Chapter 15. Emotions, Aggression, and Stress
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James Hamblin Like The Atlantic? Subscribe to the Daily, our free weekday email newsletter. Elite tennis players have an uncanny ability to clear their heads after making errors. They constantly move on and start fresh for the next point. They can’t afford to dwell on mistakes. Peter Strick is not a professional tennis player. He’s a distinguished professor and chair of the department of neurobiology at the University of Pittsburgh Brain Institute. He’s the sort of person to dwell on mistakes, however small. “My kids would tell me, dad, you ought to take up pilates. Do some yoga,” he said. “But I’d say, as far as I’m concerned, there's no scientific evidence that this is going to help me.” Still, the meticulous skeptic espoused more of a tennis approach to dealing with stressful situations: Just teach yourself to move on. Of course there is evidence that ties practicing yoga to good health, but not the sort that convinced Strick. Studies show correlations between the two, but he needed a physiological mechanism to explain the relationship. Vague conjecture that yoga “decreases stress” wasn’t sufficient. How? Simply by distracting the mind? The stress response in humans is facilitated by the adrenal glands, which sit on top of our kidneys and spit adrenaline into our blood whenever we’re in need of fight or flight. That stress response is crucial in dire circumstances. But little of modern life truly requires it (especially among academic scientists). Most of the time, our stress responses are operating as a sort of background hum, keeping us on edge. Turn that off, and we relax. © 2016 by The Atlantic Monthly Group
Link ID: 22599 - Posted: 08.25.2016
Are you a giver or a taker? Brain scans have identified a region of the cerebral cortex responsible for generosity – and some of us are kinder than others. The area was identified using a computer game that linked different symbols to cash prizes that either went to the player, or one of the study’s other participants. The volunteers readily learned to score prizes that helped other people, but they tended to learn how to benefit themselves more quickly. Read more: The kindness paradox: Why be generous? MRI scanning revealed that one particular brain area – the subgenual anterior cingulate cortex – seemed to be active when participants chose to be generous, prioritising benefits for someone else over getting rewards for themselves. But Patricia Lockwood, at the University of Oxford, and her team found that this brain area was not equally active in every volunteer. People who rated themselves as having higher levels of empathy learned to benefit others faster, and these people had more activity in this particular brain area, says Lockwood. This finding may lead to new ways to identify and understand anti-social and psychopathic behavior. Journal reference: PNAS, DOI: 10.1073/pnas.1603198113 © Copyright Reed Business Information Ltd.
In a global study of myasthenia gravis, an autoimmune disease that causes muscle weakness and fatigue, researchers found that surgical removal of an organ called the thymus reduced patients’ weakness, and their need for immunosuppressive drugs. The study, published in the New England Journal of Medicine, was partially funded by the National Institutes of Health. “Our results support the idea that thymectomy is a valid treatment option for a major form of myasthenia gravis,” said Gil Wolfe, M.D., Professor and Irvin and Rosemary Smith Chair of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, New York, and a leader of the study. The Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone (MGTX) was a randomized, controlled study conducted on 126 patients aged 18-65 between 2006 and 2012. The researchers compared the combination of surgery and immunosuppression with the drug prednisone with prednisone treatment alone. They performed extended transternal thymectomies on 57 patients. This major surgical procedure aims to remove most of the thymus, which requires opening of a patient’s chest. On average the researchers found that the combination of surgery and prednisone treatment reduced overall muscle weakness more than prednisone treatment alone. After 36 months of prednisone treatment, both groups of patients had better QMG scores, a measure of muscle strength. Scores for the patients who had thymectomies and prednisone were 2.84 points better than patients who were on prednisone alone.
