Chapter 8. General Principles of Sensory Processing, Touch, and Pain
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By Abigail Zuger, M.D. It was in 2011 that the Centers for Disease Control first drew public attention to the ongoing nationwide opioid crisis. Much earnest commentary has explored the roots of this new killer epidemic since then, focusing on the broad highway between heroin and pain pills, and the online pharmacies, pill mills, and bad-apple doctors who fueled the two-way traffic and enabled catastrophe. Forgive me for rolling my eyes. Anyone with a prescription pad and a shred of common sense saw this whole thing coming down the pike decades ago, a speeding 18-wheeler, tires squealing, no brakes. Furthermore, it has long been clear that while the bad medical apples certainly did their share of damage, there is not a health policy guru or medical school dean in the country whose sins of omission and commission are not also partly responsible. Call it an epidemic of unconscious collusion or, as Dr. Anna Lembke bluntly states, a nation’s doctors “trapped in a system gone mad.” In less than 200 pages, this may be the most important medical book of the decade for finally getting the story of the opioid epidemic exactly right. As far as I am concerned, “Drug Dealer, M.D.,” in less than 200 unassuming, readable, and carefully referenced pages, may be the most important medical book of the decade for finally getting the story of this epidemic exactly right. And it’s not the medical bad apples Lembke is talking about in her title — it’s every doctor in the country. Copyright 2017 Undark
Sarah Boseley Health editor Low back and neck pain is an increasingly widespread and expensive condition worldwide, costing the US alone $88bn a year – the third highest bill for any health condition – despite evidence most treatments do not work. Millions of people worldwide suffer from low back and neck pain, most of it unexplained, although some professionals think it may be worsened by sitting at desks all day, carrying bags and general bad posture. Episodes of acute pain are very common, but experts say that medical investigations only make things worse and the best cure is often to take painkillers, exercise gently and wait for the pain to pass. The rising bill for treatment in the US has been uncovered in a new study by the Institute of Health Metrics and Evaluation (IHME) at the University of Washington, which looked at public and private spending on all diseases in 2013. Diabetes was in first place on $101.4bn and heart disease was second with $88.1bn. But neck and lower back pain treatment costs were close behind, at $87.6bn. The team split cancer into 29 separate conditions, which meant that none of them made the top 20, although combined the costs of treatment came to $115bn. The most remarkable thing, said Joseph Dieleman, lead author of the paper published in the Journal of the American Medical Association, was the increase in treatment costs for lower back and neck pain, running at 6.5% a year against 3.5% overall. “In absolute terms, there was an increase from $30bn in 1996 to $88bn in 2013,” he told the Guardian. © 2017 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 23214 - Posted: 02.11.2017
By Anil Ananthaswamy Next time a nurse sticks a needle into your arm, don’t look away: it’ll be less painful. A new study shows that we feel less pain when we are looking at our body – and that this effect works with virtual reality too. In 2009, Patrick Haggard and Matthew Longo of University College London showed that looking at your own body has an analgesic effect. The researchers shone infrared laser light on the skin of volunteers. Those who were looking at their body rather than at a neutral object said that they felt less pain. Scalp electrodes revealed that this analgesic effect was linked to weaker activity in parts of the brain’s cortex that process pain – although why this happens is unclear. Since then, two different teams have tested the effect using the rubber hand illusion – in which a rubber hand is placed next to a person’s real hand, which is hidden from view. Stroking both the real and rubber hands with paint brushes convinces them that the rubber hand is their own. Extending this illusion, the teams wanted to know: can looking at a rubber hand that feels like one’s own alleviate pain in your real hand? The studies were contradictory: one study showed an analgesic effect, but the other did not. Maria Sanchez-Vives at the University of Barcelona, Spain, and her colleagues argue that differences in the position of the rubber hand and real hand may have led to the differing results. To test the effect of the rubber hand’s position, her team used virtual reality to induce the illusion. Instead of seeing a real rubber hand, participants were shown one via a VR headset instead. © Copyright Reed Business Information Ltd.
