Immunization with an experimental anti-cocaine vaccine resulted in a substantial reduction in cocaine use in 38 percent of vaccinated patients in a clinical trial supported by the National Institute on Drug Abuse (NIDA), a component of the National Institutes of Health. The study, published in the October issue of the Archives of General Psychiatry, is the first successful, placebo-controlled demonstration of a vaccine against an illicit drug of abuse. Like vaccines against infectious diseases such as measles and influenza, the anti-cocaine vaccine stimulates the immune system to produce antibodies. Unlike antibodies against infectious diseases, which destroy or deactivate the disease-causing agents, anti-cocaine antibodies attach themselves to cocaine molecules in the blood, preventing them from passing through the blood-brain barrier. By preventing the drug’s entry into the brain, the vaccine inhibits or blocks the cocaine-induced euphoria. This study included 115 patients from a methadone maintenance program who were randomly assigned to receive the anti-cocaine vaccine or a placebo (inactive) vaccine. Participants were recruited from a methadone maintenance program because their retention rates are substantially better than programs focused primarily on treatment for cocaine abuse. Participants in both groups received five vaccinations over a 12-week period and were followed for an additional 12 weeks. All participants also took part in weekly relapse-prevention therapy sessions with a trained substance abuse counselor, had their blood tested for antibodies to cocaine, and had their urine tested three times a week for the presence of opioids and cocaine.

Keyword: Drug Abuse
Link ID: 13327 - Posted: 06.24.2010

By Nira Liberman and Oren Shapira Love has inspired countless works of art, from immortal plays such as Romeo and Juliet, to architectural masterpieces such as the Taj Mahal, to classic pop songs, like Queen's “Love of My Life”. This raises the obvious question: why is love such a stimulating emotion? Why does the act of falling in love – or at least thinking about love – lead to such a spur of creative productivity? One possibility is that when we’re in love we actually think differently. This romantic hypothesis was recently tested by the psychologists Jens Förster, Kai Epstude, and Amina Özelsel at the University of Amsterdam. The researchers found that love really does alter our thoughts, and that this profound emotion affects us in a way that is different than simply thinking about sex. The clever experiments demonstrated that love makes us think differently in that it triggers global processing, which in turn promotes creative thinking and interferes with analytic thinking. Thinking about sex, however, has the opposite effect: it triggers local processing, which in turn promotes analytic thinking and interferes with creativity. Why does love make us think more globally? The researchers suggest that romantic love induces a long-term perspective, whereas sexual desire induces a short-term perspective. This is because love typically entails wishes and goals of prolonged attachment with a person, whereas sexual desire is typically focused on engaging in sexual activities in the "here and now". Consistent with this idea, when the researchers asked people to imagine a romantic date or a casual sex encounter, they found that those who imagined dates imagined them as occurring farther into the future than those who imagined casual sex.

Keyword: Emotions; Sexual Behavior
Link ID: 13326 - Posted: 06.24.2010

by Kathleen McGowan Why does being bad feel so good? Pride, envy, greed, wrath, lust, gluttony, and sloth: It might sound like just one more episode of The Real Housewives of New Jersey, but this enduring formulation of the worst of human failures has inspired great art for thousands of years. In the 14th century Dante depicted ghoulish evildoers suffering for eternity in his masterpiece, The Divine Comedy. Medieval muralists put the fear of God into churchgoers with lurid scenarios of demons and devils. More recently George Balanchine choreographed their dance. Today these transgressions are inspiring great science, too. New research is explaining where these behaviors come from and helping us understand why we continue to engage in them—and often celebrate them—even as we declare them to be evil. Techniques such as functional magnetic resonance imaging (fMRI), which highlights metabolically active areas of the brain, now allow neuroscientists to probe the biology behind bad intentions. The most enjoyable sins engage the brain’s reward circuitry, including evolutionarily ancient regions such as the nucleus accumbens and hypothalamus; located deep in the brain, they provide us such fundamental feelings as pain, pleasure, reward, and punishment. More disagreeable forms of sin such as wrath and envy enlist the dorsal anterior cingulate cortex (dACC). This area, buried in the front of the brain, is often called the brain’s “conflict detector,” coming online when you are confronted with contradictory information, or even simply when you feel pain. The more social sins (pride, envy, lust, wrath) recruit the medial prefrontal cortex (mPFC), brain terrain just behind the forehead, which helps shape the awareness of self.