By Effy Redman “There is no one who has not smiled at least once,” writes Marianne LaFrance, a Yale University psychology professor, in her 2011 book “Lip Service: Smiles in Life, Death, Trust, Lies, Work, Memory, Sex and Politics.” Her book explores how smiling unifies us. Like breath, the smile is universal. We smile to connect, to forgive, to love. A smile is beauty, human. But I have never smiled. Not once. I was born with Moebius syndrome — a rare form of facial paralysis that results from damage in the womb to the sixth and seventh cranial nerves, which control the muscles of the face. I was born in Britain, on the same day in 1982 the country’s first test-tube twins were born. But while science has created medical miracles like test-tube babies, there’s little that doctors can do for someone with Moebius syndrome. Decades later, I still cannot smile. Or frown. Or do any of the infinite subtle and not-so-subtle things with my face that I see others in the world around me doing every day. Doctors describe people with Moebius as having a “mask-like expression.” And that is what strangers must see. A frozen face, eyes unblinking. My mouth always open, motionless, the left corner of my lips slightly lower than the right. Walking down the street, I can feel the touch of casual observers’ eyes. A child’s very first “social smile” usually occurs six to eight weeks after birth, eagerly awaited by new parents. Because, as an infant, my face remained so expressionless, when I began laughing it took my mother a while to realize that the sound I was making was laughter. At what point, I wonder, did I begin to compensate for the absence of my smile. © 2016 The New York Times Company
Link ID: 22542 - Posted: 08.11.2016
By TATIANA SCHLOSSBERG Need a laugh? Get online and take a look at videos of baby Japanese macaques smiling as they sleep. Their faces twitch, usually just on one side and for less than a second. A lip curls, a nose wrinkles — as if they were hairy, wry elves. Newborn Japanese macaques -- like humans and chimpanzees -- were found to make facial expressions called "spontaneous smiles." Watch the full video. Credit Kyoto University Primate Research Institute Maybe you don’t laugh, maybe you just smile back — O.K., fine. But you may owe that smile to the human version of this infant’s facial spasm. Some scientists suspect spontaneous smiles in these monkeys echo the development of our own expressions. Scientists from the Primate Research Institute at Kyoto University in Japan have observed these spontaneous smiles in Japanese macaques for the first time, according to a new study published in the journal Primates. Spontaneous smiles have previously been observed in infant humans and chimpanzees, but this is the first time they have been seen in another primate species. The scientists watched seven macaque monkeys for an average of 44 minutes, during which the monkeys happened to fall asleep. During REM sleep, each of the monkeys spontaneously smiled at least once, for a little less than a second on average. All told, the seven monkeys smiled 58 times, mostly on the left side of their faces. Human and macaque infants alike primarily smile on one side of their faces. But after two months, human babies begin to smile bilaterally. Around the same time, they also begin to offer up “social smiles,” indicating to others a feeling of happiness. According to the study, scientists think that the earliest spontaneous smiles are key to the development of the zygomaticus major muscle, which is responsible for moving your lips up or to the side, allowing you to smile, among other things. Spontaneous smiles in these monkeys echo the development of our own expressions. Watch the full video.
Seth Stephens-Davidowitz Feeling worried? These days, much of America is. Over the past eight years, Google search rates for anxiety have more than doubled. They are higher this year than they have been in any year since Google searches were first tracked in 2004. So far, 2016 has been tops for searches for driving anxiety, travel anxiety, separation anxiety, anxiety at work, anxiety at school and anxiety at home. Americans have also become increasingly terrified of the morning. Searches for “anxiety in the morning” have risen threefold over the past decade. But this is nothing compared with the fear of night. Searches for “anxiety at night” have risen ninefold. For years, I have confidently pontificated on topics that I think are important but that I have little experience of — child abuse, racism, sexism, sex. Now I am ready to tackle a topic I actually know something about. Over the past few weeks, I’ve taken a break from worrying about my own anxiety to studying our country’s. While I am not sure I totally nailed down why anxiety seems to have risen so much during the Obama era, I did learn a lot. The places where anxiety is highest are not where I would have expected. When I was growing up, if you had asked me which people were the most anxious, I would have said New York Jews. And a decade of interacting with our country’s urban intelligentsia, Jewish and otherwise, has confirmed that pretty much all of us are a neurotic mess. © 2016 The New York Times Company
Link ID: 22528 - Posted: 08.08.2016
