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11/30/2011

Violent video games alter brain function in young men


A functional magnetic resonance imaging (fMRI) analysis of long-term effects of violent video game play on the brain has found changes in brain regions associated with cognitive function and emotional control in young adult men after one week of game play. The results of the study were presented today at the annual meeting of the Radiological Society of North America (RSNA). 


The controversy over whether or not violent video games are potentially harmful to users has raged for many years, making it as far as the Supreme Court in 2010. But there has been little scientific evidence demonstrating that the games have a prolonged negative neurological effect. 

"For the first time, we have found that a sample of randomly assigned young adults showed less activation in certain frontal brain regions following a week of playing violent video games at home," said Yang Wang, M.D., assistant research professor in the Department of Radiology and Imaging Sciences at Indiana University School of Medicine in Indianapolis. "These brain regions are important for controlling emotion and aggressive behavior." 

For the study, 22 healthy adult males, age 18 to 29, with low past exposure to violent video games were randomly assigned to two groups of 11. Members of the first group were instructed to play a shooting video game for 10 hours at home for one week and refrain from playing the following week. The second group did not play a violent video game at all during the two-week period. 

Each of the 22 men underwent fMRI at the beginning of the study, with follow-up exams at one and two weeks. During fMRI, the participants completed an emotional interference task, pressing buttons according to the color of visually presented words. Words indicating violent actions were interspersed among nonviolent action words. In addition, the participants completed a cognitive inhibition counting task. 

The results showed that after one week of violent game play, the video game group members showed less activation in the left inferior frontal lobe during the emotional task and less activation in the anterior cingulate cortex during the counting task, compared to their baseline results and the results of the control group after one week. After the second week without game play, the changes to the executive regions of the brain were diminished. 

"These findings indicate that violent video game play has a long-term effect on brain functioning," Dr. Wang said. 

Source: Radiological Society of North America [November 30, 2011]

Eating fish reduces risk of Alzheimer's disease


People who eat baked or broiled fish on a weekly basis may be improving their brain health and reducing their risk of developing mild cognitive impairment (MCI) and Alzheimer's disease, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA). 


"This is the first study to establish a direct relationship between fish consumption, brain structure and Alzheimer's risk," said Cyrus Raji, M.D., Ph.D., from the University of Pittsburgh Medical Center and the University of Pittsburgh School of Medicine. "The results showed that people who consumed baked or broiled fish at least one time per week had better preservation of gray matter volume on MRI in brain areas at risk for Alzheimer's disease." 

Alzheimer's disease is an incurable, progressive brain disease that slowly destroys memory and cognitive skills. According to the National Institute on Aging, as many as 5.1 million Americans may have Alzheimer's disease. In MCI, memory loss is present but to a lesser extent than in Alzheimer's disease. People with MCI often go on to develop Alzheimer's disease. 

For the study, 260 cognitively normal individuals were selected from the Cardiovascular Health Study. Information on fish consumption was gathered using the National Cancer Institute Food Frequency Questionnaire. There were 163 patients who consumed fish on a weekly basis, and the majority ate fish one to four times per week. Each patient underwent 3-D volumetric MRI of the brain. Voxel-based morphometry, a brain mapping technique that measures gray matter volume, was used to model the relationship between weekly fish consumption at baseline and brain structure 10 years later. The data were then analyzed to determine if gray matter volume preservation associated with fish consumption reduced risk for Alzheimer's disease. The study controlled for age, gender, education, race, obesity, physical activity, and the presence or absence of apolipoprotein E4 (ApoE4), a gene that increases the risk of developing Alzheimer's. 

Gray matter volume is crucial to brain health. When it remains higher, brain health is being maintained. Decreases in gray matter volume indicate that brain cells are shrinking. 

The findings showed that consumption of baked or broiled fish on a weekly basis was positively associated with gray matter volumes in several areas of the brain. Greater hippocampal, posterior cingulate and orbital frontal cortex volumes in relation to fish consumption reduced the risk for five-year decline to MCI or Alzheimer's by almost five-fold. 

"Consuming baked or broiled fish promotes stronger neurons in the brain's gray matter by making them larger and healthier," Dr. Raji said. "This simple lifestyle choice increases the brain's resistance to Alzheimer's disease and lowers risk for the disorder." 

The results also demonstrated increased levels of cognition in people who ate baked or broiled fish. 

"Working memory, which allows people to focus on tasks and commit information to short-term memory, is one of the most important cognitive domains," Dr. Raji said. "Working memory is destroyed by Alzheimer's disease. We found higher levels of working memory in people who ate baked or broiled fish on a weekly basis, even when accounting for other factors, such as education, age, gender and physical activity." 

Eating fried fish, on the other hand, was not shown to increase brain volume or protect against cognitive decline. 

Source: Radiological Society of North America [November 30, 2011]

Dieters should eat foods rich in protein, mostly from dairy, to protect bones during weight loss


New research suggests that a calorie-restricted diet higher in protein—mostly from dairy foods—and lower in carbohydrates coupled with daily exercise has a major positive impact on bone health in overweight and obese young women. 



The study, published online in the Journal of Clinical Endocrinology and Metabolism, found bone health improvements were particularly evident due to the high density of bone-supporting nutrients such as calcium, vitamin D and dairy-based protein. 

For 16 weeks, three groups of overweight and obese, but otherwise healthy, premenopausal women each consumed either low, medium or high amounts of dairy foods coupled with higher or lower amounts of protein and carbohydrates. Calcium and vitamin D levels were also graded from low to high across the groups in conjunction with the dairy foods they consumed. 

The women exercised seven days per week, a routine that included aerobic exercise every day and two additional workouts of circuit weightlifting per week. 

"Our findings demonstrate the importance of diet composition to the maintenance of bone health status during weight loss," said Andrea Josse, of the Department of Kinesiology at McMaster and lead author of the study. "Our data clearly show dairy-source protein is important when aiming to avoid harmful consequences such as accelerated bone loss during weight loss. In our view, young women attempting to lose weight should consume a diet higher in dairy-source protein." 

A previous study from the same team in the same subjects showed that there were identical total weight losses across the groups, but very different results for body composition change with the higher-protein, high-dairy group experiencing greater whole-body fat and abdomen fat losses and greater lean mass gains. 

