Chapter 19. Language and Hemispheric Asymmetry
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Stroke deaths and illnesses are likely to continue shifting younger, global research suggests. In the Global and Regional Burden of Stroke in 1999-2010 study published in Thursday's issue of the medical journal The Lancet, researchers take a comprehensive look at stroke rates by country and region. "Stroke burden worldwide continues to increase," Prof. Valery Feigin, director of the National Institute for Stroke and Applied Neurosciences at AUT University in New Zealand said in an interview. "It's increasing at increased pace, more than we expected, disproportionately affecting low-to middle-income countries." The proportion of stroke in people younger than 65 is substantial, Feigin's team said. More than 83,000 children and youths aged 20 years and younger are affected by stroke annually. Feigin said the epidemic of obesity, and Type 2 diabetes in children and young people is increasing worldwide, which will be important risk factors for stroke 20 or 30 years down the road. If the trends in low-income and middle-income countries continue, by 2030 there will be almost 12 million stroke deaths and 70 million stroke survivors worldwide, the researchers projected. More than 90 per cent of strokes are preventable through lifestyle changes such as improving diet, quitting smoking, reducing salt and alcohol intake, increasing physical activity and managing stress, Feigin said.
Link ID: 18828 - Posted: 10.24.2013
by Hal Hodson American Football is a rough game, but the toll it takes on players' grey matter is only now becoming clear. For the first time, the number of head impacts on the playing field has been linked with cognitive problems and functional brain abnormalities in ex-footballers. Brain autopsies on retired National Football League (NFL) players have previously shown levels of damage that are higher than those in the general population. Now, this damage has been correlated with performance in tasks related to reasoning, problem solving and planning and highlights the worrying impact of repeated head trauma. To investigate the relationship between head trauma and cognitive damage, Adam Hampshire of Imperial College London, and his colleagues scanned the brains of 13 retired professional American football players and 60 people who had never played the sport, while they performed a series of cognitive tests in an fMRI machine. It wasn't an easy task: David Hubbard, who ran the tests at the Applied fMRI Institute in San Diego, California, says they initially had 15 ex-sportsmen, but two were too large to fit in the machine. The football players only showed modest deficits on the cognitive tasks, which included tests of planning, spatial awareness, memory and counting, however their brains had to work a lot harder to achieve the same results as the non-footballers. Regions of the frontal cortices that normally communicate with each other to handle reasoning and planning tasks were far less efficient in the footballers' brains. © Copyright Reed Business Information Ltd.
Keyword: Brain Injury/Concussion
Link ID: 18812 - Posted: 10.19.2013
Daniel Cossins It may not always seem like it, but humans usually take turns speaking. Research published today in Current Biology1 shows that marmosets, too, wait for each other to stop calling before they respond during extended vocal exchanges. The discovery could help to explain how humans came to be such polite conversationalists. Taking turns is a cornerstone of human verbal communication, and is common across all languages. But with no evidence that non-human primates 'converse' similarly, it was not clear how such behaviour evolved. The widely accepted explanation, known as the gestural hypothesis, suggests that humans might somehow have taken the neural machinery underlying cooperative manual gestures such as pointing to something to attract another person's attention to it, and applied that to vocalization. Not convinced, a team led by Daniel Takahashi, a neurobiologist at Princeton University in New Jersey, wanted to see whether another primate species is capable of cooperative calling. The researchers turned to common marmosets (Callithrix jacchus) because, like humans, they are prosocial — that is, generally friendly towards each other — and they communicate using vocalizations. After you The team recorded exchanges between pairs of marmosets that could hear but not see each other, and found that the monkeys never called at the same time. Instead, they always waited for roughly 5 seconds after a caller had finished before responding. © 2013 Nature Publishing Group
Sending up the alarm when a predator approaches seems like a good idea on the surface. But it isn’t always, because such warnings might help the predator pinpoint the location of its next meal. So animals often take their audience into account when deciding whether or not to warn it of impending danger. And a new study in Biology Letters finds that the vulnerability of that audience matters, at least when we’re talking about baby birds and their parents. Tonya Haff and Robert Magrath of Australian National University in Canberra studied a local species, the white-browed scrubwren, by setting up an experiment to see if parents' reactions to predators changed when the babies were more vulnerable. Baby birds are vulnerable pretty much all the time but more so when they’re begging for food. That whining noise can lead a predator right to them. But a parent’s alarm call can shut them right up. Haff and Magrath began by determining that parent scrubwrens would respond normally when they heard recordings of baby birds. (They used recordings because those are more reliable than getting little chicks to act on cue.) Then they played those recordings or one of background noise near scrubwren nests. The role of the predator was played by a taxidermied pied currawong, with a harmless fake crimson rosella (a kind of parrot) used as a control. The mama and papa birds called out their “buzz” alarm more often when the pied currawong was present and the baby bird recording was being played. They barely buzzed when the parrot was present or only background noise was played. The parents weren’t alarm calling more just to be heard over the noise, the researchers say. If that were the case, then a second type of call — a contact “chirp” that mamas and papas give when approaching a nest — should also have become more common, which it didn’t. © Society for Science & the Public 2000 - 2013.
