Chapter 5. The Sensorimotor System
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James Gorman All moving animals do their best to avoid running into things. And most living things follow a tried and true strategy — Watch where you’re going! Flying and swimming animals both have to cope with some complications that walkers, jumpers and gallopers don’t confront. Not only do they have to navigate in three dimensions, but they also cope with varying air and water flow. Beyond that, they often do so without the same references points and landmarks we have on the ground. Christine Scholtyssek of Lund University in Sweden, and colleagues decided to compare how two species in different mediums, air and water, which pose similar problems, reacted to apparent obstacles as they were moving. What they found, and reported in Biology Letters in May, was that the two species they examined — bumblebees and zebra fish — have very different strategies. It was known that the bees’ navigation depended on optic flow, which is something like the sensation of watching telephone poles speed past from a seat on a moving train. They tend to fly away from apparent obstacles as they approach them. The question was whether fish would do something similar. So, in order to give both animals the same test, Dr. Scholtyssek and her colleagues devised an apparatus that could contain air or water. When one wall had vertical stripes and the other horizontal, the bees, not surprisingly, flew away from the vertical stripes, which would have appeared as one emerging obstacle after another as the bees flew past. Horizontal stripes don’t change as a creature moves past, so they provide no reference for speed or progress. The fish, however, swam closer to the vertical stripes, which wasn’t expected. “It is surprising that although fish and bees have the same challenge, moving with or against streams, they do not use the same mechanisms,” Dr. Scholtyssek said. © 2014 The New York Times Company
Keyword: Animal Migration
Link ID: 19778 - Posted: 07.01.2014
By Lori Aratani The placebo effect — the idea that a treatment works because a patient believes it does — has long been a footnote to the work of finding ways to counteract disease. Some physicians have dismissed placebos as mere hokum, a trick of the mind. But researchers have found that in some people, placebos elicit similar responses in the brain to actual drug treatments. In one experiment, researchers using a PET scanner found that the brain activity in test subjects who received placebos and reported less pain mirrored that of those who received actual treatment for their pain. As Erik Vance writes in “Why Nothing Works,” published in the July/August 2014 issue of Discover magazine, the work suggests we possess an “inner pharmacy” of some sort that, if harnessed correctly, could be used as a complement to traditional treatments. But as Vance’s overview of recent research on the topic shows, it’s complicated. A placebo’s impact is not universal. Certain individuals — and certain conditions (pain and depression, for example) — seem to respond better than others to placebos. Researchers think that something in a person’s physiological makeup makes him more sensitive to placebos, while others feel little or no impact. There are ethical considerations, too, since it’s considered wrong to mislead volunteers participating in a study. But there are ways to navigate this thicket. In one small study, researchers gave placebos to a group of people with irritable bowel syndrome — after telling them that the pills were just placebos; a second group received no treatment. Surprisingly, many more of those who received the placebos reported improvements in their symptoms than did people in the no-treatment group.
By Jim Tankersley COLUMBUS, Ohio — First they screwed the end of the gray cord into the metal silo rising out of Ian Burkhart’s skull. Later they laid his right forearm across two foam cylinders, and they wrapped it with thin strips that looked like film from an old home movie camera. They ran him through some practice drills, and then it was time for him to try. If he succeeded at this next task, it would be science fiction come true: His thoughts would bypass his broken spinal cord. With the help of an algorithm and some electrodes, he would move his once-dead limb again — a scientific first. “Ready?” the young engineer, Nick Annetta, asked from the computer to his left. “Three. Two. One.” Burkhart, 23, marshaled every neuron he could muster, and he thought about his hand. 1 of 14 The last time the hand obeyed him, it was 2010 and Burkhart was running into the Atlantic Ocean. The hand had gripped the steering wheel as he drove the van from Ohio University to North Carolina’s Outer Banks, where he and friends were celebrating the end of freshman year. The hand unclenched to drop his towel on the sand. Burkhart splashed into the waves, the hand flying above his head, the ocean warm around his feet, the sun roasting his arms, and he dived. In an instant, he felt nothing. Not his hand. Not his legs. Only the breeze drying the saltwater on his face.
