By NICHOLAS BAKALAR Depression may be an independent risk factor for Parkinson’s disease, a new study has found. In a retrospective analysis, researchers followed 4,634 patients with depression and 18,544 matched controls for 10 years. To rule out the possibility that depression is an early symptom of Parkinson’s disease, their analysis excluded patients who received a diagnosis of depression within five years of their Parkinson’s diagnosis. The average age of people with depression was 41, while it was 64 for those with both depression and Parkinson’s. The study, published online in Neurology, found that 66 patients with depression, or 1.42 percent, developed Parkinson’s disease, compared with 97, or 0.52 percent, among those who were not depressed. After controlling for age, sex, diabetes, hypertension and other factors, the researchers found clinical depression was associated with more than three times the risk for Parkinson’s disease. “Our paper does not convey the message that all depression leads to Parkinson’s disease,” said the senior author, Dr. Albert C. Yang, a professor of psychiatry at the National Yang-Ming University in Taiwan. “But particularly the depressed elderly and those with difficult-to-treat depression should be alert to the possibility of neurological disease and Parkinson’s.” Copyright 2013 The New York Times Company

Keyword: Depression; Parkinsons
Link ID: 18735 - Posted: 10.03.2013

By Travis Riddle Humans like being around other humans. We are extraordinarily social animals. In fact, we are so social, that simply interacting with other people has been shown to be use similar brain areas as those involved with the processing of very basic rewards such as food, suggesting that interacting with people tends to make us feel good. However, it doesn’t take much reflection to notice that the way people interact with each other has radically changed in recent years. Much of our contact happens not face-to-face, but rather while staring at screen-based digital representations of each other, with Facebook being the most prominent example. This raises a very fundamental question – how does online interaction with other people differ from interacting with people in person? One possible way these two interaction styles might differ is through how rewarding we find them to be. Does interacting with Facebook make us feel good as does interacting with people in real life? A recent paper suggests that the answer is “probably not.” In fact, the data from this paper suggest that the more we interact with Facebook, the worse we tend to feel. Researchers recruited participants from around a college campus. The participants initially completed a set of questionnaires, including one measuring their overall satisfaction with life. Following this, participants were sent text messages 5 times a day for two weeks. For each text, participants were asked to respond to several questions, including how good they felt at that moment, as well as how much they had used Facebook, and how much they had experienced direct interaction with others, since the last text. At the end of the two weeks, participants completed a second round of questionnaires. Here, the researchers once again measured participants’ overall satisfaction with life. © 2013 Scientific American

Keyword: Depression; Emotions
Link ID: 18734 - Posted: 10.02.2013

By DENISE GRADY Hormone therapy for menopause is one of the most divisive subjects in medicine, hailed by some as a boon to women’s comfort and well-being, vilified by others as a threat to health. A new analysis finds truth somewhere in the middle, reaffirming previous warnings that the drugs have more risks than benefits for most women — but also stating that the harms are low early in menopause and that hormones are “appropriate for symptom management in some women.” Dr. JoAnn E. Manson, the first author of the analysis and a professor of medicine at Harvard’s medical school, said in an interview that the findings “should not be used as a basis for denying women treatment if they’re in early menopause and have significant distressing symptoms.” The new report, published on Tuesday in The Journal of the American Medical Association, is based on long-term data from the Women’s Health Initiative, a large, federally funded study that turned medical thinking on its head a decade ago by uncovering the risks of hormones. The new report is the first to include extended follow-up data from the original health initiative study, an additional six to eight years’ worth of information on about 80 percent of the original participants. They took a combination of estrogen and progesterone, estrogen alone or placebos for several years. For combined hormones, for every 10,000 women taking the drugs, the new analysis found that there were six additional instances of heart problems, nine more strokes, nine more blood clots in the lungs and nine more cases of breast cancer. On the benefit side, there were six fewer cases of colorectal cancer, one fewer case of uterine cancer, six fewer hip fractures and one fewer death. Most of the effects wore off once the drugs were stopped, but the risk of breast cancer remained slightly elevated. © 2013 The New York Times Company