Brian Owens Bats that nest inside curled-up leaves may be getting an extra benefit from their homes: the tubular roosts act as acoustic horns, amplifying the social calls that the mammals use to keep their close-knit family groups together. South American Spix’s disc-winged bats (Thyroptera tricolor) roost in groups of five or six inside unfurling Heliconia and Calathea leaves. The leaves remain curled up for only about 24 hours, so the bats have to find new homes almost every day, and have highly specialized social calls to help groups stay together. When out flying, they emit a simple inquiry call. Bats inside leaves answer with a more complex response call to let group members know where the roost is. Gloriana Chaverri, a biologist at the University of Costa Rica in Golfito, took curled leaves into the lab and played recorded bat calls through them, to see how the acoustics were changed by the tapered tubular shape of the leaves. “The call emitted by flying bats got really amplified,” she says, “while the calls from inside the leaves were not amplified as much.” Sound system The inquiry calls from outside the roost were boosted by as much as 10 decibels as the sound waves were compressed while moving down the narrowing tube — the same thing that happens in an amplifying ear trumpet. Most response calls from inside the leaf were boosted by only 1–2 decibels, but the megaphone shape of the leaf made them highly directional. The results are published today in Proceedings of the Royal Society B1. © 2013 Nature Publishing Group
by Bruce Bower Babies may start to learn their mother tongues even before seeing their mothers’ faces. Newborns react differently to native and foreign vowel sounds, suggesting that language learning begins in the womb, researchers say. Infants tested seven to 75 hours after birth treated spoken variants of a vowel sound in their home language as similar, evidence that newborns regard these sounds as members of a common category, say psychologist Christine Moon of Pacific Lutheran University in Tacoma, Wash., and her colleagues. Newborns deemed different versions of a foreign vowel sound to be dissimilar and unfamiliar, the scientists report in an upcoming Acta Paediatrica. “It seems that there is some prenatal learning of speech sounds, but we do not yet know how much,” Moon says. Fetuses can hear outside sounds by about 10 weeks before birth. Until now, evidence suggested that prenatal learning was restricted to the melody, rhythm and loudness of voices (SN: 12/5/09, p. 14). Earlier investigations established that 6-month-olds group native but not foreign vowel sounds into categories. Moon and colleagues propose that, in the last couple months of gestation, babies monitor at least some vowels — the loudest and most expressive speech sounds — uttered by their mothers. © Society for Science & the Public 2000 - 2013
By Helen Briggs BBC News The brain has a critical window for language development between the ages of two and four, brain scans suggest. Environmental influences have their biggest impact before the age of four, as the brain's wiring develops to process new words, say UK and US scientists. The research in The Journal of Neuroscience suggests disorders causing language delay should be tackled early. It also explains why young children are good at learning two languages. The scientists, based at King's College London, and Brown University, Rhode Island, studied 108 children with normal brain development between the ages of one and six. They used brain scans to look at myelin - the insulation that develops from birth within the circuitry of the brain. To their surprise, they found the distribution of myelin is fixed from the age of four, suggesting the brain is most plastic in very early life. Any environmental influences on brain development will be strongest in infanthood, they predict. This explains why immersing children in a bilingual environment before the age of four gives them the best chance of becoming fluent in both languages, the research suggests. BBC © 2013
Smart, successful, and well-connected: a good description of Albert Einstein … and his brain. The father of relativity theory didn’t live to see modern brain imaging techniques, but after his death his brain was sliced into sections and photographed. Now, scientists have used those cross-sectional photos to reveal a larger-than-average corpus callosum—the bundle of nerve fibers connecting the brain’s two hemispheres. Researchers measured the thickness of the famous noggin’s corpus callosum (the lighter-colored, downward-curving region at the center of each hemisphere, above) at various points along its length, and compared it to MRIs from 15 elderly men and 52 young, healthy ones. The thickness of Einstein’s corpus callosum was greater than the average for both the elderly and the young subjects, the team reported online last week in the journal Brain. The authors posit that in Einstein’s brain, more nerve fibers connected key regions such as the two sides of the prefrontal cortex, which are responsible for complex thought and decision-making. Combined with previous evidence that parts of the physicist’s brain were unusually large and intricately folded, the researchers suggest that this feature helps account for his extraordinary gifts. © 2013 American Association for the Advancement of Science
