Chapter 8. General Principles of Sensory Processing, Touch, and Pain

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By Baland Jalal Obsessive-compulsive disorder (OCD) has puzzled artists and scientists for centuries. Afflicting one in 50 people, OCD can take several forms, such as compulsively putting things in just the right order or checking if the stove is turned off 10 times in a row. One type of OCD that affects nearly half of those with the condition entails irresistible washing urges. People with this type can spend hours scrubbing their hands in agitation after touching something as trivial as a doorknob even though they know this makes no sense. There is currently a shortage of effective therapies for OCD: 40 percent of patients do not benefit from existing treatments. A major issue is that today’s treatments are often too stressful. First-line “nonpharmacological therapies” involve telling patients to repeatedly touch things such as toilet seats and then refrain from washing their hands. But recent work by my colleagues and me has found something surprising: people diagnosed with OCD appear to have a more malleable “sense of self,” or brain-based “self-representation” or “body image”—the feeling of being anchored here and now in one’s body—than those without the disorder. This finding suggests new ways to treat OCD and perhaps unexpected insights into how our brain creates a distinction between “self” and “other.” In our recent experiments, for example, we showed that people with and without OCD responded differently to a well-known illusion. In our first study, a person without OCD watched as an experimenter used a paintbrush to stroke a rubber hand and the subject’s hidden real hand in precise synchrony. This induces the so-called rubber hand illusion: the feeling that a fake hand is your hand. When the experimenter stroked the rubber hand and the real one out of sync, the effect was not induced (or was greatly diminished). This compelling illusion illustrates how your brain creates your body image based on statistical correlations. It’s extremely unlikely for such stroking to be seen on a rubber hand and simultaneously felt on a hidden real one by chance. So your brain concludes, however illogically, that the rubber hand is part of your body. © 2021 Scientific American

Keyword: OCD - Obsessive Compulsive Disorder; Pain & Touch
Link ID: 27980 - Posted: 09.08.2021

Allison Whitten Our mushy brains seem a far cry from the solid silicon chips in computer processors, but scientists have a long history of comparing the two. As Alan Turing put it in 1952: “We are not interested in the fact that the brain has the consistency of cold porridge.” In other words, the medium doesn’t matter, only the computational ability. Today, the most powerful artificial intelligence systems employ a type of machine learning called deep learning. Their algorithms learn by processing massive amounts of data through hidden layers of interconnected nodes, referred to as deep neural networks. As their name suggests, deep neural networks were inspired by the real neural networks in the brain, with the nodes modeled after real neurons — or, at least, after what neuroscientists knew about neurons back in the 1950s, when an influential neuron model called the perceptron was born. Since then, our understanding of the computational complexity of single neurons has dramatically expanded, so biological neurons are known to be more complex than artificial ones. But by how much? To find out, David Beniaguev, Idan Segev and Michael London, all at the Hebrew University of Jerusalem, trained an artificial deep neural network to mimic the computations of a simulated biological neuron. They showed that a deep neural network requires between five and eight layers of interconnected “neurons” to represent the complexity of one single biological neuron. All Rights Reserved © 2021

Keyword: Brain imaging; Vision
Link ID: 27978 - Posted: 09.04.2021

Nicola Davis Premature babies appear to feel less pain during medical procedures when they are spoken to by their mothers, researchers have found. Babies that are born very early often have to spend time in neonatal intensive care units, and may need several painful clinical procedures. The situation can also mean lengthy separation from parents. Now researchers say they have found the sound of a mother’s voice seems to decrease the pain experienced by their baby during medical procedures. Dr Manuela Filippa, of the University of Geneva and first author of the study, said the research might not only help parents, by highlighting that they can play an important role while their baby is in intensive care, but also benefit the infants. Advertisement Last man out: the haunting image of America’s final moments in Afghanistan “We are trying to find non-pharmacological ways to lower the pain in these babies,” she said, adding that there was a growing body of evidence that parental contact with preterm babies could be important for a number of reasons, including attachment. Filippa said the team focused on voice because it was not always possible for parents to hold their babies in intensive care, while voice could be a powerful tool to share emotion. Mothers’ voices were studied in particular because infants would already have heard it in the womb. But Filippa said that did not mean a father’s voice could not become as familiar over time. “We are [also] running studies on fathers’ vocal contacts,” she said. Writing in the journal Scientific Reports, Filippa and colleagues at the University of Geneva, Parini hospital in Italy and the University of Valle d’Aosta, report how they examined the pain responses of 20 premature babies in neonatal intensive care to a routine procedure in which the foot is pricked and a few drops of blood collected. © 2021 Guardian News & Media Limited