Keyword: Pain & Touch
Link ID: 23198 - Posted: 02.08.2017
Sara Constantino Certain multisensory conditions can alter the experience of bodily ownership. For instance, in the rubber hand illusion, simultaneous visual and haptic inputs lead to the adoption of sensations applied to an artificial limb as one's own. Understanding body ownership, and its malleability, has implications for the development of prosthetics. In a recent paper, Kelly Collins and colleagues at the University of Washington and Karolinska Institute elicited the illusion of ownership of an artificial hand in two epilepsy patients with embedded electrodes through the direct electrical stimulation of the hand area in somatosensory cortex (SI) applied in synchrony with visible touches to a rubber hand. When stimulation was asynchronous or administered to a different SI area, feelings of ownership were no longer induced, stressing the importance of temporal and spatial congruence. They also found that the details of the visual signal (for example, type of touch) affected the sensation. This method extends previous studies by eliciting ownership without stimulation of the peripheral nervous system, which is damaged in patients with spinal cord or nerve lesions. Human–technology mixtures have a long history, with the first known prosthesis, a wooden toe, dating as far back as 950 bc. Today, recent materials, electronics and neuroscience advances are enabling the development of prosthetic limbs that both look and feel real. © 2017 Macmillan Publishers Limited,
Keyword: Pain & Touch
Link ID: 23168 - Posted: 01.31.2017
By Roni Caryn Rabin Neuromas of the foot, a painful condition caused by an inflamed nerve in the ball of the foot, can be effectively treated at home with daily massage and stretches and over-the-counter painkillers, said Dr. Jacqueline Sutera, a doctor of podiatric medicine and surgery. “Of all the patients with neuromas I see in the office, I would say that ultimately only two of 10 might need surgery,” said Dr. Sutera, who practices in New York City and New Jersey. Neuromas of the foot, also known as Morton's neuromas, typically cause sharp, stabbing pain in the second, third and fourth toes. The goal of massaging and stretching is to open up the space between the bones — the metatarsals — in the ball of the foot and increase circulation, which can help reduce the pain and inflammation. Focus on the ball of the foot, not the toes, since the pain in the toes is referred pain from the ball of the foot. Dr. Sutera recommends placing the thumbs at the top of the foot and the other fingers on the bottom of the foot — or vice versa — and pressing and massaging the bones of the ball of the foot, “creating pressure on both sides, top and bottom.” Follow massages with stretches, using your hands to “grab your forefoot and pull it apart so you’re stretching the spaces between the metatarsals in the ball of the foot.” Massages and stretches are most effective at the end of the day, she said, ideally after a hot shower, bath or other heat application. After the massage and stretching, the area should be iced. © 2017 The New York Times Company
Keyword: Pain & Touch
Link ID: 23161 - Posted: 01.28.2017
By Bob Grant More and more Americans are using cannabis both for medicinal and recreational purposes, but scientists still know little about the drug’s effects on human physiology, according to a National Academies report released this month (January 12). Part of this knowledge gap owes to the fact that cannabis is classified as a Schedule I drug under the US Controlled Substances Act. In the eyes of the federal government, marijuana is a dangerous substance—on par with heroin—that “has no currently accepted medical use in treatment in the United States.” But researchers in Canada are not far ahead of their US counterparts, even though cannabis has since 2001 been functionally legal for medicinal use at the federal level there. See “National Academies Detail the State of Weed Science” “I wish I could say that [legalizing medical marijuana] had led to more research” in Canada, said Mark Ware, a McGill University pain management physician who has researched the safety and efficacy of cannabinoids for the past 18 years. “I think there’s certainly a willingness to be able to document real world use of cannabis under a legal framework.” Ware, who served as a reviewer on the National Academies report, added that while there are several public registries that track the legal use of cannabis among Canadians, experimental evidence on the effects of that use are lacking. “The clinical trials, I think for most people that’s an expensive undertaking,” he said. “There are still questions around who owns the intellectual property, who’s going to sponsor the trials. . . . Those remain barriers even in a legal framework as to the cost of that kind of research and the drug development piece of it.” © 1986-2017 The Scientist