By PHYLLIS KORKKI Ever experienced a bout of anxiety at work? I just did. One day last week I had several assignments to finish in quick succession. I could feel thoughts pinging around in my brain as I tried and failed to decide what to focus on first. Once I was able to get the pandemonium under control, my brain felt like mush. So what did I do? I breathed deeply from the middle of my body. I imagined the top of my head, and pictured arrows coming out the sides of my shoulders. I stood up for a while and then walked around the newsroom. And went back to work. These simple solutions to anxiety are not so easy to practice in an era of multitasking, multiple screens and mindless distractions. I learned them only after signing a contract to write a book — and becoming so anxious about it that I developed back and stomach pains. Unable to score a prescription for Klonopin (it’s addictive, my doctor said), I was reduced to seeking out natural methods to relieve my anxiety. The methods I learned helped me write the book. But they also made me realize that workers of all stripes could use them to reduce stress, and to think more clearly and creatively. My first stop was Belisa Vranich, a clinical psychologist who teaches — or rather reteaches — people how to breathe. Dimly I sensed that the way I was inhaling and exhaling was out of whack, and she confirmed it by giving me some tests. First off, like most people, I was a “vertical” breather, meaning my shoulders moved upward when I inhaled. Second, I was breathing from my upper chest, where the lungs don’t have much presence. © 2016 The New York Times Company
Link ID: 22527 - Posted: 08.08.2016
By JoAnna Klein I expected a bumpy ride on a whitewater trip, so when I fell off my raft and coughed up the water I’d inhaled, I wasn’t afraid. But at the time I didn’t know I was swimming with a deadly parasite. I’d been at a bachelorette party at the U.S. National Whitewater Center in Charlotte, N.C., but after returning home I learned that I had shared the churning rapids with Naegleria fowleri, a single-celled amoeba found mostly in soil and warm freshwater lakes, rivers and hot springs. An Ohio teenager had contracted the amoeba infection after visiting the center around the same time I did, and some of the waters and sediment at and around the center had tested positive for the bug. News that my friends and I had all been at risk of exposure triggered a few days of worry. The illness is rare and, if infected, symptoms show up between one and 10 days after exposure. Chances were that we were fine (we were), but the experience prompted me to learn more about the parasite. Naegleria fowleri lives in fresh water, but not in salt water. If forced up the nose, it can enter the brain and feed on its tissue, resulting in an infection known as primary amebic meningoencephalitis. Death occurs in nearly all of those infected with the parasite, usually within five days after infection. The 18-year-old Ohio woman who died most likely contracted the parasite when she sucked water through her nose after falling from a raft during a church trip. Samples from a channel at the rafting center, collected by the Centers for Disease Control and Prevention, tested positive for the bug. The center’s channels are man-made, and it gets its water from the Charlotte-Mecklenburg Utilities Department and two wells on its property. The center has announced that it disinfects all water with ultraviolet radiation and chlorine, and it added more after the water tests. © 2016 The New York Times Company
Link ID: 22514 - Posted: 08.04.2016
By Colby Itkowitz On any given day people face any number of minor annoyances such as being stuck in traffic or spilling coffee on their shirts or forgetting their keys. Then there’s the persistent stressors that come from work, relationships and finances. And there’s the uncontrollable anxieties of global terrorism, mass shootings and Zika-carrying mosquitoes. But why are some people able to deal with it all so calmly, while others freak out? A team of researchers at Yale University may have found the answer in the brain. The scientists studied the brains of 30 adult volunteers with no history of mental or physical health issues as they watched a slideshow of gruesome and terrifying images for six minutes. To compare brain activity, they then showed the participants benign images that would evoke little emotion, such as a photo of a chair. They located three areas of the brain that responded to the stress of seeing photos of people mutilated or at gunpoint or in other harrowing scenarios. But what the researchers found most interesting was how the ventromedial prefrontal cortex (vmPFC), which processes risk and emotional response, adapted while viewing the photos. In everyone, activity in that region decreased initially in response to the images, as though their guard was down, but then in some people, it became hyperactive, as if working overtime to control the emotional response, or in other words, to cope. “We have not had a way of breaking that apart to see what the brain is doing,” said Rajita Sinha, director of the Yale Stress Center and lead author of the study. “How do we cope in the moment? Here, we said, in the moment under acute threat how does the brain cope and regain control?” © 1996-2016 The Washington Post
Link ID: 22506 - Posted: 08.03.2016
