By TARA PARKER-POPE Did you see the unicycling clown? Inattentional blindness while walking and talking on a cell phone (Applied Cognitive Psychology) Researchers at Western Washington University decided to study whether pedestrians engrossed in a phone conversation would notice obvious events around them. “I was trying to think about what kind of distraction we could put out there, and I talked to this student who had a unicycle,” said Ira E. Hyman Jr., a professor of psychology. “He said, ‘What’s more, I own a clown suit.’ You don’t have a student who unicycles in a clown suit every day, so you have to take advantage of these things.” The student, Dustin Randall, donned the suit — purple and yellow, with polka-dot sleeves, red shoes and a red nose — then hopped on the unicycle and pedaled around a square. After pedestrians crossed the square, researchers asked them, “Did you see anything unusual?” Among pedestrians who were listening to music or walking alone, 1 in 3 replied that they had just seen a clown on a unicycle, according to a report on the study, in the journal Applied Cognitive Psychology. Nearly 60 percent of those who were walking with a friend mentioned the clown. But among people who had been talking on a cellphone, the figure was 8 percent. When the pedestrians were asked, “Did you see the unicycling clown?” the rates rose — to as high as 71 percent for people walking with a friend. But among those who had been talking on a cellphone, just 25 percent said they had. TARA PARKER-POPE Sign in to Recommend Next Article in Health (12 of 43) » A version of this article appeared in print on October 27, 2009, on page D6 of the New York edition. Copyright 2009 The New York Times Company

Keyword: Attention
Link ID: 13407 - Posted: 06.24.2010

By RONI CARYN RABIN Many parents worry about a possible link between autism and mercury exposure. But most research dismisses those fears as groundless, and a new study says autistic children actually have lower blood levels of mercury than children who are developing normally. Mercury levels were closely related to fish intake, the study found, and children with autism and related disorders tend to be picky eaters who avoid fish. After researchers adjusted for the lower fish consumption of autistic children, they found no differences between their mercury levels and those in other children. Irva Hertz-Picciotto, a professor of public health sciences at the University of California, Davis, who was the study’s principal investigator, said the new findings did not address whether mercury might play a role in autism. “We were measuring levels after the diagnosis had already been made and was months in the past in most cases,” Dr. Hertz-Picciotto said. “So this study does not provide evidence for or against.” The report, published online on Oct. 19 in the journal Environmental Health Perspectives, is part of a continuing study comparing autistic and nonautistic children in California. The study of 452 participants includes 249 children with autism or autism spectrum disorders, 143 who are developing normally and 60 with developmental delays. Copyright 2009 The New York Times Company

Keyword: Autism; Neurotoxins
Link ID: 13406 - Posted: 06.24.2010

by Ewen Callaway If you're looking to haggle, steer clear of big, beefy salesmen. The same hormone responsible for their brawn may also reduce their generosity, new research suggests. "Our broad conclusion is that testosterone causes men essentially to be stingy," says Karen Redwine, a neuro-economist at Whittier College in California, who presented the work at the Society for Neuroscience's annual meeting in Chicago last week. A previous study of 17 City of London traders found that morning testosterone levels correlated with each day's gains and losses, with more of the hormone associated with a profit. But that study didn't establish a cause-effect relationship between testosterone and shrewdness. To make this case, Redwine and her colleague Paul Zak, at the Claremont Graduate University in California, gave a testosterone-containing gel to 25 male university students, and then tested their generosity. All the participants also got a placebo cream with no testosterone, either a few days before or after the testosterone boost. Neither the researchers nor the participants knew which was which until the end of the study. The testosterone cream worked. The next day, twice as much of the potent sex hormone coursed through the veins of volunteers, on average. © Copyright Reed Business Information Ltd.