Link ID: 19770 - Posted: 06.25.2014
Migraines have been diagnosed in about eight per cent of Canadians, a quarter or more of whom say the severe headaches impact day-to-day life such as getting a good night’s sleep or driving, Statistics Canada says. The federal agency on Wednesday released its first report on the prevalence of migraine, saying an estimated 2.7 million Canadians, or 8.3 per cent, reported they had been diagnosed with the severe headaches in 2010-2011. Chronic migraines are frequent, severe, pulsating headaches accompanied by nausea, vomiting, and sensitivity to light and sound. "I think the key finding that was quite interesting was the impact of migraine," said report author Pamela Ramage-Morin, a senior analyst in Ottawa. "For three-quarters to say that it had an impact on their getting a good night sleep, over half said it prevented them from driving on some occasions, even people feeling left out of things because of their condition. There's some social isolation that could be occurring. It may be limiting on people's education and employment opportunities. That can have a long-term effect." The sleep findings are important given lack of sleep can impact other aspects of life, Ramage-Morin said, noting how the effects can extend beyond the individual to the larger community. For both men and women surveyed, migraines were most common at ages 30 to 49, a group represents 12 per cent of the population and the prime working years. © CBC 2014
Keyword: Pain & Touch
Link ID: 19745 - Posted: 06.19.2014
THE star of the World Cup may not be able to bend it like Beckham, but they might be able to kick a ball using the power of their mind. If all goes to plan, a paralysed young adult will use an exoskeleton controlled by their thoughtsMovie Camera to take the first kick of the football tournament in Thursday's opening ceremony in São Paulo, Brazil. The exoskeleton belongs to the Walk Again Project, an international collaboration using technology to overcome paralysis. Since December, the project has been training eight paralysed people to use the suit, which supports the lower body and is controlled by brain activity detected by a cap of electrodes placed over the head. The brain signals are sent to a computer, which converts them into movement. Lead robotic engineer Gordon Cheng, at the Technical University of Munich, Germany, says that there is a phenomenal amount of technology within the exoskeleton, including sensors that feed information about pressure and temperature back to the arms of the user, which still have sensation. The team hopes this will replicate to some extent the feeling of kicking a ball. The exoskeleton isn't the only technology on show in Brazil. FIFA has announced that fans will decide who is man of the match by voting for their favourite player on Twitter during the second half of each game using #ManOfTheMatch. © Copyright Reed Business Information Ltd.
Link ID: 19720 - Posted: 06.12.2014
Haroon Siddique The forehead and fingertips are the most sensitive parts to pain, according to the first map created by scientists of how the ability to feel pain varies across the human body. It is hoped that the study, in which volunteers had pain inflicted without touching them, could help the estimated 10 million people in the UK who suffer from chronic pain by allowing physicians to use lasers to monitor nerve damage across the body. This would offer a quantitative way to monitor the progression or regression of a condition. Lead author Dr Flavia Mancini, of the UCL Institute of Cognitive Neuroscience, said: "Acuity for touch has been known for more than a century, and tested daily in neurology to assess the state of sensory nerves on the body. It is striking that until now nobody had done the same for pain." In the study, a pair of lasers were used to cause brief sensation of pinprick pain to 26 blindfolded healthy volunteers on various parts of their body without any touch, in order to define our ability to identify where it hurts, known as "spatial acuity". Sometimes only one laser would be activated, and sometimes both. The participants were asked whether they felt one sting or two, at varying distances between the two beams and researchers recorded the minimum distance between the beams at which people were able to accurately say whether it was one sting or two. © 2014 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 19708 - Posted: 06.07.2014
