Chapter 8. General Principles of Sensory Processing, Touch, and Pain
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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 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 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 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
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
Medical research and new drugs to treat human illness usually start with studies on mice and rats. But that type of research has been traditionally sexist — using far more male than female rodents. Scientists warn that has already led to drugs and treatments that are potentially dangerous for women and say the approach slows down the development of treatments and drugs that are safe and effective for everyone. Cara Tannenbaum, scientific director of the Institute of Gender and Health at the Canadian Institutes of Health Research, cited a couple of examples on CBC's The Current of cases where drug side-effects turned out to be far more harmful in women: A stomach drug called cisapride that was sold in the 1990s under the name Prepulsid was withdrawn by Health Canada in 2000 because it sometimes caused irregular heartbeat and sudden death "in women only," Tannenbaum said. Among the victims was the 15-year-old daughter of former Ontario MP Terence Young. "It's not clear that the drug was ever tested in female animals or minors," Tannenbaum added. Health Canada has issued a warning about sleeping pills containing the drug zolpiclone, also known as Ambien, Tannenbaum said. Women are recommended to take half the dose that is prescribed to men. "It was recently discovered that the level of the drug was 45 per cent higher in women the next day, which can lead to car accidents," Tannenbaum said. Jeffrey Mogil, a neuroscientist and pain specialist at McGill University, said there are lots of reasons to suspect men and women respond differently to many different kinds of drugs, but very little actual data. "We actually don't know the scope of the problem," he told The Current. ©2016 CBC/Radio-Canada.
Dr. Perri Klass First of all, nobody takes a small child on an airplane for the fun of it. I have been there and I know. Don’t get me wrong, I’m no airplane saint; you won’t generally catch me offering to hold someone else’s kid, or making friends around the seatback. I don’t usually admit to being a pediatrician, for fear of hearing a medical saga. But I have put in my time on airplanes with my own infants and toddlers and small children, and I certainly know how it feels. Probably the best thing that can be said for traveling with young children is that it teaches you to appreciate traveling without them, however puzzling the inflight announcements, however long the delays, however tightly spaced the seats. I did enough economy-class traveling with children while my own were young that my reflexive reaction to all flight cancellations, turbulence or the moment when the person in front of me reclines the seat very suddenly, knocking my laptop closed, is now: At least I don’t have a small child with me – thank heavens. Babies do not cry on airplanes for the fun of it either. Nor do they cry, by and large, to let you know that their parents are neglectful or callous. They cry for infant versions of the same reasons that adults snap at one another about reclining seats, or elbow each other with quiet savagery over the armrest. They cry because their ears hurt and they’re being made to stay in a certain position when they don’t want to or the air smells strange and the noises are loud, or their stomachs feel upset or the day has been too long and they still aren’t there yet or they’re just plain cranky. As are we all. Crying is an evolutionary strategy to summon adult aid; over millennia, crying has probably evolved to be hard to ignore. I don’t know if it’s any comfort, but when you’re the parent with the crying baby, it doesn’t particularly help to be an expert. “I remember one flight where my daughter screamed the whole way and kept trying to get out of her seatbelt,” said my old friend, Dr. Elizabeth Barnett, a professor of pediatrics at Boston University and a travel medicine specialist. “As a parent, you feel two things — you’re in distress because you’re trying to comfort your child and not succeeding, so you feel bad for your child, and you also feel guilty because you know your child is disturbing everybody else.” © 2016 The New York Times Company
By JOANNA KLEIN Misconception: Migraines are psychological manifestations of women’s inability to manage stress and emotions Actually: Neurologists are very clear that migraines are a real, debilitating medical condition related to temporary abnormal brain activity. The fact that they may be more common for some women during “that time of the month” has nothing to do with emotions. For centuries, doctors explained migraines as a woman’s problem caused by emotional disturbances like hysteria, depression or stress. “Bizarrely, the recommended cure was marriage!” said Dr. Anne MacGregor, the lead author of the British Association for the Study of Headache’s guidelines for diagnosing and managing migraines. While that prescription may be far behind us, the misconception that migraines are fueled by a woman’s inability to cope persists. “It was considered psychological, or that I was a nervous overachiever, so I would never tell people that I have them,” said Lorie Novak, an artist in her sixties who has suffered from migraines since she was 8. After reading Joan Didion’s 1968 essay “In Bed,” about the writer’s struggle with migraines, Ms. Novak decided to tackle the representation of these debilitating headaches. Starting in 2009, Ms. Novak photographed herself every time she got a migraine. Under the hashtag #notjustaheadache, hundreds of others on Twitter and Instagram have demonstrated their own frustration with a widespread lack of understanding of the reality of migraines. © 2016 The New York Times Company
By Sandhya Somashekhar African Americans are routinely under-treated for their pain compared with whites, according to research. A study released Monday sheds some disturbing light on why that might be the case. Researchers at the University of Virginia quizzed white medical students and residents to see how many believed inaccurate and at times "fantastical" differences about the two races -- for example, that blacks have less sensitive nerve endings than whites or that black people's blood coagulates more quickly. They found that fully half thought at least one of the false statements presented was possibly, probably or definitely true. Moreover, those who held false beliefs often rated black patients' pain as lower than that of white patients and made less appropriate recommendations about how they should be treated. The study, published in the Proceedings of the National Academy of Sciences, could help illuminate one of the most vexing problems in pain treatment today: That whites are more likely than blacks to be prescribed strong pain medications for equivalent ailments. A 2000 study out of Emory University found that at a hospital emergency department in Atlanta, 74 percent of white patients with bone fractures received painkillers compared with 50 percent of black patients. Similarly, a paper last year found that black children with appendicitis were less likely to receive pain medication than their white counterparts. And a 2007 study found that physicians were more likely to underestimate the pain of black patients compared with other patients.
