Chapter 15. Language and Our Divided Brain
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There is more than meets the eye following even a mild traumatic brain injury. While the brain may appear to be intact, new findings reported in Nature suggest that the brain’s protective coverings may feel the brunt of the impact. Using a newly developed mouse trauma model, senior author Dorian McGavern, Ph.D., scientist at the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health, watched specific cells mount an immune response to the injury and try to prevent more widespread damage. Notably, additional findings suggest a similar immune response may occur in patients with mild head injury. In this study, researchers also discovered that certain molecules, when applied directly to the mouse skull, can bypass the brain’s protective barriers and enter the brain. The findings suggested that, in the mouse trauma model, one of those molecules may reduce effects of brain injury. Although concussions are common, not much is known about the effects of this type of damage. As part of this study, Lawrence Latour, Ph.D., a scientist from NINDS and the Center for Neuroscience and Regenerative Medicine, examined individuals who had recently suffered a concussion but whose initial scans did not reveal any physical damage to brain tissue. After administering a commonly used dye during MRI scans, Latour and his colleagues saw it leaking into the meninges, the outer covers of the brain, in 49 percent of 142 patients with concussion. To determine what happens following this mild type of injury, researchers in Dr. McGavern’s lab developed a new model of brain trauma in mice.
Keyword: Brain Injury/Concussion
Link ID: 19010 - Posted: 12.10.2013
Helen Shen Dyslexia may be caused by impaired connections between auditory and speech centres of the brain, according to a study published today in Science1. The research could help to resolve conflicting theories about the root causes of the disorder, and lead to targeted interventions. When people learn to read, their brains make connections between written symbols and components of spoken words. But people with dyslexia seem to have difficulty identifying and manipulating the speech sounds to be linked to written symbols. Researchers have long debated whether the underlying representations of these sounds are disrupted in the dyslexic brain, or whether they are intact but language-processing centres are simply unable to access them properly. A team led by Bart Boets, a clinical psychologist at the Catholic University of Leuven in Belgium, analysed brain scans and found that phonetic representations of language remain intact in adults with dyslexia, but may be less accessible than in controls because of deficits in brain connectivity. "The authors took a really inventive and thoughtful approach," says John Gabrieli, a neuroscientist at the Massachusetts Institute of Technology in Cambridge, Massachusetts. "They got a pretty clear answer." Communication channels Boets and his team used a technique called multivoxel pattern analysis to study fine-scale brain signals as people listened to a battery of linguistic fragments such as 'ba' and 'da'. To the researchers' surprise, neural activity in the primary and secondary auditory cortices of participants with dyslexia showed consistently distinct signals for different sounds. © 2013 Nature Publishing Group
Barn owl nestlings recognise their siblings' calls, according to researchers. Instead of competing aggressively for food, young barn owls are known to negotiate by calling out. A team of scientists in Switzerland discovered that the owlets have remarkably individual calls. They suggest this is to communicate each birds' needs and identity in the nest. The findings were announced in the Journal of Evolutionary Biology by Dr Amelie Dreiss and colleagues at the University of Lausanne, Switzerland. Barn owls (Tyto alba) are considered one of the most widespread species of bird and are found on every continent except Antarctica. An average clutch size ranges between four and six eggs but some have been known to contain up to 12. Previous studies have highlighted how barn owl nestlings, known as owlets, negotiate with their siblings for food instead of fighting. While their parents search for food the owlets advertise their hunger to their brothers and sisters by calling out. "These vocal signals deter siblings from vocalizing and from competing for the prey at parental return," explained Dr Dreiss. "If there is a disagreement, they can escalate signal intensity little by little, always without physical aggression, until less hungry siblings finally withdraw from the contest." BBC © 2013
By Victoria Gill Science reporter, BBC News Great tits use different alarm calls for different predators, according to a scientist in Japan. The researcher analysed the birds' calls and found they made "jar" sounds for snakes and "chicka" sounds for crows and martens. This, he says, is the first demonstration birds can communicate vocally about the type of predator threatening them. The findings are published in the journal Animal Behaviour. From his previous observations, the researcher, Dr Toshitaka Suzuki, from the Graduate University for Advanced Studies in Kanagawa, found great tits appeared to be able to discriminate between different predators. To test whether they could also communicate this information, he placed models of three different animals that prey on nestlings - snakes, crows and martens - close to the birds' nest boxes. He then recorded and analysed the birds' responses. "Parents usually make alarm calls when they approach and mob the nest predators," said Dr Suzuki. "They produced specific 'jar' alarm calls for the snakes and the same 'chicka' alarm call in response to both the crows and martens," he said. But a closers analysis of the sounds showed the birds had used different "note combinations" in their crow alarm calls from those they had used for the martens. Dr Suzuki thinks the birds might have evolved what he called a "combinatorial communication system" - combining different notes to produce calls with different meanings. Since snakes are able to slither into nest boxes, they pose a much greater threat to great tit nestlings than other birds or mammals, so Dr Suzuki says it makes sense that the birds would have a specific snake alarm call. BBC © 2013