Keyword: Emotions; Drug Abuse
Link ID: 13325 - Posted: 06.24.2010

By Angela Harrison Students could one day face dope tests to prove they have not boosted their academic performance with so called "smart drugs", a psychologist suggests. More students are turning to drugs in an attempt to boost their grades, writes Vince Cakic of Sydney University in the Journal of Medical Ethics. Among drugs apparently being used are those designed to treat hyperactivity and dementia. Some academics think their use can be a positive thing, if regulated. They say that although much written about the extent of drug use in the UK is anecdotal, studies at American universities suggest as many as one in four students on some campuses are taking stimulants. Mr Cakic said: "The possibility of purchasing 'smartness in a bottle' is likely to have broad appeal to students seeking to gain an advantage in an increasingly competitive world." The drugs would be near impossible to ban, he said. "As laughable as it may seem, it is possible that scenarios such as this [urine testing] could very well come to fruition in the future. "However, given that the benefits of [smart drugs] could also be derived from periods of study at any time leading up to examinations, this would also require drug testing during non-exam periods," he writes. "If the current situation in competitive sport is anything to go by, any attempt to prohibit the use ... will probably be difficult or inordinately expensive to police effectively," he warns. Experts working in the UK are divided on the issue between those who believe such drugs, if taken under supervision, are a legitimate way of boosting performance and those who warn of the health and social dangers of such use. (C)BBC

Keyword: Learning & Memory; ADHD
Link ID: 13324 - Posted: 10.05.2009

By Bruce Bower It’s been 4.4 million years since a female now nicknamed Ardi lived in eastern Africa, but she still knows how to make an entrance. Analyses of her partial skeleton and the remains of at least 36 of her comrades, described in 11 papers in the Oct. 2 Science, provide the first comprehensive look at an ancient hominid species. Ardipithecus ramidus evolved a few million years after humanity’s evolutionary family diverged from a lineage that led to chimpanzees, but it is not clear exactly how this species is related to other early hominids. Ardi’s skeleton, which includes a skull with teeth, arms, hands, pelvis, legs and feet, indicates that the common ancestors of people and African apes (which include chimpanzees and gorillas) did not resemble chimpanzees, as many scientists have assumed, says anthropologist and project director Tim White of the University of California, Berkeley. Ardi displays an unexpected mix of apelike and monkeylike traits suitable for both tree climbing and upright walking. Overall, Ardipithecus looks unlike any living primate, White adds. Early hominids evolved in distinctive ways, so modern apes and monkeys provide poor models of a creature such as Ardi, in his view. “Ardipithecus is so rife with anatomical surprises that no one could have imagined it without direct fossil evidence,” White says. © Society for Science & the Public 2000 - 2009

