Links for Keyword: Aggression

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By Christof Koch Recently developed powerful, yet also delicate and refined, genetic tools can inva­sively probe nervous systems of animals, far surpassing the safer but much cruder techniques that psychologists and cognitive neuroscientists use to observe the human brain. Now in a remarkable series of experiments, researchers have located a trigger for aggression in mice—providing us with fresh insights into the workings of our human consciousness. You might object that mice and men are not the same and that studying the murine mind is different from studying the human mind. This fact is obviously true. Yet both Mus musculus and Homo sapiens are nature’s children, sharing much perceptual, cognitive and affective processing. The same process of relentless evolutionary selection has shaped both species—our last common ancestor was a mere 75 million years ago. The structure of their brains, and of their genomes, reflects this similarity. Indeed, only a neuroanatomist can tell a rice grain–size piece of mouse cortex from the same chunk of human cortex. If you think of a mouse as a mere automaton, Google “world’s smartest mouse.” The top hit will be a YouTube video of Brain Storm, a cute brown mouse running a complicated obstacle course—crossing an abyss on a rope; jumping through hoops; going up and down a seesaw, over a pencil, up a steep incline and down a ladder; and navigating around obstacles. It hesitates on occasion, sniffs the air but, once started, speedily completes the circuit. The amazing finesse and utility of contemporary molecular biology techniques are illustrated in recent experiments dealing with sex and power—the twin themes around which much of popular culture, psychoanalysis and art is centered. © 2011 Scientific American

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 15615 - Posted: 07.28.2011

By CAITLIN O’CONNELL-RODWELL Two male black rhinos are huffing and grumbling out their differences just below the tower in a darkness one can know only in wild places. The coming of the new moon makes it hard to ignore the brilliance of the Milky Way in an obsidian sky. Intermittently, the rhinos bellow when one or the other crosses some seemingly arbitrary line drawn in the sand by angry feet. Almost three weeks into the season, it’s impossible not to notice a similar line in the sand drawn by many male denizens of Mushara, and for the elephant, that line plays out in a myriad of forms, from all-out avoidance to full-on combat — not so much over territories, but over who’s in charge. And since the dynamics of male elephant dominance hierarchies are a particular focus of my studies, when and how Greg the elephant draws a line in the sand is under great scrutiny. To address this question, interactions between male elephants are painstakingly documented by my research team via video and live-scoring of behaviors using a Noldus Observer datalogger while elephants visit the water hole. And one or more members of the team are on watch, starting around 10 a.m., to scan the horizon and give the team enough warning that elephants are heading in, in order to ready the equipment for a recording session. © 2011 The New York Times Company

Related chapters from BP7e: 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: 15605 - Posted: 07.26.2011

By JAMES GORMAN From the wild to Wall Street, as everyone knows, the alpha male runs the show, enjoying power over other males and, as a field biologist might put it, the best access to mating opportunities. The beta is No. 2 in the wolf pack or the baboon troop, not such a bad position. But conversationally, the term has become an almost derisive label for the nice guy, the good boy all grown up, the husband women look for after the fling with Russell Crowe. It may now be time to take a step back from alpha worship. Field biologists, the people who gave the culture the alpha/beta trope in the first place, have found there can be a big downside to being No. 1. Laurence R. Gesquiere, a research associate in the department of ecology and evolutionary biology at Princeton, and colleagues report in the journal Science that in five troops of wild baboons in Kenya studied over nine years, alpha males showed very high stress levels, as high as those of the lowest-ranking males. The stress, they suggested, was probably because of the demands of fighting off challengers and guarding access to fertile females. Beta males, who fought less and had considerably less mate guarding to do, had much lower stress levels. They had fewer mating opportunities than the alphas, but they did get some mating in, more than any lower-ranking males. After all, when the alpha gets in another baboon bar fight, who’s going to take the girl home? © 2011 The New York Times Company

