Chapter 5. The Sensorimotor System
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By ANNA FELS ONE of the most painful experiences of being a psychiatrist is having a patient for whom none of the available therapies or medications work. A while back, I was asked to do a consultation on just such a patient. This person had been a heroin addict in her early 20s. She had quit the opioid five years earlier, but her life was plagued with anxiety, apathy and self-doubt that prior treatments had not helped. At the end of the session, almost as an afterthought, she noted with irony that the only time in her adult life when she had been able to socialize easily and function at work was when she had been hooked on heroin. We are in the midst of a devastating and often lethal opioid epidemic, one of whose victims, we learned last week, was the pop star Prince. At such a time, it is hard to remember that there are multiple opioids naturally produced in our brains and required for our well-being. The neural circuitry utilizing these substances controls some of our most fundamental feelings of pain, stress and hopelessness, as well as pleasure and even euphoria. There is obviously a need for extreme caution, but research suggests that certain opioids may actually be useful in treating psychiatric diseases that have proved frustratingly unresponsive to current medications. It is the potentially addictive subset of opioids, whose natural ancestors were originally derived from poppies, that we associate with the word. These substances have been with us for most, if not all, of human civilization. Poppy seeds have been found at archaeological sites of Neolithic man. The Sumerians wrote about “the joy plant”; an Egyptian papyrus from the second millennium B.C. described the use of a product of poppies to stop the crying of children. Hippocrates suggested its use for female ailments, and a ninth-century Persian physician advocated the use of opium for melancholia. Millenniums later, during the American Civil War, the Union Army used 10 million opium pills to treat wounded soldiers. And then there were the two Opium Wars fought between China and Britain. Unquestionably, no other psychoactive substance has played such a central role in human affairs. © 2016 The New York Times Company
By DENISE GRADY Muhammad Ali, who died on Friday after a long struggle with Parkinson’s disease, was given the diagnosis in 1984 when he was 42. The world witnessed his gradual decline over the decades as tremors and stiffness set in, replacing his athletic stride with a shuffle, silencing his exuberant voice and freezing his face into an expressionless mask. What is Parkinson’s disease? It is a progressive, incurable deterioration of the part of the brain that produces a chemical needed to carry signals to the regions that control movement. How common is Parkinson’s? About one million people in the United States, and between seven million and 10 million worldwide, are thought to have Parkinson’s, according to the Parkinson’s Disease Foundation. What causes it? Was boxing a factor for Ali? The exact cause is not known. As with many disorders, experts suspect a combination of genes and environment, meaning that people with a particular genetic makeup may be predisposed to the disease if they are exposed to certain environmental factors. Head injuries, such as those sustained repeatedly in boxing, are among the possible risk factors listed by the National Parkinson Foundation. So is exposure to certain pesticides. These factors have both been suggested as possible contributors in Muhammad Ali’s case. Can Parkinson’s disease be treated? Medication can ease the symptoms for a time, but the disease continues to progress. In some cases, implanted devices called deep-brain stimulators can also help with symptoms. But Parkinson’s is not curable. © 2016 The New York Times Company
Link ID: 22284 - Posted: 06.06.2016
By JOHN ELIGON and SERGE F. KOVALESKI Prince, the music icon who struggled with debilitating hip pain during his career, died from an accidental overdose of self-administered fentanyl, a type of synthetic opiate, officials in Minnesota said Thursday. The news ended weeks of speculation about the sudden death of the musician, who had a reputation for clean living but who appears to have developed a dependency on medications to treat his pain. Authorities have yet to discuss how he came to be in possession of the fentanyl and whether it had been prescribed by a doctor. Officials had waited several weeks for the results of a toxicology test undertaken as part of an autopsy performed after he was found dead April 21 in an elevator at his estate. He was preparing to enroll in an opioid treatment program when he died at 57, according to the lawyer for a doctor who was planning to treat him. The Midwest Medical Examiner’s Office, which conducted the autopsy, declined to comment beyond releasing a copy of its findings. The Carver County Sheriff’s Office is continuing to investigate the death with help from the federal Drug Enforcement Administration. The sheriff’s office had said it was looking into whether opioid abuse was a factor, and a law enforcement official had said that painkillers were found on Prince when investigators arrived. “The M.E. report is one piece of the whole thing,” said Jason Kamerud, the county’s chief deputy sheriff. Fentanyl is a potent but dangerous painkiller, estimated to be more than 50 times more powerful than heroin, according to the Centers for Disease Control and Prevention. The report did not list how much fentanyl was found in Prince’s blood. Last year, federal officials issued an alert that said incidents and overdoses with fentanyl were “occurring at an alarming rate throughout the United States.” © 2016 The New York Times Company