Keyword: Hormones & Behavior; Aggression
Link ID: 13405 - Posted: 06.24.2010

By NATALIE ANGIER If you’ve ever had a problem with rodents and woken up to find that mice had chewed their way through the Cheerios, the Famous Amos, three packages of Ramen noodles, and even that carton of baker’s yeast you had bought in a fit of “Ladies of the Canyon” wistfulness, you will appreciate just how freakish is the strain of laboratory mouse that lacks all motivation to eat. The mouse is physically capable of eating. It still likes the taste of food. Put a kibble in its mouth, and it will chew and swallow, all the while wriggling its nose in apparent rodent satisfaction. Yet left on its own, the mouse will not rouse itself for dinner. The mere thought of walking across the cage and lifting food pellets from the bowl fills it with overwhelming apathy. What is the point, really, of all this ingesting and excreting? Why bother? Days pass, the mouse doesn’t eat, it hardly moves, and within a couple of weeks, it has starved itself to death. Behind the rodent’s fatal case of ennui is a severe deficit of dopamine, one of the essential signaling molecules in the brain. Dopamine has lately become quite fashionable, today’s “it” neurotransmitter, just as serotonin was “it” in the Prozac-laced ’90s. People talk of getting their “dopamine rush” from chocolate, music, the stock market, the BlackBerry buzz on the thigh — anything that imparts a small, pleasurable thrill. Familiar agents of vice like cocaine, methamphetamine, alcohol and nicotine are known to stimulate the brain’s dopamine circuits, as do increasingly popular stimulants like Adderall and Ritalin. Copyright 2009 The New York Times Company

Keyword: Drug Abuse; Parkinsons
Link ID: 13404 - Posted: 06.24.2010

By Rachel Ehrenberg Phantoms take many forms — headless horseman, ghost ships, murdered fathers — and they can even reach out and grab the living: many people who have had an arm or leg amputated feel the limb is still present. The phantom pain that often accompanies these limbs has been successfully treated by using visual feedback from mirrors to trick the brain. Now similar instances of mind over non-matter have been achieved without external help — amputees have learned to mentally manipulate their phantom limbs into anatomically impossible configurations through thinking alone, scientists report October 26 in the Proceedings of the National Academy of Sciences. “It is very surprising that anybody — amputees or not — can learn impossible movements just by thinking about it,” comments neuroscientist Henrik Ehrsson of the Karolinska Institutet in Stockholm. Treatment of people with phantom limb pain usually requires starting a new conversation between the brain and the environment, typically accomplished through visual feedback, Ehrsson says. The work suggests that people with a distorted body image — such as those with anorexia — may be able to alter their self-image just by imagining a change to the body, says Lorimer Moseley of the Prince of Wales Medical Research Institute in Randwick, Australia. And those getting neural reconstructive surgery may be able to practice using their new body parts by simply imagining their use, says Moseley, who coauthored the work with colleague Peter Brugger of the University Hospital Zurich. © Society for Science & the Public 2000 - 2009

Keyword: Pain & Touch
Link ID: 13403 - Posted: 06.24.2010

By Tom McGrath Rich P. is only in his 20s, but these days he finds himself obsessing over something most guys his age never think twice about: Am I doomed to lose my mind? In some ways, Rich's anxiety is understandable. "My girlfriend is a social worker who works with the aged, specifically people with Alzheimer's," he says. "So I've seen close up what the disease does to you." Indeed, Alzheimer's disease is characterized by memory loss and confusion, and typically ends with complete disconnection from the world. People in its advanced stages can't care for themselves, recognize loved ones, or remember the lives they lived. (Worried about losing your memory and health as you age? Discover the age erasers for men that can strip away 10 years and leave you looking and feeling younger, longer!) Still, what should worry Rich most isn't what he's witnessed in other people, but what he sees in the mirror. Because there, literally right under his nose, is evidence that the monster that could be responsible for Alzheimer's is already skulking about inside his body, preparing itself-at some point, decades down the road-to attack and destroy his brain. For years, physicians and Alzheimer's experts have said that the earliest symptoms of the disease typically don't appear until you're in your 60s, 70s, or beyond. But now there's reason to believe that the first warning signs may actually crop up much earlier than that, and in a seemingly much more benign way: as cold sores, those embarrassing blisters that can erupt on the lips of people who are sick or run-down. 4 © 2009 Microsoft

Keyword: Alzheimers
Link ID: 13402 - Posted: 06.24.2010

By Michelle Roberts Antidepressants get to work immediately to lift mood, contrary to current belief, UK researchers say. Although patients may not notice the effects until months into the therapy, the team say they work subconsciously. The action is rapid, beginning within hours of taking the drugs, and changes negative thoughts, according to the Oxford University researchers. These subtle, positive cues may add up over time to lift the depression, the American Journal of Psychiatry reports. It may also explain why talking therapies designed to break negative thought cycles can also help. Psychiatrist Dr Catherine Harmer and her team at Oxford University closely studied the reactions of 33 depressed patients and 31 healthy controls given either an antidepressant or a dummy drug. The depressed patients who took the active drug showed positive improvements in three specific measures within three hours of taking them. These patients were more likely to think about themselves in a positive light, rather than dwelling on their bad points, the researchers said. They were also more likely to see the positive in others. For example, if they saw a grumpy person they no longer internalised this to think that they must have done something wrong to upset the person. This was despite feeling no improvement in mood or anxiety. Dr Harmer said: "We found the antidepressants target the negative thoughts before the patient is aware of any change in feeling subjectively. Over time, this will affect our mood and how we feel because we are receiving more positive information." (C)BBC