Keyword: Evolution
Link ID: 13323 - Posted: 06.24.2010

by Amy Barth; Biochemist Peter Davies began investigating Alzheimer’s disease in the 1970s, long before its full impact became clear. By 2030 roughly 7.5 million Americans will have this debilitating neurodegenerative disorder. Already Alzheimer’s costs the country $148 billion a year; we urgently need to find the cause—and a cure. For years the prevailing theory was that memory loss was caused by protein fragments, so-called plaques and tangles, that accumulate in the brain. Davies, now at the Litwin-Zucker Center for the Study of Alzheimer’s Disease and Memory Disorders in Manhasset, New York, suspects a different culprit. His hunch is that the mechanisms controlling cell division have gone wrong—somewhat like what happens in cancer—and that plaques and tangles are the result. In the quest for answers, Davies has led hundreds of studies and examined more than 6,000 brains. What is the central mystery of Alzheimer’s? The two main abnormalities of the disease are microscopic lesions called plaques and tangles, which occur in the brains of patients. This is how the disease was first recognized, in 1906. We want to know if these abnormalities are the result of the disease process or if they are abnormalities that cause the disease. That’s been the number-one question in the field for a long time, and there’s a lot of debate and disagreement about it—are the plaques and tangles cause or effect? If we have known about Alzheimer’s since 1906, why do we still not understand it? By the time we get to look at the brain of a patient with Alzheimer’s, it’s really end-stage disease. Alzheimer’s is an agonizingly slow process, so by the time we get to study the disease itself during its late stages, all kinds of things have gone on that may be just consequences of disease rather than causal.

Keyword: Alzheimers
Link ID: 13322 - Posted: 06.24.2010

by Jessica Hamzelou Boosting brain waves can make people move in slow motion. This finding is one of the first to show that brain waves directly influence behaviour, and it could lead to new treatments for Parkinson's disease and other disorders that affect movement. Peter Brown and his colleagues at University College London generated a small electrical current in the brains of 14 healthy volunteers using scalp electrodes. The current increased the activity of normal beta waves – a kind of brain wave that is usually active during sustained muscle activities, such as holding a book. Beta activity usually drops before people begin a movement. The participants then carried out a simple task: they moved a spot on a computer screen as quickly as possible using a joystick. When beta wave activity increased, their fastest times slowed by 10 per cent. "This is the first time that beta wave activity has been shown to slow movement," Brown says. Other studies have found that people with Parkinson's disease have greater beta activity. Brown's research suggests this could be linked to the slowing of movement seen in those with the disease. Electrical stimulation deep in the brain is used to treat people with Parkinson's, although how it works is a subject of debate. © Copyright Reed Business Information Ltd

Keyword: Parkinsons; Sleep
Link ID: 13321 - Posted: 06.24.2010

By Fergus Walsh Babies who are starved of oxygen at birth have a much lower risk of brain damage if they are given mild hypothermia, major research suggests. More than 300 babies were involved in a trial carried out at 33 hospitals in the UK and in five other countries. Researchers found full-term babies who suffered oxygen loss at birth were 57% more likely to survive without brain damage if their bodies were cooled. The findings are published in the New England Journal of Medicine. The babies' body temperature was brought down by about 4C using a fluid-filled mat under their sheet. Doctors are not exactly sure why it helps, but think that slowing their metabolism reduces the after-shocks of the birth trauma, giving the brain time to recover. Dr Denis Azzopardi, from Imperial College London and who led the trial, said: "The study builds on a 20-year body of research but gives, for the first time, irrefutable proof that cooling can be effective in reducing brain damage after birth asphyxia. "Although unfortunately it doesn't work in every case, our study showed the proportion of babies that survived without signs of brain damage went from 28% to 44% with cooling treatments - that's a 57% increase." Carmel Bartley, Family Support Manager from the children's charity Bliss, said: "This is very welcome research into an area which is known to save lives. Cooling of babies with birth asphyxia is an innovative technique already being used in some neonatal centres. "This is a specialist treatment that we would like to see used more widely to ensure the very best outcomes for our most vulnerable babies." (C) BBC

