Links for Keyword: Aggression

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By Kashmira Gander Scientists have turned off aggressive behavior in mice for weeks at a time by harnessing the power of a little-understood group of brain cells. In a new study, which sheds light on the potential biological cause of aggression, scientists tinkered with neurons in the brains of lab mice. To arrive at their findings, the researchers at the Karolinska Institutet in Sweden investigated the role of a set of neurons in the ventral premammillary nucleus (PMv) of the hypothalamus. Mice generally resort to aggression as a way to assert their dominance rather than cause harm, so the scientists tested their hypothesis using the so-called tube test. This involves pitting two mice against each other in a narrow corridor, in order to document their responses in this socially fraught situation. The study, published in the journal Nature Neuroscience, showed when male mice were confronted with a new male in their home cage, the animals responded aggressively, and showed activity in the PMv neurons. Using a technique where neurons are turned on and off using light, called optogenetics, the researchers were also able to trigger aggressive behavior in mice in scenarios where they were usually calm. In turn, they could stop a mouse mid-attack by turning off the light. What's more, when a generally submissive male was faced with a dominant male, blocking the PMv cells inverted their statuses. As well as aggression, PMv neurons also appeared to be associated with other parts of the brain—the part linked to rewards. © 2018 Newsweek LLC

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 25030 - Posted: 05.29.2018

Susan Milius Pick an animal. Choose wisely because in this fantasy you’ll transform into the creature and duel against one of your own. If you care about survival, go for the muscular, multispiked stag roaring at a rival. Never, ever pick the wingless male fig wasp. Way too dangerous. This advice sounds exactly wrong. But that’s because many stereotypes of animal conflict get the real biology backward. All-out fighting to the death is the rule only for certain specialized creatures. Whether a species is bigger than a breadbox has little to do with lethal ferocity. Many creatures that routinely kill their own kind would be terrifying, if they were larger than a jelly bean. Certain male fig wasps unable to leave the fruit they hatch in have become textbook examples, says Mark Briffa, who studies animal combat. Stranded for life in one fig, these males grow “big mouthparts like a pair of scissors,” he says, and “decapitate as many other males as they possibly can.” The last he-wasp crawling has no competition to mate with all the females in his own private fruit palace. In contrast, big mammals that inspire sports-team mascots mostly use antlers, horns and other outsize male weaponry for posing, feinting and strength testing. Duels to the death are rare. |© Society for Science & the Public 2000 - 2018.

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24944 - Posted: 05.05.2018

Kas Roussy · You think you have a dysfunctional clan? Check out the family feud involving Humphrey, Charlie and Hugh. In the early '70s, the trio was part of a tight-knit community of wild chimpanzees in Gombe National Park, Tanzania. These are some of the same chimps that British primatologist Jane Goodall was studying at the time, looking at social and family dynamics. "Jane and other researchers who came to Gombe initially had this idea that chimpanzees were these idyllic forest-dwelling species that could provide this model for what humanity could be like," says Duke University researcher Joseph Feldblum. "They thought they were peaceful and egalitarian." They were about to get a reality check of the wild kingdom variety. According to a new study, the same things that fuel deadly clashes in humans — like power, ambition, and jealousy — can also tear apart chimpanzees. You'll recall from all those wildlife documentaries that chimps are our closest animal relatives. In Gombe, Goodall and her colleagues watched a once-unified group of chimps disintegrate into two rival factions. "There's still a bit of uncertainty, even with people who were there at the time, about exactly what happened," Feldblum tells CBC News. But thanks to new digitized data taken from Goodall's own field notes from that period, Feldblum and a team of scientists were able to get a clearer, more detailed picture of what they call "the seeds of the conflict." "We were able to examine the course of the split in more detail and pinpoint when it became obvious more precisely," says co-author and Duke anthropologist Anne Pusey. ©2018 CBC/Radio-Canada