Keyword: Depression
Link ID: 13401 - Posted: 10.26.2009

By Tara Ballenger With cars, it’s a no-brainer: Drivers who split their attention between the road and talking or texting on cellphones, e-mailing colleagues, or even putting on a fresh coat of nail polish are taking chances of making potentially fatal mistakes. Just this month, President Obama and Congress convened a two-day conference to address “distracted drivers,’’ who were involved in more than 5,800 fatal collisions last year, according to the Department of Transportation. There's no way to avoid doing multiple tasks at the same time, but there are ways to save on the brain drain of switching from one to another. Here are some tips from Laura Vanderberg, assistant director of the Time Management Consulting Program at Tufts University, and David Meyer, a specialist in cognitive neuroscience at the University of Michigan. Choose easy tasks. Combining activities such as sitting in the waiting room at the doctor's office with answering e-mails on your hand-held is fine because one of the tasks is so easy. The fewer ''switches,'' the better. Time and attention are lost each time you toggle between activities. If you're working on an important project, checking e-mail every half-hour instead of every 10 minutes will cut down on inefficiency. Know yourself. Everyone multitasks differently. Experiment with watching TV, listening to music, or texting while completing other tasks, and pay attention to which ones affect your work. © 2009 NY Times Co.

Keyword: Attention
Link ID: 13400 - Posted: 06.24.2010

By Lizzie Buchen Sudden movements and sounds can trigger a battle between neurons in the brain, and the winners get to decide where an animal will look, according to new research. Working with barn owls, neuroscientists at Stanford University in California found that neurons in the midbrain, which acts as a relay for sensory information, engage in a 'winner takes all' battle with one another. To the victors go the owl's gaze and attention. The findings, presented at the annual meeting of the Society for Neuroscience in Chicago, Illinois, could explain how the brain decides where to look in an emergency. The senses detect everything around them, but the brain can only focus on one part of the world at a time. In everyday life, the conscious mind decides what this should be. But when confronted with a loud noise or fast-moving object, the urge to look becomes automatic. That response makes sense, says principal investigator Eric Knudsen. "When there are features in the environment signalling something that could be life-or-death, we'd want to know about it," he says. What is less clear is how this head-turning decision happens on a cellular level. To find out, Knudsen's team used barn owls, which have neatly arranged midbrains that are easy to study. Research focused on a circuit in the midbrain known as the isthmotectal network, which receives sensory information and tells the eyes where to look. © 1996-2009 Scientific American Inc

Keyword: Attention
Link ID: 13399 - Posted: 06.24.2010

By Jocelyn Kaiser A single injection of DNA into the eyes of four children born with a blindness-causing disease has given them enough vision to walk without help. The study, published today, confirms that if patients with this disease are given gene therapy early in life, the results can be dramatic. Several clinical trials in the United States and Europe have been using gene therapy to treat a disease called Leber's congenital amaurosis (LCA), which affects about 3000 people in the United States. Those born with LCA start losing their sight at birth and are completely blind by age 40. Children born with one form, LCA2, have defects in a gene called RPE65 that helps the retina's light-sensing cells make rhodopsin, a pigment needed to absorb light. Without rhodopsin, the photoreceptor cells gradually die. In 2001, researchers at the University of Pennsylvania (Penn) showed that they could partially restore sight to blind dogs with this defect by injecting a good copy of RPE65 into their eyes. Two years ago, the Penn team began a small safety study of the therapy in humans with collaborators at the Children's Hospital of Philadelphia. They injected each patient's worse eye with a modified virus carrying the RPE65 gene. Early results from this trial and a similar study in the United Kingdom published in April 2008 showed that four of six young adults with LCA2 who received the treatment could later sense more light and perform better in an obstacle course. But the Penn researchers knew from their studies in animals that children should improve even more because they have more intact retinal tissue than adults do. Today in an online paper in The Lancet, their team and collaborators in Europe report full study results for three of the adults they treated earlier and nine more patients, including four children ages 8 to 11. © 2009 American Association for the Advancement of Science.

