By GINA KOLATA Will Alzheimer’s disease, a terrible degenerative brain disease with no treatments and no clear guidelines for diagnosis before its end stages, become like heart disease? That might mean early markers of risk, analogous to high cholesterol levels, that predict who is likely to get it. And it might mean drugs that actually prevent it. That is the hope behind new diagnostic guidelines being proposed by the National Institute on Aging and the Alzheimer’s Association. In July, when the groups first announced their proposed guidelines, they were met with some skepticism and anger. Why suggest ways of diagnosing the disease before a person even has symptoms? Why tell people they are doomed? And are those early diagnosis guidelines just a sop to pharmaceutical companies so they can start marketing expensive, and perhaps not very effective, new drugs? So the Alzheimer’s Association, with participation from the National Institute on Aging, held a conference call on Wednesday to clarify their position. They wanted, in particular, to explain why they advocated using so-called biomarkers, like scans for amyloid plaque in the brain, a unique feature of Alzheimer’s, and tests of cerebrospinal fluid. Such brain scans are still experimental. Copyright 2010 The New York Times Company

Keyword: Alzheimers; Brain imaging
Link ID: 14327 - Posted: 08.05.2010

Q. I had migraine diagnosed when I was 24 years old (I’m now 30), but I remember having them since my teens. I usually get them during times when my hormone levels change (e.g., during periods, ovulation). There are also other triggers like stress, too little sleep, etc. If the migraines start during the day, they are often preceded and/or followed by major mood swings, the kind that make me want to go jump off the bridge. The associated depression often recedes with pain and then comes back again after the pain recedes. Afterward, I can feel on top of the world — loving, caring and full of joy. Is this normal? Espoo, Finland A. Dr. Dodick responds: What you are experiencing before and after the headache of a migraine attack is not unusual. I am glad you asked, because it speaks to why I emphasize that migraine is more than just a bad headache. Migraine is too often “bookmarked” by the start and stop of the headache, but migraine is frequently associated with symptoms other than headache before, during and after the onset of head pain. About 75 percent of migraine sufferers will experience non-headache premonitory symptoms prior to the headache pain. Patients experience a range of cognitive, emotional and physical symptoms in this phase; the most common include feeling tired and weary, difficulty concentrating, stiff neck, dizziness, light and noise sensitivity, yawning, and depression or irritability. Copyright 2010 The New York Times Company

Keyword: Pain & Touch; Emotions
Link ID: 14326 - Posted: 08.05.2010

by Alison Motluk OVERSIZED brains are to humans what trunks are to elephants and elaborate tail feathers are to peacocks - our defining glory. What would we be without our superlative, gargantuan, neuron-packed brains? Like Donald Trump without his towers, Simon Cowell without his sneering put-downs or Bridget Jones without her diaries. We would just be ordinary primates. Unquestionably smart ones, of course, just not special. Uncomfortable as it is to contemplate, it is looking increasingly likely that our brains are not something to write home about after all. One group of researchers has scrutinised the primate archaeological record and concluded that the human brain has evolved just as would be expected for a primate of our size. Meanwhile, a biologist who has compared the number of neurons in the brains of all sorts of animals says there is nothing special about the human brain compared with other primates. No one is doubting the fact of human intelligence, but they say it can no longer be attributed to a "supersized" brain. Humans, apparently, are no more than ordinary primates with ordinary-sized brains. These findings undermine a fundamental and long-standing belief about our place in the kingdom of life: that Homo sapiens is the greatest species ever to grace the Earth and that we have become the greatest because our brains are the best ever to have evolved. Admittedly, justifying this assertion has taxed our self-professed ingenuity. Clearly ours is not the biggest brain on the planet in absolute terms - whales and elephants outdo us by up to six times - but we counter this by arguing that bigger animals are bound to have bigger brains. And if you take body size into account our brain is exceptionally large, as much as seven times larger than those of other mammals (Science, vol 121, p 447). The underlying assumption is still that when it comes to intelligence, brain size matters. But does it? © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 14325 - Posted: 08.05.2010