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 15561 - Posted: 07.16.2011

By Hal Arkowitz and Scott O. Lilienfeld Earlier this year a 22-year-old college dropout, Jared Lee Loughner, shot Arizona congresswoman Gabrielle Giffords through the head near a Tucson supermarket, causing significant damage to Giffords’s brain. In the same shooting spree, Loughner killed or wounded 18 others, including a federal judge and a nine-year-old girl. Information from Loughner’s postings on YouTube and elsewhere online suggests that he is severely mentally ill. Individuals with serious mental illnesses have perpetrated other recent shoot-ings, including the massacre in 2007 at ­Virginia Tech in which a college senior, ­Seung-Hui Cho, killed 32 people and wounded 17. These events and the accompanying media coverage have probably fed the public’s perception that most profoundly mentally ill people are violent. Surveys show that 60 to 80 percent of the public believes that those diagnosed with schizophrenia, in particular, are likely to commit violent acts. Although studies have pointed to a slight increase in the risk of violent behaviors among those afflicted with major psychiatric ailments, a closer examination of the research suggests that these disorders are not strong predictors of aggressive behavior. In reality, severely mentally ill people account for only 3 to 5 percent of violent crimes in the general population. The data indicate that other behaviors are likely to be better harbingers of physical aggression—an insight that may help us prevent outbursts of rage in the future. Not all psychological and emotional disorders portend violence, even in society’s eyes. In this column, we refer only to severe mental illness—meaning schizophrenia, bipolar disorder or psychotic depression. Symptoms of schizophrenia include marked disturbances in thoughts, emotions and behaviors; delusions (fixed false beliefs); hallucinations (perceiving things that are not physically present); disorganization; and withdrawal from social activities. Bipolar disorder is usually characterized by swings between depression and mania, which involves euphoria and grandiosity, a boost in energy and less need for sleep. Psychotic depression includes acute depressive symptoms, along with delusions or hallucinations, or both. © 2011 Scientific American,

Related chapters from BP7e: Chapter 16: Psychopathology: Biological Basis of Behavior Disorders; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders; Chapter 11: Emotions, Aggression, and Stress
Link ID: 15540 - Posted: 07.09.2011

By SINDYA N. BHANOO The cruel, persistent bullying that older siblings display toward younger ones does not have lifelong consequences — at least among blue-footed boobies, a new study finds. Boobies are marine birds that typically lay two eggs that hatch four days apart. During a four-month nesting period, the senior sibling is known to peck and attack its junior sibling incessantly until the younger bird becomes habitually submissive. Senior chicks end up gaining an advantage in terms of size, strength and motor coordination over their younger siblings. Younger siblings receive fewer feedings and less fish from parents, and during the first three weeks of life their weight is 11 percent lower. Younger chicks also suffer from elevated levels of stress hormones that are 109 percent higher than in senior chicks in the first 15 to 20 days of life. Yet all adult boobies seem equally capable of displaying aggression toward intruders approaching their nests, said Oscar Sánchez-Macouzet , an evolutionary biologist at the National Autonomous University of Mexico and the study’s first author. He and his colleagues report their findings in the journal Biology Letters. “To our surprise, former junior and senior chicks did not differ in their aggressiveness defending their nests,” he said. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 13: Memory, Learning, and Development
Link ID: 15482 - Posted: 06.23.2011

Analysis by Marianne English The warning signs may seem subtle at first -- a child unable to empathize with others; another seems to fear nothing, not even the consequences of violence. With time, researchers say, these descriptions might reflect a growing association between criminality and antisocial behavior. But most recently, determining who might become a danger to society may be as easy as performing a brain scan, according to neurocriminology, a scientific discipline that uses neuroscience to predict and potentially reduce crime. Along these lines, is it realistic to use brain scans to pinpoint which individuals are more at risk for criminal behavior before they commit crimes? For some researchers, the idea is plausible, with the field reviving the nature versus nurture debate, as highlighted by Josh Fischman in a Chronicle of Higher Education article that profiles the work of University of Pennsylvania researcher Adrian Raine. Raine's work, which draws from neuroscience and the legal system, focuses on differences in the minds of criminals and non-criminals. Over the years, he's established evidence for a link between the brain and criminal behavior. By working with murderers, rapists and pedophiles, he's helped confirm that two brain structures -- the amygdala and the prefrontal cortex -- are smaller and less active in individuals with antisocial and criminal tendencies. Both areas are thought to give rise to complex behaviors shaped by emotion and fear. © 2011 Discovery Communications, LLC.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 15477 - Posted: 06.23.2011

