Chapter 15. Emotions, Aggression, and Stress
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By RICHARD A. FRIEDMAN FEELING down? Smile. Cheer up. Put on a happy face. No doubt you’ve dismissed these bromides from friends and loved ones because everyone knows that you can’t feel better just by aping a happy look. Or perhaps you can. New research suggests that it is possible to treat depression by paralyzing key facial muscles with Botox, which prevents patients from frowning and having unhappy-looking faces. In a study forthcoming in the Journal of Psychiatric Research, Eric Finzi, a cosmetic dermatologist, and Norman Rosenthal, a professor of psychiatry at Georgetown Medical School, randomly assigned a group of 74 patients with major depression to receive either Botox or saline injections in the forehead muscles whose contraction makes it possible to frown. Six weeks after the injection, 52 percent of the subjects who got Botox showed relief from depression, compared with only 15 percent of those who received the saline placebo. (You might think that patients would easily be able to tell whether they got the placebo or Botox. Actually, it wasn’t so obvious: Only about half of the subjects getting Botox guessed correctly. More important, knowing which treatment was received had no significant effect on treatment response.) Other studies over the past several years have found similar effects of Botox on mood. Michael Lewis at Cardiff University reported that nondepressed patients at a cosmetic dermatology clinic receiving Botox injection above the eyes frowned less and felt better than those who did not receive this injection. And M. Axel Wollmer at the University of Basel found that Botox injection was superior to a placebo in a group of depressed patients. © 2014 The New York Times Company
Link ID: 19410 - Posted: 03.26.2014
by Clare Wilson It's a vicious circle of the cruellest kind. Stress might be causing infertility in women, according to new research. This could explain some cases in which couples are diagnosed as infertile with no apparent cause. Taking longer than usual to conceive can lead to stress, so the problem could become self-perpetuating. A link between everyday life stresses and infertility has long been suspected, but there has been little hard evidence connecting the two. Women receiving fertility treatment are generally advised to avoid stress, but not so the average person trying to conceive. An estimated one in seven couples in the UK have fertility problems and, in about a quarter of those, there is no known medical explanation, and they are given a diagnosis of "unexplained infertility". To explore the role of stress, Courtney Lynch at Ohio State University in Columbus and her colleagues collected saliva samples from 373 women in the US who had just started trying to conceive naturally and measured levels of an enzyme called alpha-amylase, a marker of stress. After one year of regular unprotected sex, about 13 per cent of the couples had failed to get pregnant, the standard definition of infertility. The third of women who had the highest alpha-amylase levels were twice as likely to be in the infertile group as the third with the lowest levels. In a previous study, Lynch's team found that those with higher levels of the stress enzyme were slightly less likely to conceive in their first month of trying. But this is the first time that alpha-amylase has been linked to clinical infertility. © Copyright Reed Business Information Ltd.
Want to live a long, dementia-free life? Stress your cells out. That’s the conclusion of a new study, which finds that heightened cellular stress causes brain cells to produce a protein that staves off Alzheimer’s disease and other forms of dementia. The work could lead to new ways to diagnose or treat such diseases. “This paper is very impressive,” says neuroscientist Li-Huei Tsai of the Massachusetts Institute of Technology in Cambridge, who was not involved in the new work. “It puts a finger on a particular pathway that can provide some explanation as to why some people are more susceptible to Alzheimer’s.” Alzheimer’s disease, characterized by a progressive loss of memory and cognition, affects an estimated 44.4 million people worldwide, mostly over the age of 65. The illness has been linked to the accumulation of certain proteins in the brain, but what causes symptoms has been unclear. That’s because the brains of some elderly people without dementia have the same clumps of so-called amyloid β and τ proteins typically associated with Alzheimer’s. The new study deals with a protein called repressor element 1-silencing transcription factor (REST), which turns genes and off. Scientists knew that REST played a key role in fetal brain development by controlling the activity of certain genes, but they thought it was absent in adult brains. However, when Bruce Yankner, a neurologist at Harvard Medical School in Boston, looked at all the genes and proteins that change in brains as people age, he found that REST levels begin increasing again when a person hits their 30s. Stumped as to why, he and his colleagues isolated human and mouse brain cells and probed what factors altered REST levels and what consequences those levels had. © 2014 American Association for the Advancement of Science