By Lesley Richardson, Press Association A framework to understand the emotional lives of animals was revealed today. Animal choices can be assessed objectively as evidence of pessimistic or optimistic decision-making which indicates their long-term mood. Professor Mike Mendl and Dr Liz Paul, from the University of Bristol, and Dr Oliver Burman, from the University of Lincoln, looked through papers by experts from Charles Darwin to Paul Ekman and Jaak Panksepp to create the framework which can be used in the field of animal welfare and neuroscience. Professor Mike Mendl, head of the Animal Welfare and Behaviour research group at Bristol University's School of Clinical Veterinary Science, said: "Because we can measure animal choices objectively, we can use optimistic and pessimistic decision-making as an indicator of the animal's emotional state which itself is much more difficult to assess. "Recent studies by our group and others suggest that this may be a valuable new approach in a variety of animal species. Public interest in animal welfare remains high, with widespread implications for the way in which animals are treated, used and included in society. We believe our approach could help us to better understand and assess an animal's emotion." ©independent.co.uk

Keyword: Emotions; Evolution
Link ID: 14324 - Posted: 08.05.2010

NEW YORK — Want to maximize the placebo effect? A good way to do this, according to a new study, is to tell someone they have a decent chance of getting the real treatment instead of a fake pill, but keep them guessing. In the study, Parkinson's disease patients given a placebo after being told they had a 75 percent chance of receiving an active drug produced significant amounts of dopamine, a chemical key to the brain's reward system that is scarce in the brains of patients with this disease. But no dopamine response occurred in patients given placebo after being told they had a 25 percent, 50 percent, or 100 percent chance of getting real treatment. The findings show that expectations directly regulate the power of the placebo effect by kicking the brain's reward system into gear, probably not just in Parkinson's patients but in a number of different illnesses, such as chronic pain and depression, according to Dr. A. Jon Stoessl of the Pacific Parkinson's Research Center in Vancouver, British Columbia, and his colleagues. "The greatest form of reward is really to get better, so expectation of improvement is akin to expectation of reward," Stoessl explained in an interview. Stoessl and his colleagues first demonstrated a relationship between the placebo effect and dopamine release in Parkinson's patients nine years ago. Given dopamine's role in the reward system, he explained, "perhaps it would be important for the placebo effect in other conditions." SOURCE: http://link.reuters.com/cab43n Archives of General Psychiatry, August 2010. Copyright 2010 Reuters.

Keyword: Pain & Touch; Parkinsons
Link ID: 14323 - Posted: 08.05.2010

By Katherine Harmon Having a mixed up body clock has been linked to a vast array of ailments, including obesity and bipolar disorder. And researchers are still trying to understand just how these cyclical signals influence aspects of our cellular and organ system activity. Now, a study published online August 3 in Cell Metabolism shows that in mice, a disrupted circadian rhythm spurs an increase in triglycerides—heightened levels of which have been linked to heart disease and metabolic syndrome in humans. To find this link, researchers compared normal lab mice to those bred to have dysfunctional sleep-wake cycles. As nocturnal animals, the control mice had the lowest levels of triglycerides at night, when they were most active, and higher levels during the daytime rest period. The mice with out-of-whack cycles kept confused hours, fed longer and were less active overall. These mutant mice also had far less fluctuation in their triglyceride levels. "We show that the normal up and down [of triglycerides] is lost in clock mutants," M. Mahmood Hussain, of the Department of Cell Biology and Pediatrics at the State University of New York Downstate Medical Center in Brooklyn and coauthor of the paper, said in a prepared statement. The mutant mice had "high triglycerides all the time," he noted. © 2010 Scientific American,

Keyword: Biological Rhythms; Obesity
Link ID: 14322 - Posted: 08.05.2010

By Janet Raloff Cash register and other receipts may expose consumers to substantial amounts of bisphenol A, a hormone-mimicking chemical that has been linked with a host of potential health risks, according to a trio of recent studies. Each study offers preliminary evidence that a large number of retail outlets print sales receipts on certain types of heat-sensitive, or thermal, paper that use BPA as a color developer. Two of the new studies also showed that the BPA coating easily rubs off onto fingers. And one found evidence that BPA from receipts may penetrate skin. The pollutant, which mimics the biological activity of estrogen, has been tied to health risks from behavioral problems in children to obesity and heart ailments. In animals, exposures in the womb put moms and their offspring at risk for later metabolic diseases. Based on growing concern about possible risks from ubiquitous exposure to BPA, especially in children, the federal government recently issued warnings to parents about where their families were most likely to encounter the chemicals. Store receipts did not make the list, although there have been hints for years that thermal receipt paper could be a rich source. Chemist John Warner learned about the chemistry of thermal- and pressure-sensitive papers while working for Polaroid years ago. Manufacturers lay a powdery coating containing BPA, a dye and a solvent onto one side of a piece of paper. When heat or pressure is applied, the coating’s constituents merge to release the ink’s color, he explains. © Society for Science & the Public 2000 - 2010

