Chapter 16. None
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People with Parkinson's disease are dancing at the National Ballet School as part of a study into how learning dance moves can change the brain. Anecdotally, learning to dance seems to improve motor skills in the short-term among people with Parkinson's disease, a neurological disorder that interferes with gait and balance. As part of a 12-week program, 20 people with Parkinson's disease are taking weekly dance classes at the National Ballet School in Toronto. The classes began in September. The research team is led by neuroscientist Prof. Joseph DeSouza of York University's Faculty of Health and National Ballet School instructor Rachel Bar. The volunteers are also getting a series of functional MRI scans to help researchers understand how the brain reacts and learns. "We know that balance can improve and gait can improve and even there's social benefits but we want to see why that's happening, how is it happening? To do that, we're looking inside the brain," Bar said. People aren't able to dance in scanner but they are asked to visualize the dance while listening to the accompanying music. "If you visualize a dance, theoretically you're using almost all the same neural circuitry as if you were doing it," DeDouza said. The hypothesis is that the brain of someone with Parkinson's may develop new paths around damaged areas if stimulated by the movement of dance. © CBC 2013
Link ID: 18826 - Posted: 10.23.2013
By Phil Plait Thanks to my evil twin Richard Wiseman (a UK psychologist who specializes in studying the ways we perceive things around us, and how easily we can be fooled), I saw this masterful illusion video that will keep you guessing on what’s real and what isn’t. It’s only two minutes long, so give it a gander: Cool, eh? The reason you got fooled, at least twice, is that we get confused when our three-dimensional world is translated into two dimensions. We perceive distance for nearby objects using binocular vision, which depends on the angles between our eyes and the objects. If you create a picture of an object that is carefully distorted to match those changing angles, you can fool the brain into thinking it’s seeing a real object when in fact it’s a flat representation. We’re actually very good at taking subtle cues and turning them into three-dimensional interpretations. However, because of that very sensitivity, it’s easy to throw a monkey in the wrench, messing up our perception. Still don’t believe me? Then watch this, and if it doesn’t melt your brain, I can no longer help you. Our brains are very, very easy to fool. I’ll note that the way we see color is very easy to trick, too. I wrote an article about a fantastic, astonishing color illusion back in 2009, and it spurred a lot of arguments in the comments, even when I showed clearly how it works. Amazing. © 2013 The Slate Group, LLC
Link ID: 18825 - Posted: 10.23.2013
When frogs croak, the fringe-lipped bat, Trachops cirrhosus, listens. The bats use the sounds to track and feed on amphibians and to share dining tips with neighbors. In a new study, Patricia Jones of the University of Texas at Austin and colleagues trained a few frog-eating bats to associate a cell phone ringtone with food. Some of the bats reliably got food when they heard the phone ring. Others did not. The bats that failed to get food using their own cues paid more attention to new ones that their fellow mammals shared. Social learning becomes much more important if a bat is unsuccessful at finding food, the scientists report October 22 in the Proceedings of the Royal Society B. Observing how bats forage alone and together may help scientists understand the way new hunting behaviors spread through animal populations. It may also give insight to animals’ potential for cultivating culture, the authors suggest. © Society for Science & the Public 2000 - 2013.
Keyword: Learning & Memory
Link ID: 18823 - Posted: 10.23.2013
By Consumer Reports, You wake up tired after a full night’s sleep. Maybe you’ve become a bit forgetful, and you struggle to stay awake at work or behind the wheel. The problem might be obstructive sleep apnea, an often overlooked condition that has increased sharply in the past 20 years. In the United States, more than 40 percent of men and 28 percent of women between the ages of 50 and 70 experience obstructed breathing while asleep, according to researchers whose work was published online in April by the American Journal of Epidemiology. About 17 percent of the men and 9 percent of the women have cases serious enough to meet the Medicare criteria for a sleep apnea diagnosis. But even milder cases can affect your health. Obstructive sleep apnea causes the muscles and tissues in the lower throat to collapse, blocking the flow of air to the lungs during sleep. A person with obstructive sleep apnea may stop breathing, typically for 20 to 25 seconds or for as long as two minutes. The amount of carbon dioxide in the blood rises, triggering an alarm in the brain that stirs the sleeper to resume breathing. That cycle can repeat itself dozens of times an hour throughout the night, preventing the sleeper from reaching the restorative stages of deep sleep. Upon awakening, he or she usually has no recollection of those events. Overweight men are the most frequently affected because they tend to have a throat with bulkier soft tissue and fat deposits, but women and people of normal weight also develop sleep apnea. Loud snoring can be a warning sign, especially if you learn from a bed partner or roommate that you gasp for breath or choke while you are asleep. High blood pressure and heart-rhythm abnormalities are also red flags, especially if you take antihypertensive medication and still have trouble keeping blood pressure under control. Waking up with a headache may also signal the condition. © 1996-2013 The Washington Post