By C. CLAIBORNE RAY Q. Why do we become desensitized to a perfume we are wearing while others can still smell it? A. Ceasing to smell one’s perfume after continuous exposure while casual passers-by can still smell it is just one example of a phenomenon called olfactory adaptation or odor fatigue. After some time without exposure, sensitivity is usually restored. A similar weakening of odor signals with continued exposure also takes place in animals other than humans, and researchers often rely on animal studies to try to understand the cellular and molecular bases for the condition. It has been suggested that odor fatigue is useful because it enables animals to sort out the signals of a new odor from the background noise of continuous odors. It may also enable them to sense when an odor grows stronger. Studies published in the journal Science in 2002 pinpointed a chemical that seems to act as a gatekeeper for neurons involved in smell, opening and closing their electric signal channels. Genetically engineered mice that did not produce the substance, a protein called CNGA4, had profoundly impaired olfactory adaptation. A separate test-tube study found similar changes on a cellular level, with the signal channels remaining open when CNGA4 was absent. email@example.com © 2016 The New York Times Company
Keyword: Chemical Senses (Smell & Taste)
Link ID: 22042 - Posted: 03.29.2016
By Roni Caryn Rabin Sixty-five million Americans suffer from chronic lower back pain, and many feel they have tried it all: physical therapy, painkillers, shots. Now a new study reports many people may find relief with a form of meditation that harnesses the power of the mind to manage pain. The technique, called mindfulness-based stress reduction, involves a combination of meditation, body awareness and yoga, and focuses on increasing awareness and acceptance of one’s experiences, whether they involve physical discomfort or emotional pain. People with lower back pain who learned the meditation technique showed greater improvements in function compared to those who had cognitive behavioral therapy, which has been shown to help ease pain, or standard back care. Participants assigned to meditation or cognitive behavior therapy received eight weekly two-hour sessions of group training in the techniques. After six months, those learning meditation had an easier time doing things like getting up out of a chair, going up the stairs and putting on their socks, and were less irritable and less likely to stay at home or in bed because of pain. They were still doing better a year later. The findings come amid growing concerns about opioid painkillers and a surge of overdose deaths involving the drugs. At the beginning of the trial, 11 percent of the participants said they had used an opioid within the last week to treat their pain, and they were allowed to continue with their usual care throughout the trial. “This new study is exciting, because here’s a technique that doesn’t involve taking any pharmaceutical agents, and doesn’t involve the side effects of pharmaceutical agents,” said Dr. Madhav Goyal of Johns Hopkins University School of Medicine, who co-wrote an editorial accompanying the paper. © 2016 The New York Times Company
Results from a new study, funded in part by the National Center for Complementary and Integrative Health, demonstrate that mindfulness meditation works on a different pain pathway in the brain than opioid pain relievers. The researchers noted that because opioid and non-opioid mechanisms of pain relief interact synergistically, the results of this study suggest that combining mindfulness-based and pharmacologic/nonpharmacologic pain-relieving approaches that rely on opioid signaling may be particularly effective in treating pain. Previous research has shown that mindfulness meditation helps relieve pain, but researchers have been unclear about how the practice induces pain relief — specifically, if meditation is associated with the release of naturally occurring opiates. Researchers recorded pain reports in 78 healthy adults during meditation or a non-meditation control in response to painful heat stimuli and intravenous administration of the opioid antagonist naloxone (a drug that blocks the transmission of opioid activity) or placebo saline. Participants were randomized to one of four treatment groups: 1) meditation plus naloxone; 2) control plus naloxone; 3) meditation plus saline; or 4) control plus saline. People in the control groups were instructed to “close your eyes and relax until the end of the experiment.” The researchers found that participants who meditated during saline administration had significantly lower pain intensity and unpleasantness ratings compared to those who did not meditate while receiving saline. Importantly, data from the meditation plus naloxone group showed that naloxone did not block meditation’s pain-relieving effects. No significant differences in reductions of pain intensity or pain unpleasantness were seen between the meditation plus naloxone and the meditation plus saline groups. Participants who meditated during naloxone administration also had significantly greater reductions in pain intensity and unpleasantness than the control groups.