Keyword: Hormones & Behavior; Development of the Brain
Link ID: 14321 - Posted: 08.05.2010

By Dana Scarton Following a protocol demonstrated moments earlier, the Colorado youth pressed his bare hands against the rim of a urinal, licked each palm, then reached out to accept a Tic Tac. Before popping the mint into his mouth, Christian added a move of his own: He dropped it onto the tile floor and stomped on it. The ad lib elicited gasps, congratulatory pats on the back, and applause from onlookers crammed into the men's room on a lower level of the Hyatt Regency Crystal City. As the others took their turn at the bizarre ritual, Christian leaned on a wall outside, seeming pleased if perhaps a bit queasy. "I wanted to challenge myself," he said. Christian later told his father, Kern Low, that he would no longer struggle with paralyzing fears of contamination associated with public restrooms, a problem that had interfered with family outings for the past three years. Facing fears was the evening's objective for Christian and about 150 other people dealing with obsessive-compulsive disorder (OCD). Led by psychologist Jonathan Grayson, they were going "Virtual Camping" -- a two-hour after-dark excursion and germfest that was part of the 2010 International OCD Foundation Conference held at the Hyatt Regency last month. "What can you do in one night?" Grayson had asked as the evening began. "You can take a step toward learning how to deal with uncertainty." Then he led the participants into the steamy streets of Crystal City, where, among other things, they would be encouraged to shake the hand of a homeless man (to fight more contamination fears), to chant "Crash and burn" to passing motorists (to show that thoughts would not cause actual harm) and to touch ripe garbage with their bare hands (contamination, again). © 1996-2010 The Washington Post Company

Keyword: OCD - Obsessive Compulsive Disorder
Link ID: 14320 - Posted: 08.03.2010

By CLAUDIA DREIFUS About four years ago, John Donoghue’s son, Jacob, then 18, took his father aside and declared, “Dad, I now understand what you do — you’re ‘The Matrix’!” Dr. Donoghue, 61, is a professor of engineering and neuroscience at Brown University, studying how human brain signals could combine with modern electronics to help paralyzed people gain greater control over their environments. He’s designed a machine, the BrainGate, that uses thought to move objects. We spoke for two hours in his Brown University offices in Providence, R.I., and then again by telephone. An edited version of the two conversations follows: Q. WHAT EXACTLY IS BRAINGATE? A. It’s a way for people who’ve been paralyzed by strokes, spinal cord injuries or A.L.S. to connect their brains to the outside world. The system uses a tiny sensor that’s been implanted into the part of a person’s brain that generates movement commands. This sensor picks up brain signals, transmits them to a plug attached to the person’s scalp. The signals then go to a computer which is programmed to translate them into simple actions. Q. WHY MOVE THE SIGNALS OUT OF THE BODY? A. Because for many paralyzed people, there’s been a break between their brain and the rest of their nervous system. Their brains may be fully functional, but their thoughts don’t go anywhere. What BrainGate does is bypass the broken connection. Free of the body, the signal is directed to machines that will turn thoughts into action. Copyright 2010 The New York Times Company

Keyword: Robotics; Movement Disorders
Link ID: 14319 - Posted: 08.03.2010

By Jesse Bering Last week, while in a drowsy, altitude-induced delirium 35,000 feet somewhere over Iceland, I groped mindlessly for the cozy blue blanket poking out beneath my seat, only to realize—to my unutterable horror—that I was in fact tugging soundly on a wriggling, sock-covered big toe. Now with a temperament such as mine, life tends to be one awkward conversation after the next, so when I turned around, smiling, to apologize to the owner of this toe, my gaze was met by a very large man whose grunt suggested that he was having some difficulty in finding the humor in this incident. Unpleasant, yes. But I now call this event serendipitous. As I rested my head back against that sanitation paper-covered airline pillow, my mid-flight mind lighted away to a much happier memory, one involving another big toe, yet this one belonging to a noticeably more good-humored animal than the one sitting behind me. This other toe—which felt every bit as much as its overstuffed human equivalent did, I should add—was attached to a 450-pound Western Lowland gorilla, with calcified gums, named King. When I was 19, and he was 27, I spent much of the Summer of 1996 with my toothless friend King, listening to Frank Sinatra and the Three Tenors (my bizarre foray into science, which you can read about here), playing chase from one side of his exhibit to the other, and tickling his toes. He’d lean back in his night house, stick out one huge ashen grey foot through the bars of his cage and leave it dangling there in anticipation, erupting in shoulder-heaving guttural “laughter” as I’d grab hold of one of his toes and gently give it a palpable squeeze. He almost couldn’t control himself when, one day, I leaned down to act as though I was going to bite on that plump digit. If you’ve never seen a gorilla in a fit of laughter, I’d recommend searching out such a sight before you pass from this world. It’s something that would stir up cognitive dissonance in even the heartiest of creationists. © 2010 Scientific American