Link ID: 18820 - Posted: 10.22.2013
Maggie Fox NBC News Every cell in your body has a little clock ticking away in it, researchers reported on Sunday. And while most of you is aging in a coordinated way, odd anomalies that have the researchers curious: Your heart may be “younger” than the rest of your tissues, and a woman’s breasts are older. Tumors are the oldest of all, a finding reported in the journal Genome Biology that might help scientists better understand cancer, explain why breast cancer is so common and help researchers find better ways to prevent it. Less surprising, but intriguing: embryonic stem cells, the body’s master cells, look just like newborns with a biological age of zero. The new measurements might be useful in the search for drugs or other treatments that can turn back the clock on aging tissue and perhaps treating or preventing diseases of aging, such as heart disease and cancer, says Steve Horvath, a professor of genetics at the David Geffen School of Medicine at UCLA. “The big question is whether the biological clock controls a process that leads to aging,” Horvath said. Horvath looked at a genetic process called methylation. It’s a kind of chemical reaction that turns on or off stretches of DNA. All cells have the entire genetic map inside; methylation helps determine which bits of the map the cells use to perform specific functions.
Keyword: Biological Rhythms
Link ID: 18816 - Posted: 10.21.2013
By GRETCHEN REYNOLDS If you consider yourself to be a born morning person or an inveterate night owl, there is new research that supports your desire to wake up early or stay up late. Each of us has a personal “chronotype,” or unique circadian rhythm, says Till Roenneberg, a professor of chronobiology at Ludwig Maximilian University in Munich and one of the world’s experts on sleep. In broad strokes, these chronotypes are usually characterized as early, intermediate or late, corresponding to people who voluntarily go to bed and wake early, at a moderate hour or vampirishly late. If you are forced to wake up earlier than your body naturally would, you suffer from what Roenneberg calls “social jet lag.” People with an early chronotype may do well with a 7 a.m. workday rising time, but others do not. Sleeping out of sync with your innate preferences can be detrimental to your health, especially for late chronotypes, who tend to be the most at odds with typical work schedules. A study conducted by the National Institutes of Health and published in March in PLOS ONE found that obese adults with late chronotypes tended to eat larger meals, develop more sleep apnea and have higher levels of stress hormones and lower levels of HDL, or “good,” cholesterol than obese people with other chronotypes. Their chronotype may also have contributed to weight gain in the first place, Roenneberg says. Research has shown that a single hour of social jet lag, the mismatch between your chronotype and your schedule, increases your risk for obesity by about 33 percent. In a study published in June in Chronobiology International, late-night chronotypes gained more weight during their freshman years at college than other new students did, even though college is one of the best fits for night owls. Copyright 2013 The New York Times Company
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
By Jesse Bering Disgust, in its most familiar form, is our response to something vile in the world—spoiled food, a dirty floor or rats cavorting in the subway. It is a contamination-avoidance mechanism that evolved to help us make biologically adaptive decisions in the heat of the moment. Yet disgust has also come to have powerful symbolic elements. When left unchecked, these symbolic qualities can have devastating impacts on our mental states. Consider, for example, the often dramatized, heartbreaking image of a woman crouched in the corner of a shower and frantically trying to scrub her body clean after being raped. Empirical evidence supports the characterization. Seventy percent of female victims of sexual assault report a strong impulse to wash afterward, and a quarter of these continue to wash excessively up to three months later. For women, simply imagining an unwanted advance can turn on this moral-cleansing effect. Psychiatrist Nichole Fairbrother of the University of British Columbia Hospital and her colleagues looked more closely at the phenomenon of mental pollution in a study published in 2005. Two groups of female participants were told to close their eyes and picture being kissed. The members of one group were instructed to imagine being aggressively cornered and kissed against their will. The members of the other group were asked to envision themselves in a consensual embrace. Only those women in the coercive condition chose to wash up after the study. In many cases, it seems as though a person's sense of self has become contaminated. © 2013 Scientific American
Link ID: 18811 - 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.