Keyword: Development of the Brain
Link ID: 13320 - Posted: 10.01.2009

By Hal Arkowitz and Scott O. Lilienfeld Obesity is a “global epidemic,” according to the World Health Organization. Two thirds of American adults and one third of school-age children are either overweight or obese (defined as extremely overweight). These proportions have been rising steeply, report the latest surveys. From 1960 to 2002 the population of overweight and obese adults increased by roughly 50 percent, and the corresponding increase for children was 300 percent. Compounding the problem, obesity rates in other countries are rapidly approaching those in the U.S. What is causing this pandemic, and what can we do about it? Researchers have provided some tentative answers that fly in the face of commonly held beliefs. They suggest that the increase in obesity may be a result of environmental changes that tempt us into unhealthy habits and tend to overwhelm our psychological defenses against consuming too much and succumbing to fattening fare. In fact, environmental cues can exacerbate any innate tendency to use food as a balm for jittery nerves or sadness. Thus, many health experts advocate legislation—for instance, a tax on junk food—that promotes healthy eating. Others are trying to help individuals change their immediate eating milieu in ways that discourage overeating. Many people, including health care professionals, believe that obesity can be attributed simply to a lack of self-control or willpower. It is true that obese people are often unable to adequately control their eating. But lack of self-control is merely a description, not an explanation. What remains to be explained is why they cannot exercise self-control. © 1996-2009 Scientific American Inc.

Keyword: Obesity
Link ID: 13319 - Posted: 06.24.2010

By Jesse Bering fearful faceBuon giorno from Florence, where I’m presently under the Tuscan sun—sizzling like bacon, I should add—as a hive of awestruck, pale-legged American tourists wearing Nikes, cargo shorts and Polo shirts descend with digital cameras at the ready on the Renaissance city’s signature Duomo in the Piazza Della Signoria. As for me, I’m at an overpriced cafe with a “Coca-Cola Light” in my hand; in the square before me, a bedraggled carriage horse has its great tethered head to the ground, warily inspecting some lime-green gelato spilled moments ago on the cobblestones by a fussy little Australian boy. If I were of a literary rather than a scientific bent, I would find these scenes inspiring; Dante himself couldn’t imagine a stranger hell than his beloved Florence stuffed with such exotic modern characters, pigeons whiffling overhead. Instead, I’m gazing out across this piazza and wondering how many psychopaths there are milling about out there, the cleverest of whom often go unnoticed. What prompts this strange thought is my earlier visit to a lesser-known tourist attraction here in Florence called “The Museum of Serial Killers.” After all, once one is finished marveling over masterpieces like Michaelangelo’s David and Botticelli’s Birth of Venus in the famed Galleria Dell’Accademia and the Uffizi, it’s easy to get fatigued by all the religious iconography in this city. I found myself standing before fantastic, gilded works by the Italian masters and muttering, “Just another Jesus,” and “Oh, it’s only Mary again.” (What a pity so many artists of that age concentrated their talents so heavily on so few subjects.) So, though it's sensational, The Museum of Serial Killers offers respite from these more venerable Florentine sites. Unfortunately, it’s also as tacky inside as its name on the marquee promises, mostly waxworks of notorious psychopaths such as the 15th century French sadist Gilles de Rais, a smiling and unctuous Ted Bundy leaning against a fancy sports car, even a disturbingly realistic reconstruction of John Wayne Gacy’s suburban living room—complete with decomposing corpses beneath the floorboards. © 1996-2009 Scientific American Inc.

Keyword: Aggression; Emotions
Link ID: 13318 - Posted: 06.24.2010

By Michael Torrice For many animals, it pays to have a split mind. A brain with multiple lobes helps humans make more efficient decisions, and it allows birds to spot predators quickly. But a new study in fish uncovers possible hidden costs to a divided brain. Scientists once thought that only humans had a split in brain functions, called lateralization, with some tasks performed on the left side and others on the right. More recently, studies in primates, birds, and fish have suggested that asymmetric brains are common in many vertebrates and that more lateralized brains are more efficient. In a recent experiment, for example, parrots with more brain lateralization were more successful at finding seeds hidden among pebbles. But despite this cognitive boost, scientists have observed a great range of brain lateralization among fish and birds. Some of these animals can have almost completely symmetrical brains. So are there disadvantages to lateralization? To find out, Marco Dadda, a psychobiologist at the University of Padova in Italy, and his colleagues focused on goldbelly topminnows (Girardinus falcatus), a species known for its lateralized brain. For 4 years, the scientists bred three minnow groups to have different dominant sides of their brains. They determined the stronger half by watching which way the fish turned to avoid a predator: Turning right 80% of the time meant the right eye--and thus the left brain hemisphere--was dominant, whereas showing no turn preference pointed to a nonlateralized brain. © 2009 American Association for the Advancement of Science.

