Chapter 19. Language and Hemispheric Asymmetry

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By Amy Ellis Nutt There may finally be an explanation for why men are often less verbally adept than women at expressing themselves. It's the testosterone. Scientists have long known that language development is different between boys and girls. But in scanning the brains of 18 individuals before and after undergoing hormone treatment for female-to-male sex reassignment, Austrian and Dutch researchers found evidence of specific brain structure differences. In particular, they found two areas in the left hemispheres of the transgender men that lost gray matter volume during high-testosterone treatment over a period of four weeks: Broca's area, which is involved in the production of language, and Wernicke's area, which processes language. All of which suggests, according to the study, which was presented this week at the European College of Neuropsychopharmacology Congress, why verbal abilities are often stronger in women than men. "In more general terms, these findings may suggest that a genuine difference between the brains of women and men is substantially attributable to the effects of circulating hormones," said one of the researchers at the conference, Rupert Lanzenberger from Vienna. "Moreover, the hormonal influence on human brain structure goes beyond the early developmental phase and is still present in adulthood." Previous research has shown that higher testosterone is linked to smaller vocabulary in children and also that verbal fluency skills seemed to decrease after female-to-male sex reassignment testosterone treatment.

Keyword: Language; Sexual Behavior
Link ID: 21381 - Posted: 09.03.2015

Christopher Joyce Ornithologist Arthur Allen of the Cornell Lab or Ornithology was a pioneer, hauling balky recording gear into the wilderness in the 1940s, and actually cutting acetate records of bird song on-site. Let's fast forward 45 years, and talk to Ted Parker, who inherited Allen's gift for recording birds and but added a twist. "Up here in the canopy, these are the hardest birds to detect," he told an NPR Radio Expeditions team in 1991 in the Bolivian rain forest. Parker was an ornithologist with Conservation International who spent months at a time in the tropics, lugging around a portable tape recorder. His skill in using his ears to investigate the world was legendary. "My parents bought me records of bird recordings that were made by people at Cornell," Parker tells the NPR team in 1991. "I spent hours moving the needle back and forth, and back and forth, and my mother would say, 'You are going to destroy the record player.' " Some called Parker the Mozart of ornithology. He'd memorized the sounds of more than 4,000 bird species. He used this knowledge and his tape recorder to quickly take an extensive and detailed census of birds in the tropics. "These birds spend all their time in that foliage that's 130 to 140 feet above the ground," Parker explains on the tape. "And if you don't know their voices, there's no way you could come to a place like this and come up with a good list of canopy species." © 2015 NPR

Keyword: Animal Communication; Language
Link ID: 21380 - Posted: 09.03.2015

By Christian Jarrett If we’re being honest, most of us have at least some selfish aims – to make money, to win a promotion at work, and so on. But importantly, we pursue these goals while at the same time conforming to basic rules of decency. For example, if somebody helps us out, we’ll reciprocate, even if doing so costs us time or cash. Yet there is a minority of people out there who don’t play by these rules. These selfish individuals consider other people as mere tools to be leveraged in the pursuit of their aims. They think nothing of betrayal or backstabbing, and they basically believe everyone else is in it for themselves too. Psychologists call these people “Machiavellians,” and there’s a questionnaire that tests for this trait (one of the so-called “dark triad” of personality traits along with narcissism and psychopathy). People high in Machiavellianism are more likely to agree with statements like: It is wise to flatter important people and The best way to handle people is to tell them what they want to hear. Calling them Machiavellian is too kind. These people are basically jerks. Related Stories Inside the Brains of Happily Married Couples Lonely People’s Brains Work Differently Now a team of Hungarian researchers from the University of Pécs has scanned the brains of high scorers on Machiavellianism while they played a simple game of trust. Reporting their results in the journal Brain and Cognition, the researchers said they found that Machiavellians’ brains went into overdrive when they encountered a partner who exhibited signs of being fair and cooperative. Why? Tamas Bereczkei and his team say it’s because the Machiavellians are immediately figuring out how to exploit the situation for their own gain. The game involved four stages and the student participants — a mix of high and low scorers on Machiavellianism — played several times with different partners. First, the participants were given roughly $5 worth of Hungarian currency and had to decide how much to “invest” in their partner. Any money they invested was always tripled as it passed to their partner. © 2015, New York Media LLC.