By Michelle Roberts Health editor, BBC News online Statins may be useful in treating advanced multiple sclerosis (MS), say UK researchers. Early trial results in The Lancet show the cholesterol-lowering pills slow brain shrinkage in people with MS. The University College London (UCL) scientists say large trials can now begin. These will check whether statins benefit MS patients by slowing progression of the disease and easing their symptoms. MS is a major cause of disability, affecting nerves in the brain and spinal cord, which causes problems with muscle movement, balance and vision. Currently there is no cure, although there are treatments that can help in the early stages of the disease. Usually, after around 10 years, around half of people with MS will go on to develop more advanced disease - known as secondary progressive MS. It is this later stage disease that Dr Jeremy Chataway and colleagues at UCL hope to treat with low cost statins. To date, no licensed drugs have shown a convincing impact on this later stage of the disease. For their phase two trial, which is published in the Lancet, Dr Chataway's team randomly assigned 140 people with secondary progressive MS to receive either 80mg of a statin called simvastatin or a placebo for two years. The high, daily dose of simvastatin was well tolerated and slowed brain shrinkage by 43% over two years compared with the placebo. Dr Chataway said: "Caution should be taken regarding over-interpretation of our brain imaging findings, because these might not necessarily translate into clinical benefit. However, our promising results warrant further investigation in larger phase three disability-driven trials." BBC © 2014
Keyword: Multiple Sclerosis
Link ID: 19383 - Posted: 03.19.2014
By FLORENCE WILLIAMS So there’s this baby who has swallowed a .22-caliber bullet. The mother rushes into a drugstore, crying, “What shall I do?” “Give him a bottle of castor oil,” replies the druggist, “but don’t point him at anybody.” Whether you find this joke amusing depends on many more variables than you probably ever realized. It depends on a common cultural understanding of the technical properties of castor oil. It depends, as many funny jokes do and as any fourth grader can attest, on our own squeamishness about bodily functions. Getting less obvious, your sense of humor can also depend on your age, your gender, your I.Q., your political inclinations, how extroverted you are and the health of your dopamine reward circuit. If you think all this analysis sounds a bit, well, unfunny, E. B. White would back you up. He once wrote that picking apart jokes is like dissecting frogs: Few people are interested, and the subject always dies in the end. Fortunately, the cognitive neuroscientist Scott Weems isn’t afraid of being unfunny. Humor is worthy of serious academic study, he argues in his book, “Ha! The Science of When We Laugh and Why,” (Read an excerpt.) because it yields insights into how our brains process a complex world and how that, in turn, makes us who we are. Though animals laugh, humans spend more time laughing than exhibiting any other emotion. But what gives some people a better sense of humor than others? Not surprisingly, extroverts tend to laugh more and produce more jokes; yet in tests measuring the ability to write cartoon captions, people who were more neurotic, assertive, manipulative and dogmatic were actually funnier. As the old saw holds, many of the best comics really are miserable. © 2014 The New York Times Company
Link ID: 19373 - Posted: 03.18.2014
By Pippa Stephens Health reporter, BBC News People are less likely to yawn when others do as they get older, a study has found. Contagious yawning is linked more closely to a person's age than their ability to empathise, as previously thought, US-based scientists said. It also showed a stronger link to age than tiredness or energy levels. Researchers are now looking at whether the ability to catch yawns from other people is inherited, with the hope of helping treat mental health disorders. Autism and schizophrenia sufferers are reportedly less able to catch yawns, researchers said, so understanding the genes that might code for contagious yawning could illuminate new pathways for treatment. In the study, published in the journal Plos One, 328 participants were shown a three-minute video showing other people yawning. Each subject had to click a button every time they yawned. Levels of tiredness Overall, 68% of the participants yawned. Of those, 82% of people aged under 25 yawned, compared with 60% of people aged between 25 and 49, and 41% of people aged over 50. Dr Elizabeth Cirulli, assistant professor of medicine at Duke University in Durham, North Carolina, led the study. She said: "This is the first study to look at a whole bunch of factors. It is the largest study, in terms of the number of people involved, to date." Dr Cirulli said she did not know why contagious yawning decreased with age. BBC © 2014