by Laura Sanders Transplanted cells can flourish for over a decade in the brain of a person with Parkinson’s disease, scientists write in the June 26 Cell Reports. Finding that these cells have staying power may encourage clinicians to pursue stem cell transplants, a still-experimental way to counter the brain deterioration that comes with Parkinson’s. Penelope Hallett of Harvard University and McLean Hospital in Belmont, Mass., and colleagues studied postmortem brain tissue from five people with advanced Parkinson’s. The five had received stem cell transplants between four and 14 years earlier. In all five people’s samples, neurons that originated from the transplanted cells showed signs of good health and appeared capable of sending messages with the brain chemical dopamine, a neurotransmitter that Parkinson’s depletes. Results are mixed about whether these transplanted cells are a good way to ease Parkinson’s symptoms. Some patients have shown improvements after the new cells stitched themselves into the brain, while others didn’t benefit from them. The cells can also cause unwanted side effects such as involuntary movements. P. J. Hallett et al. Long-term health of dopaminergic neuron transplants in Parkinson’s disease patients. Cell Reports. Vol. 7, June 26, 2014. doi: 10.1016/j.celrep.2014.05.027. © Society for Science & the Public 2000 - 2013
By Kelly Servick During the World Cup next week, there may be 1 minute during the opening ceremony when the boisterous stadium crowd in São Paulo falls silent: when a paraplegic young person wearing a brain-controlled, robotic exoskeleton attempts to rise from a wheelchair, walk several steps, and kick a soccer ball. The neuroscientist behind the planned event, Miguel Nicolelis, is familiar with the spotlight. His lab at Duke University in Durham, North Carolina, pioneered brain-computer interfaces, using surgically implanted electrodes to read neural signals that can control robotic arms. Symbolically, the project is a homecoming for Nicolelis. He has portrayed it as a testament to the scientific progress and potential of his native Brazil, where he founded and directs the International Institute of Neuroscience of Natal. The press has showered him with attention, and the Brazilian government chipped in nearly $15 million in support. But scientifically, the project is a departure. Nicolelis first intended the exoskeleton to read signals from implanted electrodes, but decided instead to use a noninvasive, EEG sensor cap. That drew skepticism from Nicolelis’s critics—and he has a few—that the system wouldn’t really be a scientific advance. Others have developed crude EEG-based exoskeletons, they note, and it will be impossible to tell from the demo how this system compares. A bigger concern is that the event could generate false hope for paralyzed patients and give the public a skewed impression of the field’s progress. © 2014 American Association for the Advancement of Science
Link ID: 19698 - Posted: 06.06.2014
Jessica Morrison Bees, like birds and butterflies, use the Sun as a compass for navigation, whereas mammals typically find their way by remembering familiar landmarks on a continuous mental map. However, the latest research suggests that bees also use this type of map, despite their much smaller brain size. The work adds a new dimension to complex bee-navigation abilities that have long captivated researchers. “The surprise comes for many people that such a tiny little brain is able to form such a rich memory described as a cognitive map,” says co-author Randolf Menzel, a neurobiologist at the Free University of Berlin. The research by Menzel and his team, published today in the Proceedings of the National Academy of Sciences1, demonstrates that bees can find their way back to their hives without relying solely on the Sun. Instead, they seem to use a 'cognitive map' that is made up of memorized landscape snapshots that direct them home. The cognitive map used by mammals is thought to originate in the brain’s hippocampus. Humans employ such maps on a daily basis; for example, even in a windowless office, many people can point towards their home, orienting themselves in space based on knowledge of their location relative to the outside world. “They can point to their home generally even though they can’t see it, even along a path through a wall that they haven’t travelled,” explains Fred Dyer, a behavioural biologist at Michigan State University in East Lansing, who was not involved in the research. The study authors argue that bees can do something similar, albeit on a much more rudimentary level. © 2014 Nature Publishing Group
Keyword: Animal Migration
Link ID: 19684 - Posted: 06.03.2014