By Gretchen Reynolds A weekly routine of yoga and meditation may strengthen thinking skills and help to stave off aging-related mental decline, according to a new study of older adults with early signs of memory problems. Most of us past the age of 40 are aware that our minds and, in particular, memories begin to sputter as the years pass. Familiar names and words no longer spring readily to mind, and car keys acquire the power to teleport into jacket pockets where we could not possibly have left them. Some weakening in mental function appears to be inevitable as we age. But emerging science suggests that we might be able to slow and mitigate the decline by how we live and, in particular, whether and how we move our bodies. Past studies have found that people who run, weight train, dance, practice tai chi, or regularly garden have a lower risk of developing dementia than people who are not physically active at all. There also is growing evidence that combining physical activity with meditation might intensify the benefits of both pursuits. In an interesting study that I wrote about recently, for example, people with depression who meditated before they went for a run showed greater improvements in their mood than people who did either of those activities alone. But many people do not have the physical capacity or taste for running or other similarly vigorous activities. So for the new study, which was published in April in the Journal of Alzheimer’s Disease, researchers at the University of California, Los Angeles, and other institutions decided to test whether yoga, a relatively mild, meditative activity, could alter people’s brains and fortify their ability to think. © 2016 The New York Times Company
Keyword: Learning & Memory
Link ID: 22270 - Posted: 06.01.2016
By Kelly Servick There’s an unfortunate irony for people who rely on morphine, oxycodone, and other opioid painkillers: The drug that’s supposed to offer you relief can actually make you more sensitive to pain over time. That effect, known as hyperalgesia, could render these medications gradually less effective for chronic pain, leading people to rely on higher and higher doses. A new study in rats—the first to look at the interaction between opioids and nerve injury for months after the pain-killing treatment was stopped—paints an especially grim picture. An opioid sets off a chain of immune signals in the spinal cord that amplifies pain rather than dulling it, even after the drug leaves the body, the researchers found. Yet drugs already under development might be able to reverse the effect. It’s no secret that powerful painkillers have a dark side. Overdose deaths from prescription opioids have roughly quadrupled over 2 decades, in near lockstep with increased prescribing. And many researchers see hyperalgesia as a part of that equation—a force that compels people to take more and more medication, while prolonging exposure to sometimes addictive drugs known to dangerously slow breathing at high doses. Separate from their pain-blocking interaction with receptors in the brain, opioids seem to reshape the nervous system to amplify pain signals, even after the original illness or injury subsides. Animals given opioids become more sensitive to pain, and people already taking opioids before a surgery tend to report more pain afterward. © 2016 American Association for the Advancement of Scienc
By Viviane Callier Bees don’t just recognize flowers by their color and scent; they can also pick up on their minute electric fields. Such fields—which form from the imbalance of charge between the ground and the atmosphere—are unique to each species, based on the plant’s distance from the ground and shape. Flowers use them as an additional way to advertise themselves to pollinators, but until now researchers had no idea how bees sensed these fields. In a new study, published online today in the Proceedings of the National Academy of Sciences, researchers used a laser vibrometer—a tiny machine that hits the bee hair with a laser—to measure how the hair on a bee’s body responds to a flower’s tiny electric field. As the hair moves because of the electric field, it changes the frequency of the laser light that hits it, allowing the vibrometer to keep track of the velocity of motion of the hair. When the bees buzzed within 10 centimeters of the flower, the electric field—like static electricity from a balloon—caused the bee’s hair to bend. This bending activates neurons at the base of bee hair sockets, which allows the insects to “sense” the field, the team found. Electric fields can only be sensed from a distance of 10 cm or so, so they’re not very useful for large animals like ourselves. But for small insects, this distance represents several body lengths, a relatively long distance. Because sensing such fields is useful to small animals, the team suspects this ability could be important to other insect species as well. © 2016 American Association for the Advancement of Science.