By Catherine Offord In the early 20th century, Danish biologist Johannes Schmidt solved a puzzle that had confounded European fisherman for generations. Freshwater eels—popular for centuries on menus across northern Europe—were abundant in rivers and creeks, but only as adults, never as babies. So where were they coming from? In 1922, after nearly two decades of research, Schmidt published the answer: the Sargasso Sea, the center of a massive, swirling gyre in the North Atlantic Ocean. Now regarded as some of the world’s most impressive animal migrators, European eels (Anguilla anguilla) journey westward across the Atlantic to spawning sites in the Sargasso; their eggs hatch into larvae that are carried back across the ocean by the Gulf Stream, arriving two or three years later to repopulate European waterways. For decades, researchers have assumed that adults made the journey in one short and rapid migration, leaving European coastlines in autumn and arriving in the Sargasso Sea, ready to spawn, the following spring. But this assumption rests on surprisingly little evidence, says behavioral ecologist David Righton of the UK Centre for Environment, Fisheries, and Aquaculture Science. “Since Johannes Schmidt identified this spawning area in the Sargasso Sea, people have been wondering about that great journey and trying to figure out how to follow the eels,” says Righton, whose work on epic marine migrations includes appropriately titled projects such as CODYSSEY and EELIAD. “But the technology hasn’t been available. . . . They just slip away into the darkness, really, in autumn, and no one knows what happens to them.” © 1986-2017 The Scientist
Keyword: Animal Migration
Link ID: 23116 - Posted: 01.18.2017
Bruce Bower Marijuana’s medical promise deserves closer, better-funded scientific scrutiny, a new state-of-the-science report concludes. The report, released January 12 by the National Academies of Sciences, Engineering and Medicine in Washington, D.C., calls for expanding research on potential medical applications of cannabis and its products, including marijuana and chemical components called cannabinoids. Big gaps in knowledge remain about health effects of cannabis use, for good or ill. Efforts to study these effects are hampered by federal classification of cannabis as a Schedule 1 drug, meaning it has no accepted medical use and a high potential for abuse. Schedule 1 status makes it difficult for researchers to access cannabis. The new report recommends reclassifying the substance to make it easier to study. Recommendations from the 16-member committee that authored the report come at a time of heightened acceptance of marijuana and related substances. Cannabis is a legal medical treatment in 28 states and the District of Columbia. Recreational pot use is legal in eight of those states and the District. “The legalization and commercialization of cannabis has allowed marketing to get ahead of science,” says Raul Gonzalez, a psychologist at Florida International University in Miami who reviewed the report before publication. While the report highlights possible medical benefits, Gonzalez notes that it also underscores negative consequences of regular cannabis use. These include certain respiratory and psychological problems. |© Society for Science & the Public 2000 - 2017.
Rachel Ehrenberg A protein that sounds the alarm when the body encounters something painful also helps put out the fire. Called Nav1.7, the protein sits on pain-sensing nerves and has long been known for sending a red alert to the brain when the body has a brush with pain. Now, experiments in rodent cells reveal another role for Nav1.7: Its activity triggers the production of pain-relieving molecules. The study, published online January 10 in Science Signaling, suggests a new approach to pain management that takes advantage of this protein’s dual role. “This is very interesting research,” says neuroscientist Munmun Chattopadhyay of Texas Tech University Health Sciences Center El Paso. The findings suggest that when opiates are given for certain kinds of pain relief, also targeting Nav1.7 might lessen the need for those pain relievers, Chattopadhyay says. That could reduce opiate use and their associated side effects. The new research also solves a puzzle that has frustrated researchers and pharmaceutical companies alike. People with rare mutations in the gene for making Nav1.7 feel no pain at all. That discovery, made more than a decade ago, suggested that Nav1.7 was an ideal target for controlling pain. If a drug could block Nav1.7 activity, some kinds of pain might be eradicated (SN: 6/30/12, p 22). Yet drugs designed to do just that didn’t wipe out people’s pain. “It seemed so obvious and simple,” says study leader Tim Hucho, a neuroscientist at the University Hospital Cologne in Germany. “But it was not so simple.” |© Society for Science & the Public 2000 - 2017
Keyword: Pain & Touch
Link ID: 23090 - Posted: 01.12.2017
By Jessica Hamzelou One woman’s unique experiences are helping us understand the nature of synaesthesia. We don’t know yet what causes synaesthesia, which links senses and can enable people to taste words or smell sounds, for example. It may be at least partly genetic, as it tends to run in families. Some researchers think a brain chemical called serotonin might play a role, because hallucinogenic drugs that alter serotonin levels in the brain can create unusual perceptions. There’s also some evidence that synaesthesia can change or disappear, and a detailed assessment of one woman’s experiences is helping Kevin Mitchell at Trinity College Dublin in Ireland and his team investigate. The woman, referred to as “AB”, sees colours when she hears music, linked to pitch, volume or instrument – higher notes have more pastel shades. She also associates colours with people, largely based on personality. Green is linked to loyalty, for instance. But several experiences in her life have caused her synaesthesia to change. “To say she had a series of unfortunate events would be an understatement,” says Mitchell. As a teenager and young adult, AB sustained several concussions, had migraines, contracted viral meningitis and was struck by lightning. © Copyright Reed Business Information Ltd.