The same subjects consuming higher-protein and high-dairy diets for this study also showed the greatest improvements in markers of bone formation, no change in bone loss, an increase in circulating vitamin D levels, and a decrease in levels of parathyroid hormone, which when elevated is typically associated with bone loss. 

Maintaining or even improving bone health in young women, particularly in those trying to lose weight, is important for overall health, and may have great implications for decreasing the risk of diseases like osteoporosis later in life, say the researchers. 

"Our data provide further rationale to recommend consumption of dairy foods to aid in 'high quality' weight loss, which we defined as loss of fat and sparing of muscle, and the promotion of bone health in young women," says Stuart Phillips, senior author and a professor in the Department of Kinesiology. "These women are not only at the age when achieving and maintaining peak bone mass is of great importance, but in whom adequate dairy consumption would offset sub-optimal intakes of calcium and vitamin D." 

Subjects undergoing weight loss while consuming marginally adequate protein without dairy foods showed markedly elevated levels of markers of bone loss indicating that following such a diet in the long-run would weaken bones.  

Source: McMaster University [November 30, 2011]

Environment and Diet leave their prints on the heart


A University of Cambridge study, which set out to investigate DNA methylation in the human heart and the "missing link" between our lifestyle and our health, has now mapped the link in detail across the entire human genome.  


The new data collected greatly benefits a field that is still in its scientific infancy and is a significant leap ahead of where the researchers were, even 18 months ago. 

Researcher Roger Foo explains: “By going wider and scanning the genome in greater detail this time – we now have a clear picture of the ‘fingerprint’ of the missing link, where and how epigenetics in heart failure may be changed and the parts of the genome where diet or environment or other external factors may affect outcomes.” 

The study originally began investigating the differences in DNA methylation found in the human heart. Researchers compared data from a small number of people with end-stage cardiomyopathy who were undergoing heart transplantation, and the healthy hearts of age-matched victims of road traffic accidents. 

DNA methylation leaves indicators, or “marks”, on the genome and there is evidence that these “marks” are strongly influenced by external factors such as the environment and diet. The researchers have found that this process is different in diseased and normal hearts. Linking all these things together suggest this may be the “missing link” between environmental factors and heart failure. 

The findings deepen our understanding of the genetic changes that can lead to heart disease and how these can be influenced by our diet and our environment. The findings can potentially open new ways of identifying, managing and treating heart disease. 

The DNA that makes up our genes is made up of four “bases” or nucleotides – cytosine, guanine, adenine and thymie, often abbreviated to C, G, A and T. DNA methylation is the addition of a methyl group (CH3) to cytosine. 

When added to cytosine, the methyl group looks different and is recognised differently by proteins, altering how the gene is expressed i.e. turned on or off. 

DNA methylation is a crucial part of normal development, allowing different cells to become different tissues despite having the same genes. As well as happening during development, DNA methylation continues throughout our lives in a response to environmental and dietary changes which can lead to disease. 

As a result of the study, Foo likens DNA methylation to a fifth nucleotide: “We often think of DNA as being composed of four nucleotides. Now, we are beginning to think there is a fifth – the methylated C.” 

Foo also alludes to what the future holds for the study: “…and more recent basic studies now show us that our genome has even got 6th, 7th and 8th nucleotides… in the form of further modifications of cytosines. These are hydroxy-methyl-Cytosine, formylCytosine and carboxylCytosine = hmC, fC and caC! These make up an amazing shift in the paradigm…” 

As in most studies, as one question is resolved, another series of mysteries form in its place. The study shows that we are still on the frontier of Epigenetics and only just beginning to understand the link between the life we lead and the body we have. 

Source: University of Camridge [November 29, 2011]

11/29/2011

Study debunks stereotype that men think about sex all day long


Men may think about sex more often than women do, but a new study suggests that men also think about other biological needs, such as eating and sleep, more frequently than women do, as well. 


And the research discredits the persistent stereotype that men think about sex every seven seconds, which would amount to more than 8,000 thoughts about sex in 16 waking hours. In the study, the median number of young men's thought about sex stood at almost 19 times per day. Young women in the study reported a median of nearly 10 thoughts about sex per day. 

As a group, the men also thought about food almost 18 times per day and sleep almost 11 times per day, compared to women's median number of thoughts about eating and sleep, at nearly 15 times and about 8 1/2 times, respectively. 

The college-student participants carried a golf tally counter to track their thoughts about either eating, sleep or sex every day for a week. Each student was assigned to just one type of thought to record. Before receiving the tally counter, they had completed a number of questionnaires and were asked to estimate how often they had daily thoughts about eating, sleeping and sex. 

Overall, a participant's comfort with sexuality was the best predictor for which person would have the most frequent daily thoughts about sex. 

"If you had to know one thing about a person to best predict how often they would be thinking about sex, you'd be better off knowing their emotional orientation toward sexuality, as opposed to knowing whether they were male or female," said Terri Fisher, professor of psychology at Ohio State University's Mansfield campus and lead author of the study. "Frequency of thinking about sex is related to variables beyond one's biological sex." 

Correcting this stereotype about men's sexual thoughts is important, Fisher noted. 

"It's amazing the way people will spout off these fake statistics that men think about sex nearly constantly and so much more often than women do," she said. "When a man hears a statement like that, he might think there's something wrong with him because he's not spending that much time thinking about sexuality, and when women hear about this, if they spend significant time thinking about sex they might think there's something wrong with them." 

The study appears online and is scheduled for publication in the January issue of the Journal of Sex Research. 

The study involved 163 female and 120 male college students between the ages of 18 and 25 who were enrolled in a psychology research participation program. Of those, 59 were randomly assigned to track thoughts about food, 61 about sleep and 163 about sex. Most students were white and self-identified as heterosexual. The college-student sample made it comparable to previous research and involved an age group at which gender differences in sexuality are likely at their peak. 

Before the thought-tracking began, the participants completed a number of questionnaires. These included a sexual opinion survey to measure a positive or negative emotional orientation toward sexuality (erotophilia vs. erotophobia); a sociosexual orientation inventory measuring attitudes about sex and tracking sexual behavior and levels of desire; a social desirability scale to measure respondents' tendency to try to appear socially acceptable; and an eating habits questionnaire and sleepiness scale. They also were asked to estimate how many times in an average day that they thought about sleeping, eating and sex. 