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24820 - Posted: 04.04.2018

Amy Fleming Charles Ryan has a clinic in San Francisco at which he regularly relieves men of their testosterone. This “chemical castration”, as it is sometimes known, is not a punishment, but a common treatment for prostate cancer. Testosterone doesn’t cause the disease (currently the third most deadly cancer in the UK), but it fuels it, so oncologists use drugs to reduce the amount produced by the testicles. Ryan gets to know his patients well over the years, listening to their concerns and observing changes in them as their testosterone levels fall. Because it involves the so-called “male hormone”, the therapy poses existential challenges to many of those he treats. They know that every day, millions of people – from bodybuilders and cheating athletes to menopausal women – enhance their natural levels of testosterone with the aim of boosting their libido, muscle mass, confidence and energy. So what happens when production is suppressed? Might they lose their sex drive? Their strength? Their will to win? The fears are not always groundless. Side-effects can also include fatigue and weight gain. But Ryan has witnessed positives, too. As professor of medicine and urology at the University of California, he has noticed that the medical students who have passed through his clinic in the 18 years that he has been treating prostate cancer invariably comment: “Dr Ryan, your patients are so nice.” He replies, jokingly: “It’s because they don’t have any testosterone. They can’t be mean.” © 2018 Guardian News and Media Limited

Related chapters from BN: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 12: Psychopathology: The Biology of Behavioral Disorders; Chapter 8: Hormones and Sex
Link ID: 24768 - Posted: 03.20.2018

By MAYA SALAM and LIAM STACK President Trump said Thursday that violent video games and movies may play a role in school shootings, a claim that has been made — and rejected — many times since the increase in such attacks in the past two decades. Movies are “so violent,” Mr. Trump said at a meeting on school safety one day after he gathered with survivors of school shootings, including some from last week’s massacre at Marjory Stoneman Douglas High School, where, the authorities say, a former student, Nikolas Cruz, killed 17 people with a semiautomatic rifle. “We have to look at the internet because a lot of bad things are happening to young kids and young minds and their minds are being formed,” Mr. Trump said, “and we have to do something about maybe what they’re seeing and how they’re seeing it. And also video games. I’m hearing more and more people say the level of violence on video games is really shaping young people’s thoughts.” “And then you go the further step and that’s the movies,” he added. “You see these movies, they’re so violent, and yet a kid is able to see the movie if sex isn’t involved, but killing is involved.” A neighbor of Mr. Cruz’s told The Miami Herald that he played video games, often violent ones, for up to 15 hours a day. Media scholars say the claim — a common one in the wake of mass shootings — does not hold up to scrutiny. Mr. Trump is far from the first leader to argue that violence in video games or movies can lead to violence in the real world. A similar claim was made in the 1940s, when Mayor Fiorello La Guardia of New York argued that pinball — which was illegal in the city for over 30 years — was “dominated by interests heavily tainted with criminality.” © 2018 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24699 - Posted: 02.26.2018

By BENEDICT CAREY President Trump called again on Thursday for the opening of more mental hospitals to help prevent mass murders like the one at Marjory Stoneman Douglas High School in Parkland, Fla. Yet ramping up institutional care, experts say, likely would not have prevented most of the spree killings regularly making headlines in this country. “We’re going to be talking about mental institutions. And when you have some person like this, you can bring them into a mental institution, and they can see what they can do. But we’ve got to get them out of our communities,” the president said during a meeting at the White House with state and local officials. In the 1960s, states across the country began to close or shrink mental hospitals after a series of court decisions that limited the powers of state and local officials to commit people. The decline continued for decades, in part because of cuts in both state and federal budgets for mental health care. Those institutions housed people with severe mental disorders, like schizophrenia, who were deemed unable to care for themselves. And while spree killers may be angry and emotionally disordered, few have had the sorts of illnesses that would have landed them in hospital custody. The latest school shooter, Nikolas Cruz, 19, was clearly troubled and making threats, and he was stockpiling weapons. But he had no mental diagnosis. He has been described as angry, possibly depressed, perhaps isolated — not so different from millions of other teenagers. A full psychiatric evaluation, if he’d had one, might have resulted in a temporary commitment at best, but not full-time institutionalization, experts said. The idea that more such institutions would prevent this kind of violence “is ridiculous, because you can’t put half the people in the country with a mental disturbance in mental hospitals,” said Dr. Michael Stone, a forensic psychiatrist at Columbia University who has studied mass killers. © 2018 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 24691 - Posted: 02.23.2018