By NICHOLAS BAKALAR Angry enough to have a heart attack? It might actually happen. A new analysis has found that outbursts of anger can significantly increase the risk for irregular heart rhythms, angina, strokes and heart attacks. Researchers combined data from nine studies of anger outbursts among patients who had had heart attacks, strokes and related problems. Most of the studies used a widely accepted anger assessment scale; one depended on a questionnaire administered to patients. They found that in the two hours after an outburst of anger, the relative risk of angina and heart attack increased by nearly five times, while the risk of ischemic stroke and cardiac arrhythmia increased by more than three times. The findings appeared in The European Heart Journal. The researchers stressed that the actual likelihood of having an anger-induced heart attack remains small. Still, for people with other risks for heart disease, any increase in risk is potentially dangerous. The senior author, Dr. Murray A. Mittleman, an associate professor of medicine at Harvard, said that little is known about ways to prevent anger from causing heart problems. “Are there specific behavioral interventions that would be effective? Medicines?” he asked. “There have been proposals for both,” he added, “but we need more and better research.” © 2014 The New York Times Company
Link ID: 19363 - Posted: 03.15.2014
|By Allie Wilkinson Vivaldi versus the Beatles. Both great. But your brain may be processing the musical information differently for each. That’s according to research in the journal NeuroImage. [Vinoo Alluri et al, From Vivaldi to Beatles and back: Predicting lateralized brain responses to music] For the study, volunteers had their brains scanned by functional MRI as they listened to two musical medleys containing songs from different genres. The scans identified brain regions that became active during listening. One medley included four instrumental pieces and the other consisted of songs from the B side of Abbey Road. Computer algorithms were used to identify specific aspects of the music, which the researchers were able to match with specific, activated brain areas. The researchers found that vocal and instrumental music get treated differently. While both hemispheres of the brain deal with musical features, the presence of lyrics shifts the processing of musical features to the left auditory cortex. These results suggest that the brain’s hemispheres are specialized for different kinds of sound processing. A finding revealed but what you might call instrumental analysis. © 2014 Scientific American,
Imagine you’re calling a stranger—a possible employer, or someone you’ve admired from a distance—on the telephone for the first time. You want to make a good impression, and you’ve rehearsed your opening lines. What you probably don’t realize is that the person you’re calling is going to size you up the moment you utter “hello.” Psychologists have discovered that the simple, two-syllable sound carries enough information for listeners to draw conclusions about the speaker’s personality, such as how trustworthy he or she is. The discovery may help improve computer-generated and voice-activated technologies, experts say. “They’ve confirmed that people do make snap judgments when they hear someone’s voice,” says Drew Rendall, a psychologist at the University of Lethbridge in Canada. “And the judgments are made on very slim evidence.” Psychologists have shown that we can determine a great deal about someone’s personality by listening to them. But these researchers looked at what others hear in someone’s voice when listening to a lengthy speech, says Phil McAleer, a psychologist at the University of Glasgow in the United Kingdom and the lead author of the new study. No one had looked at how short a sentence we need to hear before making an assessment, although other studies had shown that we make quick judgments about people’s personalities from a first glance at their faces. “You can pick up clues about how dominant and trustworthy someone is within the first few minutes of meeting a stranger, based on visual cues,” McAleer says. To find out if there is similar information in a person’s voice, he and his colleagues decided to test “one of the quickest and shortest of sociable words, ‘Hello.’ ” © 2014 American Association for the Advancement of Science.
