Chapter 11. Emotions, Aggression, and Stress
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by Guest Writer, Emilie Reas! My first trip to a haunted house is as vivid today as when I was 5 years old. As I made my way past a taunting witch and a rattling skeleton, my eyes fell upon a blood-soaked zombie. My heart raced, my throat swelled, and the tears began to flow. Even now, as a mature (ahem) adult, the ghosts and goblins don’t faze me. But those vacant zombie eyes and pale skin? Oh, the horror! My rational brain knows how irrational my fear is, yet still I shudder, gripped by the same terror that first overwhelmed me decades ago. Unsettling experiences occur daily that we easily brush off – a creepy movie, a turbulent plane ride, or a nip at your ankle by the neighbor’s dog. But occasionally, the fear sticks, establishing a permanent memory that can haunt us for years. At their mildest, such fear memories cause discomfort or embarrassment, but at their worst, they can be downright debilitating. Do spiders make you scream? Are you unable to speak in public without a trembling voice and hands? Maybe you suffered a traumatic accident that’s made you terrified to get back behind the wheel of a car. We’ve all experienced the disruptive effects of a fearful experience we just can’t shake. Yet scientists don’t fully understand why some traumatic events are fleeting, while others are stored as lasting memories. Past research has shown that particular areas of the brain, such as the anterior cingulate and insula, are active during fearful experiences, but also during many other situations, including while monitoring surroundings and emotions or paying attention to important information. Other regions, including the amygdala, hippocampus and prefrontal cortex, are more specialized to support memory for emotional experiences, as they play important roles in emotional processing, memory and attention. While it’s clear that establishing fear memories relies on cross-talk between these regions, it’s not known how they solidify fears into memory and determine which particular ones will endure for the long-term. © Society for Science & the Public 2000 - 2013
By Victoria Stern A trolley is hurtling down a track, and if nobody intervenes it will hit and kill five people. Psychologists use variations on this hypothetical situation to gauge people's gut reactions about morality. Here are three scenarios: The driver could switch the train to another track, on which one man stands. Should the driver reroute the trolley? Now suppose the trolley is driverless and you are a bystander. Should you hit a switch to divert the trolley so it hits the lone man? You are standing above the tracks on a bridge. You could stop the trolley and save the five people by pushing a large man to his death in front of the trolley. Would you push him? Most people say that the driver should reroute the train and that they would reroute the train with the switch but that they would not push the man to his death. This typical decision is associated with increased activity in the medial prefrontal cortex (green), which indicates a strong negative emotional reaction, as well as activity in the amygdala (red), which is involved in processing emotions and stressful events. © 2013 Scientific American
By Brian Switek I’m going to ruin sea otters for you. Or at least I’m going to tarnish their reputation as some of the most charming little beasties in the seas. For as cute as they are while intertwining paws at an aquarium, frolicking among the wafting fronds of California kelp forests, or smashing sea urchins open with stones, some sea otters have developed the disturbing habit of humping and drowning baby seals. When I first heard about the behavior from a marine biologist friend of mine, I didn’t quite believe sea otters could be so diabolical. Maybe the bad behavior was just a rumor. But no, the strange sea otter attacks on baby seals are a reality and have even made their way into the technical literature. In 2010, California Department of Fish and Game biologist Heather Harris and colleagues reported 19 individual cases of male sea otters trying to mate with, and often fatally injuring, harbor seal pups in the Monterey Bay, Calif. area between 2000 and 2002 alone. Delivered in the scientific deadpan required of such papers, the Aquatic Mammals report attributes the incidents to three male sea otters “observed harassing, dragging, guarding, and copulating with harbor seals,” persisting for up to seven days after the otters killed the objects of their misguided advances. The ordeal must have been horrific for the seals. The victims that were necropsied by veterinarians had lesions around the nose, eyes, flippers, and genitals, including perforations in the vaginal and rectal tracts. A painful and confusing end for the poor pups. © 2013 The Slate Group, LLC.