By Linda Qiu and Justin Bank A heavily armed young man is accused of killing 17 people after opening fire on terrified students and teachers at Marjory Stoneman Douglas High School in Parkland, Fla., on Wednesday. It was the third mass shooting in the past four months in the United States. Nikolas Cruz, who has been linked to a history of mental illness, is believed to have used a legally obtained AR-15 in the shooting. The attack has led to widespread conversations about links between gun violence and mental illness, and how lawmakers and interest groups are debating potential policy responses. Below is a look at some facts and falsehoods uttered by Speaker Paul D. Ryan, Republican of Wisconsin; Senator Bernie Sanders, independent of Vermont; and others in the wake of Wednesday’s shooting. “Mental health is often a big problem underlying these tragedies.” — House Speaker Paul Ryan There’s a link, but it’s more limited than widely thought. Mr. Ryan’s claim reflects a common misconception. According to various polls, roughly half of Americans either believe that failing to identify people with mental health problems is the primary cause of gun violence or that addressing mental health issues would be a major deterrent. That conclusion is not shared by experts or widely accepted research. In an analysis of 235 mass killings, many of which were carried out with firearms, 22 percent of the perpetrators could be considered mentally ill. Overall, mass shootings by people with serious mental illness represent 1 percent of all gun homicides each year, according to the book “Gun Violence and Mental Illness” published by the American Psychiatric Association in 2016. To be sure, gun violence experts contacted by New York Times reporters have said that barring sales to people who are deemed dangerous by mental health providers could help prevent mass shootings. But the experts said several more measures — including banning assault weapons and barring sales to convicted violent criminals — more effective. © 2018 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 24676 - Posted: 02.17.2018

By Micah Johnson Charles Whitman lived a fairly unremarkable life until August 1, 1966, when he murdered 16 people including his wife and mother. What transformed this 25-year-old Eagle Scout and Marine into one of modern America’s first and deadliest school shooters? His autopsy suggests one troubling explanation: Charles Whitman had a brain tumor pressing on his amygdala, a region of the brain crucial for emotion and behavioral control. Can murder really be a symptom of brain disease? And if our brains can be hijacked so easily, do we really have free will? Neuroscientists are shedding new light on these questions by uncovering how brain lesions can lead to criminal behavior. A recent study contains the first systematic review of 17 known cases where criminal behavior was preceded by the onset of a brain lesion. Is there one brain region consistently involved in cases of criminal behavior? No—the researchers found that the lesions were widely distributed throughout different brain regions. However, all the lesions were part of the same functional network, located on different parts of a single circuit that normally allows neurons throughout the brain to cooperate with each other on specific cognitive tasks. In an era of increasing excitement about mapping the brain’s “connectome,” this finding fits with our growing understanding of complex brain functions as residing not in discrete brain regions, but in densely connected networks of neurons spread throughout different parts of the brain. © 2018 Scientific American

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 15: Language and Lateralization
Link ID: 24594 - Posted: 01.31.2018

By Ann Gibbons Humans are the ultimate social animals, with the ability to bond with mates, communicate through language, and make small talk with strangers on a packed bus. (Put chimpanzees in the same situation and most wouldn’t make it off the bus alive.) A new study suggests that the evolution of our unique social intelligence may have initially begun as a simple matter of brain chemistry. Neuroanatomists have been trying for decades to find major differences between the brains of humans and other primates, aside from the obvious brain size. The human brain must have reorganized its chemistry and wiring as early human ancestors began to walk upright, use tools, and develop more complex social networks 6 million to 2 million years ago—well before the brain began to enlarge 1.8 million years ago, according to a hypothesis proposed in the 1960s by physical anthropologist Ralph Holloway of Columbia University. But neurotransmitters aren’t preserved in ancient skulls, so how to spot those changes? One way is to search for key differences in neurochemistry between humans and other primates living today. Mary Ann Raghanti, a biological anthropologist at Kent State University in Ohio, and colleagues got tissue samples from brain banks and zoos of 38 individuals from six species who had died of natural causes: humans, tufted capuchins, pig-tailed macaques, olive baboons, gorillas, and chimpanzees. They sliced sections of basal ganglia—clusters of nerve cells and fibers in a region at the base of the brain known as the striatum, which is a sort of clearinghouse that relays signals from different parts of the brain for movement, learning, and social behavior. They stained these slices with chemicals that react to different types of neurotransmitters, including dopamine, serotonin, and neuropeptide Y—which are associated with sensitivity to social cues and cooperative behavior. Then, they analyzed the slices to measure different levels of neurotransmitters that had been released when the primates were alive. © 2018 American Association for the Advancement of Science.