by Bruce Bower Chimpanzees possess a flexible, humanlike sensitivity to the mental states of others, even strangers from another species, researchers suggest March 11 in the Proceedings of the Royal Society B. Empathy’s roots go back at least to the common ancestor of humans and chimps, they say. Psychologist Matthew Campbell and biologist Frans de Waal, both of Emory University in Atlanta, treated chimps’ tendency to yawn when viewing videotapes of others yawning as a sign of spontaneous empathy. Their research follows other scientists’ observations that young chimps mimic scientists’ yawns (SN Online: 10/16/13). Nineteen chimps living in an outdoor research facility yawned when they saw the same action from chimps that they lived with, researchers and staff they had seen before and people who were new to them. Unfamiliar chimps and baboons failed to elicit contagious yawning. As in the wild, unfamiliar chimps were probably viewed as threats. Chimps in the study hadn’t seen baboons before. Having socially connected with facility workers, chimps reacted empathically to human strangers who yawned, the researchers propose. Imitating others’ facial expressions represents a rapid way to forge empathic ties, Campbell says. His research didn’t test whether chimps spend a lot of time trying to read others’ thoughts and feelings, a more complex type of empathy. © Society for Science & the Public 2000 - 2013.
Link ID: 19354 - Posted: 03.12.2014
By INNA GAISLER-SALOMON WE intuitively understand, and scientific studies confirm, that if a woman experiences stress during her pregnancy, it can affect the health of her baby. But what about stress that a woman experiences before getting pregnant — perhaps long before? It may seem unlikely that the effects of such stress could be directly transmitted to the child. After all, stress experienced before pregnancy is not part of a mother’s DNA, nor does it overlap with the nine months of fetal development. Nonetheless, it is undeniable that stress experienced during a person’s lifetime is often correlated with stress-related problems in that person’s offspring — and even in the offspring’s offspring. Perhaps the best-studied example is that of the children and grandchildren of Holocaust survivors. Research shows that survivors’ children have greater-than-average chances of having stress-related psychiatric illnesses like post-traumatic stress disorder, even without being exposed to higher levels of stress in their own lives. Similar correlations are found in other populations. Studies suggest that genocides in Rwanda, Nigeria, Cambodia, Armenia and the former Yugoslavia have brought about distinct psychopathological symptoms in the offspring of survivors. What explains this pattern? Does trauma lead to suboptimal parenting, which leads to abnormal behavior in children, which later affects their own parenting style? Or can you biologically inherit the effects of your parents’ stress, after all? It may be the latter. In a study that I, together with my colleagues Hiba Zaidan and Micah Leshem, recently published in the journal Biological Psychiatry, we found that a relatively mild form of stress in female rats, before pregnancy, affected their offspring in a way that appeared to be unrelated to parental care. © 2014 The New York Times Company
by Hal Hodson WHETHER striding ahead with pride or slouching sullenly, we all broadcast our emotions through body language. Now a computer has learned to interpret those unspoken cues as well as you or I. Antonio Camurri of the University of Genoa in Italy and colleagues have built a system which uses the depth-sensing, motion-capture camera in Microsoft's Kinect to determine the emotion conveyed by a person's body movements. Using computers to capture emotions has been done before, but typically focuses on facial analysis or voice recording. Reading someone's emotional state from the way they walk across a room or their posture as they sit at a desk means they don't have to speak or look into a camera. "It's a nice achievement," says Frank Pollick, professor of psychology at the University of Glasgow, UK. "Being able to use the Kinect for this is really useful." The system uses the Kinect camera to build a stick figure representation of a person that includes information on how their head, torso, hands and shoulders are moving. Software looks for body positions and movements widely recognised in psychology as indicative of certain emotional states. For example, if a person's head is bowed and their shoulders are drooping, that might indicate sadness or fear. Adding in the speed of movement – slow indicates sadness, while fast indicates fear – allows the software to determine how someone is feeling. In tests, the system correctly identified emotions in the stick figures 61.3 per cent of the time, compared with a 61.9 per cent success rate for 60 human volunteers (arXiv.org/1402.5047). Camurri is using the system to build games that teach children with autism to recognise and express emotions through full-body movements. Understanding how another person feels can be difficult for people with autism, and recognising fear is more difficult than happiness. © Copyright Reed Business Information Ltd.