By Lenny Bernstein, Joanna Leigh describes her life in black and white, before and after. Before the Boston Marathon bombing, she says, she had “just embarked on a really beautiful future” with a new doctoral degree in international development and a career as a consultant. Today, she says, she can’t work or drive and often gets lost, sometimes on her own block. Her vision is blurry, her hearing is diminished and her ears ring constantly. She struggles to cook dinner, do her laundry, fill out a form. Mostly, she sleeps. The cause of her difficulties, according to the physician who examined her, was a traumatic brain injury on April 15. But because Leigh, 39, walked home that day after she was knocked unconscious by the second bomb and never went to a hospital, she received just $8,000 from the One Fund charity for survivors. She said her medical and other expenses have reached $70,000. She is applying for disability payments and food stamps. One Fund payouts to everyone except 16 amputees and the families of the four people who were killed were based on the number of nights spent in the hospital. A single night was worth $125,000; 32 nights qualified victims for $948,000. The 143 people who were treated as outpatients received $8,000 each. In coming days, Leigh and four other attack survivors will petition the One Fund to develop a new plan for distributing the millions of dollars in donations the charity has received since the first payout. They are seeking a formula that takes into account injuries that were slow to reveal themselves. © 1996-2013 The Washington Post
Keyword: Brain Injury/Concussion
Link ID: 18736 - Posted: 10.03.2013
By KEN BELSON Football players as young as 7 sustain hits to the head comparable in magnitude to those absorbed by high school and adult players, and most of the hits are sustained in practices, not games, according to research to be released Wednesday. The findings, which may influence how youth football organizations handle training methods and rules, were included in four studies published by researchers at the Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences. The research, though limited, is considered by experts to be a step in the effort to address the relatively shallow understanding of the potential long-term effects of head trauma on young players. More than 25,000 football players from 8 to 19 years old are taken to emergency rooms seeking treatment for concussions every year, but most of the research on head injuries in football has focused on professional and college players. The new research, which was presented at the annual Biomedical Engineering Society conference this week, tracked about 120 players in Virginia and North Carolina from 7 to 18 over two seasons. Each young athlete wore six devices, known as accelerometers, in their helmets to measure the force, position and direction of the hits, and every practice and game was videotaped to determine how they occurred. To help determine any changes in brain structure and function, many of the players received magnetic resonance imaging brain scans before and after the season, and after they sustained a concussion. Some players also received magnetoencephalography scans, or MEG scans, to map their brain activity. © 2013 The New York Times Company
By Melissa Hogenboom Science reporter, BBC News Moving in time to a steady beat is closely linked to better language skills, a study suggests. People who performed better on rhythmic tests also showed enhanced neural responses to speech sounds. The researchers suggest that practising music could improve other skills, particularly speech. In the Journal of Neuroscience, the authors argue that rhythm is an integral part of language. "We know that moving to a steady beat is a fundamental skill not only for music performance but one that has been linked to language skills," said Nina Kraus, of the Auditory Neuroscience Laboratory at Northwestern University in Illinois. More than 100 teenagers were asked to tap their fingers along to a beat. Their accuracy was measured by how closely their responses matched the timing of a metronome. Next, in order to understand the biological basis of rhythmic ability, the team also measured the brainwaves of their participants with electrodes, a technique called electroencephalography. This was to observe the electrical activity in the brain in response to sound. Using this biological approach, the researchers found that those who had better musical training also had enhanced neural responses to speech sounds. In poorer readers this response was diminished. BBC © 2013