Researchers then gave each student a tally counter device and told those assigned to the sexual thoughts condition to click the device to maintain a count their of thoughts about sex. They were told to count a thought about any aspect of sex: sexual activity of any kind, fantasies and erotic images, sexual memories and any arousing stimuli. 

Others were instructed to use the device to record thoughts about eating that included food, hunger, cravings, snacking or cooking, and thoughts about sleep that included dreaming, sleeping, napping, going to bed or needing rest. 

The questions about food and sleep were designed to mask the true intent of the study's focus on thoughts about sex, Fisher said. However, the results about these additional thoughts provided important information about differences in thinking among males and females. 

"Since we looked at those other types of need-related thoughts, we found that it appears that there's not just a sex difference with regard to thoughts about sex, but also with regard to thoughts about sleep and food," she said. "That's very significant. This suggests males might be having more of these thoughts than women are or they have an easier time identifying the thoughts. It's difficult to know, but what is clear is it's not uniquely sex that they're spending more time thinking about, but other issues related to their biological needs, as well." 

And when all of those thoughts were taken into account in the statistical analysis, the difference between men and women in their average number of daily thoughts about sex wasn't considered any larger than the gender differences between thoughts about sleep or thoughts about food. 

In raw numbers, male participants recorded between one and 388 daily thoughts about sex, compared to the range of female thoughts about sex of between one and 140 times per day. 

"For women, that's a broader range than many people would have expected. And there were no women who reported zero thoughts per day. So women are also thinking about sexuality," Fisher said. 

The questionnaire data offered some additional clues about the influences on sexual thoughts. When all participants were analyzed together, those measuring the highest in erotophilia – or comfort with their sexuality – were the most likely to think more frequently about sex. 

But when the analysis considered males and females separately, no single variable – erotophilia score, unrestrictive attitudes about sex or a lack of desire to be socially acceptable – could be defined as a predictor of how often men think about sex. 

But for women, the erotophilia score remained a good predictor of more frequent sexual thoughts. On the other hand, women who scored high on the desire to be socially acceptable were more likely to think less frequently about sex. 

"People who always give socially desirable responses to questions are perhaps holding back and trying to manage the impression they make on others," Fisher explained. "In this case, we're seeing that women who are more concerned with the impression they're making tend to report fewer sexual thoughts, and that's because thinking about sexuality is not consistent with typical expectations for women." 

The participants' estimates about how often they thought each day about eating, sleeping and sex were all much lower than the actual number of thoughts they recorded. This suggested to Fisher that previous research in this area – especially on thoughts about sex – was weak because almost all previous studies were based on participants' retrospective estimates about how often they thought about sex. 

"There's really no good reason that our society should have believed that men are thinking so much more about sex than women. Even the research that had been done previously doesn't support the stereotype that men are thinking about sex every seven seconds," she said. 

Fisher conducted the research with undergraduate Ohio State-Mansfield students Zachary Moore and Mary-Jo Pittenger. Both have since graduated. 

Source: Ohio State University [November 28, 2011]

Original Thinkers More Likely to Cheat, Study Finds


Creative people are more likely to cheat than less creative people, possibly because this talent increases their ability to rationalize their actions, according to research published by the American Psychological Association. 


"Greater creativity helps individuals solve difficult tasks across many domains, but creative sparks may lead individuals to take unethical routes when searching for solutions to problems and tasks," said lead researcher Francesca Gino, PhD, of Harvard University. 

Gino and her co-author, Dan Ariely, PhD, of Duke University, conducted a series of five experiments to test their thesis that more creative people would cheat under circumstances where they could justify their bad behavior. Their research was published online in APA's Journal of Personality and Social Psychology®. 

The researchers used a series of recognized psychological tests and measures to gauge research subjects' creativity. They also tested participants' intelligence. In each of the five experiments, participants received a small sum for showing up. Then, they were presented with tasks or tests where they could be paid more if they cheated. For example, in one experiment, participants took a general knowledge quiz in which they circled their answers on the test paper. Afterward, the experimenter told them to transfer their answers to "bubble sheets" -- but the experimenter told the group she had photocopied the wrong sheet and that the correct answers were lightly marked. The experimenters also told participants they would be paid more for more correct answers and led them to believe that they could cheat without detection when transferring their answers. However, all the papers had unique identifiers. 

The results showed the more creative participants were significantly more likely to cheat, and that there was no link between intelligence and dishonesty -- i.e., more intelligent but less creative people were not more inclined toward dishonesty. 

In another experiment, test subjects were shown drawings with dots on two sides of a diagonal line and asked to indicate whether there were more dots on the left side or right side. In half of 200 trials, it was virtually impossible to tell whether there were more dots on one side or another. However, participants were told they'd be paid 10 times as much (5 cents vs. 0.5 cents) for each time they said there were more dots on the right side. As predicted, the more creative participants were significantly more likely to give the answer that paid more. 

"Dishonesty and innovation are two of the topics most widely written about in the popular press," the authors wrote. "Yet, to date, the relationship between creativity and dishonest behavior has not been studied empirically. … The results from the current article indicate that, in fact, people who are creative or work in environments that promote creative thinking may be the most at risk when they face ethical dilemmas." 

The authors concede some important limitations in their work, most notably that they created situations in which participants were tempted by money to cheat. They suggested that future research should investigate whether creativity would lead people to satisfy selfish, short-term goals rather than their higher aspirations when faced with self-control dilemmas, such as eating a slice of cake when trying to lose weight. 

Source: American Psychological Association [November 28, 2011]

Scientists ID ‘Morning Person’ Gene


Napoleon Bonaparte, Margaret Thatcher, Leonardo da Vinci … history is full of  names of famous figures who accomplished historical feats on reportedly few hours of sleep. Now, new research suggests they may have had a  certain genetic advantage. 


Scientists at Germany’s Ludwig Maximalians University of Munich have found that one gene, called ABCC9, influences sleep duration and could explain why certain people seem able to operate on limited amounts of shut-eye. The researchers studied responses to a sleep survey from more than 4,000 Europeans in seven different countries and also scanned their genomes. They found that people who had two copies of a particular variant of the ABCC9 gene generally reported sleeping for shorter periods than those who had two copies of a different version of the gene. 