Keyword: Pain & Touch; Development of the Brain
Link ID: 27973 - Posted: 09.01.2021

By Christiane Gelitz, Maddie Bender | To a chef, the sounds of lip smacking, slurping and swallowing are the highest form of flattery. But to someone with a certain type of misophonia, these same sounds can be torturous. Brain scans are now helping scientists start to understand why. People with misophonia experience strong discomfort, annoyance or disgust when they hear particular triggers. These can include chewing, swallowing, slurping, throat clearing, coughing and even audible breathing. Researchers previously thought this reaction might be caused by the brain overactively processing certain sounds. Now, however, a new study published in the Journal of Neuroscience has linked some forms of misophonia to heightened “mirroring” behavior in the brain: those affected feel distress while their brains act as if they are mimicking the triggering mouth movements. “This is the first breakthrough in misophonia research in 25 years,” says psychologist Jennifer J. Brout, who directs the International Misophonia Research Network and was not involved in the new study. The research team, led by Newcastle University neuroscientist Sukhbinder Kumar, analyzed brain activity in people with and without misophonia when they were at rest and while they listened to sounds. These included misophonia triggers (such as chewing), generally unpleasant sounds (like a crying baby), and neutral sounds. The brain's auditory cortex, which processes sound, reacted similarly in subjects with and without misophonia. But in both the resting state and listening trials, people with misophonia showed stronger connections between the auditory cortex and brain regions that control movements of the face, mouth and throat. Kumar found this connection became most active in participants with misophonia when they heard triggers specific to the condition. © 2021 Scientific American,

Keyword: Hearing; Attention
Link ID: 27955 - Posted: 08.21.2021

By Sabrina Imbler In a way, nausea is our trusty personal bodyguard. Feeling nauseated is widely accepted to be an evolutionary defense measure that protects people from pathogens and parasites. The urge to gag or vomit is “well-suited” to defend ourselves against things we swallow that might contain pathogens, according to Tom Kupfer, a psychological scientist at Nottingham Trent University in England. But vomiting is somewhat futile against a tick, an ectoparasite that latches on to skin, not stomachs. In an experiment that produced both stomach churning and skin crawling sensations — I can confirm these and some other physiological responses firsthand — Dr. Kupfer and Daniel Fessler, an evolutionary anthropologist from the University of California, Los Angeles, argue in a paper published on Wednesday in the journal Proceedings of the Royal Society B that humans have evolved to defend themselves against ectoparasites through a skin response that elicits scratching. Although some outside experts say more research is needed, the findings align with some understandings of the evolution of disgust. “It makes sense to have developed adaptive defensive strategies against the ‘nasty’ ones,” Cécile Sarabian, a cognitive ecologist studying animal disgust at the Kyoto University Primate Research Institute in Japan, wrote in an email. The disgusting investigation began in 2017 on the grounds of Chicheley Hall in Buckinghamshire, England. Here, Dr. Kupfer was presenting findings to colleagues on trypophobia, the aversion to clustered holes experienced by some people. His data showed that participants with trypophobia often reacted to holey images with the urge to itch or scratch, sometimes to the point of bleeding. Dr. Kupfer suggested that trypophobia might not represent fear, but rather a disgust reaction to signs of parasites or infectious diseases, which can both result in clusters of lesions or pustules.