By Joshua K. Hartshorne There are two striking features of language that any scientific theory of this quintessentially human behavior must account for. The first is that we do not all speak the same language. This would be a shocking observation were not so commonplace. Communication systems and other animals tend to be universal, with any animal of the species able to communicate with any other. Likewise, many other fundamental human attributes show much less variation. Barring genetic or environmental mishap, we all have two eyes, one mouth, and four limbs. Around the world, we cry when we are sad, smile when we are happy, and laugh when something is funny, but the languages we use to describe this are different. The second striking feature of language is that when you consider the space of possible languages, most languages are clustered in a few tiny bands. That is, most languages are much, much more similar to one another than random variation would have predicted. Starting with pioneering work by Joseph Greenberg, scholars have cataloged over two thousand linguistic universals (facts true of all languages) and biases (facts true of most languages). For instance, in languages with fixed word order, the subject almost always comes before the object. If the verb describes a caused event, the entity that caused the event is the subject ("John broke the vase") not the object (for example, "The vase shbroke John" meaning "John broke the vase"). In languages like English where the verb agrees with one of its subjects or objects, it typically agrees with the subject (compare "the child eats the carrots" with "the children eat the carrots") and not with its object (this would look like "the child eats the carrot" vs. "the child eat the carrots"), though in some languages, like Hungarian, the ending of the verb changes to match both the subject and object. © 2013 Scientific American
Link ID: 18664 - Posted: 09.18.2013
By Tina Hesman Saey About 10 percent of people prefer using their left hand. That ratio is found in every population in the world and scientists have long suspected that genetics controls hand preference. But finding the genes has been no simple task, says Chris McManus, a neuropsychologist at University College London who studies handedness but was not involved in the new research. “There’s no single gene for the direction of handedness. That’s clear,” McManus says. Dozens of genes are probably involved, he says, which means that one person’s left-handedness might be caused by a variant in one gene, while another lefty might carry variants in an entirely different gene. To find handedness genes, William Brandler, a geneticist at the University of Oxford, and colleagues conducted a statistical sweep of DNA from 3,394 people. Statistical searches such as this are known as genome-wide association studies; scientists often do such studies to uncover genes that contribute to complex diseases or traits such as diabetes and height. The people in this study had taken tests involving moving pegs on a board. The difference in the amount of time they took with one hand versus the other reflected how strongly left- or right-handed they were. A variant in a gene called PCSK6 was most tightly linked with strong hand preference, the researchers report in the Sept. 12 PLOS Genetics.. The gene has been implicated in handedness before, including in a 2011 study by the same research group. PCSK6 is involved in the asymmetrical positioning of internal organs in organisms from snails to vertebrates. © Society for Science & the Public 2000 - 2013
Associated Press It's the ape equivalent of Google Maps and Facebook. The night before a big trip, Arno the orangutan plots his journey and lets others know where he is going with a long, whooping call. What he and his orangutan buddies do in the forests of Sumatra tells scientists that advance trip planning and social networking aren't just human traits. A new study of 15 wild male orangutans finds that they routinely plot out their next-day treks and share their plans in long calls, so females can come by or track them, and competitive males can steer clear. The researchers closely followed the males as they traveled on 320 days during the 1990s. The results were published Wednesday in the journal PLoS One. Typically, an orangutan would turn and face in the direction of his route and let out a whoop, sometimes for as long as four minutes. Then he'd go to sleep and 12 hours later set on the heralded path, said study author Carel van Schaik, director of the Anthropological Institute at the University of Zurich. "This guy basically thinks ahead," van Schaik said. "They're continuously updating their Google Maps, so to speak. Based on that, they're planning what to do next." The apes didn't just call once - they kept at it, calling more than 1,100 times over the 320 days. © 2013 The Hearst Corporation