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 24555 - Posted: 01.23.2018

By PATRICK SHARKEY Over the past few years, the discussion of crime and violence in the United States has focused on police brutality, mass incarceration and the sharp rise in violence in cities like Baltimore, St. Louis and Chicago. This is entirely appropriate: Any spike in violence should garner attention, and redressing the injustices of our criminal justice system is a matter of moral urgency. But it is also worth reflecting on how much the level of violence has fallen in this country over the past 25 years and how widespread the benefits of that decline have been. From the 1970s through the early part of the 1990s, the murder rate in some cities in the United States rose to levels seen only in the most violent, war-torn nations of the developing world. In the years since, violent crime has decreased in almost every city, in many cases by more than 75 percent. For well-off urbanites, the decline of crime is most visible in sanitized, closely guarded city spaces where tourists and others can now comfortably wander about. But far more consequential have been the changes in low-income, highly segregated urban communities. Indeed, my research has shown that the most disadvantaged people have gained the most from the reduction in violent crime. Start with the lives saved. Though homicide is not a common cause of death for most of the United States population, for African-American men between the ages of 15 and 34 it is the leading cause, which means that any change in the homicide rate has a disproportionate impact on them. The sociologist Michael Friedson and I calculated what the life expectancy would be today for blacks and whites had the homicide rate never shifted from its level in 1991. We found that the national decline in the homicide rate since then has increased the life expectancy of black men by roughly nine months. That figure may not seem like much, but it is exceedingly rare for any change in society to generate such a degree of change in life expectancy. For example, researchers have estimated that if the obesity epidemic in the United States was eliminated, life expectancy would increase by a similar amount. The drop in homicides is probably the most important development in the health of black men in the past several decades. © 2018 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 14: Attention and Higher Cognition
Link ID: 24528 - Posted: 01.15.2018

April Fulton In the wake of the massacre at a small-town Texas church on Sunday, many people are asking why. A large portion of the mass shootings in the U.S. in recent years have roots in domestic violence against partners and family members. Depending on how you count, it could be upwards of 50 percent. We know the Texas gunman, Devin Patrick Kelley, was court-martialed for assaulting his wife and their young child in 2012, although this information apparently was not included in the formal government database that tracks such things. There are laws on the books preventing convicted domestic violence offenders from obtaining weapons. So why does this keep happening? There are no easy answers. NPR's Alison Kodjak recently talked with Daniel Webster, director of the Johns Hopkins Center for Gun Policy and Research in Baltimore, Md., about the complexities of gun violence, mass shootings, and the difficulty we have in understanding the people who commit these crimes. While perpetrators of domestic violence account for only about 10 percent of all gun violence, they accounted for 54 percent of mass shootings between 2009 and 2016, according to the advocacy group Everytown for Gun Safety, so there is a disproportionate link, Webster tells Kodjak. "Generally, it fits a pattern of easy access to firearms of individuals who have very controlling kind of relationships with their intimate partners and are greatly threatened when their control is challenged," he says. © 2017 npr