Keyword: Emotions
Link ID: 21324 - Posted: 08.22.2015

By Catherine Saint Louis People who work 55 hours or more per week have a 33 percent greater risk of stroke and a 13 percent greater risk of coronary heart disease than those working standard hours, researchers reported on Wednesday in the Lancet. The new analysis includes data on more than 600,000 individuals in Europe, the United States and Australia, and is the largest study thus far of the relationship between working hours and cardiovascular health. But the analysis was not designed to draw conclusions about what caused the increased risk and could not account for all relevant confounding factors. “Earlier studies have pointed to heart attacks as a risk of long working hours, but not stroke,” said Dr. Urban Janlert, a professor of public health at Umea University in Sweden, who wrote an accompanying editorial. “That’s surprising.” Mika Kivimaki, a professor of epidemiology at University College London, and his colleagues combined the results of multiple studies and tried to account for factors that might skew the results. In addition to culling data from published studies, the researchers also compiled unpublished information from public databases and asked authors of previous work for additional data. Dr. Steven Nissen, the chief of cardiovascular medicine at the Cleveland Clinic, found the methodology unconvincing. “It’s based upon exclusively observational studies, many of which were unpublished,” and some never peer-reviewed, he said. Seventeen studies of stroke included 528,908 men and women who were tracked on average 7.2 years. Some 1,722 nonfatal and deadly strokes were recorded. After controlling for smoking, physical activity and high blood pressure and cholesterol, the researchers found a one-third greater risk of stroke among those workers who reported logging 55 or more hours weekly, compared with those who reported working the standard 35 to 40 hours. © 2015 The New York Times Company

Keyword: Stroke; Stress
Link ID: 21323 - Posted: 08.22.2015

Bill McQuay The natural world is abuzz with the sound of animals communicating — crickets, birds, even grunting fish. But scientists learning to decode these sounds say the secret signals of African elephants — their deepest rumblings — are among the most intriguing calls any animal makes. Katy Payne, the same biologist who recognized song in the calls of humpback whales in the 1960s, went on to help create the Elephant Listening Project in the Central African Republic in the 1980s. At the time, Payne's team was living in shacks in a dense jungle inhabited by hundreds of rare forest elephants. That's where one of us — Bill McQuay — first encountered the roar of an elephant in 2002, while reporting a story for an NPR-National Geographic collaboration called Radio Expeditions. Here's how Bill remembers that day in Africa: I was walking through this rainforest to an observation platform built up in a tree — out of the reach of the elephants. I climbed up onto the platform, a somewhat treacherous exercise with all my recording gear. Then I set up my recording equipment, put on the headphones, and started listening. That first elephant roar sounded close. But I was so focused on the settings on my recorder that I didn't bother to look around. The second roar sounded a lot closer. I thought, this is so cool! What I didn't realize was, there was this huge bull elephant standing right underneath me — pointing his trunk up at me, just a few feet away. Apparently he was making a "dominance display." © 2015 NPR

Keyword: Language; Evolution
Link ID: 21319 - Posted: 08.20.2015

Alexander Christie-Miller You could say they sent the first tweets. An ancient whistling language that sounds a little like birdsong has been found to use both sides of the brain – challenging the idea that the left side is all important for communicating. The whistling language is still used by around 10,000 people in the mountains of north-east Turkey, and can carry messages as far as 5 kilometres. Researchers have now shown that this language involves the brain’s right hemisphere, which was already known to be important for understanding music. Until recently, it was thought that the task of interpreting language fell largely to the brain’s left hemisphere. Onur Güntürkün of Ruhr University Bochum in Germany wondered whether the musical melodies and frequencies of whistled Turkish might require people to use both sides of their brain to communicate. His team tested 31 fluent whistlers by playing slightly different spoken or whistled syllables into their left and right ears at the same time, and asking them to say what they heard. The left hemisphere depends slightly more on sounds received by the right ear, and vice versa for the right hemisphere. By comparing the number of times the whistlers reported the syllables that had been played into either their right or left ear, they could tell how often each side of the brain was dominant. As expected, when the syllables were spoken, the right ear and left hemisphere were dominant 75 per cent of the time. But when syllables were whistled, the split between right and left dominance was about even. © Copyright Reed Business Information Ltd.