Keyword: Hormones & Behavior
Link ID: 18733 - Posted: 10.02.2013

By Shelly Fan Disclaimer: First things first. Please note that I am in no way endorsing nutritional ketosis as a supplement to, or a replacement for medication. As you’ll see below, data exploring the potential neuroprotective effects of ketosis are still scarce, and we don’t yet know the side effects of a long-term ketogenic diet. This post talks about the SCIENCE behind ketosis, and is not meant in any way as medical advice. The ketogenic diet is a nutritionist’s nightmare. High in saturated fat and VERY low in carbohydrates, “keto” is adopted by a growing population to paradoxically promote weight loss and mental well-being. Drinking coffee with butter? Eating a block of cream cheese? Little to no fruit? To the uninitiated, keto defies all common sense, inviting skeptics to wave it off as an unnatural “bacon-and-steak” fad diet. Yet versions of the ketogenic diet have been used to successfully treat drug-resistant epilepsy in children since the 1920s – potentially even back in the biblical ages. Emerging evidence from animal models and clinical trials suggest keto may be therapeutically used in many other neurological disorders, including head ache, neurodegenerative diseases, sleep disorders, bipolar disorder, autism and brain cancer. With no apparent side effects. Sound too good to be true? I feel ya! Where are these neuroprotective effects coming from? What’s going on in the brain on a ketogenic diet? In essence, a ketogenic diet mimics starvation, allowing the body to go into a metabolic state called ketosis (key-tow-sis). © 2013 Scientific American

Keyword: Obesity
Link ID: 18732 - Posted: 10.02.2013

by Linda Geddes They say the early bird catches the worm, but night owls may be missing far more than just a tasty snack. Researchers have discovered the first physical evidence of structural brain differences that distinguish early risers from people who like to stay up late. The differences might help to explain why night owls seem to be at greater risk of depression. Around 10 per cent of people qualify as morning people or larks, and a further 20 per cent are night owls – with the rest of us falling somewhere in between. Your lark or night owl status is called your chronotype. Previous studies have suggested that night owls experience worse sleep, more tiredness during the day and consume greater amounts of tobacco and alcohol. This has prompted some to suggest that they are suffering from a form of chronic jet lag. To investigate further, Jessica Rosenberg at RWTH Aachen University in Germany and colleagues used diffusion tensor imaging to scan the brains of 16 larks, 23 night owls and 20 intermediate chronotypes. They found a reduction in the integrity of night owls' white matter – brain tissue largely comprised of fatty insulating material that speeds up the transmission of nerve signals – in areas associated with depression. "We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag," says Rosenberg, although she cautions that further studies are needed to confirm cause and effect. © Copyright Reed Business Information Ltd.

Keyword: Biological Rhythms; Depression
Link ID: 18731 - Posted: 10.01.2013

By Julianne Wyrick Some people are drawn to the thick smell of bacon, sizzling and crackling in the skillet on a Saturday morning. For others, it’s the aroma of freshly baked cookies on a Friday night or the smell of McDonald’s fries creeping in through the car window. At this time of year, I find the scent of freshly baked pumpkin muffins irresistible. Of course, I’d like to think I’m not a slave to my nose, at least not when I’m nice and full from dinner. If I were a fruit fly, my outlook might not be so good. Already-fed fruit fly larvae exposed to certain food-related odors ate more food than larvae that didn’t experience the smells, according to research published by scientists at the University of Georgia last spring. “They’re not hungry, but they will get an extra kick in terms of appetite, so they will eat, for example, 30 percent extra,” said Ping Shen, lead author on the study. The scents, which included the sweet odor of bananas or the sharper smell of balsamic vinegar, served as “cues” or triggers that the flies associated with food. The triggers motivated the fly larvae to eat, even when they’d already had dinner. That doesn’t bode so well for flies trying to watch their weight. For the fly to feel this urge to eat, the smell has to be transported from sensory receptors in the nose to the part of the brain that regulates appetite—the brain’s “feeding center”—via a series of neurons. Part of this signal transfer involves dopamine, a neurotransmitter associated with behavior motivated by a cue or hint of something to come, like smells associated with food. © 2013 Scientific American