Keyword: Pain & Touch
Link ID: 27926 - Posted: 07.28.2021

By Tom Zeller Jr. I have headaches. Not the low-grade, annoying, “I’ve got a headache” sort of headaches. I get those, too. Most everyone does, and they are a drag. No, when I say that I get headaches, I mean that at intervals that are largely unpredictable, a knot of pain rises deep inside my head, invariably sensed behind my right eyeball. It then swiftly clicks up through the intensity scale, racing past that dull ache you might get from staring at the screen too long, leapfrogging over that doozy you had the morning after your brother’s wedding, skipping past the agonizing-but-fleeting stab of an ice-cream headache, and arriving, within a matter of minutes, at a pain so piercing and sustained that I can only grip something sturdy, rock back and forth, and grunt until it subsides. Mine are what doctors call one of the “primary headaches” — recurring and often excruciating disorders that are not byproducts of another condition (or self-inflicted by last night’s cocktails), but relentless, and in many ways still poorly understood disorders unto themselves. We know them by common names like migraine, which affects tens of millions of Americans, disproportionately women. I suffer from another flavor known as cluster headaches (technically “trigeminal autonomic cephalalgias”). And there are others, with myriad and imperfectly drawn lines distinguishing them. If you experience migraines or cluster headaches — and research suggests that more than a billion people worldwide do — you probably know something about shuttling from doctor to doctor looking for someone who “gets it.” You know what it’s like to gladly gobble up pills that don’t really work and that leave you miserable in other ways. And you might even know the same sort of incredulous exasperation that has driven me to wonder, from my fetal position on the bathroom floor: “How is it possible that science can’t fix a damn headache?” © 2021 The New York Times Company

Keyword: Pain & Touch
Link ID: 27924 - Posted: 07.24.2021

Elena Renken For decades, neuroscientists have treated the brain somewhat like a Geiger counter: The rate at which neurons fire is taken as a measure of activity, just as a Geiger counter’s click rate indicates the strength of radiation. But new research suggests the brain may be more like a musical instrument. When you play the piano, how often you hit the keys matters, but the precise timing of the notes is also essential to the melody. “It’s really important not just how many [neuron activations] occur, but when exactly they occur,” said Joshua Jacobs, a neuroscientist and biomedical engineer at Columbia University who reported new evidence for this claim last month in Cell. For the first time, Jacobs and two coauthors spied neurons in the human brain encoding spatial information through the timing, rather than rate, of their firing. This temporal firing phenomenon is well documented in certain brain areas of rats, but the new study and others suggest it might be far more widespread in mammalian brains. “The more we look for it, the more we see it,” Jacobs said. Abstractions navigates promising ideas in science and mathematics. Journey with us and join the conversation. Some researchers think the discovery might help solve a major mystery: how brains can learn so quickly. The phenomenon is called phase precession. It’s a relationship between the continuous rhythm of a brain wave — the overall ebb and flow of electrical signaling in an area of the brain — and the specific moments that neurons in that brain area activate. A theta brain wave, for instance, rises and falls in a consistent pattern over time, but neurons fire inconsistently, at different points on the wave’s trajectory. In this way, brain waves act like a clock, said one of the study’s coauthors, Salman Qasim, also of Columbia. They let neurons time their firings precisely so that they’ll land in range of other neurons’ firing — thereby forging connections between neurons. All Rights Reserved © 2021

Keyword: Brain imaging
Link ID: 27898 - Posted: 07.08.2021

By Anil Ananthaswamy “Everything became imbued with a sense of vitality and life and vividness. If I picked up a pebble from the beach, it would move. It would glisten and gleam and sparkle and be absolutely captivating,” says neuroscientist Anil Seth. “Somebody looking at me would see me staring at a stone for hours.” Or what seemed like hours to Seth. A researcher at the UK’s University of Sussex, he studies how the brain helps us perceive the world within and without, and is intrigued by what psychedelics such as LSD can tell us about how the brain creates these perceptions. So a few years ago, he decided to try some, in controlled doses and with trusted people by his side. He had a notebook to keep track of his experiences. “I didn’t write very much in the notebook,” he says, laughing. Instead, while on LSD, he reveled in a sense of well-being and marveled at the “fluidity of time and space.” He found himself staring at clouds and seeing them change into faces of people he was thinking of. If his attention drifted, the clouds morphed into animals. Seth went on to try ayahuasca, a hallucinogenic brew made from a shrub and a vine native to South America and often used in shamanistic rituals there. This time, he had a more emotional trip that dredged up powerful memories. Both experiences strengthened Seth’s conviction that psychedelics have great potential for teaching us about the inner workings of the brain that give rise to our perceptions. He’s not alone. Armed with fMRI scans, EEG recordings, computational models of the brain and reports from volunteers tripping on psychedelics, a small but growing number of neuroscientists are trying to take advantage of these drugs and the hallucinations they induce to better understand how the brain produces perceptions. © 2021 Annual Reviews, Inc