The ABCC9 gene has been previously linked  to heart disease and diabetes. These latest findings on the genetic factor’s role in sleep duration add to a growing body of evidence suggesting a connection between sleep and cardiovascular health. A 2008 study found a connection between lack of sleep and a dangerous build-up of calcium in the arteries. Sleep apnea, a sleep disorder marked by abnormal pauses in breathing,  has also been associated with high blood pressure and heart attacks. 

“Apparently, the relationships of sleep duration with other conditions, such as heart disease and diabetes, can be in part explained by an underlying common molecular mechanism,” study author Karla Allebrandt told the U.K.’s Daily Mail. 

The scientists also found that the ABCC9 gene controls sleep duration in fruit flies, providing a clue to the gene’s evolutionary age,  Allebrandt said. 

Scientists  are gradually learning more about the genetics behind sleep habits. In 2008, researchers found a gene associated with narcolepsy, a rare but devastating sleep disorder. A 2010 study identified genetic differences that make some people sleepier than others, even after they’ve had a full night’s rest. Dr. Mark Mahowald, medical director of the Minnesota Regional Sleep Disorders Center, told ABC News that there’s more to sleep habits than most people think. 

“Our society has equated sleepiness with defects of character, like laziness and depression, but really, some people are generally sleepier during the day,” Mahowald said. “We have to accept the fact that sleep duration is genetically determined and not a sign of a defect.” 

Author: Carrie Gann | Source: ABC News Website [November 28, 2011]

A Vaccination Against Social Prejudice


Evolutionary psychologists suspect that prejudice is rooted in survival: Our distant ancestors had to avoid outsiders who might have carried disease. Research still shows that when people feel vulnerable to illness, they exhibit more bias toward stigmatized groups. But a new study in Psychological Science, a journal published by the Association for Psychological Science suggests there might be a modern way to break that link. 


“We thought if we could alleviate concerns about disease, we could also alleviate the prejudice that arises from them,” says Julie Y. Huang of the University of Toronto, about a study she conducted with Alexandra Sedlovskaya of Harvard University; Joshua M. Ackerman of the Massachusetts Institute of Technology; and Yale University’s John A. Bargh. The group found that the sense of security derived through measures such as vaccination and hand washing can reduce bias against “out” groups, from immigrants to the obese. 

The researchers conducted three experiments. The first two (with 135 and 26 participants, respectively) looked at people’s reactions to threats of the flu. In the first, some participants were already vaccinated, others not. Half the subjects—including members of both groups—read a cautionary passage about the flu. In experiment 2, all the participants had been vaccinated. They read a similar text, but some of them read one with a section saying the vaccine is effective; the others received only an explanation of how it functions. In both experiments, participants answered questionnaires assessing their level of prejudice—in the first, particularly toward immigrants, in the second, toward numerous groups, including crack addicts and obese people. 

The findings: In experiment 1, among those who read the text—and were thus reminded of the disease threat—the vaccinated showed less anti-immigrant sentiment than the unvaccinated. There was no significant difference among those who didn’t read the passage. In experiment 2, those who got assurances of the vaccine’s effectiveness showed less bias. “Even when everyone is actually protected,” comments Huang, “the perception that they are well protected attenuates prejudice.” 

In the third experiment, with 26 undergraduate participants, half used a hand wipe to wipe their hands and the keyboard of a computer they were using. The others  didn’t. The text they read included the statement that anti-bacterial hand wipes help protect against contagion. These students were assessed for their nervousness about germs—a signal of feeling vulnerable to disease—and their feelings toward seven out-groups and two in-groups (undergraduates and their families). As expected, among those who did not wipe their hands, germ aversion correlated positively with aversion to stigmatized groups. But the germ-averse hand-wipers didn’t express prejudice. None showed bias toward people like themselves and their loved ones. 

The study—which is unique in uniting evolutionary psychology, social cognitive psychology, and public health—holds promise for reducing physical and social maladies at once. Write the authors, a public health intervention like vaccination or hand washing could be a “modern treatment for [an] ancient affliction.” 

Source: Association for Psychological Science [November 28, 2011]

Study Looks at the Nature of Change in Our Aging, Changing Brains


As we get older, our cognitive abilities change, improving when we're younger and declining as we age. Scientists posit a hierarchical structure within which these abilities are organized. There's the "lowest" level -- measured by specific tests, such as story memory or word memory; the second level, which groups various skills involved in a category of cognitive ability, such as memory, perceptual speed, or reasoning; and finally, the "general," or G, factor, a sort of statistical aggregate of all the thinking abilities. 


What happens to this structure as we age? That was the question Timothy A. Salthouse, Brown-Forman professor of psychology at the University of Virginia, investigated in a new study appearing in an upcoming issue of Psychological Science, a journal published by the Association for Psychological Science. His findings advance psychologists' understanding of the complexities of the aging brain. 

"There are three hypotheses about how this works," says Salthouse. "One is that abilities become more strongly integrated with one another as we age." That theory suggests the general factor influences cognitive aging the most. The second -- based on the idea that connectivity among different brain regions lessens with age -- "is almost the opposite: that the changes in cognitive abilities become more rather than less independent with age." The third was Salthouse's hypothesis: The structure remains constant throughout the aging process. 

Using a sample of 1,490 healthy adults ages 18 to 89, Salthouse performed analyses of the scores on 16 tests of five cognitive abilities -- vocabulary, reasoning, spatial relations, memory, and perceptual speed. The primary analyses were on the changes in the test scores across an interval of about two and a half years. 

The findings confirmed Salthouse's hunch: "The effects of aging on memory, on reasoning, on spatial relations, and so on are not necessarily constant. But the structure within which these changes are occurring does not seem to change as a function of age." In normal, healthy people, "the direction and magnitude of change may be different" when we're 18 or 88, he says. "But it appears that the qualitative nature of cognitive change remains the same throughout adulthood." 

The study could inform other research investigating "what allows some people to age more gracefully than others," says Salthouse. That is, do people who stay mentally sharper maintain their ability structures better than those who become more forgetful or less agile at reasoning? And in the future, applying what we know about the structures of change could enhance "interventions that we think will improve cognitive functioning" at any age or stage of life. 