Keyword: Language; Laterality
Link ID: 21309 - Posted: 08.18.2015

By Perri Klass, A little more than a year ago, the American Academy of Pediatrics issued a policy statement saying that all pediatric primary care should include literacy promotion, starting at birth. That means pediatricians taking care of infants and toddlers should routinely be advising parents about how important it is to read to even very young children. The policy statement, which I wrote with Dr. Pamela C. High, included a review of the extensive research on the links between growing up with books and reading aloud, and later language development and school success. But while we know that reading to a young child is associated with good outcomes, there is only limited understanding of what the mechanism might be. Two new studies examine the unexpectedly complex interactions that happen when you put a small child on your lap and open a picture book. This month, the journal Pediatrics published a study that used functional magnetic resonance imaging to study brain activity in 3-to 5-year-old children as they listened to age-appropriate stories. The researchers found differences in brain activation according to how much the children had been read to at home. Children whose parents reported more reading at home and more books in the home showed significantly greater activation of brain areas in a region of the left hemisphere called the parietal-temporal-occipital association cortex. This brain area is “a watershed region, all about multisensory integration, integrating sound and then visual stimulation,” said the lead author, Dr. John S. Hutton, a clinical research fellow at Cincinnati Children’s Hospital Medical Center. This region of the brain is known to be very active when older children read to themselves, but Dr. Hutton notes that it also lights up when younger children are hearing stories. What was especially novel was that children who were exposed to more books and home reading showed significantly more activity in the areas of the brain that process visual association, even though the child was in the scanner just listening to a story and could not see any pictures. © 2015 The New York Times Company

Keyword: Language; Development of the Brain
Link ID: 21308 - Posted: 08.18.2015

Every brain cell has a nucleus, or a central command station. Scientists have shown that the passage of molecules through the nucleus of a star-shaped brain cell, called an astrocyte, may play a critical role in health and disease. The study, published in the journal Nature Neuroscience, was partially funded by the National Institutes of Health (NIH). “Unexpectedly we may have discovered a hidden pathway to understanding how astrocytes respond to injury and control brain processes. The pathway may be common to many brain diseases and we’re just starting to follow it,” said Katerina Akassoglou, Ph.D., a senior investigator at the Gladstone Institute for Neurological Disease, a professor of neurology at the University of California, San Francisco, and a senior author of the study. Some neurological disorders are associated with higher than normal brain levels of the growth factor TGF-beta, including Alzheimer's disease and brain injury. Previous studies found that after brain injury, astrocytes produce greater amounts of p75 neurotrophin receptor (p75NTR), a protein that helps cells detect growth factors. The cells also react to TGF-beta by changing their shapes and secreting proteins that alter neuronal activity. Dr. Akassoglou’s lab showed that eliminating the p75NTR gene prevented hydrocephalus in mice genetically engineered to have astrocytes that produce higher levels of TGF-beta. Hydrocephalus is a disorder that fills the brain with excess cerebral spinal fluid. Eliminating the p75NTR gene also prevented astrocytes in the brains of the mice from forming scars after injuries and restored gamma oscillations, which are patterns of neuronal activity associated with learning and memory.