By James Gallagher Health and science reporter, BBC News The damage caused by concussion can be detected months after the injury and long after patients feel like they have recovered, brain scans show. Concussion has become highly controversial in sport, with concerns raised that players are putting their brain at risk. Researchers at the University of New Mexico said athletes may be being returned to action too quickly. While UK doctors said the attitude to head injury was "too relaxed" in sport. Debate over concussion and head injury has lead to resignations over new rules in rugby, controversy in football after a player was kept on the field after being knocked out, and has been a long-standing issue in American football. Concussion is an abnormal brain function that results from an external blast, jolt or impact to the head. Even if the knock does not result in a skull fracture, the brain can still experience a violent rattling that leads to injury. Because the brain is a soft gelatinous material surrounded by a rigid bony skull, such traumatic injuries can cause changes in brain function, such as bleeding, neuron damage and swelling. Research shows that repetitive concussions increase the risk of sustained memory loss, worsened concentration or prolonged headaches. Long-term The US study, published in the journal Neurology, compared the brains of 50 people who had mild concussion with 50 healthy people. BBC © 2013
Keyword: Brain Injury/Concussion
Link ID: 18951 - Posted: 11.21.2013
By Tanya Lewis and LiveScience SAN DIEGO — Being a social butterfly just might change your brain: In people with a large network of friends and excellent social skills, certain brain regions are bigger and better connected than in people with fewer friends, a new study finds. The research, presented here Tuesday (Nov. 12) at the annual meeting of the Society for Neuroscience, suggests a connection between social interactions and brain structure. "We're interested in how your brain is able to allow you to navigate in complex social environments," study researcher MaryAnn Noonan, a neuroscientist at Oxford University, in England, said at a news conference. Basically, "how many friends can your brain handle?" Noonan said. Scientists still don't understand how the brain manages human behavior in increasingly complex social situations, or what parts of the brain are linked to deviant social behavior associated with conditions like autism and schizophrenia. Studies in macaque monkeys have shown that brain areas involved in face processing and in predicting the intentions of others are larger in animals living in large social groups than in ones living in smaller groups. To investigate these brain differences in humans, Noonan and her colleagues at McGill University, in Canada, recruited 18 participants for a structural brain-imaging study. They asked people how many social interactions they had experienced in the past month, in order to determine the size of their social networks. As was the case in monkeys, some brain areas were enlarged and better connected in people with larger social networks. In humans, these areas were the temporal parietal junction, the anterior cingulate cortex and the rostral prefrontal cortex, which are part of a network involved in "mentalization" — the ability to attribute mental states, thoughts and beliefs to another. © 2013 Scientific American
by Jessica Griggs, San Diego No practice required. Wouldn't it be great if you could get better at playing sport or hone your piano skills simply by thinking about it? A small pilot study suggests that it might be possible. In the last few years, brain training using computer games that provide neurofeedback – a real-time representation of your brain activity – has become a popular, if controversial, method of enhancing cognitive abilities such as spatial memory, planning and multitasking. It has even been used to help actors get into character. Most of the games aim to enhance activation in a single part of the brain. But motor skills are known to involve two main areas – the premotor cortex and the supplementary motor cortex. Both are involved when people make movements or imagine moving. Brain activity between these regions is known to be less synchronised in people who are poor at motor tasks than in those who excel at them. So to see if brain training could target both areas and improve motor performance, Sook-Lei Liew and her colleagues from the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, recruited eight young adults. The researchers and asked the participants to watch a white circle on a screen while an fMRI machine scanned their brain. When the circle turned into a red triangle, the volunteers were told to move their fingers. This movement caused activation in their premotor cortex and supplementary motor cortex, which in turn moved a bar on the screen. The higher the synchronisation of activity between the two brain areas, the higher the bar went. © Copyright Reed Business Information Ltd.