Source: Association for Psychological Science [November 22, 2011]

When errors improve performance: Model describes how experiences influence our perception


During estimation processes we unconsciously make use of recent experiences. Scientists from Ludwig-Maximilians-Universität (LMU) in Munich and the Bernstein Center Munich asked test subjects to estimate distances in a virtual reality environment. The results revealed that estimates tended to approach the mean of all previously experienced distances. For the first time, scientists were able to accurately predict the experimental findings using a mathematical model. The model combines two well-known laws of psychophysics with a theorem from probability theory. The study could be of fundamental relevance to research on perception. 


Why do we perceive identical distances as long in one situation and short in another? It all depends on the distances that we have covered in the immediate past. This might seem a trivial conclusion, but it gives an important insight into how the brain processes signals of different intensities or even abstract elements such as numbers. Dr. Stefan Glasauer (LMU Munich), project leader at the Bernstein Center Munich, and PhD student Frederike Petzschner have investigated this effect both experimentally and theoretically. Test subjects were first asked to perform certain displacements in virtual reality and then to reproduce these displacements as accurately as possible. As in previous studies, the results showed a bias towards the mean of all previously experienced displacements. 

The scientists can now provide a general explanation for this phenomenon. With the help of a mathematical model, they can calculate how previous stimuli affect the current estimate. "The influence of prior experience most probably follows a general principle, and is likely to hold true for the estimation of quantities or sound levels also," says Glasauer. Test subjects whose distance estimates were strongly influenced by prior experience also placed greater weight on prior experience when asked to assess angular displacements. In both cases, they were learning without having received any information about the success or failure of their previous performance. Conventional learning methods, however, presuppose such feedback mechanisms. 

Whether or not a fundamental principle determines the perception of stimulus strengths, such as sound levels, brightness, or even distances, has been a controversial issue. Two important laws of psychophysics, the so-called Weber-Fechner law, published 150 years ago, and the 50-year-old Stevens' power law, seemed to contradict each other. The Munich scientists have now shown that the two laws are in fact compatible, at least for certain cases. By combining the Weber-Fechner law with Bayes' Theorem (1763), a procedure from probability theory that allows evidence to be weighted, they were able to transform it into Stevens' power law. Glasauer is therefore confident that "we have contributed to solving a problem that perception researchers have been studying for more than 50 years now." Next, the researchers want to analyze historical data and determine whether the model also applies to different stimulus modalities, such as sound levels and brightness. 

Source: Ludwig-Maximilians-Universität München [November 25, 2011]


Adenoviruses can cause respiratory, eye, and intestinal tract infections, and, like other viruses, must hijack the cellular machinery of infected organisms in order to produce proteins and their own viral spawn. Now an international research team made up of scientists from Chinese and Australian universities has found a way to disrupt the hijacking process by using plasma to damage the viruses in the laboratory environment, before they come into contact with host cells. 


The researchers prepared solutions containing adenoviruses and then treated the samples with a low-temperature plasma created by applying a voltage to a gaseous mixture in a syringe. The strong electric field energized electrons that collided with molecules in the gas, generating charged particles and highly reactive species such as oxygen atoms that likely etched away the protein shell of the viruses and damaged or destroyed the viral DNA. 

When the virus solutions were later added to colonies of embryonic kidney cells, the plasma-treated samples showed much less viral activity, as measured by the amount of a florescent virus protein the infected kidney cells produced. If the virus solution was covered during treatment to maximize plasma-virus interactions, more than 99 percent of the viruses could be deactivated in eight minutes. 

The technique is described in a paper accepted for publication in the AIP's journal Applied Physics Letters. 

Adenoviruses pose life-threatening risks to patients undergoing stem-cell therapy, so the anti-viral plasma treatment may help pave the way to safer therapies, the researchers write. Because plasma jets have multiple biomedical applications, the team is also developing a portable device that generates plasma by using a 12 V battery to decompose and ionize air, says Dr. XinPei Lu at the HuaZhong University of Science and Technology in China and leader of the team. The device might be used in rural areas and battlefields, according to Lu. 

Source: American Institute of Physics [December 14, 2011]

3pm slump? Why a sugar rush may not be the answer


A new study has found that protein and not sugar activates the cells responsible for keeping us awake and burning calories.  The research, published today in the 17 November issue of the scientific journal Neuron, has implications for understanding obesity and sleep disorders. 

Neurons [Credit: Denis Burdakov]
Wakefulness and energy expenditure rely on “orexin cells”, which secrete a stimulant called orexin/hypocretin in the brain. Reduced activity in these unique cells results in narcolepsy and has been linked to weight gain. 

Scientists at the University of Cambridge compared actions of different nutrients on orexin cells. They found that amino acids – nutrients found in proteins such as egg whites – stimulate orexin neurons much more than other nutrients. 

“Sleep patterns, health, and body weight are intertwined. Shift work, as well as poor diet, can lead to obesity,” said lead researcher Dr Denis Burdakov of the Department of Pharmacology and Institute of Metabolic Science. “Electrical impulses emitted by orexin cells stimulate wakefulness and tell the body to burn calories. We wondered whether dietary nutrients alter those impulses.” 

To explore this, the scientists highlighted the orexin cells (which are scarce and difficult to find) with genetically targeted fluorescence in mouse brains. They then introduced different nutrients, such as amino acid mixtures similar to egg whites, while tracking orexin cell impulses. 

They discovered that amino acids stimulate orexin cells. Previous work by the group found that glucose blocks orexin cells (which was cited as a reason for after-meal sleepiness), and so the researchers also looked at interactions between sugar and protein. They found that amino acids stop glucose from blocking orexin cells (in other words, protein negated the effects of sugar on the cells). 

These findings may shed light on previously unexplained observations showing that protein meals can make people feel less calm and more alert than carbohydrate meals. 

“What is exciting is to have a rational way to ‘tune’ select brain cells to be more or less active by deciding what food to eat,” Dr Burdakov said. “Not all brain cells are simply turned on by all nutrients, dietary composition is critical. 

“To combat obesity and insomnia in today’s society, we need more information on how diet affects sleep and appetite cells. For now, research suggests that if you have a choice between jam on toast, or egg whites on toast, go for the latter! Even though the two may contain the same number of calories, having a bit of protein will tell the body to burn more calories out of those consumed.” 