Sid Perkins One of the most complete early human skulls yet found suggests that what scientists thought were three hominin species may in fact be one. This controversial claim comes from a comparison between the anatomical features of a 1.8-million-year-old fossil skull with those of four other skulls from the same excavation site at Dmanisi, Georgia. The wide variability in their features suggests that Homo habilis, Homo rudolfensis and Homo erectus, the species so far identified as existing worldwide in that era, might represent a single species. The research is published in Science today1. The newly described skull — informally known as 'skull 5' — was unearthed in 2005. When combined with a jawbone found five years before and less than 2 metres away, it “is the most complete skull of an adult from this date”, says Marcia Ponce de León, a palaeoanthropologist at the Anthropological Institute and Museum in Zurich, Switzerland, and one of the authors of the study. The volume of skull 5’s braincase is only 546 cubic centimetres, about one-third that of modern humans, she notes. Despite that low volume, the hominin’s face was relatively large and protruded more than the faces of the other four skulls found at the site, which have been attributed to H. erectus. Having five skulls from one site provides an unprecedented opportunity to study variation in what presumably was a single population, says co-author Christoph Zollikofer, a neurobiologist at the same institute as Ponce de León. All of the skulls excavated so far were probably deposited within a 20,000-year time period, he notes. © 2013 Nature Publishing Group
Link ID: 18806 - Posted: 10.19.2013
by Helen Thomson ONE moment you are alive. The next you are dead. A few hours later and you are alive again. Pharmacologists have discovered a mechanism that triggers Cotard's syndrome – the mysterious condition that leaves people feeling like they, or parts of their body, no longer exist. With the ability to switch the so-called walking corpse syndrome on and off comes the prospect of new insights into how conscious experiences are constructed. Acyclovir – also known by the brand name Zovirax – is a common drug used to treat cold sores and other herpes infections. It usually has no harmful side effects. However, about 1 per cent of people who take the drug orally or intravenously experience some psychiatric side effects, including Cotard's. These occur mainly in people who have renal failure. To investigate the potential link between acyclovir and Cotard's, Anders Helldén at Karolinska University Hospital in Stockholm and Thomas Lindén at the Sahlgrenska Academy in Gothenburg pooled data from Swedish drug databases along with hospital admissions. They identified eight people with acyclovir-induced Cotard's. One woman with renal failure began using acyclovir to treat shingles. She ran into a hospital screaming, says Helldén. After an hour of dialysis, she started to talk: she said the reason she was so anxious was that she had a strong feeling she was dead. After a few more hours of dialysis she said, "I'm not quite sure whether I'm dead any more but I'm still feeling very strange." Four hours later: "I'm pretty sure I'm not dead any more but my left arm is definitely not mine." Within 24 hours, the symptoms had disappeared. © Copyright Reed Business Information Ltd.
Link ID: 18805 - Posted: 10.17.2013
by Denise Chow, LiveScience The discovery of a fossilized brain in the preserved remains of an extinct "mega-clawed" creature has revealed an ancient nervous system that is remarkably similar to that of modern-day spiders and scorpions, according to a new study. The fossilized Alalcomenaeus is a type of arthropod known as a megacheiran (Greek for "large claws") that lived approximately 520 million years ago, during a period known as the Lower Cambrian. The creature was unearthed in the fossil-rich Chengjiang formation in southwest China. VIDEO: Bugs, Arthropods, and Insects! Oh My! Researchers studied the fossilized brain, the earliest known complete nervous system, and found similarities between the extinct creature's nervous system and the nervous systems of several modern arthropods, which suggest they may be ancestrally related. [Photos of Clawed Arthropod & Other Strange Cambrian Creatures] Living arthropods are commonly separated into two major groups: chelicerates, which include spiders, horseshoe crabs and scorpions, and a group that includes insects, crustaceans and millipedes. The new findings shed light on the evolutionary processes that may have given rise to modern arthropods, and also provide clues about where these extinct mega-clawed creatures fit in the tree of life. "We now know that the megacheirans had central nervous systems very similar to today's horseshoe crabs and scorpions," senior author Nicholas Strausfeld, a professor in the department of neuroscience at the University of Arizona in Tucson, said in a statement. "This means the ancestors of spiders and their kin lived side by side with the ancestors of crustaceans in the Lower Cambrian." © 2013 Discovery Communications, LLC.