By Tanya Lewis The tangled buildup of tau protein in brain cells is a hallmark of the cognitive decline linked with Alzheimer’s disease. Antibodies have been shown to block tau’s spread, but some scientists worry it could also fuel inflammation. Now, researchers from Genentech in San Francisco and colleagues have found that an antibody’s ability to recruit immune cells—known as its effector function—is not necessary for stopping tau’s spread, the team reported today (July 28) in Cell Reports. “Our results suggest that, given that effector function is not required for efficacy [in treating tau accumulation], going without it could offer a safer approach for immunotherapy,” study coauthor Gai Ayalon of Genentech told The Scientist. Alzheimer’s disease causes a characteristic constellation of pathologies: accumulation of amyloid-β plaques outside neurons, neurofibrillary tangles of tau inside brain cells, and chronic inflammation. Clinical research has mostly focused on targeting amyloid-β with antibody therapies, and several treatments based on this approach are currently in clinical trials. But recent efforts have zeroed in on tau as a new potential target. Antibodies are known to spur the brain’s defense system, microglia, to absorb and degrade tau, but their recruitment of immune cells may also worsen inflammation. Ayalon and colleagues wondered whether effector function was necessary for stopping tau’s spread. © 1986-2016 The Scientist
Research supported by the National Institutes of Health has identified brain patterns in humans that appear to underlie “resilient coping,” the healthy emotional and behavioral responses to stress that help some people handle stressful situations better than others. People encounter stressful situations and stimuli everywhere, every day, and studies have shown that long-term stress can contribute to a broad array of health problems. However, some people cope with stress better than others, and scientists have long wondered why. The new study, by a team of researchers at Yale University, New Haven, Connecticut, is now online in the Proceedings of the National Academy of Sciences. “This important finding points to specific brain adaptations that predict resilient responses to stress,” said George F. Koob, Ph.D., director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of NIH and a supporter of the study. “The findings also indicate that we might be able to predict maladaptive stress responses that contribute to excessive drinking, anger, and other unhealthy reactions to stress.” In a study of human volunteers, scientists led by Rajita Sinha, Ph.D., and Dongju Seo, Ph.D., used a brain scanning technique called functional magnetic resonance imaging (fMRI) to measure localized changes in brain activation during stress. Study participants were given fMRI scans while exposed to highly threatening, violent and stressful images followed by neutral, non-stressful images for six minutes each. While conducting the scans, researchers also measured non-brain indicators of stress among study participants, such as heart rate, and levels of cortisol, a stress hormone, in blood. The brain scans revealed a sequence of three distinct patterns of response to stress, compared to non-stress exposure.
By Diana Kwon Few things feel worse than not knowing when your next paycheck is coming. Economic insecurity has been shown to have a whole host of negative effects, including low self-esteem and impaired cognitive functioning. It turns out financial stress can also physically hurt, according to a paper published in February in Psychological Science. Eileen Chou, a public policy professor at the University of Virginia, and her collaborators began by analyzing a data set of 33,720 U.S. households and found that those with higher levels of unemployment were more likely to purchase over-the-counter painkillers. Then, using a series of experiments, the team discovered that simply thinking about the prospect of financial insecurity was enough to increase pain. For example, people reported feeling almost double the amount of physical pain in their body after recalling a financially unstable time in their life as compared with those who thought about a secure period. In another experiment, university students who were primed to feel anxious about future employment prospects removed their hand from an ice bucket more quickly (showing less pain tolerance) than those who were not. The researchers also found that economic insecurity reduced people's sense of control, which, in turn, increased feelings of pain. Chou and her colleagues suggest that because of this link between financial insecurity and decreased pain tolerance, the recent recession may have been a factor in fueling the prescription painkiller epidemic. Other experts are cautious about taking the findings that far. “I think the hypothesis [that financial stress causes pain] has a lot of merit, but it would be helpful to see additional rigorous evidence in a real-world environment,” says Heather Schofield, an economist at the University of Pennsylvania who was not involved in the study. © 2016 Scientific American,
Ramin Skibba Is Justin Bieber a musical genius or a talentless hack? What you 'belieb' depends on your cultural experiences. Some people like to listen to the Beatles, while others prefer Gregorian chants. When it comes to music, scientists find that nurture can trump nature. Musical preferences seem to be mainly shaped by a person’s cultural upbringing and experiences rather than biological factors, according to a study published on 13 July in Nature1. “Our results show that there is a profound cultural difference” in the way people respond to consonant and dissonant sounds, says Josh McDermott, a cognitive scientist at the Massachusetts Institute of Technology in Cambridge and lead author of the paper. This suggests that other cultures hear the world differently, he adds. The study is one of the first to put an age-old argument to the test. Some scientists believe that the way people respond to music has a biological basis, because pitches that people often like have particular interval ratios. They argue that this would trump any cultural shaping of musical preferences, effectively making them a universal phenomenon. Ethnomusicologists and music composers, by contrast, think that such preferences are more a product of one’s culture. If a person’s upbringing shapes their preferences, then they are not a universal phenomenon. © 2016 Macmillan Publishers Limited