Link ID: 23054 - Posted: 01.04.2017
By KEVIN DEUTSCH An anesthetic commonly used for surgery has surpassed heroin to become the deadliest drug on Long Island, killing at least 220 people there in 2016, according to medical examiners’ records. The drug, fentanyl, is a synthetic opioid, which can be 100 times more potent than morphine. The numbers from Long Island are part of a national pattern, as fentanyl fatalities have already surpassed those from heroin in other parts of the country, including New England, as its use has skyrocketed. Part of the reason for the increase is economic — because fentanyl can be manufactured in the lab, it is much cheaper and easier than cultivating heroin. In New York City, more than 1,000 people are expected to die from drug overdoses this year — the first recorded four-digit death total in city history, according to statistics compiled by the Department of Health and Mental Hygiene. Nearly half of all unintentional drug overdose deaths in the city since July have involved fentanyl, the health department said. The medical examiners of Long Island’s two counties, Nassau and Suffolk, compiled the new numbers. “Fentanyl has surpassed heroin as the most commonly detected drug in fatal opioid overdoses,” Dr. Michael J. Caplan, the Suffolk County medical examiner, said in a written statement about the statistics, which were obtained by The New York Times ahead of their release. “The influx of illicitly manufactured fentanyl from overseas is a nationwide issue that requires a multidisciplinary intervention from all levels of government.” Nationwide, recorded deaths from opioids surpassed 30,000 in 2015, according to data compiled by the Centers for Disease Control and Prevention. And overdoses caused by synthetic opioids like fentanyl increased by 72.2 percent in 2015 over 2014 — one of the deadliest year-over-year surges for any drug in United States history, the same data shows. © 2016 The New York Times Company
By Ben Andrew Henry Traveling from the forests and fields of Europe to the grasslands south of the Sahara desert is a monumental trip for anyone, and especially for a diminutive insect. Yet every year, populations of the painted lady (Vanessa cardui) butterfly make that journey over the course of several generations. The logistics of this migratory feat had been speculated for some time, but never fully understood, in part because of the difficulty of tracking the tiny insects across long distances. In a study published October 4 in Biology Letters, researchers reported having measured the isotopic composition of butterfly wings in Europe and south of the Sahara. Since the fraction of heavy hydrogen isotopes in the environment varies geographically, the team used its analysis to identify the origins of butterflies captured, confirming that groups of butterflies in the Sahara did originate in Europe. The butterflies do not linger in Africa long. They most likely make their trip, the authors suggested, to take advantage of the burst of productivity in the tropical savannah that follows the rainy season—and to breed the generation that will start the trip back. Europe’s freshwater eels (Anguilla anguilla) live out their days in rivers and streams, but they never spawn there. Massive catches of larval eels in the Sargasso Sea tipped researchers off a century ago that eels must spawn in the swirling mid-Atlantic gyre of free-floating seaweed and then migrate to Europe. Eels leave their homes in the late fall, but other than that, the details of their journey have been a mystery. © 1986-2016 The Scientist
Keyword: Animal Migration
Link ID: 23029 - Posted: 12.28.2016
by Bethany Brookshire An opioid epidemic is upon us. Prescription painkillers such as fentanyl and morphine can ease terrible pain, but they can also cause addiction and death. The Centers for Disease Control and Prevention estimates that nearly 2 million Americans are abusing or addicted to prescription opiates. Politicians are attempting to stem the tide at state and national levels, with bills to change and monitor how physicians prescribe painkillers and to increase access to addiction treatment programs. Those efforts may make access to painkillers more difficult for some. But pain comes to everyone eventually, and opioids are one of the best ways to make it go away. Morphine is the king of pain treatment. “For hundreds of years people have used morphine,” says Lakshmi Devi, a pharmacologist at the Ichan School of Medicine Mount Sinai in New York City. “It works, it’s a good drug, that’s why we want it. The problem is the bad stuff.” The “bad stuff” includes tolerance — patients have to take higher and higher doses to relieve their pain. Drugs such as morphine depress breathing, an effect that can prove deadly. They also cause constipation, drowsiness and vomiting. But “for certain types of pain, there are no medications that are as effective,” says Bryan Roth, a pharmacologist and physician at the University of North Carolina at Chapel Hill. The trick is constructing a drug with all the benefits of an opioid painkiller, and few to none of the side effects. Here are three ways that scientists are searching for the next big pain buster, and three of the chemicals they’ve turned up. |© Society for Science & the Public 2000 - 2016
Rachel Ehrenberg Scientists investigating what keeps lungs from overinflating can quit holding their breath. Experiments in mice have identified a protein that senses when the lungs are full of air. This protein helps regulate breathing in adult mice and gets breathing going in newborn mice, researchers report online December 21 in Nature. If the protein plays a similar role in people — and a few studies suggest that it does — exploring its activity could help explain disorders such as sleep apnea or chronic obstructive pulmonary disease. “These are extremely well done, very elegant studies,” says neonatologist Shabih Hasan of the University of Calgary in Canada, a specialist in breathing disorders in newborns. Researchers knew that feedback between the lungs and brain maintains normal breathing. But “this research give us an understanding at the cellular level,” says Hasan. “It’s a major advance.” Called Piezo2, the protein forms channels in the membranes of nerve cells in the lungs. When the lungs stretch, the Piezo2 channels detect the distortion caused by the mechanical force of breathing and spring open, triggering the nerves to send a signal. Led by neuroscientist Ardem Patapoutian, researchers discovered that the channels send signals along three different pathways. Mice bred to lack Piezo2 in a cluster of nerve cells that send messages to the spinal cord had trouble breathing and died within 24 hours. Similarly, newborn mice missing Piezo2 channels in nerves that communicate with the brain stem via a structure called the jugular ganglion also died. |© Society for Science & the Public 2000 - 2016.