Keyword: Emotions; Evolution
Link ID: 14318 - Posted: 08.03.2010

By Katherine Harmon The tangled web of autism symptoms and genetic markers has left researchers searching for patterns and trends in unusual places. New work examining the subtle symptoms shared by close relatives has underscored the disease's heritability. Findings published online August 2 in Archives of General Psychiatry add to the growing list of familial clues about the disease: shared eye-movement deficits. Researchers working at the University of Illinois at Chicago's (U.I.C.) Center for Cognitive Medicine have found a striking trend: those with autistic relatives are more likely to show disrupted eye movement similar to their afflicted relation. Large-scale genetic studies have turned up nuanced and conflicting results about the genetic basis of autism and its myriad symptoms. Other research has discovered that many people with an autistic relative or child might themselves have some subtle behavior variant as well, such as obsessive-compulsive tendencies or communication problems. Eye movement is easier to study neurologically than complex social and behavioral patterns—in large part because "we know a lot about what parts of the brain are involved," says Matthew Mosconi, an assistant professor of psychiatry at the U.I.C. and lead author of the new study. And the new findings examine basic deficits unclouded by social tendencies, such as the aversion many people with autism spectrum disorder have to looking at faces. © 2010 Scientific American

Keyword: Autism; Vision
Link ID: 14317 - Posted: 08.03.2010

by Kristen Minogue "Free-range" chickens are the gold standard for consumers interested in humanely raised livestock. But for most chickens, the wide-open spaces of a free-range poultry farm aren't nearly as idyllic as they sound. The birds often peck at each other's feathers, causing painful scars, bleeding, and even death. Now, researchers have developed a mathematical model that may help farmers stop the pecking before it starts. It's unclear why chickens like to bite the feathers off their neighbors. According to bird-welfare researcher Bas Rodenburg of Wageningen University in the Netherlands, the best explanation is that they've evolved to peck for food in the wild, and this need is not satisfied on the farm. "Instead of pecking at the floor, for instance, they start pecking at each other's feathers," Rodenburg says. Right now, the only way for free-range farmers to prevent the behavior is beak trimming, a euphemism for cutting off the sharp tip of a bird's beak with a hot blade or directing infrared rays into its inner tissue until the tip falls off a few weeks later. To find a better solution, a team of zoologists and engineers studied video recordings of more than 300,000 hens living on free-range farms in the United Kingdom. The researchers applied a mathematical technique called optical flow modeling, which has been used to study traffic patterns and human crowds, to track how the chickens moved in large groups. The process involved analyzing multiple snapshots of the same 50 to 100 hens taken at different times to find patterns of movement that correlate with chicken-on-chicken violence. © 2010 American Association for the Advancement of Science.

Keyword: Aggression
Link ID: 14316 - Posted: 08.03.2010

by Karin Zeitvogel, AFP People who sleep more or fewer than seven hours a day, including naps, are increasing their risk for cardiovascular disease, the leading cause of death in the United States, a study published Sunday shows. Sleeping fewer than five hours a day, including naps, more than doubles the risk of being diagnosed with angina, coronary heart disease, heart attack or stroke, the study conducted by researchers at West Virginia University's (WVU) faculty of medicine and published in the journal Sleep says. And sleeping more than seven hours also increases the risk of cardiovascular disease, it says. Study participants who said they slept nine hours or longer a day were one-and-a-half times more likely than seven-hour sleepers to develop cardiovascular disease, the study found. The most at-risk group was adults under 60 years of age who slept five hours or fewer a night. They increased their risk of developing cardiovascular disease more than threefold compared to people who sleep seven hours. Women who skimped on sleep, getting five hours or fewer a day, including naps, were more than two-and-a-half times as likely to develop cardiovascular disease. Short sleep duration was associated with angina, while both sleeping too little and sleeping too much were associated with heart attack and stroke, the study says. Copyright © 2010 Discovery Communications, LLC.