Ed Yong Listen very carefully in the rainforests of Brazil and you might hear a series of quiet, high-pitched squeaks. These are the alarm calls of the black-fronted titi (Callicebus nigrifrons), a monkey with a rusty-brown tail that lives in small family units. The cries are loaded with information. Cristiane Cäsar, a biologist at the University of St Andrews, UK, and her colleagues report that the titis mix and match two distinct calls to tell each other about the type of predator that endangers them, as well as the location of the threat. Her results are published in Biology Letters1. Cäsar's team worked with five groups of titis that live in a private nature reserve in the Minas Gerais region of Brazil. When the researchers placed a stuffed caracara — a bird of prey — in the treetops, the titis gave out A-calls, which have a rising pitch. When the animals saw a ground-based threat — represented by an oncilla, a small spotted cat — they produced B-calls, sounds with a falling pitch. However, when the team moved the predator models around, the monkeys tweaked their calls. If the caracara was on the ground, the monkeys started with at least four A-calls before adding B-calls into the mix. If the oncilla was in a tree, the monkeys made a single introductory A-call before switching to B-calls. “A single call doesn’t really tell the recipient what’s happening, but they can infer the type of predator and its location by listening to the first five or six calls,” says co-author Klaus Zuberbühler of the University of Neuchâtel in Switzerland. “The five different groups were almost unanimous in their response. There was no deviation.” © 2013 Nature Publishing Group
By Jason G. Goldman One of the key differences between humans and non-human animals, it is thought, is the ability to flexibly communicate our thoughts to others. The consensus has long been that animal communication, such as the food call of a chimpanzee or the alarm call of a lemur, is the result of an automatic reflex guided primarily by the inner physiological state of the animal. Chimpanzees, for example, can’t “lie” by producing a food call when there’s no food around and, it is thought, they can’t not emit a food call in an effort to hoard it all for themselves. By contrast, human communication via language is far more flexible and intentional. But recent research from across the animal kingdom has cast some doubt on the idea that animal communication always operates below the level of conscious control. Male chickens, for example, call more when females are around, and male Thomas langurs (a monkey native to Indonesia) continue shrieking their alarm calls until all females in their group have responded. Similarly, vervet monkeys are more likely sound their alarm calls when their are other vervet monkeys around, and less likely when they’re alone. The same goes for meerkats. And possibly chimps, as well. Still, these sorts of “audience effects” can be explained by lower-level physiological factors. In yellow-bellied marmots, small ground squirrels native to the western US and southwestern Canada, the production of an alarm call correlates with glucocorticoid production, a physiological measurement of stress. And when researchers experimentally altered the synthesis of glucocorticoids in rhesus macaques, they found a change in the probability of alarm call production. © 2013 Scientific American
by Nancy Shute It was hard to ignore those headlines saying that people with migraine have brain damage, even if you're not among the 12 percent or so who do suffer from these painful, recurring headaches. Don't panic, says the neurologist whose work sparked those alarming headlines. "It's still not something to stay up nights worrying about," says Dr. Richard Lipton, director of the Montefiore Headache Center in New York. But knowing about the brain anomalies that Lipton and his colleagues found might help people reduce their stroke risk. Some people who get do have a slightly . And some of the brain changes identified in the study look like mini-strokes. "On the MRI they look like very tiny strokes," Lipton tells Shots. But the people aren't having any stroke symptoms. Still, Lipton is convinced that the process is the same. "We now know it's a risk factor for these very small silent strokes," he says. The scientists evaluated data from 19 studies in which people with migraine headaches got MRI scans of their brains. Just about everybody is going to have some abnormalities show up in a scan. But the people who had migraines were more likely to have two common abnormalities: white matter abnormalities and infarct-like lesions. The were published in the journal Neurology. ©2013 NPR