Keyword: Brain Injury/Concussion; Glia
Link ID: 21307 - Posted: 08.18.2015

Geoff Brumfiel Learning to make sounds by listening to others is a skill that helps make us human. But research now suggests a species of monkey may have evolved similar abilities. Marmosets have the capacity to learn calls from their parents, according to research published Thursday in the journal Science. The results mean that studying marmosets might provide insights into developmental disorders found in humans. It also suggests that vocal learning may be more widespread than many researchers thought. Many animals can link sounds with meaning. Dogs respond to simple calls; chimpanzees can even communicate with people using sign language. But the ability to hear a sound and mimic it is possessed by only a small number of species: primarily song birds and humans. "We didn't think that mammals and primates in particular — besides us — had any type of vocal learning," says Asif Ghazanfar, a neuroscientist at Princeton University who led the new study. Enter the small, adorable common marmoset. These fuzzy South American primates look more like squirrels than a monkey. "They're cute, and they smell. They wash themselves in their own urine," Ghazanfar says. "I'm not sure why they do that." But once you get over the stink, these little guys are interesting. Marmoset mommies always give birth to twins and they need help rearing them. So, unlike many mammal species, fathers lend a hand, along with siblings and other community members. Ghazanfar thinks all that child care is what gives marmosets another special trait: They're super talkative. "They're chattering nonstop," he says. "That is also very different from our close relatives the chimpanzees." © 2015 NPR

Keyword: Language; Evolution
Link ID: 21300 - Posted: 08.15.2015

By Janet Davison, CBC News Maddy Huggins would binge drink as a teenager and black out, just like other kids at her high school in Kelowna, B.C. When she went backpacking during her gap year, there were more alcoholic overloads and "really risky" moments when something bad could have transpired. "Nothing too terrible happened, but there was the potential for that," says Huggins, 22, who's just about to start fourth year at the University of Saskatchewan. As she settled into university, however, Huggins did some serious thinking about alcohol in her life. "It was just a gradual progression where I was like, 'OK, enough of this.'" These days, Huggins knows her low-risk alcoholic limits and won't hesitate to order water even if her friends are going for something stronger. But other young Canadian women haven't stepped back like that. Reports suggest the percentage of young women binge drinking — defined now as having at least four drinks per occasion at least once a month — is on the rise and encompasses nearly one in four Canadian women between 20 and 34. Indeed, the trend has become so pronounced that the Paris-based Organization of Economic Co-operation and Development warned in May that binge drinking by young people, including in Canada, has become a "major public health and social concern." Looming problems It's a concern that goes beyond the headline issues like date rape and campus horrors to where health scientists are warning that because of physiology — women generally weigh less than men, have a higher percentage of body fat and smaller livers — excessive drinking by young women is setting them up for a series of health problems down the road. ©2015 CBC/Radio-Canada

Keyword: Drug Abuse; Stroke
Link ID: 21282 - Posted: 08.10.2015

Rachel Martin The National Football League held its annual hall of fame induction ceremony Saturday night, in Canton, Ohio. Eight players were given football's highest honor, including a posthumous induction for Junior Seau, the former linebacker for the San Diego Chargers who killed himself in 2012. After his death, Seau's brain showed signs of chronic damage — the same kind of damage that has been found in dozens of other former NFL players. Scientific studies have shown that the kind of repeated hits NFL players take is linked to chronic traumatic encephalopathy, or CTE, a degenerative brain disease. CTE is associated with memory loss, impulse control problems, depression and eventually dementia. Some players are rethinking their careers — like up-and-coming linebacker Chris Borland, who quit after his first season with the 49ers a few months ago — for fear of head injuries. Parents are weighing the risks as well. So when someone like Chicago Bears coach Mike Ditka talks, they listen. When host Bryant Gumbel asked Ditka on HBO's Real Sports earlier this year whether, if he had an 8-year-old now, he would want him to play football. "No," he answered. "That's sad. I wouldn't, and my whole life was football. I think the risk is worse than the reward." Tregg Duerson's father, Dave Duerson, a defensive back who played most of his pro football career with the Chicago Bears, killed himself in 2011 in his Miami home. Duerson was part of the legendary '85 team that won the Superbowl, and five years later helped the New York Giants win their own championship. © 2015 NPR