by Bethany Brookshire Most of us see a wagging dog’s tail and think it’s got to be a good sign. Wagging = welcome, right? Especially if it’s the kind of wag that’s knocking over small items. But it turns out that not all wags are equal, and some are a lot more welcoming than others. When I walked into my college biology course freshman year, we started out with a discussion of symmetry. Most animal are built with some symmetry, either radial or bilateral — radial like a starfish, bilateral like a human. Symmetry means things, like health or attractiveness. But it turns out that asymmetry can mean things too. And an asymmetrical behavior might mean some important things for dogs. Marcello Siniscalchi of the University of Bari Aldo Moro in Italy and colleagues decided to look at asymmetry in dog wags. They noticed that sometimes, dogs wag more to the right, usually when seeing their owner or something else happy. They wag more to the left when they see something like a dominant or unfamiliar dog. So the wag itself could represent the emotional state of the dog doing the wagging. But can the dogs seeing the wagging (the wagees) tell the difference? In a paper published October 31 in Current Biology, the authors found that they can. They used videos of a real dog or the silhouette of a dog wagging to the right (the wagging dog’s right, by the way) or to the left, and examined 43 other dogs as they watched (OK, they started with 56, but 13 didn’t pay attention), to see how the wagee reacted. The observing dogs wore a vest to monitor their heart rate, and were videotaped so behaviorists could look at their behaviors afterward. © Society for Science & the Public 2000 - 2013.
By Jesse Bering Disgust, in its most familiar form, is our response to something vile in the world—spoiled food, a dirty floor or rats cavorting in the subway. It is a contamination-avoidance mechanism that evolved to help us make biologically adaptive decisions in the heat of the moment. Yet disgust has also come to have powerful symbolic elements. When left unchecked, these symbolic qualities can have devastating impacts on our mental states. Consider, for example, the often dramatized, heartbreaking image of a woman crouched in the corner of a shower and frantically trying to scrub her body clean after being raped. Empirical evidence supports the characterization. Seventy percent of female victims of sexual assault report a strong impulse to wash afterward, and a quarter of these continue to wash excessively up to three months later. For women, simply imagining an unwanted advance can turn on this moral-cleansing effect. Psychiatrist Nichole Fairbrother of the University of British Columbia Hospital and her colleagues looked more closely at the phenomenon of mental pollution in a study published in 2005. Two groups of female participants were told to close their eyes and picture being kissed. The members of one group were instructed to imagine being aggressively cornered and kissed against their will. The members of the other group were asked to envision themselves in a consensual embrace. Only those women in the coercive condition chose to wash up after the study. In many cases, it seems as though a person's sense of self has become contaminated. © 2013 Scientific American
Link ID: 18811 - Posted: 10.19.2013
by Bruce Bower Thomas Jefferson defended the right to pursue happiness in the Declaration of Independence. But that’s so 237 years ago. Many modern societies champion everyone’s right to be happy pretty much all the time. Good luck with that, says psychologist Joseph Forgas of the University of New South Wales in Sydney. A lack of close friends, unfulfilled financial dreams and other harsh realities leave many people feeling lonely and forlorn a lot of the time. But there’s a mental and social upside to occasional downers that often goes unappreciated. “Bad moods are seen in our happiness-focused culture as representing a problem, but we need to be aware that temporary, mild negative feelings have important benefits,” Forgas says. Growing evidence suggests that gloomy moods improve key types of thinking and behavior, Forgas asserts in a new review paper aptly titled “Don’t worry, be sad!” For good evolutionary reasons, positive and negative moods subtly recruit thinking styles suited to either benign or troubling situations, he says. Each way of dealing with current circumstances generally works well, if imperfectly. New and recent studies described by Forgas in the June Current Directions in Psychological Science illustrate some of the ways in which periods of sadness spontaneously recruit a detail-oriented, analytical thinking style. Morose moods have evolved as early-warning signs of problematic or dangerous situations that demand close attention, these reports suggest. © Society for Science & the Public 2000 - 2013.