|By Bret Stetka Skepticism around fibromyalgia stemmed in part from an elusive organic explanation. Symptoms appeared to arise out of nowhere, which didn't make any sense to empirically minded physicians. “I, too, have been assigned months of futility, long and weary nights of misery. When I go to bed, I think,`When will it be morning?' But the night drags on, and I toss till dawn...Depression haunts my days. My weary nights are filled with pain as though something were relentlessly gnawing at my bones.” Job suffered badly. And his Old Testament woes are considered by many to be one of the earliest descriptions of fibromyalgia, a painful, puzzling disorder that still has experts bickering and patients frustrated, bereft of relief. The Bible isn't exactly a paragon of medical accuracy, but Job’s ailment does sound an awful lot like the modern interpretation of fibromyalgia. The classic diffuse pain, aches and discomfort aren’t the half of it; depression, fatigue, stiffness, sleep loss and generally just feeling really bad are common too. Fibromyalgia patients — 2 percent to 8 percent of the population — have also endured decades of dismissals that it's all in their head — a psychosomatic conjuring, a failure of constitution. Skepticism around fibromyalgia stemmed in part from an elusive organic explanation. Symptoms appeared to arise out of nowhere, which didn't make any sense to empirically minded physicians. But over the past two decades, research has brought clinicians closer to deciphering this mysterious pain state, once thought muscular in nature, now known to be neurologic. Based on this recent work a new article in the Journal of the American Medical Association by chronic pain expert Dr. Daniel Clauw brings us up to speed on the understanding, diagnosis and management of fibromyalgia circa 2014. And the outlook for patients is rosier than you might expect given the condition’s perplexing reputation. © 2014 Scientific American
By C. CLAIBORNE RAY Q. WHY WOULD A PAIN MEDICATION LOSE ITS EFFICACY AFTER WORKING WELL FOR SEVERAL YEARS? A. The mechanism is complex, said Dr. Shakil Ahmed, a pain medicine specialist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. “It is due to a phenomenon called tolerance,” in which there is a decrease in response over time to repeated exposures of the body to pain medication, he said. “This might be due to alteration in the way the body disposes of the medication,” Dr. Ahmed suggested. Or it could occur because drug interactions or bodily changes add a substance that induces an enzyme responsible for disposing of the drug. Another explanation is that long-term administration of pain medications results in a reduction of the number of target drug receptors or a drop in their responsiveness, and in desensitization to the pain medication in question. There is also an increase in the function of other nervous system receptors, called NMDA receptors , which may lead to the development of the tolerance, Dr. Ahmed said. Dr. Ahmed’s practice and research include several alternatives to conventional drug treatment for pain, including spinal cord stimulation, use of radio frequency to interrupt the nerve pathways of pain, delivery of pain medication with a pump directly to the space around the spinal cord, and non-invasive laser therapy. © 2014 The New York Times Company
Keyword: Pain & Touch
Link ID: 19666 - Posted: 05.28.2014
Pain is a symptom of many disorders; chronic pain can present as a disease in of itself. The economic cost of pain is estimated to be hundreds of billions of dollars annually in lost wages and productivity. “This database will provide the public and the research community with an important tool to learn more about the breadth and details of pain research supported across the federal government. They can search for individual research projects or sets of projects grouped by themes uniquely relevant to pain,” said Linda Porter, Ph.D., Policy Advisor for Pain at the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH). “It also can be helpful in identifying potential collaborators by searching for topic areas of interest or for investigators.” Users of the database easily can search over 1,200 research projects in a multi-tiered system. In Tier 1, grants are organized as basic, translational (research that can be applied to diseases), or clinical research projects. In Tier 2, grants are sorted among 29 scientific topic areas related to pain, such as biobehavioral and psychosocial mechanisms, chronic overlapping conditions, and neurobiological mechanisms. The Tier 2 categories are also organized into nine research themes: pain mechanisms, basic to clinical, disparities, training and education, tools and instruments, risk factors and causes, surveillance and human trials, overlapping conditions, and use of services, treatments, and interventions.
