Chapter 5. The Sensorimotor System
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By Gretchen Reynolds Exercise may help to safeguard the mind against depression through previously unknown effects on working muscles, according to a new study involving mice. The findings may have broad implications for anyone whose stress levels threaten to become emotionally overwhelming. Mental health experts have long been aware that even mild, repeated stress can contribute to the development of depression and other mood disorders in animals and people. Scientists have also known that exercise seems to cushion against depression. Working out somehow makes people and animals emotionally resilient, studies have shown. But precisely how exercise, a physical activity, can lessen someone’s risk for depression, a mood state, has been mysterious. So for the new study, which was published last week in Cell, researchers at the Karolinska Institute in Stockholm delved into the brains and behavior of mice in an intricate and novel fashion. Mouse emotions are, of course, opaque to us. We can’t ask mice if they are feeling cheerful or full of woe. Instead, researchers have delineated certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it’s available — because, presumably, they no longer experience normal pleasures — or give up trying to escape from a cold-water maze and just freeze in place, they are categorized as depressed. And in the new experiment, after five weeks of frequent but intermittent, low-level stress, such as being restrained or lightly shocked, mice displayed exactly those behaviors. They became depressed. The scientists could then have tested whether exercise blunts the risk of developing depression after stress by having mice run first. But, frankly, from earlier research, they knew it would. They wanted to parse how. So they bred pre-exercised mice. © 2014 The New York Times Company
Link ID: 20145 - Posted: 10.01.2014
|By Tanya Lewis and LiveScience Dolphins can now add magnetic sense to their already impressive resume of abilities, new research suggests. When researchers presented the brainy cetaceans with magnetized or unmagnetized objects, the dolphins swam more quickly toward the magnets, the new study found. The animals may use their magnetic sense to navigate based on the Earth's magnetic field, the researchers said. A number of different animals are thought to possess this magnetic sense, called "magnetoreception," including turtles, pigeons, rodents, insects, bats and even deer (which are related to dolphins), said Dorothee Kremers, an animal behavior expert at the University of Rennes, in France, and co-author of the study published today (Sept. 29) in the journal Naturwissenschaften. "Inside the ocean, the magnetic field would be a very good cue to navigate," Kremers told Live Science. "It seems quite plausible for dolphins to have a magnetic sense." Some evidence suggests both dolphin and whale migration routes and offshore live strandings may be related to the Earth's magnetic field, but very little research has investigated whether these animals have a magnetic sense. Kremers and her colleagues found just one study that looked at how dolphins reacted to magnetic fields in a pool; that study found dolphins didn't show any response to the magnetic field. But the animals in that study weren't free to move around, and were trained to give certain responses. © 2014 Scientific American
Keyword: Animal Migration
Link ID: 20140 - Posted: 10.01.2014
By Bec Crew Mike meet everyone, everyone meet Mike. No, no, don’t wave. He can’t see, you’re just making this awkward. Also known as Miracle Mike, Mike the Headless Chicken was a plump, five-year-old cockerel when he was unceremoniously beheaded on 10 September 1945. Farmer Lloyd Olsen of Fruita in Colorado did the deed because his wife Clara was having her mother over for dinner that night, and Olsen knew she’d always enjoyed a bit of roast chicken neck. With that in mind, Olsen tried to save most of Mike’s neck as he lopped his head off, but in doing so, he accidentally made his axe miss Mike’s jugular vein, plus one ear and most of his brain stem, and to his surprise, Mike didn’t die. In fact, Mike stuck around for a good 18 months without his head. Immediately after it happened, Mike reeled around like any headless chicken would, but soon settled down. He even started pecking at the ground for food with his newly minted stump, and made preening motions. His crows had become throaty gurglings. Olsen, bewildered, left him to it. The next morning, when Olsen found Mike asleep in the barn, having attempted to tuck his head under his wing as he always had, the farmer took it upon himself to figure out how to feed this unwitting monstrosity. Mike had earned that much. All Olsen had to do was deposit food and water into Mike’s exposed oesophagus via a little eyedropper. He even got small grains of corn sometimes as a treat. © 2014 Scientific American