Clara Moskowitz When mathematicians describe equations as beautiful, they are not lying. Brain scans show that their minds respond to beautiful equations in the same way other people respond to great paintings or masterful music. The finding could bring neuroscientists closer to understanding the neural basis of beauty, a concept that is surprisingly hard to define. In the study, researchers led by Semir Zeki of University College London asked 16 mathematicians to rate 60 equations on a scale ranging from "ugly" to "beautiful." Two weeks later, the mathematicians viewed the same equations and rated them again while lying inside a functional magnetic resonance imaging (fMRI) scanner. The scientists found that the more beautiful an equation was to the mathematician, the more activity his or her brain showed in an area called the A1 field of the medial orbitofrontal cortex. The orbitofrontal cortex is associated with emotion, and this particular region of it has shown in previous tests to be correlated with emotional responses to visual and musical beauty. The researchers wondered whether the trend would extend to mathematical beauty, which "has a much deeper intellectual source than visual or musical beauty, which are more 'sensible' and perceptually based," they wrote in a paper reporting their results published on 13 February in Frontiers of Human Neuroscience. Investigating mathematical beauty allowed the researchers to test the role of culture and learning in aesthetic appreciation. The scientists hypothesized that while people with no musical or artistic training can still appreciate Beethoven’s and Michelangelo's works, only those who understand the meaning behind certain mathematical formulas would find them beautiful. © 2014 Nature Publishing Group,
Link ID: 19327 - Posted: 03.06.2014
Virginia Hughes When Brian Dias became a father last October, he was, like any new parent, mindful of the enormous responsibility that lay before him. From that moment on, every choice he made could affect his newborn son's physical and psychological development. But, unlike most new parents, Dias was also aware of the influence of his past experiences — not to mention those of his parents, his grandparents and beyond. Where one's ancestors lived, or how much they valued education, can clearly have effects that pass down through the generations. But what about the legacy of their health: whether they smoked, endured famine or fought in a war? As a postdoc in Kerry Ressler's laboratory at Emory University in Atlanta, Georgia, Dias had spent much of the two years before his son's birth studying these kinds of questions in mice. Specifically, he looked at how fear associated with a particular smell affects the animals and leaves an imprint on the brains of their descendants. Dias had been exposing male mice to acetophenone — a chemical with a sweet, almond-like smell — and then giving them a mild foot shock. After being exposed to this treatment five times a day for three days, the mice became reliably fearful, freezing in the presence of acetophenone even when they received no shock. Ten days later, Dias allowed the mice to mate with unexposed females. When their young grew up, many of the animals were more sensitive to acetophenone than to other odours, and more likely to be startled by an unexpected noise during exposure to the smell. Their offspring — the 'grandchildren' of the mice trained to fear the smell — were also jumpier in the presence of acetophenone. What's more, all three generations had larger-than-normal 'M71 glomeruli', structures where acetophenone-sensitive neurons in the nose connect with neurons in the olfactory bulb. In the January issue of Nature Neuroscience1, Dias and Ressler suggested that this hereditary transmission of environmental information was the result of epigenetics — chemical changes to the genome that affect how DNA is packaged and expressed without altering its sequence. © 2014 Nature Publishing Group,
By LISA FELDMAN BARRETT CAN you detect someone’s emotional state just by looking at his face? It sure seems like it. In everyday life, you can often “read” what someone is feeling with the quickest of glances. Hundreds of scientific studies support the idea that the face is a kind of emotional beacon, clearly and universally signaling the full array of human sentiments, from fear and anger to joy and surprise. Increasingly, companies like Apple and government agencies like the Transportation Security Administration are banking on this transparency, developing software to identify consumers’ moods or training programs to gauge the intent of airline passengers. The same assumption is at work in the field of mental health, where illnesses like autism and schizophrenia are often treated in part by training patients to distinguish emotions by facial expression. But this assumption is wrong. Several recent and forthcoming research papers from the Interdisciplinary Affective Science Laboratory, which I direct, suggest that human facial expressions, viewed on