By PATRICIA COHEN It was less than 20 years ago that the National Institutes of Health abruptly withdrew funds for a conference on genetics and crime after outraged complaints that the idea smacked of eugenics. The president of the Association of Black Psychologists at the time declared that such research was in itself “a blatant form of stereotyping and racism.” The tainted history of using biology to explain criminal behavior has pushed criminologists to reject or ignore genetics and concentrate on social causes: miserable poverty, corrosive addictions, guns. Now that the human genome has been sequenced, and scientists are studying the genetics of areas as varied as alcoholism and party affiliation, criminologists are cautiously returning to the subject. A small cadre of experts is exploring how genes might heighten the risk of committing a crime and whether such a trait can be inherited. The turnabout will be evident on Monday at the annual National Institute of Justice conference in Arlington, Va. On the opening day criminologists from around the country can attend a panel on creating databases for information about DNA and “new genetic markers” that forensic scientists are discovering. “Throughout the past 30 or 40 years most criminologists couldn’t say the word ‘genetics’ without spitting,” Terrie E. Moffitt, a behavioral scientist at Duke University, said. “Today the most compelling modern theories of crime and violence weave social and biological themes together.” © 2011 The New York Times Company

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 13: Memory, Learning, and Development
Link ID: 15464 - Posted: 06.21.2011

Rowan Hooper, news editor IF YOU like to think of chimps as wise, rational tool-users, gorillas as gentle giants, or bonobos as sexed-up hippie apes, be prepared for a shock. Among African Apes, a collection of field diaries, is primatology given the Tarantino treatment. In the introduction, Martha Robbins of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, emphasises that extreme violence among primates is rare. The incidents described in the book stuck in the biologists' minds because they illustrate how aggression can influence ape society. They stuck in my mind too because, infrequent as they are, these are clearly not random episodes, but key moments in the lives of characters who behave in such familiar ways that we see ourselves in them. In the course of the book we learn about infanticide and violent infighting among silverback gorillas. We get to know Mlima, a gorilla the biologists have been observing almost daily for six years. Through diary entries we are there when they find her dying from wounds inflicted by a younger member of her own species. We also meet Volker, an ambitious young bonobo the researchers have followed for most of his life. Volker has close relations with Amy, a female whose baby the researchers believe he fathered, but the attention he pays her is finally punished: he is savagely beaten by his former friends. The biologists observe Volker's screaming face as he clings to a tree trunk, then never see him again. Josephine Head, also of the Max Planck Institute, describes how she tracked a trail of blood from where chimps had been vocalising loudly the night before, and made a horrible discovery: the spread-eagled body of an adult male chimp, his face battered and bruised, throat torn open and intestines dragged out. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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: 15400 - Posted: 06.07.2011

by Shaoni Bhattacharya SEEMINGLY random acts of violence by bottlenose dolphins on porpoises could be down to sexual frustration among young males. Cases of the cetaceans killing other creatures for no apparent reason have been reported in UK waters. Now bottlenose dolphins have been seen attacking harbour porpoises in the Pacific Ocean. Crucially, these observations show for the first time that the attackers are young males (Marine Mammal Science, DOI: 10.1111/j.1748-7692.2011.00474.x). Mark Cotter at Okeanis, a non-profit conservation organisation in Moss Landing, California, and colleagues observed three acts of aggression by dolphins on lone porpoises. The dolphins chased the porpoises at high speed, rammed and then drowned them. In one particularly violent attack, three dolphins corralled their victim before seven others joined them to ram the porpoise to death. Cotter found most shocking the fact that two dolphins remained behind to play with the carcass before pushing it towards his boat. "It was almost like they said: 'We're done playing with it, here you go'." Competition for food does not seem to explain the attacks, as the dietary overlap between the two species is small, says Cotter. But the fact that 21 of the 23 attackers were males may be revealing. He believes that the attacks are "object oriented play" during the breeding season by young males who cannot get access to females because of competition from older males. "They are taking out their frustrations," he says. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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: 15399 - Posted: 06.04.2011