Source: University of Camridge [November 17, 2011]

The ethics of smart drugs


Professor Barbara Sahakian, Professor of Clinical Neuropsychology at the University of Cambridge, has been researching cognitive enhancers for over a decade.  Here she discusses the emergence of ‘smart drugs’ and the ethical and practical issues they raise.  


There is an increasing lifestyle use of cognitive enhancing drugs, or smart drugs by healthy people. Why might this be? And how will it change our society? Are people using these drugs just realize their potential, or is it that pressures to perform in a globally competitive environment means that individuals’ feel that they cannot afford an ‘off day’ due to lack of sleep or stress?  This is perhaps particularly true of certain professions, where there are issues of safety to oneself or others, such as the military, doctors, etc. 

Caffeine is the current stimulant of use for many people, as it is widely available, and effective: however, its wakefulness-promoting effects are transient. For doctors there is the undesirable side-effect of tremors at the dose required for maximum effects (600mg), which is common. Therefore, it is useful to examine whether there are more effective cognitive enhancers, with fewer detrimental side effects, for those whose failures in attention, concentration and problem solving may lead to deleterious effects, including jeopardy of safety in the military arena, or serious adverse events during operations. 

Although measures to reduce doctors’ working hours have been implemented in both the United Sates and Europe, surgeons performing long, arduous operations remain susceptible to the effects of fatigue, and frequent transitions from day to night work expose junior doctors to the risk of impaired psychomotor performance. Indeed, fatigued doctors risk making poor judgements and committing serious medical errors. Given the continued need for innovation in this area, pharmacological methods could conceivably be used to combat fatigue at some time in the future. 

In an exciting collaboration between the University of Cambridge, Department of Psychiatry and the Imperial College London, Division of Surgery, it has recently been discovered that the ‘smart drug’ Modafinil improves cognitive flexibility and reduces impulsivity in sleep deprived doctors. These results have just been published in the journal Annals of Surgery. 

In a proof of concept randomized placebo controlled study, run by Charlotte Housden (Cambridge) and Dr Colin Sugden (Imperial), 39 doctors were deprived of sleep overnight and given a dose of 200mg of Modafinil or placebo. The doctors taking Modafinil had cognitive improvements, including flexibility of thinking, and reduced impulsivity. These executive functions are clearly important for conducting surgical operations under stress and time pressure. However, there was no change on their clinical psychomotor performance on a laparoscopic task, which mimics and measures the dexterity necessary to perform surgery. 

While a chronic Modafinil study is required to determine the long term effects of the drug as a safe and effective means of improving cognitive impairment due to sleep deprivation, this acute study has demonstrated that benefits are obvious on at least the first occasion. 

Given these important findings, it is possible to speculate that doctors who take these drugs may be able to plan an intervention more effectively or show greater cognitive flexibility when approaching a challenging clinical problem.  However, it is critical that the long-term safety of the use of these drugs in healthy people remains to be determined. 

The many ethical discussions that I and Charlotte Housden have had with the public on the use of cognitive enhancing drugs by healthy people have been revealing.  A variety of views have emerged, ranging from ‘These drugs should only be used by people with neuropsychiatric disorders such as Attention Deficit Hyperactivity disorder, or Alzheimer’s Disease’, to ‘If they are safe, why not use them, to make up for fatigue, to improve memory or other forms of cognition?’, and ‘Why not use them to get in an especially productive working day?’. 

This increasing lifestyle use has to be balanced against other important facets of life, such as a good work/life balance. The possibility to accelerate into a 24/7 society for many people is a serious concern, as are issues of cheating and coercion. As a society, we certainly need to be concerned about the use of these drugs by healthy children and adolescents where their brains are still in development. Furthermore, the purchasing of prescription medication over the internet is dangerous. However, if long-term safety and efficacy are proven in healthy people, it may well be, at least for certain segments of the population, these drugs will prove life-savers. 

Source: University of Camridge [October 31, 2011]

11/28/2011

Denying mental qualities to animals in order to eat them

New research by Dr Brock Bastian from UQ's School of Psychology highlights the psychological processes that people engage in to reduce their discomfort over eating meat. 


This paper will be published in an upcoming edition of the Personality and Social Psychology Bulletin, where Dr Bastian and his co-authors show that people deny mental qualities to animals they eat. 

"Many people like eating meat, but most are reluctant to harm things that have minds. Our studies show that this motivates people to deny minds to animals," Dr Bastian said. 

The research demonstrates when people are confronted with the harm that their meat-eating brings to food animals they view those animals as possessing fewer mental capacities compared to when they are not reminded. 

The findings also reveal that this denial of mind to food animals is especially evident when people expect to eat meat in the near future. 

Dr Bastian said it shows that denying mind to animals that are used for food makes it less troublesome for people to eat them. 

"Meat is central to most people's diets and a focus of culinary enjoyment, yet most people also like animals and are disturbed by harm done to them; therefore creating a 'meat paradox' - people's concern for animal welfare conflicts with their culinary behavior. 

"For this reason, people rarely enjoy thinking about where meat comes from, the processes it goes through to get to their tables, or the living qualities of the animals from which it is extracted," he said. 

Dr Bastian's research argues that meat eaters go to great lengths to overcome these inconsistencies between their beliefs and behaviours. 

"In our current research we focus on the processes by which people facilitate their practice of eating meat. People often mentally separate meat from animals so they can eat pork or beef without thinking about pigs or cows. 

"Denying minds to animals reduces concern for their welfare, justifying the harm caused to them in the process of meat production," he added. 

Meat is pleasing to the palate for many, and although the vegetarian lifestyle is increasingly popular, most people continue to make meat a central component of their diet. 

"In short, our work highlights the fact that although most people do not mind eating meat, they do not like thinking of animals they eat as having possessed minds," Dr Bastian said.  

Source: University of Queensland [November 25, 2011]

DNA discovery may boost stem cell safety

A region of DNA that can boost the growth of stem cells has been found in the largest ever study of human embryonic stem cells. 

Stem cells need to be grown in the best possible way to stop gene mutations [Credit: iStockphoto]
The discovery could lead to safer cell therapies, says study co-author Dr Andrew Laslett from CSIRO Materials Science and Engineering. 

The research by the International Stem Cell Initiative involved 38 laboratories across the globe studying 125 ethnically diverse cell lines in parallel experiments. 