Keyword: Vision; Genes & Behavior
Link ID: 13398 - Posted: 06.24.2010

By ANNE EISENBERG WHEN disease destroys vital parts of the eye, causing degrees of blindness, scientists can sometimes replace damaged tissue with electronic implants that help patients see lines and basic shapes. A model of an eye with a newly designed implant from a Boston group of researchers. The tips of the implant's electrodes, which help replace the work of diseased rods and cones, slide into a snug berth just below the retina. But as with any electrical connection, these implants must fit snugly and not jiggle or shake loose after a few months, like a drooping plug in a wall socket. Now groups of scientists have demonstrated retinal implants that they say will resist the jarring of daily use. The implant contains a tiny array of electrodes whose tips slide into a snug berth just beneath the retina, the nerve tissue lining the back of the eye, and are held in place by natural suction. The electrodes prompt the remains of retinal circuits to transmit signals to the brain, said John L. Wyatt, a professor of electrical engineering at the Massachusetts Institute of Technology and co-founder of the Boston Retinal Implant Project, one of the groups that has developed a prototype of the new design. The research team includes scientists from the Massachusetts Eye and Ear Infirmary, the VA Boston Health Care System and Cornell University. Copyright 2009 The New York Times Company

Keyword: Vision; Robotics
Link ID: 13397 - Posted: 10.26.2009

Researchers in southwestern Ontario are trying to determine if chewing gum will ease swallowing problems among people with Parkinson's disease. Parkinson's is a degenerative nerve disease that affects more than 100,000 Canadians, and can cause swallowing difficulty as the disease progresses, according to the Parkinson Society Canada. That's because Parkinson's symptoms such as tremor, stiffness and slow movements can affect the mechanisms used in speaking and swallowing, said neurologist and researcher Dr. Mandar Jog of the London Health Sciences Centre. Early research points to improved swallowing among Parkinson's patients who chew gum several hours a day. Chewing is a form of exercise for the mouth. The researchers think that having gum in the mouth and chewing it may help to train Parkinson's patients to also move their tongues while eating and swallowing. "Gum acts like sensory cue to train the system," said Jog, who is also director of the Movement Disorders Centre. Other types of training have helped people with Parkinson's. For example, when lights are placed in front of patients, the visual cue seems to help them improve their gait, Jog said. Now the team is investigating how long the benefits of gum chewing last. © CBC 2009

Keyword: Parkinsons
Link ID: 13396 - Posted: 06.24.2010

By ERIK ECKHOLM PHILADELPHIA — As a teenager, Keith Garrett was desperate to be accepted by the guys on the corner. His first arrest for shoplifting was a point of pride with the gang, he recalled, and using heroin, cocaine and alcohol was natural. Like many others in his group, he ended up addicted and scrounging to survive in abandoned houses. William Baker, left, a recovering drug addict who has become a certified peer specialist, advises Keith Garrett, 54, right, who has been struggling with his addictions and depression at a COMHAR Center in Philadelphia. Mr. Garrett, now 54, was first sent to drug treatment in 1975, for six months. When he got out, he joined a 12-step program, but soon enough, he lighted a joint with an old friend and was drawn back to the streets. The halfhearted efforts at rehabilitation followed by relapse were repeated over the years. “I didn’t get much support in building a new life,” he said of earlier treatments. Finally, a year ago, Mr. Garrett said, he realized that “nobody cared if I lived or died.” He entered into a new world of addiction recovery services developing in Philadelphia, where public and private agencies have teamed up to give struggling addicts far more social and practical support than before. The city relies on a network of treatment centers, recovery houses and a community center that provide counseling and practical aid. They are mainly staffed by peers in recovery who are trained to help others navigate a shaky new world of sobriety. Copyright 2009 The New York Times Company