By Jason G. Goldman Scientists love yawning. No, that’s not quite right. Scientists love doing research on yawning. It seems to be of interest to folks in fields ranging from primatology to developmental psychology to psychopathology to animal behavior. If the notion of scientifically investigation the purpose of yawning makes you, well, yawn, then you’re missing one of the more interesting debates in the social cognition literature. To understand why yawning is about more than feeling tired or bored, we have to go back a few years. Once upon a time, scientists thought that yawning might be process through which the brain keeps itself cool (PDF). Yawning is associated with increases in blood pressure, and the consequential increase in blood flow might mean that the vascular system acts as a radiator, replacing the warm blood in the brain with cooler blood. It could also be that the deep inhalation of cold air during a yawn can, through convection, alter blood temperature which in turn could cool the brain. Even if it turns out that some yawns can be explained through purely physiological means, yawning is also contagious for humans and other species. If someone watches someone else yawning, they’ll be likely to yawn as well. That means that there is social component to yawning, and it might be related to empathy. It turns out that there’s a correlation between a person’s self-reported empathy and their susceptibility to reacting to a yawn contagion, and those who are more skilled at theory of mind tasks are also more likely (PDF) to yawn contagiously. © 2013 Scientific American
By Sandra G. Boodman, Janet Ruddock was crushed: She had dreamed of greeting her first grandchild, and now that once-in-a-lifetime experience had been marred by the embarrassing problem that had derailed her life for nearly a decade. In June 2010, Ruddock, then 59, and her husband had flown to Vancouver, B.C., from Washington to meet their new grandson. But soon after they arrived, Ruddock’s intractable sweating went into overdrive. As she sat in a rocking chair, perspiration drenched her head and upper body, soaking her shirt and dripping onto the 4-week-old infant. “I burst into tears,” Ruddock recalled. “All I can remember is the feeling that I’m wet, this poor baby’s wet and a moment you should always remember is ruined. You’re never going to get it back. “ For Ruddock, that event precipitated a suicidal depression. For the previous eight years she had undergone tests, taken drugs and endured the bafflement — and skepticism — of a parade of doctors she consulted about the extreme, unpredictable sweating that engulfed her head and upper body. After confiding her despair to a relative, she began seeing a psychiatrist. By chance, a few months later she learned about a woman whose experience mirrored her own and provided her a much-needed road map. “It’s a fascinoma,” said retired Washington internist Charles Abrams, using the medical slang for an unusual — or unusually interesting — case. “You usually hate for patients to come in and say, ‘I found this on the Internet,’ ” said Abrams, who treated Ruddock until his retirement last year. “But every once in a while, something is brought to your attention.” © 1996-2013 The Washington Post
Link ID: 18787 - Posted: 10.15.2013
by Stephanie Pappas, LiveScience Apes orphaned by the African bushmeat trade lack the social savvy of apes raised by their mothers, a new study finds. The study links the emotional development of bonobos (Pan paniscus), one of humans' closest living relatives, with the ability to interact nicely with others, echoing how human emotions develop. Bonobos who are good at soothing themselves out of a bad mood are more likely to comfort other bonobos in distress, researchers report today (Oct. 14) in the journal Proceedings of the National Academy of Sciences. "By measuring the expression of distress and arousal in great apes, and how they cope, we were able to confirm that efficient emotion regulation is an essential part of empathy," study researcher Frans de Waal, of Emory University's National Primate Research Center, said in a statement. PHOTOS: How Santino, the Chimp, Attacks Visitors Though animal emotions "have long been scientifically taboo," de Waal said, he and his colleagues suspected that emotions might have evolved similarly before the bonobo and human lines split about 6 million years ago. The researchers observed juvenile bonobos at a sanctuary near Kinshasa in the Democratic Republic of the Congo. They watched as the young primates fought, threw tantrums and comforted one another by hugging or stroking. (See Video of a Bonobo Hug) In 373 post-distress interactions (318 caused by fights and 55 caused by tantrums), the researchers found that the better a bonobo was at soothing his or her own emotions, the more likely he or she was to rush to aid a friend in need. A similar pattern is seen in human interactions, the researchers reported. © 2013 Discovery Communications, LLC.
By Deborah Kotz / Globe Staff As much as you may hate hearing honking traffic or rumbling trains breaking up the silence while you drift off to sleep, can such irritating noises do serious damage to your health? That’s a question researchers have been trying to answer for years, and they’ve come a bit closer to finding out in a new study looking at the impact of airplane noise in those who live close to airports. Two new studies published in the British Medical Journal this week found that living in a home directly in the flight-path of low-flying planes was associated with an increased risk of being hospitalized for heart disease or a stroke. One study, conducted by Boston-based researchers, examined Medicare records from 6 million seniors living near 89 U.S. airports and found that every 10 decibel level increase in noise from planes that seniors were exposed was linked to a 3.5 percent higher hospitalization rate for heart disease. (About 6 percent of the study population was hospitalized for heart problems during 2009 when the data was collected.) The second study, performed by British researchers, found that folks living near London’s Heathrow airport who were regularly exposed to the greatest levels of noise from planes—greater than 63 decibels which is louder than the sounds of close conversation—were more than 20 percent more likely to be hospitalized for a stroke or for heart disease than those with the least noise exposure. Neither study could prove that the airport noise led to more hospitalizations, but researchers controlled for certain factors like air pollution and road traffic noise which could also raise heart and stroke risks. They couldn’t control for others like smoking habits or diet. © 2013 NY Times Co.