Link ID: 20126 - Posted: 09.29.2014
By Rachel Feltman With the help of electrical stimulation, a paralyzed rat is "walking" again. It's actually being controlled by a computer that monitors its gait and adjusts it to keep the rat balanced. When a spinal cord is severed, the electrical pulses sent out by the brain to control limb movement are interrupted. With this method of treatment, the rat's leg movements are driven by electrical pulses shot directly into the spinal cord (which has unfortunately been severed in the name of science). Scientists have been working on this method in humans for awhile, but have only had moderate success — some subjects have regained sensation and movement in their legs, but haven't walked on their own. In the experiment described in the video above, published Wednesday in Science Translational Medicine, researchers tweaked this use of electrical stimulation: They primed the rats with a drug to boost their ability to respond to the electrical signal. Then, while the rats were placed in treadmill harnesses to support their weight, the researchers trained a camera on their subjects. The camera tracked the rats as they took electrically stimulated steps, and corrected their movement in real time. This instant feedback made the system precise enough to get the rats up tiny sets of stairs. MIT Technology Review reports that the team hopes to use a human volunteer within the next year. If the system works on humans, doctors can prescribe its use in rehabilitation therapy. You can watch the actual experiment in the video below:
By Roni Caryn Rabin When I was in college, my father David started walking with an odd, barely perceptible limp. He was in his mid-40s, a gregarious physician, teacher and researcher who was always upbeat. He told his four kids that he had a “back problem” — a deliberately vague cover story that I, for one, was willing to believe. I had never heard of the real culprit — amyotrophic lateral sclerosis, or A.L.S. In fact, no one had. A.L.S. was a disease in the shadows. During my father’s life, it didn’t even have its own advocacy organization. This was the early ’80s, long before support groups and the Internet and a colored ribbon for every cause. And it was way before ice bucket challenges. My parents continued to use their code — “back problem” — to talk about the disease. They used it to protect my younger sisters, who were about to start high school, but I think they were also protecting themselves. My mother was also a physician, and they both knew exactly what lay ahead. Saying “A.L.S.” out loud was too threatening. But soon there was no getting around it. My father’s legs were getting weaker, his muscles were wasting, and he started relying on a cane to get around. I was 19, and my mother and I were out running errands one afternoon when she pulled the car over to the curb and stopped. She told me the truth. This was no slipped disc. She laid it all out for me in black and white: A.L.S. is a progressive, degenerative neurological disease that causes paralysis in the entire body. It’s fatal. There is no cure. It sounded like something from a horror movie. Over the next five years, as my father’s health deteriorated, he remained remarkably determined. He ate a high-protein diet and swam laps every day in an attempt to maintain his muscle and fend off the atrophy caused by the disease. He kept on swimming laps in our next-door neighbor’s pool, even when he had to use a walker — and later a wheelchair — to get there. © 2014 The New York Times Company
Keyword: ALS-Lou Gehrig's Disease
Link ID: 20120 - Posted: 09.27.2014