Keyword: Obesity; Chemical Senses (Smell & Taste)
Link ID: 18730 - Posted: 10.01.2013

By NICHOLAS BAKALAR Black and Hispanic children who go to an emergency room with stomach pain are less likely than white children to receive pain medication, a new study reports, and more likely to spend long hours in the emergency room. The analysis, published in the October issue of Pediatrics, examined the records of 2,298 emergency room visits by people under 21, a nationally representative sample from a large survey conducted by the Centers for Disease Control and Prevention. About 53 percent were white, 24 percent non-Hispanic black, 21 percent Hispanic, and the rest from other ethnic or racial groups. Over all, 27.1 percent of white children with severe pain received analgesics, but only 15.8 percent of blacks, 18.9 percent of Hispanics and 7.1 percent of children of other races did. Black children were about 68 percent more likely than white children to spend longer than six hours in the emergency room, although there were no statistically significant differences among races in results for any diagnostic test. “This data set will not answer the question of why,” said the lead author, Dr. Tiffani J. Johnson, an instructor at the University of Pennsylvania School of Medicine. “It could be that white parents are more likely to ask for pain meds, or that minority patients are likely to get care in E.R.’s that have longer wait times. And it could be racial bias.” Copyright 2013 The New York Times Company

Keyword: Pain & Touch; Emotions
Link ID: 18729 - Posted: 10.01.2013

By Kendall Powell, Although my grandmother received a diagnosis of Alzheimer’s disease in her 80s, my family was never sure that’s what she had. She certainly suffered from dementia: She was able to recall childhood memories but couldn’t remember what she had had for lunch. But dementia and Alzheimer’s are not synonymous. Back then, the only way to look for the telltale Alzheimer’s plaques — deposits of the protein fragment beta amyloid that accumulate in the spaces between nerve cells — was through an autopsy, which we didn’t do. Over the past 15 years, researchers have developed a greater understanding of how the disease works. We now have more accurate ways of diagnosing Alzheimer’s and are moving closer to developing drugs to directly attack the disease. Much of this work is still in the early stages, but experts are growing more hopeful about dealing with the debilitating disease, which currently has no cure. Now, for example, we no longer have to rely on autopsies to confirm the existence of Alzheimer’s plaques. In a major advance last year, the Food and Drug Administration approved a method that uses a radioactive dye, known commercially as Amyvid, to light up amyloid plaques in a PET scan. The FDA approved Amyvid to rule out Alzheimer’s when the scan is negative and to confirm the presence of plaques when positive, but that does not necessarily indicate the disease is present. However, some doctors are using the scans to confirm the disease, which experts say is misdiagnosed up to a quarter of the time. Paul Aisen, director of the Alzheimer’s Disease Cooperative Study at University of California at San Diego, calls Amyvid an “enormous advance” because a positive scan, combined with his clinical diagnosis, means he can tell patients and their families the disease is “present, not probable.” © 1996-2013 The Washington Post

Keyword: Alzheimers
Link ID: 18728 - Posted: 10.01.2013

Mid-life stress may increase a woman's risk of developing dementia, according to researchers. In a study of 800 Swedish women, those who had to cope with events such as divorce or bereavement were more likely to get Alzheimer's decades later. The more stressful events there were, the higher the dementia risk became, BMJ Open reports. The study authors say stress hormones may be to blame, triggering harmful alterations in the brain. Stress hormones can cause a number of changes in the body and affect things such as blood pressure and blood sugar control. And they can remain at high levels many years after experiencing a traumatic event, Dr Lena Johansson and colleagues explain. But they say more work is needed to confirm their findings and ascertain whether the same stress and dementia link might also occur in men. In the study, the women underwent a battery of tests and examinations when they were in either their late 30s, mid-40s or 50s, and then again at regular intervals over the next four decades. At the start of the study, one in four women said they had experienced at least one stressful event, such as widowhood or unemployment. BBC © 2013