Keyword: Brain Injury/Concussion
Link ID: 21281 - Posted: 08.10.2015

A dipstick inserted into the brain can check its energy levels, just like checking oil levels in a car. The dipstick is already available and can save lives, according to some neuroscientists. “The goal is to save brain tissue,” says Elham Rostami of the Karolinska Institute in Stockholm, Sweden. Last month, Rostami and 47 others published guidelines about how and when to use the technique, known as brain microdialysis, in the hope of encouraging more hospitals to adopt it. The approach involves inserting a slim, 1-centimetre-long probe directly into the brain. It measures levels of chemicals in the fluid that bathes brain cells, including glucose, the brain’s main energy source. When used to monitor the brains of people in intensive care after a stroke or head injury, it warns doctors if glucose starts to dip – which can cause brain damage. The probe can theoretically monitor almost any molecule, but Rostami says the most useful parameters are glucose, which shows if there is a good blood supply, and lactate and pyruvate, two metabolites that indicate if brain cells are using the glucose to release energy. Although widely available, the device has so far mainly been used as a research tool rather than to guide treatment. Rostami believes her use of the probe helped save a woman’s life last year. The woman was in intensive care after a stroke involving bleeding on the surface of her brain. The probe revealed that although the bleeding had stopped, the woman’s brain glucose levels had fallen, probably caused by other blood vessels constricting. © Copyright Reed Business Information Ltd.

Keyword: Stroke; Brain imaging
Link ID: 21270 - Posted: 08.05.2015

// by Richard Farrell Bonobos have a capacity to do something human infants have been shown to do: use a single sound whose meaning varies based on context, a form of "flexible" communication previously thought specific to humans. The finding was made by researchers from the University of Birmingham and the University of Neuchatel, in a paper just published in the journal Peer J. The newly identified bonobo call is a short, high-pitched "peep," made with a closed mouth. The scientists studied the call's acoustic structure and observed that it did not change between what they termed "neutral" and "positive" circumstances (for example, between activities such as feeding or resting), suggesting that other bonobos receiving the call would need to weigh contextual information to discern its meaning. Human babies do something similarly flexible, using sounds called protophones -- different from highly specific sounds such as crying or laughter -- that are made independent of how they are feeling emotionally. The appearance of this capability in the first year of life is "a critical step in the development of vocal language and may have been a critical step in the evolution of human language," an earlier study on infant vocalization noted. The find challenges the idea that calls from primates such as bonobos -- which, along with chimpanzees, are our closest relatives -- are strictly matched with specific contexts and emotions, whether those sounds are territorial barks or shrieks of alarm. © 2015 Discovery Communications, LLC.

Keyword: Language; Evolution
Link ID: 21265 - Posted: 08.05.2015

By Michael Balter Have you ever wondered why you say “The boy is playing Frisbee with his dog” instead of “The boy dog his is Frisbee playing with”? You may be trying to give your brain a break, according to a new study. An analysis of 37 widely varying tongues finds that, despite the apparent great differences among them, they share what might be a universal feature of human language: All of them have evolved to make communication as efficient as possible. Earth is a veritable Tower of Babel: Up to 7000 languages are still spoken across the globe, belonging to roughly 150 language families. And they vary widely in the way they put sentences together. For example, the three major building blocks of a sentence, subject (S), verb (V), and object (O), can come in three different orders. English and French are SVO languages, whereas German and Japanese are SOV languages; a much smaller number, such as Arabic and Hebrew, use the VSO order. (No well-documented languages start sentences or clauses with the object, although some linguists have jokingly suggested that Klingon might do so.) Yet despite these different ways of structuring sentences, previous studies of a limited number of languages have shown that they tend to limit the distance between words that depend on each other for their meaning. Such “dependency” is key if sentences are to make sense. For example, in the sentence “Jane threw out the trash,” the word “Jane” is dependent on “threw”—it modifies the verb by telling us who was doing the throwing, just as we need “trash” to know what was thrown, and “out” to know where the trash went. Although “threw” and “trash” are three words away from each other, we can still understand the sentence easily. © 2015 American Association for the Advancement of Science.