Keyword: Pain & Touch
Link ID: 23006 - Posted: 12.22.2016
.By JOANNA KLEIN A honey bee gathering pollen on a white flower. Dagmar Sporck/EyeEm, via Getty Images Set your meetings, phone calls and emails aside, at least for the next several minutes. That’s because today you’re a bee. It's time to leave your hive, or your underground burrow, and forage for pollen. Pollen is the stuff that flowers use to reproduce. But it’s also essential grub for you, other bees in your hive and your larvae. Once you’ve gathered pollen to take home, you or another bee will mix it with water and flower nectar that other bees have gathered and stored in the hive. But how do you decide which flowers to approach? What draws you in? In a review published last week in the journal Functional Ecology, researchers asked: What is a flower like from a bee’s perspective, and what does the pollinator experience as it gathers pollen? And that's why we're talking to you in the second person: to help you understand how bees like you, while hunting for pollen, use all of your senses — taste, touch, smell and more — to decide what to pick up and bring home. Maybe you're ready to go find some pollen. But do you even know where to look? © 2016 The New York Times Company
By Melissa Dahl Considering its origin story, it’s not so surprising that hypnosis and serious medical science have often seemed at odds. The man typically credited with creating hypnosis, albeit in a rather primitive form, is Franz Mesmer, a doctor in 18th-century Vienna. (Mesmer, mesmerize. Get it?) Mesmer developed a general theory of disease he called “animal magnetism,” which held that every living thing carries within it an internal magnetic force, in liquid form. Illness arises when this fluid becomes blocked, and can be cured if it can be coaxed to flow again, or so Mesmer’s thinking went. To get that fluid flowing, as science journalist Jo Marchant describes in her recent book, Cure, Mesmer “simply waved his hands to direct it through his patients’ bodies” — the origin of those melodramatic hand motions that stage hypnotists use today.” After developing a substantial following — “mesmerism” became “the height of fashion” in late 1780s Paris, writes Marchant — Mesmer became the subject of what was essentially the world’s first clinical trial. King Louis XVI pulled together a team of the world’s top scientists, including Benjamin Franklin, who tested mesmerism and found its capacity to “cure” was, essentially, a placebo effect. “Not a shred of evidence exists for any fluid,” Franklin wrote. “The practice … is the art of increasing the imagination by degrees.” Maybe so. But that doesn’t mean it doesn’t work. © 2016, New York Media LLC.