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24303 - Posted: 11.08.2017

Susan Milius Kleptopredation klep-toe-preh-day-shun n. A food-gathering strategy of eating an organism and the meal it just ate. A wily sea slug has a way to get two meals in one: It gobbles up smaller predators that have recently gulped in their own prey. “Kleptopredation” is the term Trevor Willis of the University of Portsmouth in England and his colleagues propose for this kind of food theft by well-timed predation. Researchers knew that the small Mediterranean nudibranch Cratena peregrina, with a colorful mane of streamers rippling off its body, climbs and preys on pipe cleaner‒skinny, branched colonies of Eudendrium racemosum hydroids, which are distant relatives of corals. The nudibranchs devour the individual hydroid polyps and, new tests show, prefer them well fed. In experimental buffets with fed or hungry polyps, the nudibranchs ate faster when polyps were fat with just-caught plankton. In this way, at least half of a nudibranch’s diet is plankton. This quirk explains why some biochemical signatures that distinguish predators from prey don’t work out clearly for nudibranchs and hydroids, the researchers report November 1 in Biology Letters. A weird echo of this meal-stealing strategy shows up in certain jumping spiders. The arachnids don’t have the biology to drink vertebrate blood themselves. Instead, they catch a lot of female mosquitoes that have just tanked up (SN: 10/15/05, p. 246). |© Society for Science & the Public 2000 - 2017. All rights reserved.

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 11: Emotions, Aggression, and Stress
Link ID: 24271 - Posted: 11.01.2017

By Michael Price Good luck finding a legislative issue more controversial than gun violence—at least in the United States. Compounding the controversy is a dearth of reliable data, thanks largely to a de facto ban on federally funded firearms research enacted in 1996. Yet a new study funded by Harvard Business School suggests that one policy—a mandatory waiting period between the sale of a gun and its delivery—could save hundreds of U.S. lives each year if implemented nationally. “Absolutely, this study demonstrates a robust association between waiting periods and gun deaths,” says Margaret Formica, a public health researcher at the State University of New York Upstate Medical University in Syracuse who studies firearms deaths but wasn’t involved in the new work. “It’s an innovative way of looking at this issue.” More than 33,000 Americans die each year in gun-related incidents, including accidents, homicides, and suicides, about as many as in vehicle accidents. But regulations that place limits on the sale and ownership of firearms vary widely from state to state, and it’s unclear which measures might actually prevent gun violence. Some research from other countries has suggested that a “cooling off” period between the sale and delivery of a gun can tamp down suicidal impulses and anger-driven violence. So when Harvard University researchers were motivated to contribute to policy-relevant gun research in the wake of the 2012 Sandy Hook Elementary School shooting, such “waiting periods” were an easy jumping-off point. Not only was there past research, but data on waiting-period laws are relatively easy to track down. “Instead of saying, ‘Isn’t it a tragedy, children are dying, oh well, on to the next meeting,’ we decided we wanted to do something,” says Deepak Malhotra, a negotiation and conflict resolution researcher who co-authored the new study with economist Michael Luca. © 2017 American Association for the Advancement of Science

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24205 - Posted: 10.17.2017

By Jessica Hamzelou A rare sighting of a chimpanzee giving birth in the wild came to a grisly conclusion. Within seconds of the birth, the baby was snatched away and eaten by a male of the same group. The observation explains why female chimpanzees tend to go into hiding for weeks or months when they have their babies. Little is known about how chimpanzees give birth in the wild because only five births have ever been observed, says Hitonaru Nishie of Kyoto University in Japan. Nishie and his colleagues have been studying chimpanzees in Tanzania’s Mahale mountains for the last few years. One of the reasons so few have been witnessed is that the soon-to-be mothers often leave the group when the baby is due, and don’t return until the infant is weeks or months old. This absence has been described as a chimpanzee’s “maternity leave”. So Nishie and his colleague Michio Nakamura were surprised when, at around 11 am one December day, a female member of the chimpanzee group they were observing began to give birth in front of the 20 other members. As soon as the baby was out – and before the mother had even had a chance to touch it – the baby was snatched away by a male member of the group, who then disappeared into the bush. The researchers found him around 1½ hours later, sitting up a tree and eating the infant from the lower half of its body. He ate the entire body within an hour. © Copyright New Scientist Ltd.