By Sarah C. P. Williams Press the backs of your hands against the inside of a door frame for 30 seconds—as if you’re trying to widen the frame—and then let your arms down; you’ll feel something odd. Your arms will float up from your sides, as if lifted by an external force. Scientists call this Kohnstamm phenomenon, but you may know it as the floating arm trick. Now, researchers have studied what happens in a person’s brain and nerve cells when they repress this involuntary movement, holding their arms tightly by their sides instead of letting them float up. Two theories existed as to how this repression worked: The brain could send a positive “push down” signal to the arm muscles at the same time as the involuntary “lift up” signal was being transmitted to cancel it out; or the brain could entirely block the involuntary signal at the root of the nerves. The new study, which analyzed brain scans and muscle activity recordings from 39 volunteers, found that the latter was true—when a person stifles Kohnstamm phenomenon, the involuntary “lift” signal is blocked before it reaches the muscle. The difference between the repression mechanisms may seem subtle, but understanding it could help people repress other involuntary movements—including the tremors associated with Parkinson’s disease and the tics associated with Tourette syndrome, the team reports online today in the Proceedings of the Royal Society B. © 2014 American Association for the Advancement of Science
By Jocelyn Kaiser A virus that shuttles a therapeutic gene into cells has strengthened the muscles, improved the motor skills, and lengthened the lifespan of mice afflicted with two neuromuscular diseases. The approach could one day help people with a range of similar disorders, from muscular dystrophy to amyotrophic lateral sclerosis, or ALS. Many of these diseases involve defective neuromuscular junctions—the interface between neurons and muscle cells where brain signals tell muscles to contract. In one such disease, a form of familial limb-girdle myasthenia, people carry two defective copies of the gene called DOK7, which codes for a protein that’s needed to form such junctions. Their hip and shoulder muscles atrophy over many years, and some eventually have trouble breathing or end up in a wheelchair. Mice similarly missing a properly working Dok7 gene are severely underweight and die within a few weeks. In the new study, researchers led by molecular biologist Yuji Yamanashi of the University of Tokyo first injected young mice engineered to have defective Dok7 with a harmless virus carrying a good copy of the Dok7 gene, which is expressed only in muscle. Within about 7 weeks, the rodents recovered. Their muscle cells cranked out the DOK7 protein, and under a microscope their muscles had larger neuromuscular junctions than those of untreated mice with defective Dok7. What’s more, the mice grew to a healthy body weight and had essentially normal scores on tests of motor skills and muscle strength. © 2014 American Association for the Advancement of Science.
by Helen Thomson DON'T mind the gap. A woman has reached the age of 24 without anyone realising she was missing a large part of her brain. The case highlights just how adaptable the organ is. The discovery was made when the woman was admitted to the Chinese PLA General Hospital of Jinan Military Area Command in Shandong Province complaining of dizziness and nausea. She told doctors she'd had problems walking steadily for most of her life, and her mother reported that she hadn't walked until she was 7 and that her speech only became intelligible at the age of 6. Doctors did a CAT scan and immediately identified the source of the problem – her entire cerebellum was missing (see scan, below left). The space where it should be was empty of tissue. Instead it was filled with cerebrospinal fluid, which cushions the brain and provides defence against disease. The cerebellum – sometimes known as the "little brain" – is located underneath the two hemispheres. It looks different from the rest of the brain because it consists of much smaller and more compact folds of tissue. It represents about 10 per cent of the brain's total volume but contains 50 per cent of its neurons. Although it is not unheard of to have part of your brain missing, either congenitally or from surgery, the woman joins an elite club of just nine people who are known to have lived without their entire cerebellum. A detailed description of how the disorder affects a living adult is almost non-existent, say doctors from the Chinese hospital, because most people with the condition die at a young age and the problem is only discovered on autopsy (Brain, doi.org/vh7). © Copyright Reed Business Information Ltd.