Keyword: Language; Evolution
Link ID: 21263 - Posted: 08.04.2015

A protein previously linked to acute symptoms following a traumatic brain injury (TBI), may also be responsible for long-term complications that can result from TBI, according to research from the National Institute of Nursing Research (NINR), a component of the National Institutes of Health. Using an ultra-sensitive technology, researchers — led by NIH Lasker Clinical Research Scholar and Chief of NINR’s Brain Injury Unit, Tissue Injury Branch Jessica Gill, Ph.D., R.N., — were able to measure levels of the protein, tau, in the blood months and years after individuals (in this case, military personnel) had experienced TBI. They found that these elevated levels of tau — a protein known to have a role in the development of Alzheimer’s disease and Parkinson’s disease — are associated with chronic neurological symptoms, including post-concussive disorder (PCD), during which an individual has symptoms such as headache and dizziness in the weeks and months after injury. These chronic neurological symptoms have been linked to chronic traumatic encephalopathy (CTE) — progressive brain degeneration that leads to dementia following repetitive TBIs — independent of other factors such as depression and post-traumatic stress disorder (PTSD). The study and an accompanying editorial appear in the August 3 issue of JAMA Neurology. “Our study was limited to identifying the effects of tau accumulation in military personnel who experienced long-term neurological symptoms after a TBI. With further study, our findings may provide a framework for identifying patients who are most at risk for experiencing chronic symptoms related to TBI. Identifying those at risk early in the progression of the disease provides the best opportunity for therapies that can lessen the cognitive declines that may result from these long-term effects,” said Dr. Gill, the study’s lead author.

Keyword: Brain Injury/Concussion
Link ID: 21259 - Posted: 08.04.2015

By Ariana Eunjung Cha Children who suffer an injury to the brain -- even a minor one -- are more likely to experience attention issues, according to a study published Monday in the journal Pediatrics. The effects may not be immediate and could occur long after the incident. Study author Marsh Konigs, a doctoral candidate at VU University Amsterdam, described the impact as "very short lapses in focus, causing children to be slower." Researchers looked at 113 children, ages six to 13, who suffered from traumatic brain injuries (TBIs) ranging from a concussion that gave them a headache or caused them to vomit, to losing consciousness for more than 30 minutes, and compared them with a group of 53 children who experienced a trauma that was not head-related. About 18 months after the children's accidents, parents and teachers were asked to rate their attention and other indicators of their health. They found that those with TBI had more lapses in attention and other issues, such as anxiety, a tendency to internalize their problems and slower processing speed. Based on studies of adults who experienced attention issues after suffering from a brain injury, doctors have theorized for years that head injuries in children might be followed by a "secondary attention deficit hyperactivity disorder." This study appears to confirm that association.

Keyword: ADHD; Brain Injury/Concussion
Link ID: 21258 - Posted: 08.04.2015

By Ariana Eunjung Cha Think you have your hands full making sure your baby is fed and clean and gets enough sleep? Here's another thing for the list: developing your child's social skills by the way you talk. People used to think that social skills were something kids were born with, not taught. But a growing body of research shows that the environment a child grows up in as an infant and toddler can have a major impact on how they interact with others as they get older. And it turns out that a key factor may be the type of language they hear around them, even at an age when all they can do is babble. Psychologists at the University of York observed 40 mothers and their babies at 10, 12, 16 and 20 months and logged the kind of language mothers used during play. They were especially interested in "mind-related comments," which include inferences about what someone is thinking when a behavior or action happens. Elizabeth Kirk, a lecturer at the university who is the lead author of the study, published in the British Journal of Developmental Psychology on Monday, gave this as an example: If an infant has difficulty opening a door on a toy, the parent might comment that the child appears "frustrated." Then researchers revisited the children when they were 5 or 6 years of age and assessed their socio-cognitive ability. The test involved reading a story and having the children answer comprehension questions that show whether they understood the social concept -- persuasion, joke, misunderstanding, white lies, lies, and so forth -- that was represented.