Keyword: Pain & Touch
Link ID: 22263 - Posted: 05.31.2016
by Bruce Bower For a landmark 1977 paper, psychologist Andrew Meltzoff stuck his tongue out at 2- to 3-week-old babies. Someone had to do it. After watching Meltzoff razz them for 15 seconds, babies often stuck out their own tongues within the next 2½ minutes. Newborns also tended to respond in kind when the young researcher opened his mouth wide, pushed out his lips like a duck and opened and closed the fingers of one hand. Meltzoff, now at the University of Washington in Seattle, and a colleague were the first to report that babies copy adults’ simple physical deeds within weeks of birth. Until then, most scientists assumed that imitation began at around 9 months of age. Newborns don’t care that imitation is the sincerest form of flattery. For them, it may be a key to interacting with (and figuring out) those large, smiley people who come to be known as mommy and daddy. And that’s job number one for tykes hoping to learn how to talk and hang out with a circle of friends. Meltzoff suspected that babies enter the world able to compare their own movements — even those they can feel but not see, such as a projecting tongue — to corresponding adult actions. Meltzoff’s report has inspired dozens of papers on infant imitation. Some have supported his results, some haven’t. A new report, published May 5 in Current Biology, falls in the latter group. The study of 106 Australian babies tracked from 1 to 9 weeks of age concludes that infants don’t imitate anyone. © Society for Science & the Public 2000 - 201
Keyword: Development of the Brain
Link ID: 22246 - Posted: 05.25.2016
By Ian Randall As if you needed another reason to hate the gym, it now turns out that exercise can exhaust not only your muscles, but also your eyes. Fear not, however, for coffee can perk them right up again. During strenuous exercise, our muscles tire as they run out of fuel and build up waste products. Muscle performance can also be affected by a phenomenon called “central fatigue,” in which an imbalance in the body’s chemical messengers prevents the central nervous system from directing muscle movements effectively. It was not known, however, whether central fatigue might also affect motor systems not directly involved in the exercise itself—such as those that move the eyes. To find out, researchers gave 11 volunteers a carbohydrate solution either with a moderate dose of caffeine—which is known to stimulate the central nervous system—or as a placebo without, during 3 hours of vigorous cycling. After exercising, the scientists tested the cyclists with eye-tracking cameras to see how well their brains could still control their visual system. The team found that exercise reduced the speed of rapid eye movements by about 8%, impeding their ability to capture new visual information. The caffeine—the equivalent of two strong cups of coffee—was sufficient to counteract this effect, with some cyclists even displaying increased eye movement speeds, the team reports today in Scientific Reports. So it might be a good idea to get someone else to drive you home after that marathon. © 2016 American Association for the Advancement of Science.