Keyword: Drug Abuse; Vision
Link ID: 27883 - Posted: 06.29.2021

By Emily Conover Scientists could be a step closer to understanding how some birds might exploit quantum physics to navigate. Researchers suspect that some songbirds use a “quantum compass” that senses the Earth’s magnetic field, helping them tell north from south during their annual migrations (SN: 4/3/18). New measurements support the idea that a protein in birds’ eyes called cryptochrome 4, or CRY4, could serve as a magnetic sensor. That protein’s magnetic sensitivity is thought to rely on quantum mechanics, the math that describes physical processes on the scale of atoms and electrons (SN: 6/27/16). If the idea is shown to be correct, it would be a step forward for biophysicists who want to understand how and when quantum principles can become important in various biological processes. In laboratory experiments, the type of CRY4 in retinas of European robins (Erithacus rubecula) responded to magnetic fields, researchers report in the June 24 Nature. That’s a crucial property for it to serve as a compass. “This is the first paper that actually shows that birds’ cryptochrome 4 is magnetically sensitive,” says sensory biologist Rachel Muheim of Lund University in Sweden, who was not involved with the research. Scientists think that the magnetic sensing abilities of CRY4 are initiated when blue light hits the protein. That light sets off a series of reactions that shuttle around an electron, resulting in two unpaired electrons in different parts of the protein. Those lone electrons behave like tiny magnets, thanks to a quantum property of the electrons called spin. © Society for Science & the Public 2000–2021.

Keyword: Animal Migration; Vision
Link ID: 27882 - Posted: 06.29.2021

Ed Yong Carl Schoonover and Andrew Fink are confused. As neuroscientists, they know that the brain must be flexible but not too flexible. It must rewire itself in the face of new experiences, but must also consistently represent the features of the external world. How? The relatively simple explanation found in neuroscience textbooks is that specific groups of neurons reliably fire when their owner smells a rose, sees a sunset, or hears a bell. These representations—these patterns of neural firing—presumably stay the same from one moment to the next. But as Schoonover, Fink, and others have found, they sometimes don’t. They change—and to a confusing and unexpected extent. Schoonover, Fink, and their colleagues from Columbia University allowed mice to sniff the same odors over several days and weeks, and recorded the activity of neurons in the rodents’ piriform cortex—a brain region involved in identifying smells. At a given moment, each odor caused a distinctive group of neurons in this region to fire. But as time went on, the makeup of these groups slowly changed. Some neurons stopped responding to the smells; others started. After a month, each group was almost completely different. Put it this way: The neurons that represented the smell of an apple in May and those that represented the same smell in June were as different from each other as those that represent the smells of apples and grass at any one time. This is, of course, just one study, of one brain region, in mice. But other scientists have shown that the same phenomenon, called representational drift, occurs in a variety of brain regions besides the piriform cortex. Its existence is clear; everything else is a mystery. Schoonover and Fink told me that they don’t know why it happens, what it means, how the brain copes, or how much of the brain behaves in this way. How can animals possibly make any lasting sense of the world if their neural responses to that world are constantly in flux? (c) 2021 by The Atlantic Monthly Group