by Jacob Aron DOES your brain work like a dictionary? A mathematical analysis of the connections between definitions of English words has uncovered hidden structures that may resemble the way words and their meanings are represented in our heads. "We want to know how the mental lexicon is represented in the brain," says Stevan Harnad of the University of Quebec in Montreal, Canada. As every word in a dictionary is defined in terms of others, the knowledge needed to understand the entire lexicon is there, as long as you first know the meanings of an initial set of starter, or "grounding", words. Harnad's team reasoned that finding this minimal set of words and pinning down its structure might shed light on how human brains put language together. The team converted each of four different English dictionaries into a mathematical structure of linked nodes known as a graph. Each node in this graph represents a word, which is linked to the other words used to define it – so "banana" might be connected to "long", "bendy", "yellow" and "fruit". These words then link to others that define them. This enabled the team to remove all the words that don't define any others, leaving what they call a kernel. The kernel formed roughly 10 per cent of the full dictionary – though the exact percentages depended on the particular dictionary. In other words, 90 per cent of the dictionary can be defined using just the other 10 per cent. © Copyright Reed Business Information Ltd.
Link ID: 18587 - Posted: 08.31.2013
Beth Skwarecki Be careful what you say around a pregnant woman. As a fetus grows inside a mother's belly, it can hear sounds from the outside world—and can understand them well enough to retain memories of them after birth, according to new research. It may seem implausible that fetuses can listen to speech within the womb, but the sound-processing parts of their brain become active in the last trimester of pregnancy, and sound carries fairly well through the mother's abdomen. "If you put your hand over your mouth and speak, that's very similar to the situation the fetus is in," says cognitive neuroscientist Eino Partanen of the University of Helsinki. "You can hear the rhythm of speech, rhythm of music, and so on." A 1988 study suggested that newborns recognize the theme song from their mother's favorite soap opera. More recent studies have expanded on the idea of fetal learning, indicating that newborns already familiarized themselves with sounds of their parent’s native language; one showed that American newborns seem to perceive Swedish vowel sounds as unfamiliar, sucking on a high-tech pacifier to hear more of the new sounds. Swedish infants showed the same response to English vowels. But those studies were based on babies' behaviors, which can be tricky to test. Partanen and his team decided instead to outfit babies with EEG sensors to look for neural traces of memories from the womb. "Once we learn a sound, if it's repeated to us often enough, we form a memory of it, which is activated when we hear the sound again," he explains. This memory speeds up recognition of sounds in the learner's native language and can be detected as a pattern of brain waves, even in a sleeping baby. © 2012 American Association for the Advancement of Science.
Virginia Morell A wolf’s howl is one of the most iconic sounds of nature, yet biologists aren’t sure why the animals do it. They’re not even sure if wolves howl voluntarily or if it’s some sort of reflex, perhaps caused by stress. Now, scientists working with captive North American timber wolves in Austria report that they’ve solved part of the mystery. Almost 50 years ago, wildlife biologists suggested that a wolf’s howls were a way of reestablishing contact with other pack members after the animals became separated, which often happens during hunts. Yet, observers of captive wolves have also noted that the pattern of howls differs depending on the size of the pack and whether the dominant, breeding wolf is present, suggesting that the canids’ calls are not necessarily automatic responses. Friederike Range, a cognitive ethologist at the University of Veterinary Medicine in Vienna, was in a unique position to explore the conundrum. Since 2008, she and her colleagues have hand-raised nine wolves at the Wolf Science Center in Ernstbrunn, which she co-directs. “We started taking our wolves for walks when they were 6 weeks old, and as soon as we took one out, the others would start to howl,” she says. “So immediately we became interested in why they howl.” Although the center’s wolves don’t hunt, they do howl differently in different situations, Range says. “So we also wanted to understand these variations in their howling.” © 2012 American Association for the Advancement of Science.