Link ID: 22243 - Posted: 05.25.2016
By Jessica Hamzelou People who experience migraines that are made worse by light might be better off seeing the world in green. While white, blue, red and amber light all increase migraine pain, low-intensity green light seems to reduce it. The team behind the finding hope that specially developed sunglasses that screen out all wavelengths of light except green could help migraineurs. Many people experience sensitivity to light during a migraine. Photophobia, as it is known, can leave migraineurs resorting to sunglasses in well-lit rooms, or seeking the comfort of darkness. The reaction is thought to be due to the brain’s wiring. In a brain region called the thalamus, neurons that transmit sensory information from our retinas cross over with other neurons that signal pain. As a result, during migraine, light can worsen pain and pain can cause visual disturbance, says Rami Burstein at Harvard University. But not all colours of light have the same effect. Six years ago, Burstein and his colleagues studied migraine in sufferers who are blind, either due to the loss of an eye or retina, or because of retinal damage. They found that people who had some remaining retinal cells had worse migraines when they were in brightly lit environments, and that blue light seemed to have the strongest impact. The finding caused a flurry of excitement, and the promotion of sunglasses that filter out blue light. © Copyright Reed Business Information Ltd.
By D. T. Max When a spinal cord is damaged, location is destiny: the higher the injury, the more severe the effects. The spine has thirty-three vertebrae, which are divided into five regions—the coccygeal, the sacral, the lumbar, the thoracic, and the cervical. The nerve-rich cord traverses nearly the entire length of the spine. The nerves at the bottom of the cord are well buried, and sometimes you can walk away from damage to these areas. In between are insults to the long middle region of the spine, which begins at the shoulders and ends at the midriff. These are the thoracic injuries. Although they don’t affect the upper body, they can still take away the ability to walk or feel below the waist, including autonomic function (bowel, bladder, and sexual control). Injuries to the cord in the cervical area—what is called “breaking your neck”—can be lethal or leave you paralyzed and unable to breathe without a ventilator. Doctors who treat spinal-cord-injury patients use a letter-and-number combination to identify the site of the damage. They talk of C3s (the cord as it passes through the third cervical vertebra) or T8s (the eighth thoracic vertebra). These morbid bingo-like codes help doctors instantly gauge the severity of a patient’s injury. Darek Fidyka, who is forty-one years old, is a T9. He was born and raised in Pradzew, a small farming town in central Poland, not far from Lodz. ... Several of the wounds punctured his lungs, and one nearly cut his spinal cord in half. As Fidyka lay on the ground, he felt his body change. “I can remember very vividly losing feeling in my legs, bit by bit,” he says. “It started in the upper part of the spine and was moving down slowly while I lay waiting for the ambulance to arrive.”
Link ID: 22230 - Posted: 05.19.2016
A bionic body is closer than you think By Dwayne Godwin, Jorge Cham Dwayne Godwin is a neuroscientist at the Wake Forest University School of Medicine. Jorge Cham draws the comic strip Piled Higher and Deeper at www.phdcomics.com. © 2016 Scientific American
Link ID: 22222 - Posted: 05.17.2016
Dara Mohammadi As the small motorboat chugs to a halt, three travellers, wind-beaten from the three-hour journey along the Atrato river, step on to the muddy banks of Bellavista, an otherwise inaccessible town in the heart of the heavily forested north-west of Colombia. They swing their hessian bags – stuffed with bedsheets, dried beans and cuddly toys – to their shoulders and clamber up a dusty path. Tucked inside the bag of one of the travellers, neuropsychologist Sonia Moreno, is the reason they are here: a wad of unfinished, hand-drawn charts of family trees. The people whose names are circled on the charts have Huntington’s disease, an incurable genetic brain disorder that usually starts between the ages of 35 and 45 years. It begins with personality changes that