Keyword: Stress; Alzheimers
Link ID: 18727 - Posted: 10.01.2013

By Larry Greenemeier The leaves of the herb kratom (Mitragyna speciosa), a native of Southeast Asia in the coffee family, are used to relieve pain and improve mood as an opiate substitute and stimulant. The herb is also combined with cough syrup to make a popular beverage in Thailand called “4x100.” Because of its psychoactive properties, however, kratom is illegal in Thailand, Australia, Myanmar (Burma) and Malaysia. The U.S. Drug Enforcement Administration lists kratom as a “drug of concern” because of its abuse potential, stating it has no legitimate medical use. The state of Indiana has banned kratom consumption outright. Now, looking to control its population’s growing dependence on methamphetamines, Thailand is attempting to legalize kratom, which it had originally banned 70 years ago. At the same time, researchers are studying kratom’s ability to help wean addicts from much stronger drugs, such as heroin and cocaine. Studies show that a compound found in the plant could even serve as the basis for an alternative to methadone in treating addictions to opioids. The moves are just the latest step in kratom’s strange journey from home-brewed stimulant to illegal painkiller to, possibly, a withdrawal-free treatment for opioid abuse. With kratom’s legal status under review in Thailand and U.S. researchers delving into the substance’s potential to help drug addicts, Scientific American spoke with Edward Boyer, a professor of emergency medicine and director of medical toxicology at the University of Massachusetts Medical School. Boyer has worked with Chris McCurdy, a University of Mississippi professor of medicinal chemistry and pharmacology, and others for the past several years to better understand whether kratom use should be stigmatized or celebrated. © 2013 Scientific American

Keyword: Drug Abuse
Link ID: 18726 - Posted: 10.01.2013

Erika Check Hayden The power of thought alone is not enough to move inanimate objects — unless the object is a robotic leg wired to your brain, that is. A 32-year-old man whose knee and lower leg were amputated in 2009 after a motorcycle accident is apparently the first person with a missing lower limb to control a robotic leg with his mind. A team led by biomedical engineer Levi Hargrove at the Rehabilitation Institute of Chicago in Illinois reported the breakthrough last week in the New England Journal of Medicine1, including a video that shows the man using the bionic leg to walk up stairs and down a ramp, and to kick a football. The major advance is that the man does not have to use a remote-control switch or exaggerated muscle movements to tell the robotic leg to switch between types of movements, and he does not have to reposition the leg with his hands when seated, Hargrove says. “To our knowledge, this is the first time that neural signals have been used to control both a motorized knee and ankle prosthesis,” he says. Scientists had previously shown that paralysed people could move robotic arms using their thoughts and that able-bodied people can walk using robotic legs controlled by their brains (see, for example, go.nature.com/dgtykw). The latest work goes a step further by using muscle signals to amplify messages sent by the brain when the person intends to move. © 2013 Nature Publishing Group

Keyword: Robotics
Link ID: 18725 - Posted: 10.01.2013

Selectively bred strains of laboratory rats that either prefer or avoid alcohol have been a mainstay of alcohol research for decades. So-called alcohol-preferring rats voluntarily consume much greater amounts of alcohol than do non-preferring rats. Scientists at the National Institutes of Health now report that a specific gene plays an important role in the alcohol-consuming tendencies of both types of rats. “This study advances our understanding of the genetics and neurobiology of alcohol consumption in an important animal model of human alcoholism,” says Kenneth R. Warren, Ph.D., acting director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of NIH. As reported online in the Proceedings of the National Academy of Sciences, a diverse team of scientists, led by David Goldman, M.D., chief of NIAAA’s Laboratory of Neurogenetics, used exome sequencing, an approach that comprehensively analyzes the DNA that encodes proteins. They found a severely dysfunctional form of the gene for a brain signaling molecule called metabotropic glutamate receptor 2 (Grm2), known as a stop codon, in alcohol-preferring rats but not in non-preferring rats. The researchers then demonstrated that drugs and genetic changes that block Grm2 increased alcohol consumption in normal rats and mice. “We’ve long known that genes play an important role in alcoholism,” says Dr. Goldman. “However, the genes and genetic variants that cause alcoholism have remained largely unknown. This first discovery of a gene accounting for alcohol preference in a mammalian model illustrates that genomic analysis of a model organism is a powerful approach for a complex disease such as alcoholism.”