Study findings, reported in today's issue of Nature Biotechnology, uncover changes that arise from how cells are grown. 

Embryonic stem cells are powerful for their ability to become any other cell in the body. 

Stem cell therapy, which is entering early-stage human trials, turns stem cells into other cell types, like healthy nerve cells, to treat spinal cord injury, blindness and other ailments. 

The cells need to be grown in nutritious culture to produce enough cells for therapy. Many stem cells die when they are first moved to a new culture, leading to natural selection and adaptation. 

Cells with a growth advantage expand faster and dominate. However, this can come at the price of genetic mutation, so growing fast is not always desirable. 

"It's the small fraction of cells that become abnormal that can be dangerous in a clinical situation," says Laslett. "If they find growth situations that suit them, they could grow into cancers." 

One in five cell-lines mutated a particular region of chromosome 20. Gaining extra copies of the region seemed to give them a growth advantage. 

From the three genes in the region, it's likely the advantage is from BCL2L1. It's known to stop controlled cell death, or apoptosis. The same mutation is also found in some cancer cells. 

By targeting this region of chromosome 20, Laslett says we can "develop better tests to tell more quickly if the cells are going bad in culture." 

Scientists could use these tests to improve current techniques used to grow stem cells. 

"Embryonic stem cells walk a tightrope with maintaining their normal genetic nature," he says. "We need to culture them in the best possible way so they keep those genes normal." 

International collaboration 

Associate Professor Paul Thomas at the University of Adelaide, who was not involved in the study, says the research is impressive in its scale. 

"This kind of paper wouldn't be possible without international collaboration." 

"One of the interesting findings is that most of the embryonic stem cells are normal, even though they have been cultured for a long period. About two thirds were unchanged," he says. 

Author: Sarah Kellett | Source: ABC News Website [November 28, 2011]

Scientists identify defect in brain cell channel that may cause autism-like syndrome

Neuroscientists at Stanford University School of Medicine have homed in on potential differences in autistic people's brain cells by studying brainlike spheres grown in an elaborate process from skin cells. 


The scientists studied cells from patients with Timothy syndrome, a rare genetic condition that is associated with one of the most penetrant forms of autism: In other words, most people with the Timothy syndrome mutation have autism as a symptom, among other problems. 

Autism is a spectrum of developmental disorders of impaired social and verbal interaction. Currently, no medication exists to treat its underlying causes, according to the U.S. National Library of Medicine. Understanding what goes awry in autistic brain development could improve prospects for treating the condition. 

In this study, the scientists suggest that the autism in Timothy syndrome patients is caused by a gene mutation that makes calcium channels in neuron membranes defective, interfering with how those neurons communicate and develop. The flow of calcium into neurons enables them to fire, and the way that the calcium flow is regulated is a pivotal factor in how our brains function. 

The researchers also found brain cells grown from individuals with Timothy syndrome resulted in fewer of the kind of cells that connect both halves of the brain, as well as an overproduction of two of the brain's chemical messengers, dopamine and norepinephrine. Furthermore, they found they could reverse these effects by chemically blocking the faulty channels. 

Postdoctoral scholar Sergiu Pasca, MD, and Ricardo Dolmetsch, PhD, associate professor of neurobiology, led the study, which will be published online Nov. 27 in Nature Medicine. Dolmetsch, a biophysicist, redirected his research to study autism after his son was diagnosed with Timothy syndrome. It's unclear what leads to autism, but its incidence is increasing, he said. 

The gaps in our understanding of the causes of psychiatric disorders such as autism have made them difficult to treat. Perhaps the biggest obstacle to research into autism and other psychiatric and neurological diseases is that scientists can't get living brain cell samples from people with these conditions, for obvious reasons. Dolmetsch and his colleagues figured out a solution to this dilemma, using a novel approach involving what are known as induced pluripotent stem cells, or iPS cells. 

"We developed a way of taking skin cells from humans with Timothy syndrome and converting them into stem cells, then converting those stem cells into neurons," said Dolmetsch. 

The scientists grew these iPS cells as free-floating clumps in a nutrient-rich solution, later transferring the clumps to tissue culture plates. Here, some of them formed three-dimensional, brainlike spheres whose cells later migrated outward and matured into neurons. These neurons formed three distinct layers, a good first approximation of living tissue in the brain. By visualizing these neurons under a microscope and quantifying their gene expression, the scientists were able to characterize at the cellular level abnormalities that may be associated with autism. 

The neurons grown from Timothy-syndrome iPS cells showed larger-than-normal spikes in calcium levels, suggesting the calcium channels lost their ability to shut off. This set off dramatic changes in neuronal signaling, reconfiguring how genes were expressed. 

The cerebral cortex, the outer layer of the brain, has six distinct layers. In Timothy syndrome cell cultures, the proportion of neurons of specific layers differed from that in normal brains — additional biological evidence for the disorder. The neurons grown from the Timothy syndrome cells were less characteristic of lower-level neurons, which include neurons that bridge the left and right halves of the brain via the bundle of fibers known as the corpus callosum. This reinforces the view that autism results from defects in brain connectivity. 

Pasca and Dolmetsch had an "aha" moment when they realized the neurons grown from Timothy syndrome cells were making too much of the enzyme most critical for producing dopamine and norepinephrine, which play an important role in sensory processing and social behavior. The realization may offer important clues about what causes the problems seen in autism. 

To determine whether the enzyme upsurge was reversible, the scientists treated the neurons with a chemical that blocks the defective calcium channels, called roscovitine. They saw a nearly 70 percent reduction in the proportion of cells producing the enzyme, confirming the defective calcium channel was the culprit in producing too much dopamine and norepinephrine. Such reversibility suggests that certain cellular abnormalities in autism may be treatable. 

Dolmetsch warned, however, that roscovitine is not currently approved for use in humans and has never been tested in children. While it is currently in clinical trials for lung cancer, it reportedly causes nausea and other side effects. "The reported side effects are probably due to the fact that, in addition to targeting the channel that is mutated in autism, roscovitine also inhibits kinases that are required for cell proliferation," he said. "We think that roscovitine is a good starting point, but probably has to be optimized before it would be useful for autism." 

In the meantime, the study represents a major achievement with its success in developing a technique to recreate how the neurons of individuals with Timothy syndrome develop in a lab setting. It's the first time it's been possible to study the disorder in human cells rather than mouse cells, so it represents a better clinical model, Dolmetsch said. 