Keyword: Laterality
Link ID: 13317 - Posted: 06.24.2010

The drug vorinostat is able to cross the blood-brain barrier and reduce the development of large metastatic tumors in mice brains by 62 percent when compared to mice that did not receive the drug, according to a new study. In humans, the drug has been approved by the U.S. Food and Drug Administration for the treatment of a cancer called cutaneous T-cell lymphoma but can be used experimentally to study its effectiveness against other cancers. This research, by investigators at the National Cancer Institute (NCI), part of the National Institutes of Health, and their collaborators, appears online Sept. 29, 2009, in Clinical Cancer Research. For people, while various therapies are improving the survival of breast cancer patients, the incidence of breast cancer spreading to the brain is increasing. Brain metastases of breast cancer have proven to be largely untreatable because the blood-brain barrier, which arises from the specialized structure of blood capillaries in the brain, severely limits drug access and many drugs are actively transported out of brain at this barrier. Consequently, the one-year survival estimate for breast cancer patients after a diagnosis of brain metastasis is only about 20 percent. Vorinostat has been found to slow the growth of primary tumors of several different types of cancer in mice. Previous studies have suggested that the drug can be taken up by the brain, although little was known about its effects on metastatic tumors. Therefore, to study the effect of vorinostat on the formation of brain metastases, scientists used a mouse model of human breast cancer. Human breast cells were cultured in the laboratory and were injected into mice with compromised immune systems. The breast cancer cells then migrated to the brain, forming metastases.

Keyword: Miscellaneous
Link ID: 13316 - Posted: 10.01.2009

by Amanda Gefter New Scientist caught up with husband-and-wife writing team David Barash and Judith Eve Lipton to discuss their latest book, Strange Bedfellows: The surprising connection between sex, evolution and monogamy. We ask them what we can learn about monogamy from other species, and how writing a book about monogamy affected their own marriage. Your last book, The Myth of Monogamy (W. H. Freeman, 2001) talked about the rarity of monogamy in nature. What made you decide to write another book on the subject? David: Intellectual honesty or a scientific balancing of the scales if you will. Myth of Monogamy was looking at the glass half empty, at the problems that biology poses for monogamy, but we were aware that monogamy, for all its difficulties, does happen. It happens in animals, it happens in humans. We didn't want to give the impression that it's impossible. Judith: There were both scientific and personal reasons. We thought it was important to point out that the promiscuous behaviour we were describing in ducks, for example, doesn't necessarily hold for people. David and I have been married and monogamous since 1977. There are different kinds of monogamy – for instance, there's a tapeworm that has only one partner until it dies. That's extremely unusual, but there are other forms of monogamy that are more common, like us! We were each married before and have had other sexual partners, but have been monogamous in our own marriage. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 13315 - Posted: 06.24.2010

by Nic Fleming A diminutive chihuahua and a lumbering Irish wolfhound look completely different, yet most us know they both belong to the concept called "dog". Now the brain regions responsible for our ability to organise the world into separate concepts have been pinpointed. Forming a concept involves selecting the important characteristics of our experiences and categorising them. The degree to which we are able to do this effectively is a defining characteristic of human intelligence. Yet little is known about how conceptual knowledge is created and used in the brain. In an attempt to identify the brain regions responsible, Dharshan Kumaran and colleagues at the Wellcome Trust Centre for Neuroimaging, University College London, showed 25 volunteers pairs of fractal patterns that represented the night sky and asked them to forecast the weather – either rain or sun – based on the patterns. Conceptual rules based on the positions and combinations of the patterns governed whether the resulting outcome would be rain or sun, but the volunteers were not told this. Instead correct predictions were rewarded with cash prizes, encouraging the volunteers to deduce these conceptual rules. In an initial learning phase, the different possible combinations were repeatedly shown to the participants. While they could make their predictions by simply memorising previous outcomes, they could also begin to realise that rules based on the positions and combinations of the patterns governed whether the result would be rain or sun. © Copyright Reed Business Information Ltd