can make them aggressive, violent, uninhibited, anxious and depressed. The disease progresses slowly, robbing them first of the control of their body, which jerks and twists seemingly of its own will, and then their ability to walk, talk and think until, about 20 years after the symptoms first begin, they die. Their children, each of whom has a 50% chance of inheriting the disease, watch and wait to see if it will happen to them. It is in this way that the disease strangles families. With Moreno is Ignacio Muñoz-Sanjuan, vice president of translational biology at CHDI Foundation, a US nonprofit research organisation that aims to find ways to prevent or slow down the progression of the disease. The foundation spent $140m–$150m (£97m-£104m) on research last year, but Muñoz-Sanjuan is not here on official business. He’s here for Factor-H, an initiative he founded four years ago to help with the other end of the problem – poor families with Huntington’s struggling in Latin America. © 2016 Guardian News and Media Limited o
Rae Ellen Bichell For Tim Goliver and Luther Glenn, the worst illness of their lives started in the same way — probably after having a stomach bug. Tim was 21 and a college student at the University of Michigan. He was majoring in English and biology and active in the Lutheran church. "I was a literature geek," says Tim. "I was really looking forward to my senior year and wherever life would take me." Luther was in his 50s. He'd spent most of his career as a U.S. military policeman and was working in security in Washington, D.C. He'd recently separated from his wife and had just moved into a new house with his two daughters, who were in their 20s. Both men recovered from their stomach bugs, but a few days later they started to feel sluggish. "Here we are trying to unpack, prepare ourselves for new life together and I'm flat out, dead tired," says Luther. He fell asleep in the car one morning and never made it out of the garage. Then he fell in the bathroom. For Tim, it started to feel like running a marathon just to lift a spoonful of soup. One morning, he tried to comb his hair and realized he couldn't lift his arm above his shoulder. "At that moment I started to freak out," he says. Both men got so weak that their families had to wheel them into the emergency room in wheelchairs. They got the same diagnosis: Guillain-Barre syndrome, a neurological disorder which can leave people paralyzed for weeks. © 2016 npr
By Adam Gopnik On a bitter, soul-shivering, damp, biting gray February day in Cleveland—that is to say, on a February day in Cleveland—a handless man is handling a nonexistent ball. Igor Spetic lost his right hand when his forearm was pulped in an industrial accident six years ago and had to be amputated. In an operation four years ago, a team of surgeons implanted a set of small translucent “interfaces” into the neural circuits of his upper arm. This afternoon, in a basement lab at a Veterans Administration hospital, the wires are hooked up directly to a prosthetic hand—plastic, flesh-colored, five-fingered, and articulated—that is affixed to what remains of his arm. The hand has more than a dozen pressure sensors within it, and their signals can be transformed by a computer into electric waves like those natural to the nervous system. The sensors in the prosthetic hand feed information from the world into the wires in Spetic’s arm. Since, from the brain’s point of view, his hand is still there, it needs only to be recalled to life. Now it is. With the “stimulation” turned on—the electronic feed coursing from the sensors—Spetic feels nineteen distinct sensations in his artificial hand. Above all, he can feel pressure as he would with a living hand. “We don’t appreciate how much of our behavior is governed by our intense sensitivity to pressure,” Dustin Tyler, the fresh-faced principal investigator on the Cleveland project, says, observing Spetic closely. “We think of hot and cold, or of textures, silk and cotton. But some of the most important sensing we do with our fingers is to register incredibly minute differences in pressure, of the kinds that are necessary to perform tasks, which we grasp in a microsecond from the feel of the outer shell of the thing. We know instantly, just by touching, whether to gently squeeze the toothpaste or crush the can.”