Keyword: Drug Abuse; Genes & Behavior
Link ID: 18724 - Posted: 10.01.2013

By Tanya Lewis, Look closely at the FedEx logo and you'll notice the space between the "E" and the "x" creates the outline of an arrow. Now, a new study reveals the part of the brain that creates such invisible shapes. The FedEx arrow is just one example of a common optical illusion, whereby the brain "sees" shapes and surfaces within a fragmented background, although they don't exist. Scientists studied the effect in monkeys, finding a group of neurons in part of the visual cortex that fire when the animals viewed an illusion pattern. Besides monkeys, studies have shown that a host of other animals experience shape illusions, including cats, owls, goldfish and honeybees. Scientists think the mental quirk might have evolved to help animals spot predators or prey in the bushes. "Basically, the brain is acting like a detective," study leader Alexander Maier, a psychologist at Vanderbilt University in Nashville, Tenn., said in a statement. "It is responding to cues in the environment and making its best guesses about how they fit together. In the case of these illusions, however, it comes to an incorrect conclusion." The visual cortex, a part of the brain at the back of the head, processes visual information in mammals. Scientists often divide the visual cortex into five regions labeled V1 through V5. Visual signals from the eyes go to the primary visual cortex, V1, which detects their orientation, color and spatial arrangement. The brain splits that information into two streams, known as the dorsal and ventral streams. Both pathways go to V2, which makes some connections to V3.

Keyword: Vision
Link ID: 18723 - Posted: 10.01.2013

By BRANDON A. GAUDIANO PROVIDENCE, R.I. — PSYCHOTHERAPY is in decline. In the United States, from 1998 to 2007, the number of patients in outpatient mental health facilities receiving psychotherapy alone fell by 34 percent, while the number receiving medication alone increased by 23 percent. This is not necessarily for a lack of interest. A recent analysis of 33 studies found that patients expressed a three-times-greater preference for psychotherapy over medications. As well they should: for patients with the most common conditions, like depression and anxiety, empirically supported psychotherapies — that is, those shown to be safe and effective in randomized controlled trials — are indeed the best treatments of first choice. Medications, because of their potential side effects, should in most cases be considered only if therapy either doesn’t work well or if the patient isn’t willing to try counseling. So what explains the gap between what people might prefer and benefit from, and what they get? The answer is that psychotherapy has an image problem. Primary care physicians, insurers, policy makers, the public and even many therapists are largely unaware of the high level of research support that psychotherapy has. The situation is exacerbated by an assumption of greater scientific rigor in the biologically based practices of the pharmaceutical industries — industries that, not incidentally, also have the money to aggressively market and lobby for those practices. For the sake of patients and the health care system itself, psychotherapy needs to overhaul its image, more aggressively embracing, formalizing and promoting its empirically supported methods. My colleague Ivan W. Miller and I recently surveyed the empirical literature on psychotherapy in a series of papers we edited for the November edition of the journal Clinical Psychology Review. It is clear that a variety of therapies have strong evidentiary support, including cognitive-behavioral, mindfulness, interpersonal, family and even brief psychodynamic therapies (e.g., 20 sessions). © 2013 The New York Times Company