Keyword: Learning & Memory; Attention
Link ID: 13314 - Posted: 06.24.2010

by Peter Aldhous You cannot grow up without leaving your mother's protection and learning to make your own way in the world. Now for rat pups, at least, we have a clear idea of the changes in the brain involved in this vital transition. A team led by Regina Sullivan of New York University's Langone Medical Center previously found that young pups will become attracted to odours – even when those odours are paired with electric shocks. Only when pups reach about 10 days old do they become capable of associating odours with negative stimuli. What enables this transition from blind attraction to the ability to learn about potential danger? Sullivan found previously that odours associated with their mother suppress the release in rat pups of the stress hormone corticosterone. Now her team has shown that corticosterone suppression in turn reduces levels of the neurotransmitter dopamine in the amygdala, a structure that acts as the brain's "fear centre". Smelling a rat The researchers found that in 8-day-old pups exposed to shock-paired odours, genes involved in the release of dopamine were relatively inactive. But these genes were much more active in 12-day-old pups, which learned to avoid the shock-linked odours. What's more, when the team injected 8-day-olds with corticosterone, the activity of the dopamine-associated genes rose, and the pups learned to avoid the shock-paired odours just like older rats. Directly infusing dopamine into the amygdala of the young pups had the same effect on behaviour. "Dopamine was the only thing really correlated with what the pup was learning," says Sullivan. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory; Stress
Link ID: 13313 - Posted: 06.24.2010

by Ewen Callaway Victorious gamers enjoy a surge of testosterone – but only if their vanquished foe is a stranger. When male gamers beat friends in a shoot-em-up video game, levels of the potent sex hormone plummeted. This suggests that multiplayer video games tap into the same mechanisms as warfare, where testosterone's effect on aggression is advantageous. Against a group of strangers – be it an opposing football team or an opposing army – there is little reason to hold back, so testosterone's effects on aggression offer an advantage. "In a serious out-group competition you can kill all your rivals and you're better for it," says David Geary, an evolutionary psychologist at the University of Missouri in Columbia, who led the study. However, when competing against friends or relatives to establish social hierarchy, annihilation doesn't make sense. "You can't alienate your in-group partners, because you need them," he says. It's his hormones Measuring these effects, however, hasn't been easy. Victors in sporting events are known to experience a burst in testosterone – particularly if they contributed to the win. But physical exertion also boosts testosterone, so it is hard to be sure just what causes an athlete's hormonal surge. © Copyright Reed Business Information Ltd

Keyword: Aggression; Hormones & Behavior
Link ID: 13312 - Posted: 06.24.2010

A warning or mini-stroke occurs before one in every eight strokes, according to an Ontario study. A transient ischemic attack or TIA is a mild stroke that causes stroke symptoms such as sudden numbness of the face, arm or leg. The symptoms last for less than 24 hours and then resolve on their own without disabling neurological effects. Dr. Daniel Hackam of the University of Western Ontario in London, Ont., and his colleagues analyzed all patients hospitalized with a diagnosis of stroke between July 2003 and September 2007. Of the 16,400 patients reviewed, 2,032, or 12.4 per cent, had a TIA prior to the stroke that landed them in hospital, the team reported in Tuesday's issue of the journal Neurology. "These results illustrate the need for better risk assessment tools for preventing strokes before they occur," Hackam said in a release. "Other studies have shown that up to 80 per cent of strokes after TIA can be prevented when risk factors are managed intensively." Go to emergency for minor stroke People who did not have a TIA were more likely to have a more serious stroke than those who did have a warning stroke. © CBC 2009