Keyword: Pain & Touch
Link ID: 22215 - Posted: 05.14.2016
By Nicholas Bakalar Exposure to pesticides may increase the risk for amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, a new study has found. The study, in JAMA Neurology, included 156 patients with A.L.S. and 128 controls. All participants completed questionnaires providing information on age, sex, ethnicity, education, marital status, residential history, occupational history, smoking and military service. The researchers used the information on residence and occupation to estimate long-term exposure to pesticides, and then took blood samples to determine serum levels of 122 persistent environmental pollutants. The scientists divided exposure into four time periods: ever exposed, exposed in the last 10 years, exposed 10 to 30 years ago, and exposed more than 30 years ago. Exposure to pesticides at any time was associated with a fivefold increased relative risk for A.L.S. compared to no exposure. Even exposure more than 30 years ago tripled the risk. Military service was associated with double the risk, confirming findings of previous studies. “This is an association, not causality,” cautioned the senior author, Dr. Eva L. Feldman, a professor of neurology at the University of Michigan. “We found that people with A.L.S. were five times more likely to have been exposed to pesticides, but we don’t want people to conclude that pesticides cause A.L.S.” © 2016 The New York Times Company
By Dan Kiefer I’m on the heavy bag, throwing left jabs, ignoring the relentless blare of Kanye’s “Drive Slow, Homie” played at a volume that would raise the dead. I punch to a one-two count: left jab, right cross. I’m working as hard as I’ve ever worked, and even in this unheated gym I sweat as if it’s a sauna. Finally, the bell rings. It feels as if I’ve been at it for an hour; actually, three minutes have passed. The ensuing one-minute break seems to last four seconds. Let’s be clear: Boxing, even when the opponent is only a heavy bag, is a brutal sport. But brutality is needed, even welcome, when you’re facing a progressive, incurable neurological disease. I have Parkinson’s disease, and it causes my body to just freeze up. Weirdly enough, boxing helps me get unstuck. All 12 of us in this class bear the unmistakable signs of Parkinson’s disease. I spot a dapper, cheerful white-haired fellow shaking like a leaf (tremor). Next, a balding, heavyset guy stumbling forward awkwardly on his toes (dystonia, or muscle cramping). Then I see myself in a mirror: a man in a white T-shirt, khaki shorts and Nike running shoes, standing still, seemingly paralyzed. I’m in the midst of a Parkinson’s freeze (an extreme form of bradykinesia, or slow movement). Although Parkinson’s is generally thought of as an old-person’s disease, I was diagnosed with a young-onset version 18 years ago, at age 35. Since then, I’ve taken every sort of medication known to science. I’ve had brain surgery — two tiny electrodes were implanted deep in my brain to stimulate an area affected by Parkinson’s — which unquestionably have helped treat some of my symptoms. But medicine and surgery have not cured my freezing and falling, my gait and balance issues that worsen as my disease progresses: When walking across a busy street, I may suddenly, inexplicably come to a full stop as the light is about to change. Even the slightest downhill slope of a path causes me to fall forward.
Link ID: 22198 - Posted: 05.10.2016
By JAN HOFFMAN The pop superstar Prince may have lived an outsize life, but emerging details about his long struggle with pain and reliance on opioids will resonate with thousands of patients who have stumbled down that well-trod path. It is a remarkably common narrative in the unfolding story of the nation’s opioid epidemic. Many details have yet to be confirmed about Prince’s case, but a typical trajectory can go something like this. A patient undergoes a procedure to address a medical issue — extracted wisdom teeth for example, or, as Prince did, orthopedic surgery. To help the patient get through recovery, a dentist or surgeon writes a prescription for opioid painkillers, like Percocet or Vicodin. Procedure over, problem addressed. But that prescription may not be written judiciously. “Opioids may be required after a procedure for a few days, but sometimes, physicians practice sloppy prescribing habits and they give patients much more than they need,” said Dr. Patrick G. O’Connor, a professor of medicine at Yale School of Medicine and a past president of the American Board of Addiction Medicine. “And the more patients take, the more likely they are to become dependent.” After a follow-up visit or two, the specialist who did the procedure has no reason to continue seeing the patient. (That doctor could also be an emergency room physician who treated kidney stones, sciatica or any number of other conditions involving stabbing pain.) Yet the patient’s pain may persist, demanding to be tamed. The patient, who now knows just how effective these drugs are, wants to refill the prescription. “The default approach is you go to your primary care provider, and they’ll take care of it,” said Dr. Jonathan H. Chen, an instructor at the Stanford University School of Medicine, who has researched the distribution of opioid prescriptions. As he spoke during a break in his shift in a same-day urgent care clinic, he had just attended to a patient who had recently had shoulder surgery but said she was still in pain. © 2016 The New York Times Company