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24193 - Posted: 10.14.2017

By John Horgan “The Forgotten Era of Brain Chips,” published in Scientific American in October 2005, has provoked as much interest as anything I’ve ever written. It focuses on Jose Manuel Rodriguez Delgado, a pioneer in brain-stimulation research. I keep hearing from journalists and others wanting more information on Delgado, whom I interviewed in 2005 and who died in 2011. Delgado fascinates conspiracy theorists, too. An article on Infowars.com describes him as a “madman” who believed that “no human being has an inherent right to his own personality.” Given widespread interest in and misinformation about Delgado, whose work prefigures current research on brain implants (see “Further Reading”), I’m posting an edited version of my 2005 article. --John Horgan Once among the world’s most acclaimed scientists, Jose Manuel Rodriguez Delgado has become an urban legend, whose career is shrouded in misinformation. Delgado pioneered that most unnerving of technologies, the brain chip, which manipulates the mind by electrically stimulating neural tissue with implanted electrodes. Long a McGuffin of science fictions, from The Terminal Man to The Matrix, brain chips are now being tested as treatments for epilepsy, Parkinson’s disease, paralysis, depression, and other disorders. In part because it was relatively unencumbered by ethical regulations, Delgado’s research rivaled and even surpassed much of what is being done today. In 1965, The New York Times reported on its front page that he had stopped a charging bull in its tracks by sending a radio signal to a device implanted in its brain. He also implanted radio-equipped electrode arrays, which he called “stimoceivers,” in dogs, cats, monkeys, chimpanzees, gibbons, and humans. With the push of a button, he could evoke smiles, snarls, bliss, terror, hunger, garrulousness, lust, and other responses. © 2017 Scientific American,

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 24131 - Posted: 10.02.2017

By Avi Selk Five minutes in the life of a guppy in the terrible spring of 2015: You’re swimming around with your friends in a tank. You’ve been here for days. Food falls from the sky. Everything is fine. Then suddenly, you’re netted up and dropped into an alien world, all alone, just you and the glass. You panic at first, but in time your courage returns and you investigate. Glass wall; glass wall; glass wall; glass wall. A scrap of plastic on the aquarium floor provides the only scant shelter. Hmm … Splash! A huge beak crashes into the water. If you knew what the University of Exeter is, you might wonder how a heron even got inside. Instead, you just cower under the plastic and wait for death. But the beak does not return, and you peek out after a minute or so, and soon the net delivers you back to familiar surroundings. Food and friends again. The terrible memory fades, and life returns to normal. For three days. Then the net again, and the same strange tank of terror. Again and again and again — for you are a guppy in Tom Houslay’s lab, and he wants to understand the very core of your being. The fish could have been any one of the 105 Trinidadian guppies that Houslay’s team at Exeter’s Penryn campus subjected to regular doses of fear two years ago, in an effort to determine whether they have personalities. It turns out they do, of a sort. According to the team’s study, published Monday in the journal Functional Ecology, each fish demonstrated a unique response to stress — which they endured every three days in the form of a pulley-rigged lawn-ornament heron named “Grim,” or a predatory cichlid suddenly revealed on the other side of the glass. “Some of them go straight to the shelter,” said Houslay, an evolutionary biologist and the study’s lead author. “Some just stop moving, maybe hoping they won’t be seen. Some rush to the side and just swim up and down trying to escape.” © 1996-2017 The Washington Post

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24118 - Posted: 09.28.2017

By NATALIE ANGIER Tom Vaughan, a photographer then living in Colorado’s Mancos Valley, kept a hummingbird feeder outside his house. One morning, he stepped through the portico door and noticed a black-chinned hummingbird dangling from the side of the red plastic feeder like a stray Christmas ornament. At first, Mr. Vaughan thought he knew what was going on. “I’d previously seen a hummingbird in a state of torpor,” he said, “when it was hanging straight down by its feet, regenerating its batteries, before dropping down and flying off.” On closer inspection, Mr. Vaughan saw that the hummingbird was hanging not by its feet but by its head. And forget about jumping its batteries: the bird was in the grip of a three-inch-long green praying mantis. The mantis was clinging with its back legs to the rim of the feeder, holding its feathered catch in its powerful, seemingly reverent front legs, and methodically chewing through the hummingbird’s skull to get at the nutritious brain tissue within. “It was staring at me as it fed,” Mr. Vaughan said. “Of course, I took a picture of it.” Startled by the clicking shutter, the mantis dropped its partially decapitated meal, crawled under the feeder — and began menacing two hummingbirds on the other side. “Talk about cognitive dissonance,” Mr. Vaughan said. “I always thought of mantises as wonderful things to have in your garden to get rid of bugs, but it turns out they sometimes go for larger prey, too.” “It gave me new respect for mantises,” he added. © 2017 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24101 - Posted: 09.23.2017