By Mo Costandi The nerve endings in your fingertips can perform complex neural computations that were thought to be carried out by the brain, according to new research published in the journal Nature Neuroscience. The processing of both touch and visual information involves computations that extract the geometrical features of objects we touch and see, such as the edge orientation. Most of this processing takes place in the brain, which contains cells that are sensitive to the orientation of edges on the things we touch and see, and which pass this information onto cells in neighbouring regions, that encode other features. The brain has outsourced some aspects of visual processing, such as motion detection, to the retina, and the new research shows that something similar happens in the touch processing pathway. Delegating basic functions to the sense organs in this way could be an evolutionary mechanism that enables the brain to perform other, more sophisticated information processing tasks more efficiently. Your fingertips are among the most sensitive parts of your body. They are densely packed with thousands of nerve endings, which produce complex patterns of nervous impulses that convey information about the size, shape and texture of objects, and your ability to identify objects by touch and manipulate them depends upon the continuous influx of this information. © 2014 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 20051 - Posted: 09.09.2014
By Tanya Lewis, In an experiment that sounds more like science fiction than reality, two humans were able to send greetings to each other using only a digital connection linking their brains. Using noninvasive means, researchers made brain recordings of a person in India thinking the words "hola" and "ciao," and then decoded and emailed the messages to France, where a machine converted the words into brain stimulation in another person, who perceived the signals as flashes of light. From the sequence of flashes, the French recipient was able to successfully interpret the greetings, according to a new study published today (Sept. 5) in the journal PLOS ONE. The researchers wanted to know if it is possible for two people to communicate by reading out the brain activity of one person and injecting that activity into a second person. "Could we develop an experiment that would bypass the talking or typing part of [the] Internet and establish direct brain-to-brain communication between subjects located far away from each other, in India and France?" co-author Dr. Alvaro Pascual-Leone said in a statement. Pascual-Leone is a neurologist at Beth Israel Deaconess Medical Center in Boston, and a professor at Harvard Medical School, in Cambridge, Massachusetts. To answer that question, Pascual-Leone and his colleagues at Starlab Barcelona, in Spain, and Axilum Robotics, in Strasbourg, France, turned to several widely used brain technologies. Electroencephalogram, or EEG, recordings are taken by placing a cap of electrodes on a person's scalp, and recording the electrical activity of large regions of the brain's cortex. Previous studies have recorded EEG from a person thinking about an action, such as moving his or her arm, while a computer translates the signal into an output used to move a robotic exoskeleton or drive a wheelchair.
By GRETCHEN REYNOLDS Amyotrophic lateral sclerosis has been all over the news lately because of the ubiquitous A.L.S. ice bucket challenge. That attention has also reinvigorated a long-simmering scientific debate about whether participating in contact sports or even vigorous exercise might somehow contribute to the development of the fatal neurodegenerative disease, an issue that two important new studies attempt to answer. Ever since the great Yankees first baseman Lou Gehrig died of A.L.S. in 1941 at age 37, many Americans have vaguely connected A.L.S. with athletes and sports. In Europe, the possible linkage has been more overtly discussed. In the past decade, several widely publicized studies indicated that professional Italian soccer players were disproportionately prone to A.L.S., with about a sixfold higher incidence than would have been expected numerically. Players were often diagnosed while in their 30s; the normal onset is after 60. These findings prompted some small, follow-up epidemiological studies of A.L.S. patients in Europe. To the surprise and likely consternation of the researchers, they found weak but measurable associations between playing contact sports and a heightened risk for A.L.S. The data even showed links between being physically active — meaning exercising regularly — and contracting the disease, raising concerns among scientists that exercise might somehow be inducing A.L.S. in susceptible people, perhaps by affecting brain neurons or increasing bodily stress. But these studies were extremely small and had methodological problems. So to better determine what role sports and exercise might play in the risk for A.L.S., researchers from across Europe recently combined their efforts into two major new studies. The results should reassure those of us who exercise. The numbers showed that physical activity — whether at work, in sports or during exercise — did not increase people’s risk of developing A.L.S. © 2014 The New York Times Company
