer's disease is a degenerative brain malady that is the most common form of dementia among the elderly. "An elderly person who starts to see memory loss might well deteriorate fairly rapidly, particularly if he or she has a high education or high IQ," Charles Hall, a professor of epidemiology at Albert Einstein College of Medicine who led the study, said in a telephone interview. Exercise your mind © 2007 MSNBC.com © 2007 Microsoft

Keyword: Alzheimers; Learning & Memory
Link ID: 10879 - Posted: 06.24.2010

Our genes and not just our upbringing may play a key role in our food likes and dislikes, UK researchers believe. Experts from Kings College London compared the eating habits of thousands of pairs of twins. Identical twins were far more likely to share the same dietary patterns - like a penchant for coffee and garlic - suggesting tastes may be inherited. A health psychologist said this meant childhood food foibles might be harder to put right than previously thought. Identical twins have exactly the same genetic make-up as each other, so scientists, by comparing them to non-identical twins, can work out the likelihood that their characteristics are due to "nature" or "nurture". The Kings College researchers looked at a total of more than 3,000 female twins aged between 18 and 79, working out their broad preferences using five different dietary "groups". These included diets heavy in fruit and vegetables, alcohol, fried meat and potatoes, and low-fat products or low in meat, fish and poultry. Their results, published in the journal Twin Research and Human Genetics, suggested that between 41% and 48% of a person's leaning towards one of the food groups was influenced by genetics. The strongest link between individual liking and genes involved a taste for garlic and coffee. Professor Tim Spector, who led the research, said: "For so long we have assumed that our upbringing and social environment determine what we like to eat. This has blown that theory out of the water - more often than not, our genetic make-up influences our dietary patterns." (C)BBC

Keyword: Obesity; Genes & Behavior
Link ID: 10878 - Posted: 10.23.2007

By Edyta Zielinska Sex differences in addictive behavior, long linked to female hormones, may also be driven by genetic factors, according to a new study published online in Nature Neuroscience. "I think [the study is] very cool," said Ronald See at the Medical University of South Carolina, who was not involved in this research. The investigators have established a simple method for teasing out sex and hormonal differences that can now be applied to behavioral tests, he said. A now-classic study that compared male and female responses to cocaine showed that females were more sensitive to the drug's reward effects during the estrus phase of their menstrual cycle, establishing the theory that hormone levels influence addictive behavior. But the contribution of sex chromosomes was not previously examined because there was no technique for separating hormonal factors from genetic ones. Jane Taylor of Yale University and colleagues identified a naturally occurring mutant mouse in which males lacked a gene on the Y chromosome called SRY that is responsible for the formation of testes. These mutants, while chromosomally male, did not develop testes. The researchers then inserted the SRY gene onto an autosomal chromosome of a mutant male -- which developed normal testes -- and crossed that animal with a normal female. The resulting strain consisted of four phenotypes: genetic males with testes; genetic males with ovaries; genetic females with ovaries; and genetic females with testes. © 1986-2007 The Scientist

Keyword: Sexual Behavior; Drug Abuse
Link ID: 10877 - Posted: 06.24.2010

By INGFEI CHEN On a sun-drenched morning this month, a small, black, bushy-haired dog trotted out from the animal care center at Stanford. The Belgian schipperke, Bear, soon veered off to lift a hind leg over a shrub. He was, clearly, oblivious to the gravitas of the day. Bear had spent nearly seven years in the underground kennels as part of a colony of narcoleptic dogs studied by Dr. Emmanuel Mignot, director of the Stanford Center for Narcolepsy. Dr. Mignot had just signed papers to adopt the dog, the last of the colony. Bear’s freedom ended 30 years of investigations that led to the discovery of the importance of a neurochemical called hypocretin in human and animal narcolepsy, and in normal sleep. Bear will now be a pet. And Dr. Mignot has turned to less huggable research subjects, like wet, cold-blooded and, unexpectedly, less cooperative zebrafish. Investigators now understand that narcolepsy arises from a deficiency of the brain cells that make hypocretin, similar to the way that Parkinson’s is caused by the loss of dopamine-producing neurons. Copyright 2007 The New York Times Company

Keyword: Narcolepsy
Link ID: 10876 - Posted: 06.24.2010

By CARL ZIMMER Last month, a bird known as a bar-tailed godwit took flight from Alaska and headed south. A day later, it was still flapping its way over the Pacific. An airplane pilot would have a hard time staying awake after 24 hours of flight (the Federal Aviation Administration allows pilots to fly just eight hours in a row). But the godwit kept flying for an additional week. After eight days and 7,200 miles, it landed in New Zealand, setting a record for nonstop flight. “If they spend so many hours flying,” said Ruth M. Benca of the University of Wisconsin, “where do they find the time to sleep?” Bird sleep is so mysterious that scientists are considering several answers, all intriguing. The godwit may have managed to stay awake for the entire journey. Or it may have been able to sleep while flying. Or, as Dr. Benca and other scientists suspect, its brain may have been in a bizarre state of semilimbo that they do not understand. Bird brains produce patterns of electrical activity that look strikingly like human brains during sleep, a remarkable similarity considering that birds and their brains have been on a separate evolutionary course from mammals for 300 million years. But similarities reach just so far. The amount of sleep birds need can change drastically through the year. Birds may be able to put parts of their brains to sleep while keeping others awake. They may be able to adjust sleep in the course of minutes, even seconds. By figuring out the mysteries of bird sleep, scientists hope to understand some universal rules of sleep. Copyright 2007 The New York Times Company