their own, are not universally understood. The pioneering work in the field of “emotion recognition” was conducted in the 1960s by a team of scientists led by the psychologist Paul Ekman. Research subjects were asked to look at photographs of facial expressions (smiling, scowling and so on) and match them to a limited set of emotion words (happiness, anger and so on) or to stories with phrases like “Her husband recently died.” Most subjects, even those from faraway cultures with little contact with Western civilization, were extremely good at this task, successfully matching the photos most of the time. Over the following decades, this method of studying emotion recognition has been replicated by other scientists hundreds of times. In recent years, however, at my laboratory we began to worry that this research method was flawed. In particular, we suspected that by providing subjects with a preselected set of emotion words, these experiments had inadvertently “primed” the subjects — in effect, hinting at the answers — and thus skewed the results. © 2014 The New York Times Company
Link ID: 19316 - Posted: 03.03.2014
Sara Reardon Two monkeys sit at computer screens, eyeing one another as they wait for a promised reward: apple juice. Each has a choice — it can either select a symbol that results in juice being shared equally, or pick one that delivers most of the juice to itself. But being selfish is risky. If its partner also chooses not to share, neither gets much juice. This game, the ‘prisoner’s dilemma’, is a classic test of strategy that involves the simultaneous evaluation of an opponent’s thinking. Researchers have now discovered — and manipulated — specific brain circuits in rhesus macaques (Macaca mulatta) that seem to be involved in the animals’ choices, and in their assessments of their partners’ choices. Investigating the connections could shed light on how social context affects decision-making in humans, and how disorders that affect social skills, such as autism spectrum disorder, disrupt brain circuitry. “Once we have identified that there are particular neural signals necessary to drive the processes, we can begin to tinker,” says Michael Platt, a neurobiologist at Duke University in Durham, North Carolina. Neurobiologists Keren Haroush and Ziv Williams of Harvard Medical School in Boston, Massachusetts, zoomed in on neural circuits in rhesus macaques by implanting electrode arrays into a brain area called the dorsal anterior cingulate cortex (dACC), which is associated with rewards and decision-making. The arrays recorded the activity of hundreds of individual neurons. When the monkeys played the prisoner’s dilemma (see ‘A juicy experiment’) against a computer program, they rarely chose to cooperate. But when they played with another monkey that they could see, they were several times more likely to choose to share the juice. © 2014 Nature Publishing Group
|By Lila Stanners Beauty seems mysterious and subjective. Scientists have long attempted to explain why the same object can strike some individuals as breathtaking and others as repulsive. Now a study finds that applying stimulation to a certain brain area enhances people's aesthetic appreciation of visual images. First, participants viewed 70 abstract paintings and sketches and 80 representational (realistic) paintings and photographs and rated how much they liked each one. Then they rated a similar set of images after receiving transcranial direct-current stimulation or sham stimulation. Transcranial direct-current stimulation sends small electrical impulses to the brain through electrodes attached to the head. The technique is noninvasive and cannot be felt, so subjects in the trials were not aware when they received real stimulation. The researchers aimed the impulses at the left dorsolateral prefrontal cortex, an area just behind the brow that is known to be a region critical for emotional processing. They found that the stimulation increased participants' appreciation of representational images, according to the study published online in October 2013 inSocial Cognitive and Affective Neuroscience. The scientists believe the stimulation facilitated a shift from object recognition to aesthetic appraisal for the figurative images; the abstract art was probably being processed by a different area of the brain. This study is one of many recent successful attempts at subtly altering cognition with noninvasive brain stimulation. Some experiments have found that stimulating certain areas allows people to solve math problems or puzzles that formerly had them stumped. Other work suggests these techniques can enhance motor learning, helping athletes or musicians improve at a new sport or a new instrument more rapidly. Experts are quick to point out, however, that these effects are modest enhancements at best—thought induction remains firmly in the realm of science fiction. © 2014 Scientific American