Keyword: ALS-Lou Gehrig's Disease
Link ID: 20031 - Posted: 09.03.2014
By JOHN MARKOFF STANFORD, Calif. — In factories and warehouses, robots routinely outdo humans in strength and precision. Artificial intelligence software can drive cars, beat grandmasters at chess and leave “Jeopardy!” champions in the dust. But machines still lack a critical element that will keep them from eclipsing most human capabilities anytime soon: a well-developed sense of touch. Consider Dr. Nikolas Blevins, a head and neck surgeon at Stanford Health Care who routinely performs ear operations requiring that he shave away bone deftly enough to leave an inner surface as thin as the membrane in an eggshell. Dr. Blevins is collaborating with the roboticists J. Kenneth Salisbury and Sonny Chan on designing software that will make it possible to rehearse these operations before performing them. The program blends X-ray and magnetic resonance imaging data to create a vivid three-dimensional model of the inner ear, allowing the surgeon to practice drilling away bone, to take a visual tour of the patient’s skull and to virtually “feel” subtle differences in cartilage, bone and soft tissue. Yet no matter how thorough or refined, the software provides only the roughest approximation of Dr. Blevins’s sensitive touch. “Being able to do virtual surgery, you really need to have haptics,” he said, referring to the technology that makes it possible to mimic the sensations of touch in a computer simulation. The software’s limitations typify those of robotics, in which researchers lag in designing machines to perform tasks that humans routinely do instinctively. Since the first robotic arm was designed at the Stanford Artificial Intelligence Laboratory in the 1960s, robots have learned to perform repetitive factory work, but they can barely open a door, pick themselves up if they fall, pull a coin out of a pocket or twirl a pencil. © 2014 The New York Times Company
Learning is easier when it only requires nerve cells to rearrange existing patterns of activity than when the nerve cells have to generate new patterns, a study of monkeys has found. The scientists explored the brain’s capacity to learn through recordings of electrical activity of brain cell networks. The study was partly funded by the National Institutes of Health. “We looked into the brain and may have seen why it’s so hard to think outside the box,” said Aaron Batista, Ph.D., an assistant professor at the University of Pittsburgh and a senior author of the study published in Nature, with Byron Yu, Ph.D., assistant professor at Carnegie Mellon University, Pittsburgh. The human brain contains nearly 86 billion neurons, which communicate through intricate networks of connections. Understanding how they work together during learning can be challenging. Dr. Batista and his colleagues combined two innovative technologies, brain-computer interfaces and machine learning, to study patterns of activity among neurons in monkey brains as the animals learned to use their thoughts to move a computer cursor. “This is a fundamental advance in understanding the neurobiological patterns that underlie the learning process,” said Theresa Cruz, Ph.D., a program official at the National Center for Medical Rehabilitations Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “The findings may eventually lead to new treatments for stroke as well as other neurological disorders.”
Erin Allday It's well established that chronic pain afflicts people with more than just pain. With the pain come fatigue and sleeplessness, depression and frustration, and a noticeable disinterest in so many of the activities that used to fill a day. It makes sense that chronic pain would leave patients feeling weary and unmotivated - most people wouldn't want to go to work or shop for a week's worth of groceries or even meet friends for dinner when they're exhausted and in pain. But experts in pain and neurology say the connection between chronic pain and a lousy mood may be biochemical, something more complicated than a dour mood brought on from persistent, long-term discomfort alone. Now, a team of Stanford neurologists have found evidence that chronic pain triggers a series of molecular changes in the brain that may sap patients' motivation. "There is an actual physiologic change that happens," said Dr. Neil Schwartz, a post-doctoral scientist who helped lead the Stanford research. "The behavior changes seem quite primary to the pain itself. They're not just a consequence of living with it." Schwartz and his colleagues hope their work could someday lead to new treatments for the behavior changes that come with chronic pain. In the short term, the research improves understanding of the biochemical effects of chronic pain and may be a comfort to patients who blame themselves for their lack of motivation, pain experts said. © 2014 Hearst Communications, Inc.