By Virginia Morell Infanticide—the killing of offspring—is generally rare among birds. And when it happens, it’s usually because of outsiders that want the nesting site or territory. But what happens among birds, such as the greater ani (Crotophaga major, pictured), which have a more socialist approach to nesting? Two to four pairs of the Central and South American cuckoos (which are usually unrelated) build a single nest, and then work together to raise their chicks, which generally hatch at the same time. Intriguingly, the adults cannot recognize either their own eggs or chicks, so they care for all of them. To find out why—and if the simultaneous hatching protects the chicks from infanticide—a scientist analyzed data on nestling mortality gathered at 104 communal greater ani nests from 2006 to 2015. Of the 741 nestlings, 321 (43%) fledged and 420 (57%) died. Most of the deaths (78.5%) were due to predation. But another 13.8%, or 58 nestlings, died from infanticide, the scientist reports online today in Evolution. The remaining 32 (7.7%) died from starvation. At most of the nests, the chicks hatched within 1 day of each other. Those that first emerged from their eggs were the most likely to be dispatched by one of the nest founders, not an outsider. Chicks that hatched last were also unlucky; weaker than their older and larger nest-mates, they weren’t able to compete for food and starved. Those two pressures—infanticide and food competition—end up favoring the chicks in the middle and those that hatch on the same day, the researcher reports. © 2016 American Association for the Advancement of Science
By Rebecca Brewer, Jennifer Murphy, There is a persistent stereotype that people with autism are individuals who lack empathy and cannot understand emotion. It’s true that many people with autism don’t show emotion in ways that people without the condition would recognize. But the notion that people with autism generally lack empathy and cannot recognize feelings is wrong. Holding such a view can distort our perception of these individuals and possibly delay effective treatments. We became skeptical of this notion several years ago. In the course of our studies of social and emotional skills, some of our research volunteers with autism and their families mentioned to us that people with autism do display empathy. Many of these individuals said they experience typical, or even excessive, empathy at times. One of our volunteers, for example, described in detail his intense empathic reaction to his sister’s distress at a family funeral. Yet some of our volunteers with autism agreed that emotions and empathy are difficult for them. We were not willing to brush off this discrepancy with the ever-ready explanation that people with autism differ from one another. We wanted to explain the difference, rather than just recognize it. So we looked into the overlap between autism and alexithymia, a condition defined by a difficulty understanding and identifying one’s own emotions. People with high levels of alexithymia (which we assess with questionnaires) might suspect they are experiencing an emotion, but are unsure which emotion it is. They could be sad, angry, anxious or maybe just overheated. About 10 percent of the population at large — and about 50 percent of people with autism — has alexithymia. © 2016 Scientific American
By Bret Stetka Beloved crank and Seinfeld co-creator Larry David once told an interviewer that he tolerates people like he tolerates lactose — which is to say, I'm assuming, not well. David's particular degree of grumpiness might be extreme, and perhaps embellished in the interest his shtick, but his social misgivings echo those of many in their dotage who’d rather spend time with old friends than deal with the sweat and small talk required to go out and make new ones. Humans may not be alone here. According to new research, our primate cousins also become more socially selective with age, preferring the companionship of their “friends” to monkeys that are less familiar (or maybe just a drag at parties). The findings also hint at a possible evolutionary explanation for why our social preferences change over the years. The work, conducted primarily by researchers from the German Primate Center in Göttingen, Germany, was recently published in the journal Current Biology and entailed observing the behaviors of over 100 Barbary macaque monkeys, an out-going, some might say "screechy," species hailing from North Africa. To get a sense of how interest in non-social vs social stimulation changes over the course of their lifetimes, monkeys of varying ages were observed in the presence of both inanimate objects and other monkeys. They were first presented with three novel objects: animal toys, a see-through cube filled with glitter in a viscous liquid, and a tube baited with food. Those that had reached early adulthood were not interested in the objects without a reward. The younger ones were intrigued by all three. © 2016 Scientific American