Keyword: Sleep
Link ID: 14315 - Posted: 08.03.2010

By WALT BOGDANICH When Alain Reyes’s hair suddenly fell out in a freakish band circling his head, he was not the only one worried about his health. His co-workers at a shipping company avoided him, and his boss sent him home, fearing he had a contagious disease. Only later would Mr. Reyes learn what had caused him so much physical and emotional grief: he had received a radiation overdose during a test for a stroke at a hospital in Glendale, Calif. Other patients getting the procedure, called a CT brain perfusion scan, were being overdosed, too — 37 of them just up the freeway at Providence Saint Joseph Medical Center in Burbank, 269 more at the renowned Cedars-Sinai Medical Center in Los Angeles and dozens more at a hospital in Huntsville, Ala. The overdoses, which began to emerge late last summer, set off an investigation by the Food and Drug Administration into why patients tested with this complex yet lightly regulated technology were bombarded with excessive radiation. After 10 months, the agency has yet to provide a final report on what it found. But an examination by The New York Times has found that radiation overdoses were larger and more widespread than previously known, that patients have reported symptoms considerably more serious than losing their hair, and that experts say they may face long-term risks of cancer and brain damage. Copyright 2010 The New York Times Company

Keyword: Brain imaging
Link ID: 14314 - Posted: 08.02.2010

By Laura Sanders As people grow older, sad films seem sadder. In a recent study, people in their sixties felt sadder than people in their twenties did after viewing an emotionally distressing scene from a movie. This heightened emotional response to sorrow may reflect a greater compassion for other people and may strengthen social bonds, researchers propose. The finding is an important contribution to emotion studies because it adds to a growing body of work showing that emotions don’t deteriorate, says Stanford University psychologist Laura Carstensen, who was not involved in the research. “One of the important findings of this is that the emotion system is in no way broken in old age,” she says. To explore how feelings of sadness change with age, researchers led by Robert Levenson of the University of California, Berkeley brought 222 study participants into the laboratory to watch neutral, disgusting or sad movie clips. The volunteers made up three age groups: young people in their twenties, middle-aged people in their forties, and older people in their sixties. Before watching the movies, participants were hooked up to monitors that recorded physiological responses such as blood pressure, heart rate and breathing patterns. Levenson and his team chose two gut-wrenchingly sad scenes to elicit responses: In the first clip, from the movie 21 Grams, a mother is told of the deaths of her two young daughters. The second scene, from The Champ, depicts a young boy watching his father die after a boxing match. © Society for Science & the Public 2000 - 2010

Keyword: Emotions; Development of the Brain
Link ID: 14313 - Posted: 08.02.2010

by Nazlie Latefi People who smoke pot can feel lost in time—for some, it's part of the draw. Now researchers may have figured out one reason why cannabinoids, the psychoactive compounds in marijuana and hashish, make people feel this way; they disrupt the body's internal clock. Sleeping, eating, and other activities are all part of a 24-hour physiological cycle known as the circadian rhythm. This internal clock is controlled by neurons in a region of the brain called the suprachiasmatic nucleus (SCN). The SCN normally uses light to reset the clock. That's what happens when you travel from one time zone to another. But absent any sensory input, SCN neurons will still maintain a circadian rhythm: People and animals kept in total darkness continue to eat and sleep at the usual times. Several years ago, researchers discovered that SCN neurons possess receptors for cannabinoids. In the new study, a team led by Yale University circadian biologist Anthony van den Pol tried to figure out what role these receptors play. The researchers housed 42 mice in total darkness for 2 weeks to synchronize their internal clocks. In this environment the animals cycled through active and inactive phases lasting about 12 hours each. After 2 weeks, the researchers shined a light into some of the cages shortly after the mice had entered their active phase. Because mice are nocturnal, they became active about 2 hours later in the day than did mice not exposed to light, a phenomenon called "phase delay." But mice given brain injections of cannabinoids before light exposure exhibited much less of a phase delay; they became active only 1 hour later than did animals not exposed to light. © 2010 American Association for the Advancement of Science.

Keyword: Drug Abuse; Biological Rhythms
Link ID: 14312 - Posted: 08.02.2010

by Michael Marshall The selective breeding of some domestic dogs has made their brains rotate forwards, and relocated one key component. Michael Valenzuela at the University of New South Wales in Sydney, Australia, and colleagues, used a brain scanner to look at the heads of 11 dogs that had recently been put down, and two live ones. The dogs came from a variety of breeds, which have been bred over thousands of years to have – among other characteristics – snouts of different lengths. They found that dogs with shorter snouts had brains which were rotated forwards by up to 15 degrees. They also found that the olfactory lobe at the front of the brain, which processes the sense of smell, was shunted downwards. "As a dog's head or skull shape becomes flatter – more pug-like – the brain rotates forward and the smell centre of the brain drifts further down to the lowest position in the skull," Valenzuela says. "It's something that hasn't been documented in other species." "This is the first evidence to suggest that selective breeding to meet specific physical characteristics in breed standards has had an impact on brain organisation," says Lisa Collins of the Royal Veterinary College in Hatfield, UK. It might help explain why long-snouted dogs are better at scent work, such as sniffing out drugs, than short-snouted breeds, she says. © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 14311 - Posted: 08.02.2010