by Tom Siegfried René Descartes was a very clever thinker. He proved his own existence, declaring that because he thought, he must exist: “I think, therefore I am.” But the 17th century philosopher-mathematician-scientist committed a serious mental blunder when he decided that the mind doing the thinking was somehow separate from the brain it lived in. Descartes believed that thought was insubstantial, transmitted from the ether to the pineal gland, which played the role of something like a Wi-Fi receiver embedded deep in the brain. Thereafter mind-brain dualism became the prevailing prejudice. Nowadays, though, everybody with a properly working brain realizes that the mind and brain are coexistent. Thought processes and associated cognitive mental activity all reflect the physics and chemistry of cells and molecules inhabiting the brain’s biological tissue. Many people today do not realize, though, that there’s a modern version of Descartes’ mistaken dichotomy. Just as he erroneously believed the mind was distinct from the brain, some scientists have mistakenly conceived of the brain as distinct from the body. Much of the early research in artificial intelligence, for instance, modeled the brain as a computer, seeking to replicate mental life as information processing, converting inputs to outputs by logical rules. But even if such a machine could duplicate the circuitry of the brain, it would be missing essential peripheral input from an attached body. Actual intelligence requires both body and brain, as the neurologist Antonio Damasio pointed out in his 1994 book, Descartes’ Error. “Mental activity, from its simplest aspects to its most sublime, requires both brain and body proper,” Damasio wrote. © Society for Science & the Public 2000 - 2013.
Link ID: 20002 - Posted: 08.27.2014
By Sandra G. Boodman When the Philadelphia specialist gently tweaked a spot deep inside Heidi Gribble Camp’s back, she screamed, an expression of both anguish and elation.Camp’s vindication was fueled in large part by her persistence. In 2006, her complaints of severe abdominal pain early in her first pregnancy were brushed aside by her doctor — until she nearly bled to death from a ruptured ectopic pregnancy. That near-fatal hemorrhage was swiftly followed by her sudden lapse into unconsciousness and the discovery of large blood clots in her lung and abdomen, requiring additional emergency surgery. “I told him, ‘You found the pain, this is the best day of my life!’ ” Camp, 32, recalled saying during the June 18 procedure at the Hospital of the University of Pennsylvania. The fact that the interventional radiologist, an expert in minimally invasive surgical procedures, was able to pinpoint and replicate the stabbing pain she had suffered for more than eight years was sweet validation. It proved that Camp wasn’t exaggerating her pain and that it had an identifiable, physical cause, something a series of doctors had come to doubt. Months of recovery followed — as did the first episode of searing back pain. But doctors in Florida, Toronto and Northern Virginia, where Camp lived at various times with her husband, a recently retired professional baseball player — told her they could not find a reason for her agony. Some implied that she was dramatizing normal aches; others rebuffed her inquires about a potential cause that would later prove to be prescient.
Keyword: Pain & Touch
Link ID: 19992 - Posted: 08.26.2014
Ian Sample, science editor Scientists have prevented muscle wastage in mice with a form of muscular dystrophy by editing the faulty gene that causes the disease. The radical procedure could not be performed in humans, but researchers believe the work raises hopes for future gene-editing therapies to stop the disease from progressing in people. Duchenne muscular dystrophy is caused by mutations in a gene on the X chromosome and affects around one in 3,500 boys. Because girls have two X chromosomes they tend not to be affected, but can be carriers of the disease. The pivotal gene is used to make a protein called dystrophin which is crucial for muscle fibre strength. Without the protein, muscles in the body, including the heart and skeletal muscles, weaken and waste away. Most patients die by the age of 25 from breathing or heart problems. Researchers in the US used a powerful new gene-editing procedure called CRISPR to correct mutations in the dystrophin gene in mice that were destined to develop the disease. They extracted mouse embryos from their mothers and injected them with the CRISPR biological machinery, which found and corrected the faulty gene. After the injections, the mouse embryos were reimplanted in females and carried to term. Tests on the mice found that the therapy helped to restore levels of dystrophin, and that their skeletal muscle performed normally, even when only 17% of their cells contained corrected genes. The procedure could not be done in humans, but the proof-of-principle experiment demonstrates that correcting only a small proportion of cells could lead to a dramatic improvement for patients. © 2014 Guardian News and Media Limited