Keyword: Pain & Touch
Link ID: 22006 - Posted: 03.19.2016
BRAINS get data about the world through senses – sight, hearing, taste, smell and touch. In a lab in North Carolina, a group of rats is getting an extra one. Thanks to implants in their brains, they have learned to sense and react to infrared light. The rats show the brain’s ability to process unfamiliar data– an early step towards augmenting the human brain. Miguel Nicolelis of Duke University School of Medicine is leading the experiment. His team implanted four clusters of electrodes in the rats’ barrel cortex – the part of the brain that handles whisker sensation (doi.org/bdb6). Each cluster is connected to a sensor that converts infrared light into an electrical signal. Feeding stations placed at the four corners of the rats’ cage take turns emitting infrared signals that guide the rats to them, releasing a reward only when the rats press a button on the feeding station that is emiting the infrared signal. In an older, single sensor version of the experiment, it took the rats one month to adapt. With four sensors, it took them just three days. “This is a truly remarkable demonstration of the plasticity of the mammalian brain,” says Christopher James of the University of Warwick, UK. All the extra data that goes into making the rats’ new sense doesn’t appear to diminish their original senses. “The results show that nature has apparently designed the adult mammalian brain with the possibility of upgrades, and Nicolelis’ team is leading the way showing how to do it,” says Andrea Stocco of the University of Washington in Seattle. © Copyright Reed Business Information Ltd.
The CDC recommends non-opioid therapy, including exercise and over-the-counter pain medications, as the preferred treatment for chronic pain. It says opioids should only be prescribed — at the lowest effective dosage possible — when the benefits from pain reduction and bodily function outweigh the risks. In 2014, American doctors wrote nearly 200 million prescriptions for opioid painkillers, while deaths linked to the drugs climbed to roughly 19,000 — the highest number on record. The number of Canadians who die every year from opioids is not readily known — the Canadian Centre on Substance Abuse does not track the statistics — but Toronto physician Nav Persaud told CBC News in 2014 that more than 1,000 Canadians die from painkillers every year. A 2012 study says one in eight deaths among young adults age 25 to 34 in Ontario and one out of every 170 deaths in the province as a whole are opioid overdoses. One in four people who entered a withdrawal management program at St. Joseph's Healthcare in Hamilton, Ont., were opioid patients in 2012, up from one in ten in 2002. Other studies have cast doubt on the effectiveness of opioids on chronic pain, raising questions on whether its limited long-term effects are worth the harmful risks. "The science is clear," CDC director Tom Frieden said Tuesday. "For the vast majority of patients, the known and often fatal risks [of opioids] far outweigh the proven and transient benefits." ©2016 CBC/Radio-Canada.
By Sandra G. Boodman Kim Pace was afraid he was dying. In six months he had lost more than 30 pounds because a terrible stabbing sensation on the left side of his face made eating or drinking too painful. Brushing his teeth was out of the question and even the slightest touch triggered waves of agony and a shocklike pain he imagined was comparable to electrocution. Painkillers, even morphine, brought little relief. Unable to work and on medical leave from his job as a financial consultant for a bank, Pace, then 59, had spent the first half of 2012 bouncing among specialists in his home state of Pennsylvania, searching for help from doctors who disagreed about the nature of his illness. Some thought his searing pain might be the side effect of a drug he was taking. Others suspected migraines, a dental problem, mental illness, or an attempt to obtain painkillers. Even after a junior doctor made what turned out to be the correct diagnosis, there was disagreement among specialists about its accuracy or how to treat Pace. His wife, Carol, a nurse, said she suspects that the couple’s persistence and propensity to ask questions led her husband to be branded “a difficult case” — the kind of patient whom some doctors avoid. And on top of that, a serious but entirely unrelated disorder further muddied the diagnostic picture. So on July 17, 2012, when Pace told his wife he thought he was dying, she fired off an emotional plea for help to the office of a prominent specialist in Baltimore. “I looked at Kim and it hit me: He was going to die,” she said. “He was losing weight and his color was ashen” and doctors were “blowing him off. I thought, ‘Okay, that’s it,’ and the nurse in me took over.”