by Jessica Hamzelou BASEBALL star Barry Bonds is back in the spotlight this week, for all the wrong reasons. The sports legend is on trial in the US, accused of lying to a grand jury when he denied that he had ever knowingly taken performance-enhancing steroids. Meanwhile, psychologists are beginning to work out how these drugs can trigger aggressive behaviour and suggesting potential therapies that could be taken alongside steroids to block this unwelcome side effect. But could such a therapy encourage drug abuse? At the end of 2007, Bonds was charged with making false statements and obstruction of justice. He pleaded not guilty and his trial commenced on 21 March this year. In support of the case that Bonds took steroids, his ex-girlfriend, Kimberly Bell, gave evidence in which she claimed that he exhibited periods of aggressive behaviour. Aggression is one of the better-known side effects of steroid use and is often referred to as "roid rage". A survey in 2008 of 7000 American teenage boys found those who took anabolic steroids reported significantly higher levels of violent behaviour than boys who did not take them (American Journal of Public Health, DOI: 10.2105/ajph.2008.137018). Now, Thomas Hildebrandt's team at Mount Sinai School of Medicine in New York are conducting the first longitudinal study of anabolic steroid users. By monitoring participants before, during and after cycles of steroid use, the group hopes to work out how the drugs exert their effects and how long these might last. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 15185 - Posted: 04.07.2011

The brains of some aggressive and antisocial teenage boys look different than those of normal teenagers, British researchers have found. Conduct disorder is psychiatric condition characterized by higher than normal levels of aggressive and antisocial behaviour. It can develop in childhood or in adolescence and affects around five out of every 100 teenagers in the UK, researchers say. People affected by conduct disorder run a greater risk of further mental and physical health problems in adulthood. The new brain scan findings published in Friday's online issue of the American Journal of Psychiatry suggest adolescents who develop conduct disorder have differences in their brain and are not merely imitating misbehaving peers. "Changes in grey matter volume in these areas of the brain could explain why teenagers with conduct disorder have difficulties in recognizing emotions in others. Further studies are now needed to investigate whether these changes in brain structure are a cause or a consequence of the disorder," said Prof. Ian Goodyer of the University of Cambridge. For the study, scientists used MRIs to look at the brains of 65 teenage boys with conduct disorder and 27 healthy teenage boys.The volume of the insula, in yellow, was smallest in those with the most severe behaviour problems.The volume of the insula, in yellow, was smallest in those with the most severe behaviour problems. University of Cambridge © CBC 2011

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 13: Memory, Learning, and Development
Link ID: 15167 - Posted: 04.02.2011

by Sara Reardon If you want to know whether your new fluffy puppy will be a cuddly friend or snarl at and bite anything that moves, you might want to check out the length of its genes. Researchers at the University of Tokyo in Japan asked 100 Akita owners to fill out questionnaires about whether their pooches were naughty or nice. When they looked at the doggies' DNA, the scientists found that the meanest males more often had a shortened gene for a receptor that responds to various male hormones. The gene variant produces a form of the protein that has previously been shown to respond more strongly to testosterone. This is the first time that canine aggression has been associated with genetic differences in the male hormone receptor, the researchers report in Biology Letters this week. Over half of the Akitas they studied had this variant. Yet mean female dogs weren't more likely to have the short variant than the gentle dogs, suggesting that females respond differently to these hormones. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 8: Hormones and Sex
Link ID: 15156 - Posted: 03.31.2011

by Shanta Barley Female hamadryas baboons may be vulnerable to a form of domestic violence from which they feel unable to escape – even if they have the opportunity. Most large papionin monkeys – a group including macaques, baboons and mandrills – rely on wandering males to disperse genes through the population. But studies suggest that gene flow through populations of hamadryas baboons (Papio hamadryas) in north-east Africa is mainly through females – even though males keep tight control of them and punish wanderers through vicious biting. In 1968, biologist Hans Kummer suggested that females move when they are abducted by another male – but only now have biologists observed such abductions. Mathew Pines at the Filoha Hamadryas Project in Addis Ababa, Ethiopia, witnessed three abductions between 2007 and 2009. Each time, the original male embarked on an often bloody rescue mission to locate and retrieve the female. Larissa Swedell at the City University of New York, Pines's co-author on the new study, speculates that abduction is not considered a "fair" way to gain a new female, and so the loss isn't accepted by the original male. The rescue missions were helped by the females, who willingly returned to the rescuer despite a history of violent treatment by that male. "The bond is so strong that a female will run to her male when she is frightened, even if he is the source of the threat," says Swedell. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: 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: 15130 - Posted: 03.24.2011