By Lenny Bernstein Comedian Robin Williams was grappling with severe depression when he committed suicide Monday, and on Thursday we learned that he also was in the early stages of Parkinson's disease. Sadly, the two conditions are often found together. In a 2012 study conducted by the National Parkinson Foundation, 61 percent of 5,557 Parkinson's patients surveyed reported that they also suffered from depression, with symptoms that ranged from mild to severe. Both conditions are associated with a shortage of dopamine, a neurotransmitter that helps regulate movement and control the brain's pleasure center. "Dopamine is a feel-good chemical. If you are low in dopamine, you are not going to feel so good," said Joyce Oberdorf, president and CEO of the National Parkinson Foundation. "There are [also] other neurotransmitters that can be low." A separate study published Friday found that newly-diagnosed Parkinson's patients have higher rates of depression, anxiety, fatigue, and apathy than a control group of people without Parkinson's. Researchers from the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania found that 13.9 percent of patients had symptoms of depression when they were diagnosed with Parkinson's, a proportion that rose to 18.7 percent after 24 months. Just 6.6 percent of people without the disease had depression, and that dropped to just 2.4 percent after 24 months. Despite their depressive symptoms, most of the Parkinson's patients who also had that condition were not treated with anti-depressants at any point in the two-year study. The findings were published in the journal Neurology.
by Catherine Brahic Think crayfish and you probably think supper, perhaps with mayo on the side. You probably don't think of their brains. Admittedly, crayfish aren't known for their grey matter, but that might be about to change: they can grow new brain cells from blood. Humans can make new neurons, but only from specialised stem cells. Crayfish, meanwhile, can convert blood to neurons that resupply their eyestalks and smell circuits. Although it's a long way from crayfish to humans, the discovery may one day help us to regenerate our own brain cells. Olfactory nerves are continuously exposed to damage and so naturally regenerate in many animals, from flies to humans, and crustaceans too. It makes sense that crayfish have a way to replenish these nerves. To do so, they utilise what amounts to a "nursery" for baby neurons, a little clump at the base of the brain called the niche. In crayfish, blood cells are attracted to the niche. On any given day, there are a hundred or so cells in this area. Each cell will split into two daughter cells, precursors to full neurons, both of which migrate out of the niche. Those that are destined to be part of the olfactory system head to two clumps of nerves in the brain called clusters 9 and 10. It's there that the final stage of producing new smell neurons is completed. © Copyright Reed Business Information Ltd.
By GRETCHEN REYNOLDS Regular exercise may alter how a person experiences pain, according to a new study. The longer we continue to work out, the new findings suggest, the greater our tolerance for discomfort can grow. For some time, scientists have known that strenuous exercise briefly and acutely dulls pain. As muscles begin to ache during a prolonged workout, scientists have found, the body typically releases natural opiates, such as endorphins, and other substances that can slightly dampen the discomfort. This effect, which scientists refer to as exercise-induced hypoalgesia, usually begins during the workout and lingers for perhaps 20 or 30 minutes afterward. But whether exercise alters the body’s response to pain over the long term and, more pressing for most of us, whether such changes will develop if people engage in moderate, less draining workouts, have been unclear. So for the new study, which was published this month in Medicine & Science in Sports & Exercise, researchers at the University of New South Wales and Neuroscience Research Australia, both in Sydney, recruited 12 young and healthy but inactive adults who expressed interest in exercising, and another 12 who were similar in age and activity levels but preferred not to exercise. They then brought all of them into the lab to determine how they reacted to pain. Pain response is highly individual and depends on our pain threshold, which is the point at which we start to feel pain, and pain tolerance, or the amount of time that we can withstand the aching, before we cease doing whatever is causing it. © 2014 The New York Times Company
Keyword: Pain & Touch
Link ID: 19952 - Posted: 08.13.2014