Link ID: 18928 - Posted: 11.14.2013
The long-term impact of roadside bombings on the brains of Canadian soldiers in Afghanistan is the focus of two research projects underway in Western Canada. "In recent years, encounters with improvised explosive devices or IEDs in Afghanistan have inflicted traumatic brain injury on a number of Canadian soldiers," said Dr. Robert Thirsk, a former Canadian astronaut who is now a vice-president with the Canadian Institute of Health Research. "The impact of these blasts may not be immediately apparent. Months after the event the soldiers can suffer from the neurological problems and the mental disorders like anxiety that we're reading about in the newspapers. These weapons may be improvised, but our response to them needs to be strategic." Dr. Yu Tian Wang of the Brain Research Center at the University of British Columbia is looking at the biological changes that occur in the brain at the cellular level following an injury by an explosive device. Wang is studying whether a drug can reduce the death and dysfunction of brain cells following injury. "We know that during traumatic brain injuries some synaptic connections become weakened and the information from one neuron to another is slowed down," Wang said. "Now we know the underlying reason is due to a particular memory surface protein being reduced." Wang said an injection of peptides could provide protection to brain cells before a blast and possibly help repair damage if given immediately after an explosion. © CBC 2013
Keyword: Brain Injury/Concussion
Link ID: 18907 - Posted: 11.11.2013
by Catherine de Lange Speak more than one language? Bravo! It seems that being bilingual helps delay the onset of several forms of dementia. Previous studies of people with Alzheimer's disease in Canada showed that those who are fluent in two languages begin to exhibit symptoms four to five years later than people who are monolingual. Thomas Bak at the University of Edinburgh, UK, wanted to know whether this was truly down to language, or whether education or immigration status might be driving the delay, since most bilingual people living in Toronto, where the first studies were conducted, tended to come from an immigrant background. He also wondered whether people suffering from other forms of dementia might experience similar benefits. He teamed up with Suvarna Alladi, a neurologist working on memory disorders at Nizam's Institute of Medical Sciences (NIMSH) in Hyderabad, India. "In India, bilingualism is part of everyday life," says Bak. The team compared the age that dementia symptoms appeared in some 650 people who visited the NIMSH over six years. About half spoke at least two languages. This group's symptoms started on average four and a half years later than those in people who were monolingual. "Incredibly the number of years in delay of symptom onset they reported in the Indian sample is identical to our findings," says Ellen Bialystok, at Toronto's York University, who conducted the original Canadian studies. What's more, the same pattern appeared in three different types of dementia: Alzheimer's, frontotemporal and vascular. The results also held true for a group of people who were illiterate, suggesting that the benefits of being bilingual don't depend on education. © Copyright Reed Business Information Ltd.
Elizabeth Pennisi Speak easy. The language gene FOXP2 may work through a protein partner that stimulates the formation of excitatory connections (green) in nerve cells (magenta). Few genes have made the headlines as much as FOXP2. The first gene associated with language disorders, it was later implicated in the evolution of human speech. Girls make more of the FOXP2 protein, which may help explain their precociousness in learning to talk. Now, neuroscientists have figured out how one of its molecular partners helps Foxp2 exert its effects. The findings may eventually lead to new therapies for inherited speech disorders, says Richard Huganir, the neurobiologist at Johns Hopkins University School of Medicine in Baltimore, Maryland, who led the work. Foxp2 controls the activity of a gene called Srpx2, he notes, which helps some of the brain's nerve cells beef up their connections to other nerve cells. By establishing what SRPX2 does, researchers can look for defective copies of it in people suffering from problems talking or learning to talk. Until 2001, scientists were not sure how genes influenced language. Then Simon Fisher, a neurogeneticist now at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, and his colleagues fingered FOXP2 as the culprit in a family with several members who had trouble with pronunciation, putting words together, and understanding speech. These people cannot move their tongue and lips precisely enough to talk clearly, so even family members often can’t figure out what they are saying. It “opened a molecular window on the neural basis of speech and language,” Fisher says. © 2013 American Association for the Advancement of Science
by Bethany Brookshire Most of us see a wagging dog’s tail and think it’s got to be a good sign. Wagging = welcome, right? Especially if it’s the kind of wag that’s knocking over small items. But it turns out that not all wags are equal, and some are a lot more welcoming than others. When I walked into my college biology course freshman year, we started out with a discussion of symmetry. Most animal are built with some symmetry, either radial or bilateral — radial like a starfish, bilateral like a human. Symmetry means things, like health or attractiveness. But it turns out that asymmetry can mean things too. And an asymmetrical behavior might mean some important things for dogs. Marcello Siniscalchi of the University of Bari Aldo Moro in Italy and colleagues decided to look at asymmetry in dog wags. They noticed that sometimes, dogs wag more to the right, usually when seeing their owner or something else happy. They wag more to the left when they see something like a dominant or unfamiliar dog. So the wag itself could represent the emotional state of the dog doing the wagging. But can the dogs seeing the wagging (the wagees) tell the difference? In a paper published October 31 in Current Biology, the authors found that they can. They used videos of a real dog or the silhouette of a dog wagging to the right (the wagging dog’s right, by the way) or to the left, and examined 43 other dogs as they watched (OK, they started with 56, but 13 didn’t pay attention), to see how the wagee reacted. The observing dogs wore a vest to monitor their heart rate, and were videotaped so behaviorists could look at their behaviors afterward. © Society for Science & the Public 2000 - 2013.