Tom Goldman Voters in seven more states said "yes" to marijuana this month. Pot now is legal for recreational or medicinal use in more than half the country. It's still against federal law and classified as a Schedule 1 drug, meaning U.S. officials consider marijuana to have a high risk of abuse or harm, and no accepted medical use in treatment. Also, it's still banned in professional sports. Many athletes hope that will change as momentum grows nationwide for legalization. That's especially true in the National Football League, where pain is a constant companion. Advocates say marijuana could offer a safer and better way to manage the pain. Football hurts. As a fan watching from home, that's not always obvious — players collide, fall down, pop back up. They rarely wince or show weakness. That's just not how it's done in football. Kyle Turley hurt plenty during his eight NFL seasons in the 1990s and 2000s. As an offensive lineman, he was involved in jarring collisions nearly every play when his team had the ball. He hurt after his career -– Turley sometimes walks with a cane. And in a recent video, he displayed one by one the bottles of powerful painkillers he used. "Vicodin, Flexeril, Percocets, Vioxx, morphine," Turley recited as he plopped the bottles down on a kitchen counter. © 2016 npr
By Alice Klein Alzheimer’s disease can be prevented by stopping a crucial brain protein from turning rogue, a study in mice suggests. Tau protein has long been suspected to play a role in causing the condition. In healthy brains, tau is essential for normal cell functioning. But during Alzheimer’s disease, the protein goes haywire, clumping together to form twisted tangles and, it is thought, releasing toxic chemicals that harm the brain. Now Lars Ittner at the University of New South Wales, Australia, and his colleagues have pinpointed a crucial enzyme that controls how tau proteins behave in the brain. The enzyme, called p38γ kinase, helps keep tau in a healthy, tangle-free state, preventing the onset of memory loss and other symptoms in mice that have been bred to develop Alzheimer’s disease. The enzyme seems to block Alzheimer’s by interfering with the action of another problem protein, called beta-amyloid. Like tau, clumps of this protein accumulate in the brains of people with Alzheimer’s, making it another suspected cause of the disease. When beta-amyloid forms these sticky plaques, it can also modify the structure of tau proteins, causing them to form tangles and release toxic chemicals. But Ittner’s team found that p38γ kinase makes a different kind of structural change to tau. If this change is made first, it prevents beta-amyloid from being able to turn tau bad, and mice do not develop the disease. © Copyright Reed Business Information Ltd.
Link ID: 22883 - Posted: 11.18.2016
By CHRIS BUCKLEY BEIJING — When Flappy McFlapperson and Skybomb Bolt sprang into the sky for their annual migration from wetlands near Beijing, nobody was sure where the two cuckoos were going. They and three other cuckoos had been tagged with sensors to follow them from northern China. But to where? “These birds are not known to be great fliers,” said Terry Townshend, a British amateur bird watcher living in the Chinese capital who helped organize the Beijing Cuckoo Project to track the birds. “Migration is incredibly perilous for birds, and many perish on these journeys.” The answer to the mystery — unfolding in passages recorded by satellite for more than five months — has been a humbling revelation even to many experts. The birds’ journeys have so far covered thousands of miles, across a total of a dozen countries and an ocean. The “common cuckoo,” as the species is called, turns out to be capable of exhilarating odysseys. “It’s impossible not to feel an emotional response,” said Chris Hewson, an ecologist with the British Trust for Ornithology in Thetford, England, who has helped run the tracking project. “There’s something special about feeling connected to one small bird flying across the ocean or desert.” But to follow a cuckoo, you must first seduce it. The common cuckoo is by reputation a cynical freeloader. Mothers outsource parenting by laying their eggs in the nests of smaller birds, and the birds live on grubs, caterpillars and similar soft morsels. British and Chinese bird groups decided to study two cuckoo subspecies found near Beijing, because their winter getaways were a puzzle. In an online poll for the project, nearly half the respondents guessed they went somewhere in Southeast Asia. © 2016 The New York Times Company
By Diana Kwon In people who suffer from pain disorders, painful feelings can severely worsen and spread to other regions of the body. Patients who develop chronic pain after surgery, for example, will often feel it coming from the area surrounding the initial injury and even in some parts of the body far from where it originates. New evidence suggests glia, non-neuronal cells in the brain, may be the culprits behind this effect. Glia were once thought to simply be passive, supporting cells for neurons. But scientists now know they are involved in everything from metabolism to neurodegeneration. A growing body of evidence points to their key role in pain. In a study published today in Science, researchers at the Medical University of Vienna report that glia are involved in long-term potentiation (LTP), or the strengthening of synapses, in pain pathways in the spinal cord. Neuroscientists Timothy Bliss and Terje Lømo first described LTP in the hippocampus, a brain area involved in memory, in the 1970s. Since then scientists have been meticulously studying the role this type of synaptic plasticity—the ability of synapses to change in strength—plays in learning and memory. More recently, researchers discovered that LTP could also amplify pain in areas where injuries or inflammation occur. “We sometimes call this a ‘memory trace of pain’ because the painful insult may lead to subsequent hypersensitivity to painful stimuli, and it was clear that synaptic plasticity can play a role here,” says study co-author Jürgen Sandkühler, a neuroscientist also at the Medical University of Vienna. But current models of how LTP works could not explain why discomfort sometimes becomes widespread or experienced in areas a person has never felt it before, he adds. © 2016 Scientific American