By Clara Moskowitz The latest neuroscience research is presenting intriguing evidence that the brains of certain kinds of criminals are different from those of the rest of the population. While these findings could improve our understanding of criminal behavior, they also raise moral quandaries about whether and how society should use this knowledge to combat crime. In one recent study, scientists examined 21 people with antisocial personality disorder – a condition that characterizes many convicted criminals. Those with the disorder "typically have no regard for right and wrong. They may often violate the law and the rights of others," according to the Mayo Clinic. Brain scans of the antisocial people, compared with a control group of individuals without any mental disorders, showed on average an 18 percent reduction in the volume of the brain's middle frontal gyrus, and a 9 percent reduction in the volume of the orbital frontal gyrus — two sections in the brain's frontal lobe. Another brain study, published in the September 2009 Archives of General Psyciatry, compared 27 psychopaths — people with severe antisocial personality disorder — to 32 non-psycopaths. In the psychopaths, the researchers observed deformations in another part of the brain called the amygdala, with the psychopaths showing a thinning of the outer layer of that region called the cortex and, on average, an 18-percent volume reduction in this part of brain. © 2011 LiveScience.com.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 15068 - Posted: 03.05.2011

By Bruce Bower WASHINGTON — When an unrelenting penchant for misbehaving joins forces with lack of emotion, guilt and empathy, 7-year-olds are headed for years of severe conduct problems, a long-term study of English youngsters suggests. Youngsters who regularly misbehave and get into trouble at age 7, and who also display so-called callous-unemotional traits, frequently stay on a troubled course until at least age 12, according to a new investigation described February 20 in Washington, D.C., at the annual meeting of the American Association for the Advancenent of Science. “I’m not suggesting that these children are psychopaths, but callous-unemotional traits can be used to identify kids at risk of persistent, severe antisocial behavior,” said psychologist Nathalie Fontaine of Indiana University in Bloomington, who directed the study. Adult psychopaths similarly show no remorse for crimes and blunted emotional reactions, although they often possess considerable empathy that they use to prey on others. These findings indicate that callous-unemotional traits should be factored into the definition of a particularly virulent form of childhood conduct disorder in the next manual of psychiatric disorders, Fontaine said. Chronic misbehavior alone defines conduct disorder in the current fourth edition of the psychiatric manual used by doctors to define mental ailments, now being revised. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 11: Emotions, Aggression, and Stress
Link ID: 15027 - Posted: 02.21.2011

Ewen Callaway Sex and violence are intertwined in mice. A tiny patch of cells buried deep within a male's brain determines whether it fights or mates, and there is good reason to believe humans possess a similar circuit. The study, published in Nature today1, shows that when these neurons are quieted, mice ignore intruding males they would otherwise attack. Yet when the cells are activated, mice assault inanimate objects, and even females they ought to court. The cells lie within an area of the hypothalamus with known links to violent behaviour. An electrical jolt to this vicinity causes cats and rats to turn violent, but neurophysiological experiments conducted decades ago stimulated too big an area to identify the specific brain circuits, let alone the individual neurons, involved in aggression. More recently, scientists studying mice engineered to lack specific genes have found that some of them act more aggressively than normal mice. "We really don't know which part of the brain went wrong in those mice. Consequently it's tough to make sense of that behaviour," says Dayu Lin, a neuroscientist now at New York University and an author of the study, who began searching for the seat of aggression in mice while working with David Anderson at the California Institute of Technology in Pasadena. © 2011 Nature Publishing Group,

Related chapters from BP7e: 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: 14994 - Posted: 02.12.2011

Jessica Marshall Mild-mannered male squid turn into furious fighting machines when their tentacles brush a chemical on the surface of squid eggs, a finding that could give insights into how aggression works. The discovery also reveals how male squid compete for female mating partners. "I think that this is really a novel and kind of wonderful addition to our understanding of how aggression might work," said Russell Fernald of Stanford University, who was not a part of the study. Researchers diving on squid spawning grounds had noticed that not just female squid would hang around the many mop-like clusters of egg capsules. "We noticed underwater that the males were attracted to the eggs, too. This made no sense. All the eggs are fertilized already. This caught our attention," lead author Roger Hanlon of the Marine Biological Laboratory in Woods Hole, Mass. told Discovery News. A key to solving the puzzle came during a Cape Cod dive. "There was absolutely nothing that was happening, it was Deadsville." Hanlon said. So, he fetched some squid eggs from the boat and brought them back to the dive site. "I just put the squid eggs on the bottom. Within a minute or two, one bold male squid went down and touched them. He came back up to the squid above him and started fighting with other squid." © 2011 Discovery Communications, LLC.