Link ID: 18804 - Posted: 10.17.2013
by Bob Holmes The great flowering of human evolution over the past 2 million years may have been driven not by the African savannahs, but by the lakes of that continent's Great Rift Valley. This novel idea, published this week, may explain why every major advance in the evolution of early humans, from speciation to the vast increase in brain size, appears to have taken place in eastern Africa. Anthropologists have surmised for several years that early humans, or hominins, might have evolved their unusually large, powerful brains to cope with an increasingly variable climate over the past few million years. However, studies testing this hypothesis have been equivocal, perhaps because most use global or continental-scale measures of climate, such as studying trends in the amount of airborne dust from dry earth that is blown into the ocean and incorporated into deep-sea sediments. Mark Maslin, a palaeoclimatologist at University College London, and his colleague Susanne Shultz at the University of Manchester, UK, have taken a local approach instead, by studying whether the presence or absence of lakes in the Rift Valley affected the hominins living there. Maslin's hunch is that relatively short periods of extreme variability 2.6, 1.8, and 1 million years ago – which are important periods for human evolution – corresponded to times of rapid change in the large lakes of the Great Rift Valley. Because the valley concentrates rainfall from a wide area into relatively small basins, these lakes are unusually sensitive to rainfall and swell or disappear depending on climate. © Copyright Reed Business Information Ltd.
Link ID: 18802 - Posted: 10.17.2013
By Jason G. Goldman Scientists love yawning. No, that’s not quite right. Scientists love doing research on yawning. It seems to be of interest to folks in fields ranging from primatology to developmental psychology to psychopathology to animal behavior. If the notion of scientifically investigation the purpose of yawning makes you, well, yawn, then you’re missing one of the more interesting debates in the social cognition literature. To understand why yawning is about more than feeling tired or bored, we have to go back a few years. Once upon a time, scientists thought that yawning might be process through which the brain keeps itself cool (PDF). Yawning is associated with increases in blood pressure, and the consequential increase in blood flow might mean that the vascular system acts as a radiator, replacing the warm blood in the brain with cooler blood. It could also be that the deep inhalation of cold air during a yawn can, through convection, alter blood temperature which in turn could cool the brain. Even if it turns out that some yawns can be explained through purely physiological means, yawning is also contagious for humans and other species. If someone watches someone else yawning, they’ll be likely to yawn as well. That means that there is social component to yawning, and it might be related to empathy. It turns out that there’s a correlation between a person’s self-reported empathy and their susceptibility to reacting to a yawn contagion, and those who are more skilled at theory of mind tasks are also more likely (PDF) to yawn contagiously. © 2013 Scientific American
Henry Astley In the Mark Twain story The Celebrated Jumping Frog of Calaveras County, a frog named Daniel Webster "could get over more ground at one straddle than any animal of his breed you ever see." Now, scientists have visited the real Calaveras County in hopes of learning more about these hopping amphibians. They’ve found that what they see in the lab doesn’t always match the goings-on in the real world. If you wanted to know how far the bullfrog Rana catesbeiana could jump, the scientific literature would give you one answer: 1.295 meters, published in Smithsonian Contributions to Zoology in 1978. If you looked at the Guinness Book of World Records, though, you'd find a different answer. In 1986, a bullfrog called Rosie the Ribeter covered 6.55 meters in three hops. If you divide by three, at least one of those hops had to be no shorter than 2.18 meters—about four bullfrog body lengths more than the number in the scientific paper. The disparity matters. If bullfrogs can hop only 1.3 meters, they have enough power in their muscles to pull off the jump without any other anatomical help. But if they can jump farther, they must also be using a stretchy tendon to power their hops—an ability that other frogs have but that researchers thought bullfrogs had lost. These particular amphibians, scientists speculated, might have made some kind of evolutionary tradeoff that shortened their jumps but enabled them to swim better in the water, where they spend much of their lives. © 2013 American Association for the Advancement of Science
Link ID: 18800 - Posted: 10.17.2013
Anne Trafton, MIT News Office Schizophrenia patients usually suffer from a breakdown of organized thought, often accompanied by delusions or hallucinations. For the first time, MIT neuroscientists have observed the neural activity that appears to produce this disordered thinking. The researchers found that mice lacking the brain protein calcineurin have hyperactive brain-wave oscillations in the hippocampus while resting, and are unable to mentally replay a route they have just run, as normal mice do. Mutations in the gene for calcineurin have previously been found in some schizophrenia patients. Ten years ago, MIT researchers led by Susumu Tonegawa, the Picower Professor of Biology and Neuroscience, created mice lacking the gene for calcineurin in the forebrain; these mice displayed several behavioral symptoms of schizophrenia, including impaired short-term memory, attention deficits, and abnormal social behavior. In the new study, which appears in the Oct. 16 issue of the journal Neuron, Tonegawa and colleagues at the RIKEN-MIT Center for Neural Circuit Genetics at MIT’s Picower Institute for Learning and Memory recorded the electrical activity of individual neurons in the hippocampus of these knockout mice as they ran along a track. Previous studies have shown that in normal mice, “place cells” in the hippocampus, which are linked to specific locations along the track, fire in sequence when the mice take breaks from running the course. This mental replay also occurs when the mice are sleeping. These replays occur in association with very high frequency brain-wave oscillations known as ripple events.