Keyword: Language; Development of the Brain
Link ID: 21239 - Posted: 07.30.2015

Tara Haelle To tell if a baby has been injured or killed by being shaken, the courts use three hallmark symptoms: Bleeding and swelling in the brain and retinal bleeding in the eyes. Along with other evidence, those standards are used to convict caregivers of abusive head trauma, both intentional and unintentional, that can result in blindness, seizures, severe brain damage or death. But in recent years a small cadre of experts testifying for the defense in cases across the country has called into question whether those symptoms actually indicate abuse. Though they are in the minority – disputing the consensus of child abuse experts, pediatricians and an extensive evidence base – they have gained traction in the media and in courtrooms by suggesting that shaking a child cannot cause these injuries. Instead, they argue that undiagnosed medical conditions, falls or other accidents are the cause. So researchers have developed and validated a tool doctors can use to distinguish between head injuries resulting from abuse and those from accidents or medical conditions. The method, described in the journal Pediatrics Monday, asks doctors to check for six other injuries, each of which increases the likelihood that a head injury resulted from severe shaking, blunt force or both. "It is vitally important that abuse head trauma is diagnosed accurately so that the team looking after the child can ensure that they receive appropriate support and are protected from further harm," lead study author Laura Elizabeth Cowley, a PhD student at the Cardiff University School of Medicine in the U.K., said in an email. "However, it is also important that accidental head injury cases are not wrongly diagnosed as abusive," she continues, "because this can have devastating consequences for the families involved." © 2015 NPR

Keyword: Brain Injury/Concussion; Development of the Brain
Link ID: 21238 - Posted: 07.30.2015

A panel of independent experts has decided that a clot-busting drug often used to treat strokes is "safe and effective". The UK medicines watchdog wanted the benefits and risks of alteplase to be analysed after concerns were raised about its safety. The panel concluded that the best time to use the drug is up to four and a half hours after the start of symptoms. But some other doctors are still not convinced by the evidence. Most strokes are caused by a clot blocking the flow of blood to the brain. Many patients are given the drug alteplase to break down and disperse the clot - a treatment known as thrombolysis. The independent expert panel, chaired by Prof Sir Ian Weller, said it had looked at all available data on alteplase and decided that the earlier the drug was given to patients, the greater the chance of a good outcome. Used up to four and a half hours after the onset of symptoms, the benefits of the drug were found to outweigh the risks. But it added that the benefits of using alteplase to treat strokes were "highly time-dependent" and, in a small number of people, there was a risk of haemorrhage. Prof Weller explained: "The evidence shows that for every 100 patients treated with alteplase, whilst there is an early risk of a fatal bleed in two patients, after three to six months, around 10 more in every 100 are disability-free when treated within three hours." © 2015 BBC.

Keyword: Stroke
Link ID: 21218 - Posted: 07.25.2015

Carl Zimmer An ant colony is an insect fortress: When enemies invade, soldier ants quickly detect the incursion and rip their foes apart with their oversize mandibles. But some invaders manage to slip in with ease, none more mystifyingly than the ant nest beetle. Adult beetles stride into an ant colony in search of a mate, without being harassed. They lay eggs, from which larva hatch. As far as scientists can tell, workers feed the young beetles as if they were ants. When the beetles grow into adults, the ants swarm around them, grooming their bodies. In exchange for this hospitality, the beetles sink their jaws into ant larvae and freshly moulted adults in order to drink their body fluids. “They’re like vampire beetles wandering in the ant nests,” said Andrea Di Giulio, an entomologist at Roma Tre University in Rome. Dr. Di Giulio and his colleagues have now uncovered a remarkable trick that the beetles use to fool their hosts. It turns out they can perform uncanny impressions, mimicking a range of ant calls. Dr. Di Giulio and his colleagues study a species of ant nest beetle called Paussus favieri, which lives in the Atlas Mountains of Morocco, where it infiltrates the nests of Moroccan ants, known as Pheidole pallidula. Like many ant species, Pheidole pallidula makes noises by rubbing its legs against ridges on its body. The meanings of these signals vary from species to species; leaf-cutting ants summon bodyguards for the march back to the nest; in other species, a queen trills to her workers to attend to her. Scientists have found that Pheidole pallidula ants make three distinct sounds, each produced by a different caste: soldiers, workers and the queen. © 2015 The New York Times Company

Keyword: Evolution; Language
Link ID: 21193 - Posted: 07.20.2015