Keyword: Drug Abuse
Link ID: 13395 - Posted: 06.24.2010

By Charles Q. Choi On election night last year, testosterone levels dropped rapidly among male voters of losing parties. After the outcome of the U.S. presidential election was declared, neuroscientists at Duke University found that although male voters for Barack Obama, the winner, had stable levels of testosterone, the hormone's levels rapidly dropped in males who cast ballots for John McCain or Robert Barr, the losers. In a questionnaire, the McCain and Barr voters reported feeling significantly more controlled, submissive, unhappy and unpleasant after the loss than the Obama backers. The researchers monitored testosterone levels from the saliva of 163 college-age volunteers in North Carolina and Michigan by asking them to chew sugar-free gum and then spit before and after the results were announced. The male participants would normally have shown a slight nighttime drop in testosterone levels anyway, because the body doesn't need it during sleep, but on election night, they departed dramatically from this routine: Obama voters' levels did not fall as they should have, whereas those of McCain and Barr backers dropped more than would have been expected. No significant effects were seen in the 106 female volunteers. Women have testosterone, but in much lesser amounts, making them less likely to experience rapid testosterone changes following victory or defeat. © 1996-2009 Scientific American Inc.

Keyword: Hormones & Behavior; Aggression
Link ID: 13394 - Posted: 06.24.2010

By Tina Hesman Saey HONOLULU — Humans may owe the gift of gab to a newly discovered gene that helps keeps vocal pipes limber. Researchers discovered the gene, dubbed tospeak, in an Australian family with a speaking disorder. Many of the women in the family have weak, husky voices, while several of their male relatives cannot speak above a whisper, reported Raymond Clarke of the University of New South Wales’ St. George Hospital in Kogarah, Australia, October 21 at the annual meeting of the American Society of Human Genetics. Clarke and his colleagues traced the source of the family’s disorder to a region of chromosome 8. Part of the chromosome had been rearranged, causing a break in the tospeak gene. Tospeak probably doesn’t code for a protein, Clarke says. The gene is sprinkled with stop signals and its RNA product doesn’t resemble other RNAs that have specific functions in the cell. But production of the tospeak RNA seems to be important for proper development of the larynx. Members of the family who have the speaking problem have short, thick vocal cords that don’t vibrate properly. Some of the family members also have fused bones in the wrists and feet, known as the carpals and tarsals, and fused vertebrae in their spines. All of the defects may be linked to a breakdown in relations between tospeak and a neighboring gene, known as GDF6, the researchers report. © Society for Science & the Public 2000 - 2009

Keyword: Language; Genes & Behavior
Link ID: 13393 - Posted: 06.24.2010

An international team led by a National Institutes of Health researcher has found that carriers of a rare, genetic condition called Gaucher disease face a risk of developing Parkinson’s disease more than five times greater than the general public. The findings were published today in the New England Journal of Medicine. In previous studies, several genes have been linked to Parkinson's disease. However, researchers say their work conclusively shows that mutations in the gene responsible for Gaucher disease are among the most significant risk factors found to date for Parkinson's disease. The discovery was made by investigators from the National Human Genome Research Institute (NHGRI) and the National Institute on Aging (NIA), both parts of the National Institutes of Health, in collaboration with scientists from 16 research centers across four continents. Parkinson's disease, a neurological condition that typically causes tremors and stiffness in movement, affects about 1 to 2 percent of people over the age of 60. The chance of developing Parkinson's disease increases with age and involves a combination of environmental risk factors and genetic susceptibility. Gaucher disease occurs when an individual inherits two defective copies of the GBA gene, which codes for an enzyme called glucocerebrosidase. This enzyme breaks down a fatty substance called glucocerebroside, which, when not properly disposed of, can harm the spleen, liver, lungs, bone marrow and, in some cases, the brain. The enzyme functions in a part of the cell called the lysosome, where cellular components are broken down, or metabolized, for recycling.

Keyword: Parkinsons; Genes & Behavior
Link ID: 13392 - Posted: 06.24.2010

Susan Milius, Science News -- Like a songbird calling another out, one male humpback whale may make another change his tune. Studying humpbacks with methods adapted from bird research has uncovered the first known instances of what look like whales responding musically to each other's songs, says Danielle Cholewiak, a researcher for the Stellwagen Bank National Marine Sanctuary based in Scituate, Mass. Cholewiak and colleagues detected melodic adjustments when a solo singer encountered another singer nearby and when researchers played their song remixes for whales. Male whales may be using music to tell another male, "Hey, I'm talking to you," Cholewiak reported Oct. 14 at the Society of Marine Mammology's biennial conference. Cholewiak "showed short-term acoustic interactions between males -- that was the new thing," said Adam S. Frankel of Marine Acoustics Inc., an independent consulting firm in Arlington, Va. Among humpback whales, only males boom out long strings of repeating phrases of hums and whups and chirps. The sounds can make a boat vibrate, said Salvatore Cerchio of the Wildlife Conservation Society in New York City, who worked with Cholewiak on the new study. Scientists use the word song to describe this patterned male vocalization, just as they do for elaborate bird serenades. © 2009 Discovery Communications, LLC.