When you hear a friend’s voice, you immediately picture her, even if you can’t see her. And from the tone of her speech, you quickly gauge if she’s happy or sad. You can do all of this because your human brain has a “voice area.” Now, scientists using brain scanners and a crew of eager dogs have discovered that dog brains, too, have dedicated voice areas. The finding helps explain how canines can be so attuned to their owners’ feelings. “It’s absolutely brilliant, groundbreaking research,” says Pascal Belin, a neuroscientist at the University of Glasgow in the United Kingdom, who was part of the team that identified the voice areas in the human brain in 2000. “They’ve made the first comparative study using nonhuman primates of the cerebral processing of voices, and they’ve done it with a noninvasive technique by training dogs to lie in a scanner.” The scientists behind the discovery had previously shown that humans can readily distinguish between dogs’ happy and sad barks. “Dogs and humans share a similar social environment,” says Attila Andics, a neuroscientist in a research group at the Hungarian Academy of Sciences at Eötvös Loránd University in Budapest and the lead author of the new study. “So we wondered if dogs also get some social information from human voices.” To find out, Andics and his colleagues decided to scan the canine brain to see how it processes different types of sounds, including voices, barks, and natural noises. In humans, the voice area is activated when we hear others speak, helping us recognize a speaker’s identity and pick up on the emotional content in her voice. If dogs had voice areas, it could mean that these abilities aren’t limited to humans and other primates. © 2014 American Association for the Advancement of Science
By GRETCHEN REYNOLDS Watching participants in slopestyle and half-pipe skiing and snowboarding flip, curl, cartwheel and otherwise contort themselves in the air during the Winter Olympics competition, many of us have probably wondered not only how the athletes managed to perform such feats but also why. Helpfully, a recent study of the genetics of risk-taking intimates that their behavior may be motivated, at least in part, by their DNA. For some time, scientists and many parents have suspected that certain children are born needing greater physical stimulation than others, suggesting that sensation seeking, as this urge is known in psychological terms, has a genetic component. A thought-provoking 2006 study of twins, for instance, concluded that risk-taking behavior was shared by the pairs to a much greater extent than could be accounted for solely by environmental factors. If one twin sought out risks, the other was likely to do so as well. But finding which genes or, more specifically, which tiny snippets of DNA within genes, might be influencing the desire to huck oneself off of a snow-covered slope has proven to be troublesome. In recent years, scientists zeroed in on various sections of genes that affect the brain’s levels of or response to the neurotransmitter dopamine, a substance that is known to influence our feelings of pleasure, reward and gratification. People who engage in and enjoy extreme, daredevil conduct, researchers presumed, would likely process dopamine differently than those of us content to watch. But the results of some early genetic studies comparing dopamine-related portions of genes with sensation seeking were inconsistent. Some found that people with certain variations within genes, including a gene called DRD4 that is believed to be closely involved in the development and function of dopamine receptors in our brain, gravitated toward risky behavior. Others, though, found no such links. But most of these studies focused on so-called deviant risk-taking, such as gambling and drug addiction. © 2014 The New York Times Company
By Geoffrey Mohan Stress can damage the brain. The hormones it releases can change the way nerves fire, and send circuits into a dangerous feedback loop, leaving us vulnerable to anxiety, depression and post-traumatic stress disorder. But how stress accomplishes its sinister work on a cellular level has remained mysterious. Neuroscientists at a UC Berkeley lab have uncovered evidence that a well-known stress hormone trips a switch in stem cells in the brain, causing them to produce a white matter cell that ultimately can change the way circuits are connected in the brain. This key step toward hardening wires, the researchers found, may be at the heart of the hyper-connected circuits associated with prolonged, acute stress, according to the study published online Tuesday in the journal Molecular Psychiatry. The findings strengthen an emerging view that cells once written off as little more than glue, insulation and scaffolding may regulate and reorganize the brain's circuitry. Researchers examined a population of stem cells in the brain’s hippocampus, an area critical to fusing emotion and memory, and one that has been known to shrink under the effects of prolonged acute stress. Under normal circumstances, these cells form new neurons or glia, a type of white matter. Los Angeles Times Copyright 2014