Keyword: Depression
Link ID: 18722 - Posted: 09.30.2013

The Conservative government is launching a $1.3-billion free market in medical marijuana on Tuesday, eventually providing an expected 450,000 Canadians with quality weed. Health Canada is phasing out an older system on Monday that mostly relied on small-scale, homegrown medical marijuana of varying quality, often diverted illegally to the black market. In its place, large indoor marijuana farms certified by the RCMP and health inspectors will produce, package and distribute a range of standardized weed, all of it sold for whatever price the market will bear. The first sales are expected in the next few weeks, delivered directly by secure courier. "We're fairly confident that we'll have a healthy commercial industry in time," Sophie Galarneau, a senior official with the department, said in an interview. "It's a whole other ball game." The sanctioned birth of large-scale, free-market marijuana production comes as the Conservatives pillory Liberal Leader Justin Trudeau's campaign to legalize recreational marijuana. Health Canada is placing no limits on the number of these new capital-intensive facilities, which will have mandatory vaults and security systems. Private-dwelling production will be banned. Imports from places such as the Netherlands will be allowed. Already 156 firms have applied for lucrative producer and distributor status since June, with the first two receiving licences just last week. © CBC 2013

Keyword: Drug Abuse; Pain & Touch
Link ID: 18721 - Posted: 09.30.2013

By WILLIAM J. BROAD SCIENCE has looked into some strange things over the centuries — reports of gargantuan sea monsters, purported images of Jesus, sightings of alien spaceships and so on. When I first heard of spontaneous orgasm, while researching a book on yoga, including its libidinal cousin, tantra, I figured it was more allegory than reality and in any event would prove beyond the reach of even the boldest investigators. Well, I was wrong. It turns out science has tiptoed around the subject for more than a century and of late has made considerable progress in determining not only the neurophysiological basis of the phenomenon but also its prevalence. Men are mentioned occasionally. But sex researchers have found that the novel type of autoerotism shows up mainly in women. Ground zero for the research is Rutgers University, where scientists have repeatedly had female volunteers put their heads into giant machines and focus their attention on erotic fantasies — the scans reveal that the pleasure centers of their brains light up in ways indistinguishable from everyday orgasms. The lab atmosphere is no-nonsense, with plenty of lights and white coats and computer monitors. Subjects often thrash about so forcefully that obtaining clear images of their brains can be difficult. “Head movement is a huge issue,” Nan Wise, a doctoral candidate at Rutgers who helps run the project, said in an interview. “It’s hard to get a decent signal.” She said a volunteer’s moving her head more than two millimeters — less than a 10th of an inch — can make for a bad day in the lab. It is easy to dismiss this as a new kind of narcissism in search of scientific respectability, a kinky pleasure coming out of the shadows. Many YouTube videos now purport to show people using controlled breathing and erotic introspection to achieve what they describe as “thinking off” and “energy orgasms.” © 2013 The New York Times Company

Keyword: Sexual Behavior; Brain imaging
Link ID: 18720 - Posted: 09.30.2013

Neuroscience students at the University of Lethbridge are stepping into a maze of memory functions, hoping to help people with dementia or brain injuries through new research that tests people’s memory in the field. That is, the field outside Markin Hall on the U of L’s campus, where neuroscience PhD student Erin Zelinski has set up a life-sized version of a navigation experiment that until now has only been done locally with rats. In it, participants walk around the field until they reach an invisible target spot. When they do, they’ll hear a whistle letting them know they’re in the right place. Then, while researchers time their progress, following their every move with GPS and an overhead remote-controlled camera, participants must find their way back to the same spot two days later. The idea is to first study the brain functions of people without memory impairments so that researchers can later compare that data to a future study of people with memory loss. “We’re trying to describe what normal performance on this test looks like, so if you take a person who’s healthy and you have them perform the task, what we’ll see is that there will probably be commonalities that are going to emerge,” Zelinski said. “And then if you start to look at people that have memory impairments or a brain injury, when they perform the task there might be some things that are different. The better we are at characterizing it in normal people, the better we’re going to be at identifying where the impairments are in those individuals that are having memory problems.” © 1996-2013 The Lethbridge Herald