A new report released today by the Institute of Medicine (IOM) may help dispel some common misconceptions about sport-related concussions in youth—for example, that wearing helmets can prevent them. First and foremost, however, it highlights the large gaps in knowledge that make it difficult for parents, coaches, and physicians to navigate decisions about prevention and treatment. The report also suggests where federal research agencies should focus their attention. The study, by a 17-member committee assembled by the Washington, D.C.-based IOM, which advises the government on health issues, comes amid growing concern about sports-related brain injuries. Although much of the attention has focused on adult professional athletes playing American football, health professionals have highlighted the need to understand risks among young athletes as well. To help clarify matters, a number of agencies, including the Centers for Disease Control and Prevention (CDC), the Department of Defense, and the Department of Education, asked IOM to conduct its study. The most glaring obstacle to understanding youth concussion at this point is a lack of data, the report finds. Most published research on sports-related concussions has been conducted in adults, and “there’s little-to-no information about concussions in youth,” particularly for ages 5 to 21, says panel member Susan Margulies, a bioengineer at the University of Pennsylvania. It’s dangerous to assume that findings in adults can be mapped onto children, she says, because of the changes that occur during brain development. “It’s possible that the threshold for injury might be different across different age ranges.” © 2013 American Association for the Advancement of Science
By Ajai Raj Football has become notorious for the degeneration it causes in players' brains. Now a preliminary study of soccer players has found that frequently hitting the ball with the head may adversely affect brain structure and cognition. The study imaged the brains of 37 amateur soccer players, 21 to 44 years old, and found that players who reported “heading the ball” more frequently had microstructural changes in the white matter of their brains similar to those observed in patients with traumatic brain injury. These players also performed poorly on cognitive tests, compared with players who reported heading the ball less. The study, published online in June in Radiology, found evidence of a threshold—1,800 headings—above which the effects on memory begin to manifest. Neuroradiologist Michael Lipton of the Albert Einstein College of Medicine of Yeshiva University, who led the study, says the findings may indicate that heading causes mild concussions, even when players do not show symptoms. The results are noteworthy but far from conclusive, comments Jonathan French, a neuropsychologist in the Sports Medicine Concussion Program at the University of Pittsburgh Medical Center, who was not involved in the study. “The majority of soccer players who are concussed don't have any functional problems in everyday life,” he says. The structural changes detected in the study, he points out, are "so microscopic that we don't know what they actually mean” for long-term function. Lipton agrees more work is needed to determine the significance of the brain changes, but he hopes to call attention to the potential risk because soccer is the most popular sport in the world. © 2013 Scientific American
By NELSON GRAVES Six years ago I suffered a stroke that forced me to relearn how to walk. The other day I ran a half-marathon. Strokes strike with stealth, but for me it was not entirely a surprise. During a physical in Milan in 2007, the doctor listened to my heart, then ordered an electrocardiogram. “Fair enough,” I reassured myself. “I’m 52 years old, and it’s no use taking anything for granted.” The nurse furrowed her brow as she studied the first read-out, then conducted a second, longer EKG. I put my shirt back on and returned to the doctor’s office. “I have some news for you,” he said. “You have atrial fibrillation. AF for short.” He wrote down the two words and explained they meant an irregular beating of the heart’s upper chambers. “It’s not life threatening. But it increases the risk of stroke six-fold.” I was too young to have a stroke. “I work 12-hour days, play squash three times a week and haven’t missed a day of work in 24 years,” I said. My attention piqued, I could now hear my heart’s irregular beat as I lay my head on my pillow. That must explain the dizziness when I get up at night to go to the bathroom. Or the fatigue at the end of a squash match. So when, on a September afternoon in Tokyo, my head began to spin wildly and I could hardly speak, I knew what was happening. After an ambulance ride to the hospital and an M.R.I., I heard the doctor say, “You’ve had a cerebral embolism.” That would be a stroke. Copyright 2013 The New York Times Company
Link ID: 18833 - Posted: 10.26.2013
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