By Sandra G. Boodman, Cheron Wicker sank to her knees and began weeping, the contents of her purse and the bags of groceries she had dropped littering the floor of her suburban Maryland kitchen. As the searing pain in her index finger left her unable to reach the counter with the bags, Wicker felt an overwhelming sense of despair. Looking up, her gaze fell on a rack of kitchen knives. An idea that would have been unthinkable months earlier flickered through her mind. That morning in the fall of 2012 when she briefly considered cutting off her finger was the lowest point in her seven-year ordeal, recalled Wicker, a former public affairs official at the U.S. Maritime Administration. The Columbia resident had repeatedly consulted pain specialists and orthopedic surgeons, as well as her internist and endocrinologist; all were mystified by the persistence of her constant, excruciating pain. Wicker had even undergone two operations to replace the herniated disks in her neck that were believed to be the cause of the pain. She had taken all sorts of painkillers and become dependent on the sleeping pill Ambien to buy her a few hours of relief each night. She was increasingly convinced that she must be crazy; madness seemed to be the only reason that nothing had worked. The real reason, she would learn weeks later when she saw a new doctor, was simple: The pain in her fingertip was caused by something inside it, not by a pinched nerve in her neck. In December 2012, after a third surgery, her pain vanished. “I had to convince her that I knew what I was doing,” recalled Baltimore orthopedic surgeon Raymond Pensy, who diagnosed Wicker’s unusual disorder minutes after meeting her. “She was at her wit’s end.” © 1996-2014 The Washington Post
Keyword: Pain & Touch
Link ID: 19660 - Posted: 05.26.2014
Jasmin Fox-Skelly Scientists have found a way to beat back the hands of time and fight the ravages of old age, at least in mice. A new study finds that mice bred without a specific pain sensor, or receptor, live longer and are less likely to develop diseases such as diabetes in old age. What’s more, exposure to a molecule found in chili peppers and other spicy foods may confer the same benefits as losing this pain receptor—meaning that humans could potentially benefit, too. When you touch something hot or get a nasty paper cut, pain receptors in your skin are activated, causing neurons to relay a message to your brain: “Ouch!” Although pain protects your body from damage, it also causes harm. People who experience chronic pain, for example, are more likely to have shorter lifespans, but the reason for this has remained unclear. To investigate further, researchers from the University of California (UC), Berkeley, bred mice without a pain receptor called TRPV1. Found in the skin, nerves, and joints, it’s known to be activated by the spicy compound found in chili peppers, known as capsaicin. (When you feel like your mouth is burning after eating a jalapeño, that’s TRPV1 at work.) Surprisingly, the mice without TRPV1 lived on average 14% longer than their normal counterparts, the team reports today in Cell. (Meanwhile, calorie restriction—another popular way of lengthening mouse lifespans—can make them live up to 40% longer.) When the TRPV1-less mice got old, they still showed signs of fast, youthful metabolisms. Their bodies continued to quickly clear sugar from the blood—a trait called glucose tolerance that usually declines with age—and they burned more calories during exercise than regular elderly mice. © 2014 American Association for the Advancement of Science
Keyword: Pain & Touch
Link ID: 19652 - Posted: 05.23.2014
By MICHAEL BEHAR One morning in May 1998, Kevin Tracey converted a room in his lab at the Feinstein Institute for Medical Research in Manhasset, N.Y., into a makeshift operating theater and then prepped his patient — a rat — for surgery. A neurosurgeon, and also Feinstein Institute’s president, Tracey had spent more than a decade searching for a link between nerves and the immune system. His work led him to hypothesize that stimulating the vagus nerve with electricity would alleviate harmful inflammation. “The vagus nerve is behind the artery where you feel your pulse,” he told me recently, pressing his right index finger to his neck. The vagus nerve and its branches conduct nerve impulses — called action potentials — to every major organ. But communication between nerves and the immune system was considered impossible, according to the scientific consensus in 1998. Textbooks from the era taught, he said, “that the immune system was just cells floating around. Nerves don’t float anywhere. Nerves are fixed in tissues.” It would have been “inconceivable,” he added, to propose that nerves were directly interacting with immune cells. Nonetheless, Tracey was certain that an interface existed, and that his rat would prove