By Stephen L. Macknik and Susana Martinez-Conde Dennis Rogers is an unassuming guy. He's on the short side. And though muscular, he doesn't come across as the kind of towering Venice Beach, muscle-bound Arnold that you might expect from someone billed as the World's Strongest Man. Rather he has the kind of avuncular intensity you find in a great automobile mechanic—a mechanic who happens to be able to lift an engine with one hand while using the fingertips of the other hand to wrench the spark plugs out. Like it's nothing. Rogers, who has been known to keep two U.S. Air Force fighter planes from blasting away in opposite directions by holding them back with his bare hands, performed at the most recent Gathering for Gardner—a conference that celebrates the interests of one of Scientific American's greatest columnists, the late mathemagician Martin Gardner. We asked Rogers about the source of his incredible powers after the show, and we were surprised to learn that he did not know. Bill Amonette of the University of Houston–Clear Lake found that Rogers could recruit an abnormally high number of muscle fibers. But was this ability because of a freak genetic mutation? Another possibility, which Rogers thinks is more likely, is the way he processes pain when he strains those muscles. What if, instead of superpowered muscles, Rogers has a normal—though extremely well exercised—body, and his abilities arise because he can withstand more pain than most mere mortals? He claims that he does feel pain and is actually scared of dentists. In fact, during one stunt in which he held back four souped-up Harley motorbikes with straps, he bit down so hard he split a tooth from top to bottom. Rather than taking his chances at the dentist, he reached into his mouth, clamped his viselike fingertips onto the broken tooth, and extracted it, root and all. Rogers reasons that, unlike in the dentist's office—where he has no control over the pain that is inflicted on him—he has direct executive control over pain that he inflicts on himself. “I know it's coming, I have an idea of what to expect and I can decide to ignore it,” he says. © 2013 Scientific American
by Colin Barras Male marsupial mice just don't know when to stop. For Antechinus stuartii, their debut breeding season is so frenetic and stressful that they drop dead at the end of it from exhaustion or disease. It may be the females of the species that are driving this self-destructive behaviour. Suicidal breeding, known as semelparity, is seen in several marsupials. This is likely linked to short breeding seasons and the fact that the marsupial mice only breed once a year. It is not clear why this is, but it may be that females can only breed when the population of their insect prey reaches its peak. A year is a long and dangerous time for a small animal, so under these circumstances males might do best to pump all their resources into a single breeding season. To test this idea, Diana Fisher of the University of Queensland in St Lucia, Australia, and her colleagues tracked how insect abundance changed with the seasons in the marsupials' home forests. Sure enough, they found that the marsupials' breeding seasons were shortest where insect abundance followed a predictable annual pattern. But the insects are not the whole explanation. It turns out that females do sometimes survive the year and breed again. So why do the males always die? The key factor is that the females are highly promiscuous, says Fisher. Coupled with the short breeding season, this leads to intense competition between males. "Males that exert extreme effort in this short time are at an advantage." © Copyright Reed Business Information Ltd.
By Matthew D. Lieberman The popular conception of human nature emerging from psychology over the last century suggests that we are something of a hybrid, combining reptilian, instinct-driven motivational tendencies with superior higher-level analytic powers. Our motivational tendencies evolved from our reptilian brains eons ago and focus on the four Fs: fighting, fleeing, feeding, and fooling around. In contrast, our intellectual capacities are relatively recent advances. They are what makes us special. One of the things that distinguishes primates from other animals, and humans from other primates, is the size of our brains—in particular, the size of our prefrontal cortex, that is, the front part of the brain sitting right behind the eyes. Our big brains allow us to engage in all sorts of intelligent activities. But that doesn’t mean our brains evolved to do those particular things. Humans are the only animals that can learn to play chess, but no one would argue that the prefrontal cortex evolved specifically so that we could play the game of kings. Rather, the prefrontal cortex is often thought of as an all-purpose computer; we can load it up with almost any software (that is, teach it things). Thus, the prefrontal cortex seems to have evolved for solving novel hard problems, with chess being just one of an endless string of problems it can solve. From this perspective there might not be anything special at all about our ability and tendency to think about the social world. Other people can be thought of as a series of hard problems to be solved because they stand between us and our reptilian desires. Just as our prefrontal cortex can allow us to master the game of chess, the same reasoning suggests that our all-purpose prefrontal cortex can learn to master the social game of chess—that is, the moves that are permissible and advantageous in social life. From this perspective, intelligence is intelligence whether it’s being applied to social life, chess, or studying for a final exam. The creator of one of the most widely used intelligence tests espoused this view, arguing that social intelligence is just “general intelligence applied to social situations.” This view implies social intelligence isn’t special and our interest in the social world is just an accident—a consequence of the particular problems we are confronted with. © 2013 Salon Media Group, Inc