Keyword: Sleep; Evolution
Link ID: 10875 - Posted: 06.24.2010

By STEPHANIE SAUL Your dreams miss you. Or so says a television commercial for Rozerem, the sleeping pill. In the commercial, the dreams involve Abraham Lincoln, a beaver and a deep-sea diver. Not the stuff most dreams are made of. But if the unusual pitch makes you want to try Rozerem, consider that it costs about $3.50 a pill; gets you to sleep 7 to 16 minutes faster than a placebo, or fake pill; and increases total sleep time 11 to 19 minutes, according to an analysis last year. If those numbers send you out to buy another brand, consider this, as well: Sleeping pills in general do not greatly improve sleep for the average person. American consumers spend $4.5 billion a year for sleep medications. Their popularity may lie in a mystery that confounds researchers. Many people who take them think they work far better than laboratory measurements show they do. An analysis of sleeping pill studies found that when people were monitored in the lab, newer drugs like Ambien, Lunesta and Sonata worked better than fake pills. But the results were not overwhelming, said the analysis, which was published this year and financed by the National Institutes of Health. Copyright 2007 The New York Times Company

Keyword: Sleep
Link ID: 10874 - Posted: 10.23.2007

By BENEDICT CAREY The task looks as simple as a “Sesame Street” exercise. Study pairs of Easter eggs on a computer screen and memorize how the computer has arranged them: the aqua egg over the rainbow one, the paisley over the coral one — and there are just six eggs in all. Most people can study these pairs for about 20 minutes and ace a test on them, even a day later. But they’re much less accurate in choosing between two eggs that have not been directly compared: Aqua trumped rainbow but does that mean it trumps paisley? It’s hazy. It’s hazy, that is, until you sleep on it. In a study published in May, researchers at Harvard and McGill Universities reported that participants who slept after playing this game scored significantly higher on a retest than those who did not sleep. While asleep they apparently figured out what they didn’t while awake: the structure of the simple hierarchy that linked the pairs, paisley over aqua over rainbow, and so on. “We think what’s happening during sleep is that you open the aperture of memory and are able to see this bigger picture,” said the study’s senior author, Matthew Walker, a neuroscientist who is now at the University of California, Berkeley. He added that many such insights occurred “only when you enter this wonder-world of sleep.” Copyright 2007 The New York Times Company

Keyword: Sleep; Learning & Memory
Link ID: 10873 - Posted: 06.24.2010

By GINA KOLATA As every sleep researcher knows, the surest way to hear complaints about sleep is to ask the elderly. “Older people complain more about their sleep; they just do,” said Dr. Michael Vitiello, a sleep researcher who is a professor of psychiatry and behavioral sciences at the University of Washington. And for years, sleep scientists thought they knew what was going on: sleep starts to deteriorate in late middle age and steadily erodes from then on. It seemed so obvious that few thought to question the prevailing wisdom. Now, though, new research is leading many to change their minds. To researchers’ great surprise, it turns out that sleep does not change much from age 60 on. And poor sleep, it turns out, is not because of aging itself, but mostly because of illnesses or the medications used to treat them. “The more disorders older adults have, the worse they sleep,” said Sonia Ancoli-Israel, a professor of psychiatry and a sleep researcher at the University of California, San Diego. “If you look at older adults who are very healthy, they rarely have sleep problems.” Copyright 2007 The New York Times Company

Keyword: Sleep
Link ID: 10872 - Posted: 06.24.2010

By Scott McCredie The photograph, even today, arrests the eye and titillates the mind. It's from the early 20th century, and the young man it shows -- tipping back on the rear legs of his chair -- is using his own legs, splayed in front of him, as a counterbalance. The feat itself isn't that impressive. It's his location, perched high over a cityscape of tall buildings. A wobble would be fatal. What strikes me most about the photo is what it suggests about the extraordinary adaptability of our sense of balance. Here's what I mean: Suppose the photographer grabbed a guy off the street and forced him to change places with the unnamed acrobat in the chair. The results would be predictable: Without a safety net, the new guy would almost certainly fall to his death. That's because his balance system wouldn't have had time to adjust to the specific demands of balancing on two legs of a chair while perched on the edge of a tall building. But if that guy off the street had gone through the same training as the acrobat, chances are he might well eventually become adroit enough to perform the trick. © 2007 The Washington Post Company

Keyword: Miscellaneous
Link ID: 10871 - Posted: 06.24.2010