it. After anesthetizing the animal, Tracey cut an incision in its neck, using a surgical microscope to find his way around his patient’s anatomy. With a hand-held nerve stimulator, he delivered several one-second electrical pulses to the rat’s exposed vagus nerve. He stitched the cut closed and gave the rat a bacterial toxin known to promote the production of tumor necrosis factor, or T.N.F., a protein that triggers inflammation in animals, including humans. “We let it sleep for an hour, then took blood tests,” he said. The bacterial toxin should have triggered rampant inflammation, but instead the production of tumor necrosis factor was blocked by 75 percent. “For me, it was a life-changing moment,” Tracey said. What he had demonstrated was that the nervous system was like a computer terminal through which you could deliver commands to stop a problem, like acute inflammation, before it starts, or repair a body after it gets sick. “All the information is coming and going as electrical signals,” Tracey said. For months, he’d been arguing with his staff, whose members considered this rat project of his harebrained. “Half of them were in the hallway betting against me,” Tracey said. © 2014 The New York Times Company
Link ID: 19649 - Posted: 05.23.2014
A drug to treat a particular form of Duchenne muscular dystrophy has been given the green light by the European Medicines Agency and could be available in the UK in six months. Translarna is only relevant to patients with a 'nonsense mutation', who make up 10-15% of those affected by Duchenne. The EMA decided not to pass the drug in January, but they have since re-examined the evidence. A campaign group said the drug must reach the right children without delay. There are currently no approved therapies available for this life-threatening condition. The patients who will benefit the most are those aged five years and over who are still able to walk, the EMA said. Duchenne muscular dystrophy is a genetic disease that gradually causes weakness and loss of muscle function. Patients with the condition lack normal dystrophin, a protein found in muscles, which helps to protect muscles from injury. In patients with the disease, the muscles become damaged and eventually stop working. There are 2,400 children in the UK living with muscular dystrophy, but only those whose condition is caused by a particular 'nonsense mutation' - namely 200 children - are suitable to use Translarna. The drug, ataluren, will be known by the brand name of Translarna in the EU. It was developed by PTC Therapeutics. The next step will see the European Commission rubberstamp the EMA's scientific 'green light' within the next three months and authorise the drug to be marketed in the European Union. At that point, individual member states, including the UK, must decide how it will be funded. The Muscular Dystrophy Campaign is calling for urgent meetings with National Institute of Health of Clinical Excellence (NICE) and NHS England to discuss how Translarna can be cleared for approval and use in the UK. It said families in the UK could have access to the drug by spring 2015. Robert Meadowcroft, chief executive of the campaign, said: "This decision by the EMA is fantastic news. BBC © 2014
Four common chronic pain conditions share a genetic element, suggesting they could - at least in part - be inherited diseases, say UK researchers. The four include irritable bowel syndrome, musculoskeletal pain, pelvic pain and dry eye disease. The study of more than 8,000 sets of twins found the ailments were common in identical pairs sharing the same DNA. The King's College London team say the discovery could ultimately help with managing these debilitating diseases. While environmental factors probably still play a role in the four conditions, genes could account for as much as two-thirds of someone's chances of developing the disease, they believe. They told the journal Pain that more research is needed to pinpoint the precise genes involved. Chronic pain - pain which persists or recurs for months on end - is common and has many different causes, which can make it difficult to diagnose and treat. While the pain can be related to other medical conditions, it is thought to be caused by problems with the nervous system, sending pain signals to the brain despite no obvious tissue damage. Experts are keen to understand more about chronic pain to improve the quality of life of the millions of people who have to endure it. Some have suspected that some people may have a genetic predisposition to chronic pain since many sufferers share similar symptoms and often have more than one of the different types of chronic pain conditions. The team at King's College London decided to study identical and non-identical twins because these two groups provide an ideal comparison for investigating inherited genes - identical twins share the same DNA while non-identical twins do not. BBC © 2014