Link ID: 18752 - Posted: 10.07.2013
By R. Douglas Fields Human beings are utterly dependent on a complex social structure for their survival. Since all behavior is controlled by the brain, human beings may have evolved specialized neural circuits that are responsible for compliance with society’s rules. A new study has identified such a region in the human brain, and researchers can increase or decrease a person’s good behavior by electrodes on the scalp that stimulate or inhibit this brain circuit. Individuals must adhere to rules of society, which are ultimately enforced by punishments ranging from peer criticism to severe legal sanctions. “Our findings suggest a neural mechanism that is specialized for social norm compliance,” says Christian Ruff, one of the researchers in this new study published in the October 4, 2013 edition of the journal Science. In addition to illuminating the neurobiological basis for the evolution of social structure in humans, this new finding suggests new therapeutic treatments for people who have problems complying with normal social behavior. “That this mechanism can be upregulated by brain stimulation indeed suggests that targeted influences on these neural processes (by brain stimulation or pharmacology) may help to ameliorate problems with social norm compliance in medical and forensic contexts,” he says. It was already known from fMRI studies that neural activity increased in a specific part of the human cerebral cortex when participants comply with social norms. This region is located in the prefrontal region of the right cerebral hemisphere, called the right lateral prefrontal cortex (rLPFC). However, a correlation between brain activity and behavior does not prove that this neural circuit causes people to comply with social norms. Such proof would require manipulating electrical activity in this brain region to see if people altered their behavior in terms of complying with social expectations. © 2013 Scientific American
Link ID: 18743 - Posted: 10.05.2013
By PAM BELLUCK Say you are getting ready for a blind date or a job interview. What should you do? Besides shower and shave, of course, it turns out you should read — but not just anything. Something by Chekhov or Alice Munro will help you navigate new social territory better than a potboiler by Danielle Steel. That is the conclusion of a study published Thursday in the journal Science. It found that after reading literary fiction, as opposed to popular fiction or serious nonfiction, people performed better on tests measuring empathy, social perception and emotional intelligence — skills that come in especially handy when you are trying to read someone’s body language or gauge what they might be thinking. The researchers say the reason is that literary fiction often leaves more to the imagination, encouraging readers to make inferences about characters and be sensitive to emotional nuance and complexity. “This is why I love science,” Louise Erdrich, whose novel “The Round House” was used in one of the experiments, wrote in an e-mail. The researchers, she said, “found a way to prove true the intangible benefits of literary fiction.” “Thank God the research didn’t find that novels increased tooth decay or blocked up your arteries,” she added. The researchers, social psychologists at the New School for Social Research in New York City, recruited their subjects through that über-purveyor of reading material, Amazon.com. To find a broader pool of participants than the usual college students, they used Amazon’s Mechanical Turk service, where people sign up to earn money for completing small jobs. Copyright 2013 The New York Times Company
Link ID: 18742 - Posted: 10.05.2013
By Travis Riddle Humans like being around other humans. We are extraordinarily social animals. In fact, we are so social, that simply interacting with other people has been shown to be use similar brain areas as those involved with the processing of very basic rewards such as food, suggesting that interacting with people tends to make us feel good. However, it doesn’t take much reflection to notice that the way people interact with each other has radically changed in recent years. Much of our contact happens not face-to-face, but rather while staring at screen-based digital representations of each other, with Facebook being the most prominent example. This raises a very fundamental question – how does online interaction with other people differ from interacting with people in person? One possible way these two interaction styles might differ is through how rewarding we find them to be. Does interacting with Facebook make us feel good as does interacting with people in real life? A recent paper suggests that the answer is “probably not.” In fact, the data from this paper suggest that the more we interact with Facebook, the worse we tend to feel. Researchers recruited participants from around a college campus. The participants initially completed a set of questionnaires, including one measuring their overall satisfaction with life. Following this, participants were sent text messages 5 times a day for two weeks. For each text, participants were asked to respond to several questions, including how good they felt at that moment, as well as how much they had used Facebook, and how much they had experienced direct interaction with others, since the last text. At the end of the two weeks, participants completed a second round of questionnaires. Here, the researchers once again measured participants’ overall satisfaction with life. © 2013 Scientific American