Keyword: Learning & Memory
Link ID: 18719 - Posted: 09.30.2013

By DAVID P. BARASH WAR is in the air. Sad to say, there’s nothing new about this. Nor is there anything new about the claim that war has always been with us, and always will be. What is new, it seems, is the degree to which this claim is wrapped in the apparent acquiescence of science, especially the findings of evolutionary biology with respect to a war-prone “human nature.” This year, an article in The National Interest titled “What Our Primate Relatives Say About War” answered the question “Why war?” with “Because we are human.” In recent years, a piece in New Scientist asserted that warfare has “played an integral part in our evolution” and an article in the journal Science claimed that “death in warfare is so common in hunter-gatherer societies that it was an important evolutionary pressure on early Homo sapiens.” The emerging popular consensus about our biological predisposition to warfare is troubling. It is not just scientifically weak; it is also morally unfortunate, as it fosters an unjustifiably limited vision of human potential. Although there is considerable reason to think that at least some of our hominin ancestors engaged in warlike activities, there is also comparable evidence that others did not. While it is plausible that Homo sapiens owed much of its rapid brain evolution to natural selection’s favoring individuals that were smart enough to defeat their human rivals in violent competition, it is also plausible that we became highly intelligent because selection favored those of our ancestors who were especially adroit at communicating and cooperating. Conflict avoidance, reconciliation and cooperative problem solving could also have been altogether “biological” and positively selected for. © 2013 The New York Times Company

Keyword: Aggression; Evolution
Link ID: 18718 - Posted: 09.30.2013

By Laura Sanders By hijacking connections between neurons deep within the brain, scientists forced full mice to keep eating and hungry mice to shun food. By identifying precise groups of cells that cause eating and others that curb it, the results begin to clarify the intricate web of checks and balances in the brain that control feeding. “This is a really important missing piece of the puzzle,” says neuroscientist Seth Blackshaw of Johns Hopkins University in Baltimore. “These are cell types that weren’t even predicted to exist.” A deeper understanding of how the brain orchestrates eating behavior could lead to better treatments for disorders such as anorexia and obesity, he says. Scientists led by Joshua Jennings and Garret Stuber of the University of North Carolina at Chapel Hill genetically tweaked mice so that a small group of neurons would respond to light. When a laser shone into the brain, these cells would either fire or, in a different experiment, stay quiet. These neurons reside in a brain locale called the bed nucleus of the stria terminalis, or BNST. Some of the message-sending arms of these neurons reach into the lateral hypothalamus, a brain region known to play a big role in feeding. When a laser activated these BNST neurons, the mice became ravenous, voraciously eating their food, the researchers report in the Sept. 27 Science. “As soon as you turn it on, they start eating and they don’t stop until you turn it off,” Stuber says. The opposite behavior happened when a laser silenced BNST neurons’ messages to the lateral hypothalamus: The mice would not eat, even when hungry. © Society for Science & the Public 2000 - 2013

Keyword: Obesity
Link ID: 18717 - Posted: 09.28.2013

Heather Saul Stress can make the world around us smell unpleasant, the results of a new study are suggesting. Researchers from the University of Wisconsin-Madison used powerful brain imaging technologies to examine how stress and anxiety "re-wire" the brain. A team of psychologists led by Professor Wen Li discovered that when a person experiences stress, emotion systems and olfactory processing in the brain become linked, making inoffensive smells become unpleasant. Although the emotion and olfactory systems within the brain are usually found next to each other, there is rarely 'crosstalk' between the two. Writing in the Journal of Neuroscience, Prof Li said results from their research will now help to uncover the biological mechanisms at work when a person feels stressed. Using functional MRI scans, the team analysed the brain activity of 12 participants after showing them images designed to induce anxiety as they smelled familiar, neutral odours. The subjects were then asked to rate the different smells before being shown the disturbing image and afterwards. The majority showed a more negative response to odours that they had previously considered neutral. This fuels a 'feedback loop' that heightens distress, and can even lead to clinical issues such as depression. Prof Li explained: "After anxiety induction, neutral smells become clearly negative." “In typical odor processing, it is usually just the olfactory system that gets activated,” says Li. “But when a person becomes anxious, the emotional system becomes part of the olfactory processing stream. © independent.co.uk

Keyword: Stress; Chemical Senses (Smell & Taste)
Link ID: 18716 - Posted: 09.28.2013