By Jocelyn Kaiser Gene therapy is living up to its promise of halting a rare, deadly brain disease in young boys. In a new study presented in Washington, D.C., yesterday at the annual meeting of the American Society of Gene and Cell Therapy, all but one of 17 boys with adrenoleukodystrophy (ALD) remained relatively healthy for up to 2 years after having an engineered virus deliver into their cells a gene to replenish a missing protein needed by the brain. The results, which expand on an earlier pilot study, bring this ALD therapy one step closer to the clinic. About one in 21,000 boys are born with ALD, which is caused by a flaw in a gene on the X chromosome that prevents cells from making a protein that the cells need to process certain fats—females have a backup copy of the gene on their second X chromosome. Without that protein, the fats build up and gradually destroy myelin sheaths that protect nerves in the brain. In the cerebral form of ALD, which begins in childhood, patients quickly lose vision and mobility, usually dying by age 12. The disease achieved some degree of fame with the 1992 film Lorenzo’s Oil, inspired by a family’s struggle to prolong their son’s life with a homemade remedy. The only currently approved treatment for ALD is a bone marrow transplant -- white blood cells in the marrow go to the brain and turn into glial cells that produce normal ALD proteins. But bone marrow transplants carry many risks, including immune rejection, and matching donors can’t always be found. As an alternative, in the late 2000s, French researchers treated the bone cells of two boys with a modified virus carrying the ALD gene. They reported in Science in 2009 that this halted progression of the disease. © 2016 American Association for the Advancement of Science
Laura Sanders Iron, says aging expert Naftali Raz, is like the Force. It can be good or bad, depending on the context. When that context is the human brain, though, scientists wrangle over whether iron is a dark force for evil or a bright source of support. Some iron is absolutely essential for the brain. On that, scientists agree. But recent studies suggest to some researchers that too much iron, and the chemical reactions that ensue, can be dangerous or deadly, especially to nerve cells in the vulnerable brain area that deteriorates with Parkinson’s disease. Yet other work raises the possibility that those cells die because of lack of iron, rather than too much. “There are a lot of surprises in this field,” says iron biologist Nancy Andrews of Duke University. The idea that too much iron is dangerous captivates many researchers, including analytical neurochemist Dominic Hare of the University of Technology Sydney. “All of life is a chemical reaction,” he says, “so the start of disease is a chemical reaction as well.” And as Raz points out, reactions involving iron are both life-sustaining and dangerous. “Iron is absolutely necessary for conducting the very fundamental business in every cell,” says Raz, of Wayne State University in Detroit. It helps produce energy-storing ATP molecules. And that’s a dirty job, throwing off dangerous free radicals that can cause cellular mayhem as energy is made. But those free radicals are not the most worrisome aspect of iron, Hare believes. “The reaction that is much more dangerous is the reaction you get when iron and dopamine come together,” he says. © Society for Science & the Public 2000 - 2016.
Link ID: 22173 - Posted: 05.03.2016
Nicola Davis People with a larger circle of friends are better able to tolerate pain, according to research into the pain thresholds and social networks of volunteers. The link is thought to be down a system in the brain that involves endorphins: potent pain-killing chemicals produced by the body that also trigger a sense of wellbeing. “At an equivalent dose, endorphins have been shown to be stronger than morphine,” said Katerina Johnson, a doctoral student at the University of Oxford, who co-authored the research. Writing in the journal Scientific Reports, Johnson and Robin Dunbar, professor of evolutionary psychology at the University of Oxford, sought to probe the theory that the brain’s endorphin system might have evolved to not only handle our response to physical discomfort, but influence our experience of pleasure from social interactions too. “Social behaviour and being attached to other individuals is really important for our survival - whether that is staying close to our parents, or our offspring or cooperating with others to find food or to help defend ourselves,” said Johnson. To test the link, the authors examined both the social networks and pain thresholds of 101 adults aged between 18 and 34. Each participant was asked to complete a questionnaire, designed to quiz them on friends they contacted once a week and those they got in touch with once a month. The personality of each participant was probed, looking at traits such as “agreeableness”; they were also asked to rate their fitness and stress levels. © 2016 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 22156 - Posted: 04.28.2016