Link ID: 18798 - Posted: 10.17.2013
By MICHAEL WINES NEW HOLSTEIN, Wis. — Next to their white clapboard house on a rural road here, in long rows of cages set beneath the roofs of seven open-air sheds, Virginia and Gary Bonlander are raising 5,000 minks. Or were, anyway, until two Saturdays ago, when the police roused them from bed at 5 a.m. with a rap on their door. The Bonlanders woke one recent morning to find thousands of the creatures zipping across their lawn. Outside, 2,000 minks were scampering away — up to 50 top-quality, full-length and, suddenly, free-range mink coats. “The backyard was full of mink. The driveway was full of mink,” Mrs. Bonlander recalled a few days ago. “Then, pshew” — she made a whooshing sound — “they were gone.” And not only in Wisconsin, the mink-raising capital of the United States. After something of a hiatus, the animal rights movement has resumed a decades-old guerrilla war against the fur industry with a vengeance — and hints of more to come. In New Holstein; in Grand Meadow, Minn.; in Coalville, Utah; in Keota, Iowa; and four other states, activists say, eight dark-of-night raids on mink farms have liberated at least 7,700 of the critters — more than $770,000 worth of pelts — just since late July. That is more such raids than in the preceding three years combined. Two more raids in Ontario and British Columbia freed 1,300 other minks and foxes during the same period, according to the North American Animal Liberation Press Office, which bills itself as a conduit for messages from anonymous animal rights activists. “What we’re seeing now is unprecedented,” Peter Young, a Santa Cruz, Calif., activist who was imprisoned in 2005 for his role in raids on six mink ranches, said in a telephone interview. Though still an outspoken defender of the animal rights movement and mink-ranch raids, Mr. Young says he has no contact with those who raid fur farms or commit other illegal acts and, in fact, does not know who they are. © 2013 The New York Times Company
Keyword: Animal Rights
Link ID: 18797 - Posted: 10.17.2013
by Colin Barras A part of all of us loves sums. Eavesdropping on the brain while people go about their daily activity has revealed the first brain cells specialised for numbers. Josef Parvizi and his colleagues at Stanford University in California enlisted the help of three people with epilepsy whose therapy involved placing a grid of electrodes on the surface of their brain that record activity. Neurons fired in a region called the intraparietal sulcus when the three volunteers performed arithmetic tests, suggesting they dealt with numbers. The team continued to monitor brain activity while the volunteers went about their normal activity in hospital. Comparing video footage of their stay with their brain activity (see video, above) revealed that the neurons remained virtually silent for most of the time, bursting into life only when the volunteers talked about numbers or numerical concepts such as "more than" or "less than". There is debate over whether some neural populations perform many functions or are involved in very precise tasks. "We show here that there is specialisation for numeracy," says Parvizi. Journal reference: Nature Communications, DOI: 10.1038/ncomms3528 © Copyright Reed Business Information Ltd.
Link ID: 18796 - Posted: 10.16.2013
Ewen Callaway As a new study in the British Medical Journal reveals that 1 in 2000 people in the UK may harbour the infectious prion protein which causes variant Creutzfeldt–Jakob disease (vCJD), Nature explains what this means. The usually fatal condition is the human form of bovine spongiform encepalpoathy — dubbed 'mad cow disease' in the UK after an outbreak of the disease in the 1980s. Both diseases are caused by misfolded proteins called prions, which induce other proteins in the brain to clump, eventually destoying neurons. Humans are thought to contract the disease by consuming beef containing infected bovine brain or other central nervous system tissue. But it also spreads through blood transfusions, and some worry that the prion disease is transmitted via contaminated surgical instruments . The BSE outbreak in the 1980s and 1990s led to a surge in British vCJD cases, and a total of 177 have been detected in the UK to date, with just one in the last two years. Cases of vCJD peaked in 2000, leading some scientists to speculate that the disease takes about a decade to develop. Yet other studies of different forms of CJD suggest its incubation time could be much longer — indicating that many Britons may be carrying the infection without symtoms. Studies have come to varying conclusions as to just how many people harbour the abnormal prion protein (PrP) that causes vCJD. Surveys of tens of thousands of appendices and tonsil, discarded after surgery, have come up with prevalence rates ranging from 1 in 40001 to 1 in 10,0002 to 03. © 2013 Nature Publishing Group
Link ID: 18795 - Posted: 10.16.2013