"These results could lead to a very powerful research tool," he said. "It's human psychiatric disease in a petri dish." 

Source: Stanford University Medical Center [November 27, 2011]

11/27/2011

Exercise helps us to eat a healthy diet

A healthy diet and the right amount of exercise are key players in treating and preventing obesity but we still know little about the relationship both factors have with each other. A new study now reveals that an increase in physical activity is linked to an improvement in diet quality. 

A healthy diet and the right amount of exercise are key players in treating and preventing obesity but we still know little about the relationship both factors have with each other. A new study now reveals that an increase in physical activity is linked to an improvement in diet quality [Credit: SINC]
Many questions arise when trying to lose weight. Would it be better to start on a diet and then do exercise, or the other way around? And how much does one compensate the other? 

"Understanding the interaction between exercise and a healthy diet could improve preventative and therapeutic measures against obesity by strengthening current approaches and treatments," explains Miguel Alonso Alonso, researcher at Harvard University (USA) who has published a bibliographical compilation on the subject, to SINC. 

The data from epidemiological studies suggest that tendencies towards a healthy diet and the right amount of physical exercise often come hand in hand. Furthermore, an increase in physical activity is usually linked to a parallel improvement in diet quality. 

Exercise also brings benefits such as an increase in sensitivity to physiological signs of fullness. This not only means that appetite can be controlled better but it also modifies hedonic responses to food stimuli. Therefore, benefits can be classified as those that occur in the short term (of metabolic predominance) and those that are seen in the long term (of behavioural predominance). 

According to Alonso Alonso, "physical exercise seems to encourage a healthy diet. In fact, when exercise is added to a weight-loss diet, treatment of obesity is more successful and the diet is adhered to in the long run." 

The authors of the study state how important it is for social policy to encourage and facilitate sport and physical exercise amongst the population. This should be present in both schools and our urban environment or daily lives through the use of public transport or availability of pedestrianised areas and sports facilities. 

Exercise modifies the brain 

Eating and physical activity are behaviours and are therefore influenced by cognitive processes that are a result of activity in different areas of the brain. Previous studies have already assessed changes in the brain and cognitive functions in relation to exercise: regular physical exercise causes changes in the working and structure of the brain. 

The experts point out that these changes seem to have a certain specificity. The Harvard researcher supports the notion that "regular exercise improves output in tests that measure the state of the brain's executive functions and increases the amount of grey matter and prefrontal connections." 

Inhibitory control is one of the executive functions of the brain and is basically the ability to suppress inadequate and non-conforming answers to an aim (the opposite of this would be impulsiveness), which makes modification or self-regulations of a behaviour possible. 

With regards to losing weight and sustaining weight loss in the long run, various recent studies suggest that executive functions such as inhibitory control and optimal functioning of the brain's prefrontal areas could be the key to success. This success is mainly the fruit of a behavioural change. Inhibitory control could also help to prevent weight gain in healthy people. 

The researcher outlines that "in time, exercise produces a potentiating effect of executive functions including the ability for inhibitory control, which can help us to resist the many temptations that we are faced with everyday in a society where food, especially hypercaloric food, is more and more omnipresent." 

Spain – leader in obesity 

There has been an alarming rise in cases of obesity in Spain in recent years, so much so that prevalence in various areas of the country is higher than in many parts of the USA, which is traditionally thought of as the paradigm of obesity in the western world. 

Furthermore, along with other Mediterranean countries, Spain has one of the highest rates of childhood obesity in Europe. The experts are urging society to become aware of the problem and join forces to prevent and treat all types of obesity. 

Source: FECYT - Spanish Foundation for Science and Technology via EurekAlert! [November 23, 2011]

Finger (mal)formation reveals surprise function of desert DNA

Scientists from the EPFL and the University of Geneva have discovered a genetic mechanism that defines the shape of our members in which, surprisingly, genes play only a secondary role. The research published in Cell, online the 23rd of November, shows the mechanism is found in a DNA sequence that was thought, incorrectly, to play no role. 


This long string has seven enhancers which, when combined with one another, modulate the activity of the genes responsible for the formation of the fingers – an important fundamental discovery for the field of genetics. The discovery could notably help better understand anomalies that are transmitted from generation to generation such as welded fingers or extra or abnormally short fingers (Kantaputra syndrome) even if the genes appear perfectly normal. 

Turbos on the genome 

DNA is composed of only about 2% genes. But it has other types of sequences, such as enhancers that increase the activity of certain genes at key moments. "The discovery we have made is that the group of genes involved in finger growth is modulated by seven enhancers, not just one, and they combine through contact," says Thomas Montavon, lead author of the article and researcher at the EPFL. 

When the fingers in the embryo begin to take shape, the string of DNA folds and the enhancers, located on different parts of the string, come into contact. They then bring together various proteins that stimulate the activity of the genes, and the fingers start to grow. If one of these seven enhancers is missing, the fingers will be shorter, or abnormally shaped. When two are missing, the defects are even more pronounced. Without enhancers, the genes work slowly, and generate only the beginnings of fingers. 

How does the DNA fold in exactly the right way so that the enhancers will correctly do their job? The recently discovered process remains largely unexplained. "In other tissues, such as the brain, the string of DNA folds differently," says Denis Duboule, director of the study and researcher at both the EPFL and the University of Geneva. "To our knowledge, it is only in the fingers that it adopts this shape." 

An explanation for evolutionary diversity 

Statistically, the seven enhancers involved in finger growth create seven opportunities for a mutation to occur. The flexibility of this mechanism, with no known equivalent to date, causes not only hereditary malformations, but also the many variations in the hands, legs and other appendages in nature. "Just think of some ungulates, which walk on a single finger, or the ostrich, which has only two, and the human hand, of course" explains Denis Duboule. 

Other genetic processes may also function on the basis of a similar principle. This could explain the diversity of the products of evolution, in areas other than the fingers, according to Denis Duboule. "When a mutation occurs on a gene, for instance in cystic fibrosis, it is often binary. This amounts to an 'all or nothing' situation. With the mechanism we have discovered, it is a 'more or less' situation. It is combined, it is modulated."  

Source: Ecole Polytechnique Federale de Lausanne [November 23, 2011]

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