By Emma Wilkinson Health reporter, BBC News A combination pill of two drugs used to treat addiction may help people lose weight, say US researchers. The Lancet reports that Naltrexone, commonly used to treat alcoholics and heroin addicts, and the anti-smoking drug bupropion led to greater weight loss than diet and exercise alone. It is thought the treatment may help beat food cravings. However, one UK expert said he would like to see much higher weight loss for the drug to be used in clinics. Professor Nick Finer, an obesity expert from University College London (UCL), said the drug may prove more useful if researchers can better identify who would benefit. In the study, 1,700 overweight and obese adults were all offered a weight-loss programme with diet and exercise advice. Two-thirds were also given the combination treatment (in one of two doses) and a third were given a placebo, or dummy pill, to take twice a day. Only half completed the trial, which lasted a year. Overall those taking the treatment lost an average of 5% to 6% of their weight depending on the dose, compared with 1.3% in the placebo group. The researchers said if only those who completed the trial were included, weight loss was 8% of body weight for those on the anti-addiction drugs. The treatment was not without side effects which included nausea, headaches, constipation, dizziness, vomiting and a dry mouth. (C)BBC

Keyword: Obesity; Drug Abuse
Link ID: 14310 - Posted: 07.31.2010

Janelle Weaver A Canadian research team that induced pain in mice to help develop a 'grimace scale' recently came under fire from a researcher-support organization, which posted an online commentary suggesting that the scientists may not have complied with Canada's animal welfare regulations. But Canadian officials have since determined that the study did follow national rules for the care of laboratory animals. The research team, led by pain geneticist Jeffrey Mogil of McGill University in Montreal, Quebec, videotaped the facial expressions of mice during 14 pain-inducing procedures, such as immersing the tail in hot water, putting a binder clip on tails, cutting the paw, injecting chemicals into the paw or stomach and constricting or damaging nerves during surgery. The researchers coded the intensity of facial expressions and reported their technique this May in the journal Nature Methods1. Two weeks ago, the Principal Investigators Association, a non-profit organization in Naples, Florida, that "communicates and promotes best practices and continuing professional education", posted a discussion-board topic about the study on Lab Animal eAlert, its online subscription newsletter for researchers. The commentary accused the McGill team of causing severe pain to mice that were not anaesthetized, and questioned whether Mogil and his collaborators followed regulations set by the Canadian Council on Animal Care, the national organization that oversees the use of animals in research. Canadian animal-research guidelines preclude or strongly discourage procedures that elicit severe pain "at or above the pain tolerance threshold". © 2010 Nature Publishing Group,

Keyword: Pain & Touch; Animal Rights
Link ID: 14309 - Posted: 07.31.2010

By Katherine Harmon Binge-shoppers and serial daters might perpetually be living at the whim of their latest impulse, and now research is getting to the biological basis of their seemingly random behavior. "Individuals vary widely in their capacity to deliberate on the potential consequences of their choices before they act," note the authors of a new study on the impulsive tendency. "Highly impulsive people frequently make rash, destructive decisions." Impulsivity has long been linked to the neurotransmitter dopamine, which is involved in learning and reward. And a new model helps to illuminate the connection between the two. The work is described in a study published online July 29 in Science. A team of researchers led by Joshua Buckholtz, a PhD candidate in neuroscience at Vanderbilt University, proposed that people who were more impulsive might have less active dopamine receptors in their midbrain but their brains would be more likely to fire off large quantities of the neurotransmitter when stimulated. To verify their hypothesis, the researchers used PET scans to watch the brains of 32 healthy and psychiatrically normal test subjects ages 18 to 35 (who had no history of substance abuse) while they were taking a classic test to measure impulsivity. Before the first testing round, subjects had taken a placebo pill, but before the second, they were given an oral dose of amphetamine, which can stimulate the brain's reward pathways, mobilizing dopamine. © 2010 Scientific American

Keyword: Drug Abuse; Attention
Link ID: 14308 - Posted: 07.31.2010