By JAMES GORMAN If an exercise wheel sits in a forest, will mice run on it? Every once in a while, science asks a simple question and gets a straightforward answer. In this case, yes, they will. And not only mice, but also rats, shrews, frogs and slugs. True, the frogs did not exactly run, and the slugs probably ended up on the wheel by accident, but the mice clearly enjoyed it. That, scientists said, means that wheel-running is not a neurotic behavior found only in caged mice. They like the wheel. Two researchers in the Netherlands did an experiment that it seems nobody had tried before. They placed exercise wheels outdoors in a yard garden and in an area of dunes, and monitored the wheels with motion detectors and automatic cameras. They were inspired by questions from animal welfare committees at universities about whether mice were really enjoying wheel-running, an activity used in all sorts of studies, or were instead like bears pacing in a cage, stressed and neurotic. Would they run on a wheel if they were free? Now there is no doubt. Mice came to the wheels like human beings to a health club holding a spring membership sale. They made the wheels spin. They hopped on, hopped off and hopped back on. “When I saw the first mice, I was extremely happy,” said Johanna H. Meijer at Leiden University Medical Center in the Netherlands. “I had to laugh about the results, but at the same time, I take it very seriously. It’s funny, and it’s important at the same time.” Dr. Meijer’s day job is as a “brain electrophysiologist” studying biological rhythms in mice. She relished the chance to get out of the laboratory and study wild animals, and in a way that no one else had. © 2014 The New York Times Company
Dr. Mark Saleh Bell's palsy is a neurological condition frequently seen in emergency rooms and medical offices. Symptoms consist of weakness involving all muscles on one side of the face. About 40,000 cases occur annually in the United States. Men and women are equally affected, and though it can occur at any age, people in their 40s are especially vulnerable. The facial weakness that occurs in Bell's palsy prevents the eye of the affected side from blinking properly and causes the mouth to droop. Because the eyelid doesn't close sufficiently, the eye can dry and become irritated. Bell's palsy symptoms progress fairly rapidly, with weakness usually occurring within three days. If the progression of weakness is more gradual and extends beyond a week, Bell's palsy may not be the problem, and other potential causes should be investigated. Those with certain medical conditions, such as diabetes or pregnancy, are at greater risk of developing Bell's palsy, and those who have had one episode have an 8 percent chance of recurrence. Bell's palsy is thought to occur when the seventh cranial (facial) nerve becomes inflamed. The nerve controls the muscles involved in facial expression and is responsible for other functions, including taste perception, eye tearing and salivation. The cause of the inflammation is unknown, although the herpes simplex virus and autoimmune inflammation are possible causes. © 2014 Hearst Communications, Inc.
Keyword: Movement Disorders
Link ID: 19637 - Posted: 05.20.2014
Katia Moskvitch The hundreds of suckers on an octopus’s eight arms leech reflexively to almost anything they come into contact with — but never grasp the animal itself, even though an octopus does not always know what its arms are doing. Today, researchers reveal that the animal’s skin produces a chemical that stops the octopus’s suckers from grabbing hold of its own body parts, and getting tangled up. “Octopus arms have a built-in mechanism that prevents the suckers from grabbing octopus skin,” says neuroscientist Guy Levy at the Hebrew University of Jerusalem, the lead author of the work, which appears today in Current Biology1. It is the first demonstration of a chemical self-recognition mechanism in motor control, and could help scientists to build better bio-inspired soft robots. To find out just how an octopus avoids latching onto itself, Levy and his colleagues cut off an octopus’s arm and subjected it to a series of tests. (The procedure is not considered traumatic, says Levy, because octopuses occasionally lose an arm in nature and behave normally while the limb regenerates.) The severed arms remained active for more than an hour after amputation, firmly grabbing almost any object, with three exceptions: the former host; any other live octopus; and other amputated arms. “But when we peeled the skin off an amputated arm and submitted it to another amputated arm, we were surprised to see that it grabbed the skinned arm as any other item,” says co-author Nir Nesher, also a neuroscientist at the Hebrew University. © 2014 Nature Publishing Group,
Link ID: 19623 - Posted: 05.15.2014