Laura Sanders Feeling good may help the body fight germs, experiments on mice suggest. When activated, nerve cells that help signal reward also boost the mice’s immune systems, scientists report July 4 in Nature Medicine. The study links positive feelings to a supercharged immune system, results that may partially explain the placebo effect. Scientists artificially dialed up the activity of nerve cells in the ventral tegmental area — a part of the brain thought to help dole out rewarding feelings. This activation had a big effect on the mice’s immune systems, Tamar Ben-Shaanan of Technion-Israel Institute of Technology in Haifa and colleagues found. A day after the nerve cells in the ventral tegmental area were activated, mice were infected with E. coli bacteria. Later tests revealed that mice with artificially activated nerve cells had less E. coli in their bodies than mice without the nerve cell activation. Certain immune cells seemed to be ramped up, too. Monocytes and macrophages were more powerful E. coli killers after the nerve cell activation. If a similar effect is found in people, the results may offer a biological explanation for how positive thinking can influence health. |© Society for Science & the Public 2000 - 2016
By Maya Smith Bonobos (pictured) are known as the peaceful ape. They’re less aggressive than their chimpanzee cousins, and when they have disagreements they’re more likely to make love, not war. Now, a new study reveals one way females keep the peace. In most primate societies, female genitals swell to advertise that they’re ready to mate, leading to fighting among males as they jostle for a partner. But in bonobos, the swellings only indicate fertility half the time, according to a study in the wild published this week in BMC Evolutionary Biology. The findings confirm what scientists have observed in captivity. The researchers behind the new study hypothesize females may have evolved the behavior to gain the upper hand in mating. Because males cannot look to sexual swellings as a reliable indicator of fertility, the females are free to choose their mates. And that helps everyone get along. © 2016 American Association for the Advancement of Science.
by Bethany Brookshire There’s an osprey nest just outside Jeffrey Brodeur’s office at the Woods Hole Oceanographic Institution in Massachusetts. “I literally turn to my left and they’re right there,” says Brodeur, the organization’s communications and outreach specialist. WHOI started live-streaming the osprey nest in 2005. For the first few years, few people really noticed. All that changed in 2014. An osprey pair had taken up residence and produced two chicks. But the mother began to attack her own offspring. Brodeur began getting e-mails complaining about “momzilla.” And that was just the beginning. “We became this trainwreck of an osprey nest,” he says. In the summer of 2015, the osprey family tried again. This time, they suffered food shortages. The camera received an avalanche of attention, complaints and e-mails protesting the institute’s lack of intervention. One scolded, “it is absolutely disgusting that you will not take those chicks away from that demented witch of a parent!!!!! Instead you let them be constantly abused and go without [sic] food. Yes this is nature but you have a choice to help or not. This is totally unacceptable. She should be done away with so not to abuse again.” By mid-2015, Brodeur began to receive threats. “People were saying ‘we’re gonna come help them if you don’t,’” he recalls. The osprey cam was turned off, and remains off to this day. Brodeur says he’s always wondered why people had such strong feelings about a bird’s parenting skills. Why do people spend so much time and emotion attempting to apply their own moral sense to an animal’s actions? The answer lies in the human capacity for empathy — one of the qualities that helps us along as a social species. © Society for Science & the Public 2000 - 2016.
By Gary Stix Bullies often like being bullies—and an entire line of research links aggressive behaviors to brain areas tied to sensations of reward—sites deep below the organ’s surface with names like the ventromedial hypothalamus and the extended amygdala. One lingering puzzle is what precedes the aggressive act. What makes a person—or, in this case, a mouse—lash out? A new study, published June 29 in Nature, shows that the thought of being the aggressor simply feels good to certain animals. I had a fascinating talk this week with Scott Russo from the Icahn School of Medicine at Mount Sinai, the paper’s senior author, who described the significance of these findings. What did your study find? We discovered a brain circuit—connecting the basal forebrain and lateral habenula—that appears to control the motivation of a male mouse to be aggressive and subordinate another male mouse. The significance of these findings is that the circuit seems to be telling an animal that subordinating, or “bullying,” another animal is a rewarding behavior. To test this, we adapted a conditioned place preference protocol—often used to measure the rewarding properties of addictive drugs, whereby mice were allowed to attack an intruder mouse within one of two environmental contexts: When asked which of the two environmental contexts they preferred, aggressive mice chose the environment in which they were allowed to attack the intruder mouse over the environment in which they had no access to the intruder mouse. Interestingly, the basal forebrain and lateral habenula have been previously shown to support conditioned place preference to drugs of abuse, such as nicotine and cocaine, suggesting that similar neural processes mediate rewarding aspects of aggression and addictive substances. © 2016 Scientific American
Link ID: 22380 - Posted: 06.30.2016