Keyword: Language; Sexual Behavior
Link ID: 13391 - Posted: 06.24.2010

(HealthDay News) -- Exposure to too much light at night may cause depression, suggests a new study. Ohio State University researchers found that mice kept in a lighted room 24 hours a day had more depressive symptoms than mice that had a normal day-night cycle. The study also found that mice that lived in a constantly lit room, but could take refuge in a dark tube when they desired, had fewer depressive symptoms than mice that couldn't get away from the 24-hour light. "The ability to escape light seemed to quell the depressive effects," lead author Laura Fonken, a graduate student in psychology, said in a news release from Ohio State University. The findings indicate the need to learn more about how artificial light affects humans, said study co-author Randy Nelson, a professor of neuroscience and psychology. "Constant light with no chance of escape increased depressive symptoms," Nelson said in the news release. "The increasing rate of depressive disorders in humans corresponds with the increasing use of light at night in modern society. Many people are now exposed to unnatural light cycles, and that may have real consequences for our health," he added. The study, presented at the annual meeting of the Society for Neuroscience held Oct. 17 to 21 in Chicago, is scheduled to be published in the Dec. 28 issue of the journal Behavioural Brain Research. © 2009 ScoutNews, LLC.

Keyword: Biological Rhythms; Depression
Link ID: 13390 - Posted: 06.24.2010

(HealthDay News) -- While adult male monkeys exposed to cocaine in the womb have poor impulse control, the same is not true for female monkeys, new research has found. The male monkeys continued to have poor impulse control 15 years after birth. Impulsivity is a risk factor for drug abuse, said the researchers, who added that their findings could help improve understanding of human drug abuse. "This is the first time that so many different measures of impulsivity, which is considered a risk factor for drug abuse, have been looked at in the same group of animals," lead investigator Lindsey Hamilton, of Wake Forest University School of Medicine, said in a university news release. "We're looking for ways to predict which individuals are going to take drugs during their lives. It was very surprising to see that, even more than a decade after the prenatal cocaine exposure, the monkeys ended up being more impulsive and possibly more susceptible to drug use. It was particularly interesting, however, that this effect was only seen in the males. Something is either protecting the females from the effects of the cocaine exposure in the womb or making the males more susceptible to the lasting effects," Hamilton explained. Hamilton and colleagues conducted four impulse control tests with male and female monkeys exposed to cocaine in the womb and monkeys with no cocaine exposure. © 2009 U.S.News & World Report LP

Keyword: Drug Abuse; ADHD
Link ID: 13389 - Posted: 06.24.2010

By Frederik Joelving When you've spent the weekend splurging on greasy fast foods, your bathroom scale isn't alone in reeling from the impact. Your brain does, too. New research shows just how saturated fat tricks us into eating more and elucidates the evolutionary basis for the propensity for poundage in developed nations. Our brain physiology, it seems, is glaringly out-of-date in the modern world. Researchers have long known that the hormones leptin and insulin play key roles in appetite and food intake. In healthy people leptin, which is secreted by fat tissue, acts as a molecular measuring tape for our waistlines, quashing feelings of hunger. Insulin spikes when the pancreas gets a whiff of the blood sugar increase after a meal; once the brain detects the spike, it knows to tamp down the desire for food. Certain foods and metabolic disorders, however, can disrupt our ability to respond appropriately to these hormonal signals. In a study published in the September issue of The Journal of Clinical Investigation, scientists report unraveling a central biochemical mechanism behind fat's effect on the mammalian brain . They found that after only three days on a diet high in saturated fat—a common ingredient in beef and cheese—the brains of rats and mice became resistant to leptin and insulin. In contrast, unsaturated fats, such as those found in olive oil, did not trigger resistance. As a result of the hormone resistance, a meal high in saturated fat can crank up our appetite well after dessert. "Taking time off from a healthy diet to eat most fast foods may have consequences that last for some days, even after one resumes the healthy diet," says University of Cincinnati behavioral neuroscientist Stephen Benoit, who led the study. He believes the findings are likely to apply to humans, too. © 1996-2009 Scientific American Inc.

Keyword: Obesity
Link ID: 13388 - Posted: 06.24.2010