Related chapters from BP7e: 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: 14991 - Posted: 02.12.2011

By Laura Sanders A cluster of nerve cells have founded their own tiny fight club. These cells, nestled deep in a primitive part of the brain, compel mice to aggressively maul not just intruder males, but also females and blown-up rubber gloves, a study finds. What’s more, the fight cells have an intertwined and thorny relationship with nearby “mate” cells, a discovery that may shed light on human sexual violence. “This is absolutely awesome,” says neuroscientist Newton Canteras of the University of São Paulo, who was not involved in the study. “They [researchers] were able to pinpoint one tiny region in the hypothalamus that is responsible for the aggressive response.” The research, led by Dayu Lin of New York University’s Langone Medical Center, was published in the Feb. 10 Nature. Earlier studies had pointed to the hypothalamus, an almond-sized structure important for hunger, thirst and body temperature, as an aggression center in the brain. Electrical stimulation there made cats and rats attack targets. But researchers didn’t have a clear idea of where in the hypothalamus the fight neurons reside. Now, for the first time, scientists have pinpointed the exact location, says study coauthor David Anderson, a Howard Hughes Medical Institute investigator at Caltech. Researchers found the cells by monitoring the brains of male mice during attacks on male mouse intruders. If the hypothalamus is a country, “these cells are located in one neighborhood in a city in a state in that country,” he says. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 14974 - Posted: 02.10.2011

By SINDYA N. BHANOO For some genes, either the father’s version or the mother’s version is active, but not both. Which version of the gene works is determined before conception, as the sperm and egg are developing, in a process called imprinting. By mimicking that process in the lab, and turning off a gene in mice, scientists have produced a change in social dominance behavior. In laboratory tests, mice with the paternal version of the gene known as Grb10 inactivated were more aggressive in their behavior, according to new research in the journal Nature. The researchers had two methods of measuring social dominance. They found that mice with the inactive gene engaged in more social grooming, and nibbled off more fur and whiskers of other mice. Also, when two mice were placed in a tube and approached each other, mice with the inactive gene were less likely to back down and turn away. “Both males and females with the paternal gene off are adopting this socially dominant behavior,” said Andrew Ward, a geneticist with the Center for Regenerative Medicine at the University of Bath in Britain. In natural reproduction, the paternal version of the gene is generally active, Dr. Ward said, but some mice may have a greater number of active versions than others. “We’ve shown the extreme,” he said. “But you might have a more subtle variation in how much this behavior is expressed.” © 2011 The New York Times Company

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress
Link ID: 14931 - Posted: 01.29.2011

by Greg Miller Testimony on the brain activity of a convicted murderer may have saved him from the death penalty. Earlier this month, a jury in Miami rejected the death penalty and chose life in prison for Grady Nelson, who in 2005 stabbed his wife 61 times, killing her, and stabbed and raped her 11-year-old, mentally handicapped daughter. A report in The Miami Herald last weekend suggests that measurements of Nelson's brain activity may have influenced some members of the jury, who viewed the results as evidence of a brain injury that would partially explain his behavior. But some scientists are critical of the way this technology was used in the case. During the sentencing phase of the trial, the court heard testimony from Robert Thatcher, a neuroscientist and president of by Applied Neuroscience Inc. of St. Petersburg, Florida. Thatcher's company examined Nelson using a method called quantitative electroencephalography (QEEG). As in standard EEG, technicians place electrodes on the skull to record electrical activity in the brain. In QEEG, a computer program analyzes these recordings to locate regions of abnormal activity. In Nelson's case, there was an obvious abnormality in the left frontal lobe, Thatcher says. Thatcher also testified that Nelson exhibited "sharp waves" originating from this region. These large spikes in the EEG trace are typically seen in people with epilepsy. Grady is not epileptic, but he does have a history of at least three traumatic brain injuries, Thatcher said yesterday in an interview. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: 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 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 14789 - Posted: 12.16.2010