Cathleen O'Grady When we speak, listen, read, or write, almost all of the language processing that happens in our brains goes on below the level of conscious awareness. We might be aware of grasping for a particular forgotten word, but we don’t actively think about linguistic concepts like morphemes (the building blocks of words, like the past tense morpheme “-ed”). Psycholinguists try to delve under the surface to figure out what’s actually going on in the brain, and how well this matches up with our theoretical ideas of how languages fit together. For instance, linguists talk about morphemes like “-ed”, but do our brains actually work with morphemes when we’re producing or interpreting language? That is, do theoretical linguistic concepts have any psychological reality? An upcoming paper in the journal Cognition suggests an unusual way to investigate this: by testing synaesthetes. Synaesthesia comes in many forms. Some synaesthetes associate musical tones or notes with particular colours; others attach personalities to letters or numbers. A huge number of synaesthetes have associations that are in some way linguistic, and one of the most common forms of all is grapheme-colour (GC) synaesthesia, which is the association of colours with particular letters or numbers. For instance, a GC synaesthete might have a consistent perception of the letter “A” being red. This association often extends to a whole word, so “ant” might be red, too. © 2016 Guardian News and Media Limited
Link ID: 21937 - Posted: 02.27.2016
Jo Marchant The brain cells of people with Parkinson’s disease can be trained to reliably respond to placebo drugs, Italian neuroscientists report. The training wears off after 24 hours but the effect shows it may be possible to reduce the medication needed to treat Parkinson’s by interspersing real drugs with inert injections or pills, says placebo researcher Fabrizio Benedetti at the University of Turin, Italy, who led the work. A few people with Parkinson’s disease do respond dramatically to placebos, but most do not1. People with the condition suffer characteristic tremors and stiff muscles because their dopamine-producing brain cells are gradually dying off. They alleviate their symptoms by taking drugs such as apomorphine, which activate receptors for dopamine. For some conditions — such as pain and immune disorders — trials have shown2 that it is possible to train people to respond to placebos, although this practice hasn’t made its way into clinical care. Benedetti and his colleagues wondered whether the same effect might be possible for neurological disorders. They studied 42 people with advanced Parkinson’s disease who were having electrodes implanted into their brains for a therapy called deep brain stimulation, which eases symptoms by stimulating affected brain areas directly. That surgery gave Benedetti’s team a rare opportunity to measure the activity of individual neurons in the thalamus, a brain region known to be inhibited by lack of dopamine in people with Parkinson's. © 2016 Nature Publishing Grou
Link ID: 21884 - Posted: 02.10.2016
Rare ‘allergy’ to vibrations tied to faulty gene By Kelly Servick If you have the rare condition known as vibratory urticaria, you may be wary of handling lawnmowers and electric mixers. Rubbing or vibration against your skin—even from drying off with a towel—can cause you to break out in hives, make your face flush, give you headaches, or produce the sensation of a metallic taste. The condition, which runs in families, is so rare that the researchers who work on it have only tracked down a few cases over years of searching. But a genetic study on three such unique families has revealed a potential mechanism for the strange symptoms. Research published online today in the New England Journal of Medicine describes a mutation in a gene called ADGRE2, found in 22 people with vibratory urticaria, but not in 14 of their unaffected relatives. The gene codes for a receptor protein that was found on the surface of mast cells—immune cells in the skin that dump out inflammatory molecules such as histamines that increase blood flow to an area and can cause hives. The researchers observed that shaking mast cells in a dish breaks apart two subunits of this receptor protein, which prompts histamine release. In people with the newly discovered mutation, the receptor is more prone to breakage, which causes this protective immune response at the site of physical trauma to run amok. © 2016 American Association for the Advancement of Science.
A map for other people’s faces has been discovered in the brain. It could help explain why some of us are better at recognising faces than others. Every part of your body that you can move or feel is represented in the outer layer of your brain. These “maps”, found in the motor and sensory cortices (see diagram, below), tend to preserve the basic spatial layout of the body – neurons that represent our fingers are closer to neurons that represent our arms than our feet, for example. The same goes for other people’s faces, says Linda Henriksson at Aalto University in Helsinki, Finland. Her team scanned 12 people’s brains while they looked at hundreds of images of noses, eyes, mouths and other facial features and recorded which bits of the brain became active. This revealed a region in the occipital face area in which features that are next to each other on a real face are organised together in the brain’s representation of that face. The team have called this map the “faciotopy”. The occipital face area is a region of the brain known to be involved in general facial processing. “Facial recognition is so fundamental to human behaviour that it makes sense that there would be a specialised area of the brain that maps features of the face,” she says. © Copyright Reed Business Information Ltd.