By NICHOLAS BAKALAR Black and Hispanic children who go to an emergency room with stomach pain are less likely than white children to receive pain medication, a new study reports, and more likely to spend long hours in the emergency room. The analysis, published in the October issue of Pediatrics, examined the records of 2,298 emergency room visits by people under 21, a nationally representative sample from a large survey conducted by the Centers for Disease Control and Prevention. About 53 percent were white, 24 percent non-Hispanic black, 21 percent Hispanic, and the rest from other ethnic or racial groups. Over all, 27.1 percent of white children with severe pain received analgesics, but only 15.8 percent of blacks, 18.9 percent of Hispanics and 7.1 percent of children of other races did. Black children were about 68 percent more likely than white children to spend longer than six hours in the emergency room, although there were no statistically significant differences among races in results for any diagnostic test. “This data set will not answer the question of why,” said the lead author, Dr. Tiffani J. Johnson, an instructor at the University of Pennsylvania School of Medicine. “It could be that white parents are more likely to ask for pain meds, or that minority patients are likely to get care in E.R.’s that have longer wait times. And it could be racial bias.” Copyright 2013 The New York Times Company
Mid-life stress may increase a woman's risk of developing dementia, according to researchers. In a study of 800 Swedish women, those who had to cope with events such as divorce or bereavement were more likely to get Alzheimer's decades later. The more stressful events there were, the higher the dementia risk became, BMJ Open reports. The study authors say stress hormones may be to blame, triggering harmful alterations in the brain. Stress hormones can cause a number of changes in the body and affect things such as blood pressure and blood sugar control. And they can remain at high levels many years after experiencing a traumatic event, Dr Lena Johansson and colleagues explain. But they say more work is needed to confirm their findings and ascertain whether the same stress and dementia link might also occur in men. In the study, the women underwent a battery of tests and examinations when they were in either their late 30s, mid-40s or 50s, and then again at regular intervals over the next four decades. At the start of the study, one in four women said they had experienced at least one stressful event, such as widowhood or unemployment. BBC © 2013
By DAVID P. BARASH WAR is in the air. Sad to say, there’s nothing new about this. Nor is there anything new about the claim that war has always been with us, and always will be. What is new, it seems, is the degree to which this claim is wrapped in the apparent acquiescence of science, especially the findings of evolutionary biology with respect to a war-prone “human nature.” This year, an article in The National Interest titled “What Our Primate Relatives Say About War” answered the question “Why war?” with “Because we are human.” In recent years, a piece in New Scientist asserted that warfare has “played an integral part in our evolution” and an article in the journal Science claimed that “death in warfare is so common in hunter-gatherer societies that it was an important evolutionary pressure on early Homo sapiens.” The emerging popular consensus about our biological predisposition to warfare is troubling. It is not just scientifically weak; it is also morally unfortunate, as it fosters an unjustifiably limited vision of human potential. Although there is considerable reason to think that at least some of our hominin ancestors engaged in warlike activities, there is also comparable evidence that others did not. While it is plausible that Homo sapiens owed much of its rapid brain evolution to natural selection’s favoring individuals that were smart enough to defeat their human rivals in violent competition, it is also plausible that we became highly intelligent because selection favored those of our ancestors who were especially adroit at communicating and cooperating. Conflict avoidance, reconciliation and cooperative problem solving could also have been altogether “biological” and positively selected for. © 2013 The New York Times Company
Heather Saul Stress can make the world around us smell unpleasant, the results of a new study are suggesting. Researchers from the University of Wisconsin-Madison used powerful brain imaging technologies to examine how stress and anxiety "re-wire" the brain. A team of psychologists led by Professor Wen Li discovered that when a person experiences stress, emotion systems and olfactory processing in the brain become linked, making inoffensive smells become unpleasant. Although the emotion and olfactory systems within the brain are usually found next to each other, there is rarely 'crosstalk' between the two. Writing in the Journal of Neuroscience, Prof Li said results from their research will now help to uncover the biological mechanisms at work when a person feels stressed. Using functional MRI scans, the team analysed the brain activity of 12 participants after showing them images designed to induce anxiety as they smelled familiar, neutral odours. The subjects were then asked to rate the different smells before being shown the disturbing image and afterwards. The majority showed a more negative response to odours that they had previously considered neutral. This fuels a 'feedback loop' that heightens distress, and can even lead to clinical issues such as depression. Prof Li explained: "After anxiety induction, neutral smells become clearly negative." “In typical odor processing, it is usually just the olfactory system that gets activated,” says Li. “But when a person becomes anxious, the emotional system becomes part of the olfactory processing stream. © independent.co.uk