Keyword: Stroke
Link ID: 13311 - Posted: 06.24.2010

Alison Abbott Two patients, partially blind because of damage to one side of their brain, were able to sense, and respond to, emotions expressed by people in pictures presented to their blind sides. A study by an international team of researchers found that the patients unconsciously twitched a facial muscle uniquely involved in smiling when a picture showed a happy person, and a muscle involved in frowning when the person depicted looked fearful1. The patients, both from the United Kingdom, have the very rare condition known as partial cortical blindness. Their eyes are intact but they have damage to the visual cortex on one side of their brain. This means that they cannot process information from the visual field on the opposite side of their nose. The scientists, who were led by Marco Tamietto and Beatrice de Gelder at Tilburg University in the Netherlands, say the results show that our spontaneous tendency to synchronize our facial expressions with those of other people in face-to-face situations — known as emotional contagion — occurs even if we cannot consciously see them. "This is interesting evidence that we can recognize the emotions of others without needing to be visually aware of them," says neuroscientist Christian Keysers, an expert in the neurophysiology of emotion at the University of Groningen, the Netherlands, who was not involved in the study. © 2009 Nature Publishing Group,

Keyword: Vision; Emotions
Link ID: 13310 - Posted: 06.24.2010

By Frans de Waal Two young bonobos exhibit the ape equivalent of the human laugh, a “play face,” which is accompanied by laugh-like panting sounds. Just as in humans, if one ape laughs others usually do as well, especially during wrestling and tickling games. Frans de Waal One morning, the principal’s voice sounded over the intercom of my high school with the shocking announcement that a popular teacher of French had just died in front of his class. Everyone fell silent. While the headmaster went on to explain that the teacher had suffered a heart attack, I couldn’t keep myself from a laughing fit. To this day, I feel embarrassed. What is it about laughter that makes it unstoppable even if triggered by inappropriate circumstances? Extreme bouts of laughter are awkward: they involve loss of control, shedding of tears, gasping for air, leaning on others, and even wetting of pants while rolling on the floor! What weird trick has been played on our linguistic species, that we express ourselves with stupid “ha ha ha!” sounds? Why don’t we leave it at a cool “That was funny!”? Philosophers who regard a sense of humor as one of humanity’s finest achievements may find it puzzling that it is expressed with the sort of crude abandon associated with mere animals. But laughter is an inborn, universal human trait, one that we share with our closest relatives, the apes (see “The Laughing Species,” December 2000-January 2001). © 2008–2009 Natural History Magazine, Inc.

Keyword: Emotions; Evolution
Link ID: 13309 - Posted: 06.24.2010

Physiologically, why is the sound of fingernails on a blackboard so unnerving? Is this effect particular to human beings, or are other creatures similarly affected? —Rowan Snyder, via e-mail Neuroscientist Josh McDermott of New York University explains: Probably a couple of factors combine to make such sounds unpleasant. The first, perhaps unsurprisingly, is the presence of high frequencies. The range between two and four kilohertz—approximately that covered by the highest octave of a standard piano—seems to contribute the most to the nastiness of the sound. It is unclear why people tend to find these frequencies unpleasant, but we know that noise-induced hearing loss most commonly occurs in roughly this region, so it is conceivable that the aversive reaction partly reflects the ear’s vulnerability. The spectrum of screeching sounds is also much noisier than that of an instrument; that is, there is a strong random component to the sound. The noisiness probably results from the fingernails repeatedly catching on part of the chalkboard surface before sliding forward. This catching and sliding also causes rapid fluctuations in intensity, giving the sound a “rough” character. Roughness is known to be unpleasant—car manufacturers, who aim to produce minimally unpleasant engine noise, for instance, find that smooth sounds with minimal variation in intensity are preferred by listeners over those that are rough. It’s a bit harder to say why sound roughness is considered unpleasant—as far as we know it is not harmful to the ears.

Keyword: Hearing
Link ID: 13308 - Posted: 06.24.2010