By Jessica Hamzelou Aggression and sexual behaviour are controlled by the same brain cells in male mice – but not in females. The finding suggests that males are more likely to become aggressive when they see a potential mate than females. The brain regions that contain these cells look similar in mice and humans, say the researchers behind the study, but they don’t yet know if their finding has relevance to human behaviour. Similar to humans, male mice are, on the whole, more aggressive than females. Because of this, most research into aggression has overlooked females, says Dayu Lin at New York University. “I would say 90 per cent of aggression studies have been done in males,” she says. “We know very little about aggression in females.” But females can be aggressive too. For instance, female mice can be aggressive when protecting their newborn pups. In 2011, Lin and her colleagues studied a region of the brain called the hypothalamus, responsible for regulating many different behaviours. They discovered a set of cells within this region in male mice that controlled both aggressive and sexual behaviours. When the cells were shut off, the mice didn’t mate or show aggression, but both behaviours could be triggered when the cells were stimulated. © Copyright New Scientist Ltd.

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 24076 - Posted: 09.19.2017

Mariah Quintanilla Kenneth Catania knows just how much it hurts to be zapped by an electric eel. For the first time, the biologist at Vanderbilt University in Nashville has measured the strength of a defensive electrical attack on a real-life potential predator — himself. Catania placed his arm in a tank with a 40-centimeter-long electric eel (relatively small as eels go) and determined, in amperes, the electrical current that flowed into him when the eel struck. At its peak, the current reached 40 to 50 milliamperes in his arm, he reports online September 14 in Current Biology. This zap was painful enough to cause him to jerk his hand from the tank during each trial. “If you’ve ever been on a farm and touched an electric fence, it’s pretty similar to that,” he says. This is Catania’s latest study in a body of research analyzing the intricacies of an electric eel’s behavior. The way electric eels have been described by biologists in the past has been fairly primitive, says Jason Gallant, a biologist who heads the Michigan State University Electric Fish Lab in East Lansing who was not involved in the study. Catania’s work reveals that “what the electric eel is doing is taking the electric ability that it has and using that to its absolute advantage in a very sophisticated, deliberate way,” he says. Electric eels use electric current to navigate, communicate and hunt for small prey. But when faced with a large land-based predator, eels will launch themselves from the water and electrify the animal with a touch of the head. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 5: The Sensorimotor System
Link ID: 24068 - Posted: 09.15.2017

James Gorman African wild dogs sneeze. And that’s a first. No other social animal has been reported to cast a vote, of sorts, by sneezing, although in humans sneezing may once have expressed a negative opinion, as in, “nothing to sneeze at.” Wild dog sneezing is different. For one thing it seems to indicate a positive reaction to a proposal before a group of dogs. When a pack of these dogs is getting ready to hunt, scientists reported Tuesday, the more sneezes, the more likely they are to actually get moving. Just about all social organisms make group decisions that require reaching a consensus. If monkeys or meerkats are looking for a better place to forage, they need to reach a consensus about moving on among a minimum number of animals — called a quorum, just like in Congress. Even some bacteria do this before releasing toxins or lighting up with bioluminescence. Bacteria use chemical signals but larger animals often use sounds as a way of saying, I’m in. However, among grunts, huffs, piping signals and others, the sneeze had not been reported as one of those signals until a group of American, British and Australian researchers published their observations of African dogs in the Proceedings of the Royal Society B. They were studying the dogs where they live in Botswana to see how they decide to go on a hunt. Like most carnivores, the wild dogs sleep a lot. But at some point one of the pack will start what is called a rally, getting all the other members excited and milling around as if they want to play. Sometimes the rallies are successful, and off the pack goes. Sometimes the pack members lie down and go back to sleep. Neil R. Jordan of the University of New South Wales in Sydney, the senior author of the report, noticed that the successful rallies there seemed to have more sneezing. © 2017 The New York Times Company

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 24045 - Posted: 09.07.2017