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27852 - Posted: 06.11.2021

By Nikk Ogasa Most Uber drivers need a smartphone to get to their destinations. But sharks, it seems, need nothing more than their own bodies—and Earth’s magnetic field. A new study suggests some sharks can read Earth’s field like a map and use it to navigate the open seas. The result adds sharks to the long list of animals—including birds, sea turtles, and lobsters—that navigate with a mysterious magnetic sense. “It’s great that they’ve finally done this magnetic field study on sharks,” says Michael Winklhofer, a biophysicist at the Carl von Ossietzky University of Oldenburg in Germany, who was not involved in the study. In 2005, scientists reported that a great white shark swam from South Africa to Australia and back again in nearly a straight line—a feat that led some scientists to propose the animals relied on a magnetic sense to steer themselves. And since at least the 1970s, researchers have suspected that the elasmobranchs—a group of fish containing sharks, rays, skates, and sawfish—can detect magnetic fields. But no one had shown that sharks use the fields to locate themselves or navigate, partly because the animals aren’t so easy to work with, Winklhofer says. “It’s one thing if you have a small lobster, or a baby sea turtle, but when you work with sharks, you have to upscale everything.” Bryan Keller, an ecologist at Florida State University, and his colleagues decided to do just that. The researchers lined a bedroom-size cage with copper wire and placed a small swimming pool in the center of the cage. By running an electrical current through the wiring, they could generate a custom magnetic field in the center of the pool. The team then collected 20 juvenile bonnethead sharks—a species known to migrate hundreds of kilometers—from a shoal off the Florida coast. They placed the sharks into the pool, one at a time, and let them swim freely under three different magnetic fields, applied in random succession. One field mimicked Earth’s natural field at the spot where the sharks were collected, whereas the others mimicked the fields at locations 600 kilometers north and 600 kilometers south of their homes. © 2021 American Association for the Advancement of Science.

Keyword: Animal Migration
Link ID: 27814 - Posted: 05.12.2021

By Jackie Rocheleau Placebos can make us feel better. Mild electric zaps to the brain can make that effect even stronger, scientists report online May 3 in Proceedings of the National Academy of Sciences. The finding raises the possibility of enhancing the power of expectations to improve treatments. This is the first study to boost placebo and blunt pain-inducing nocebo effects by altering brain activity, says Jian Kong, a pain researcher at Massachusetts General Hospital in Charlestown. The placebo effect arises when someone feels better after taking an inactive substance, like a sugar pill, because they expect the substance to help. The nocebo effect is the placebo’s evil twin: A person feels worse after taking an inactive substance that they expect to have unpleasant effects. To play with people’s expectations, Kong’s team primed 81 participants for painful heat. The heat was delivered by a thermal stimulator to the forearm while participants lay in a functional MRI scanner. Each person received three creams, each to a different spot on their arms. One cream, participants were told, was a numbing lidocaine cream, one was a regular cream and one was a pain-increasing capsaicin cream. But in fact, all the creams were the same inert lotion, dyed different colors. © Society for Science & the Public 2000–2021

Keyword: Pain & Touch
Link ID: 27810 - Posted: 05.08.2021

By Kathiann Kowalski On most mornings, Jeremy D. Brown eats an avocado. But first, he gives it a little squeeze. A ripe avocado will yield to that pressure, but not too much. Brown also gauges the fruit’s weight in his hand and feels the waxy skin, with its bumps and ridges. “I can’t imagine not having the sense of touch to be able to do something as simple as judging the ripeness of that avocado,” says Brown, a mechanical engineer who studies haptic feedback — how information is gained or transmitted through touch — at Johns Hopkins University. Many of us have thought about touch more than usual during the COVID-19 pandemic. Hugs and high fives rarely happen outside of the immediate household these days. A surge in online shopping has meant fewer chances to touch things before buying. And many people have skipped travel, such as visits to the beach where they might sift sand through their fingers. A lot goes into each of those actions. “Anytime we touch anything, our perceptual experience is the product of the activity of thousands of nerve fibers and millions of neurons in the brain,” says neuroscientist Sliman Bensmaia of the University of Chicago. The body’s natural sense of touch is remarkably complex. Nerve receptors detect cues about pressure, shape, motion, texture, temperature and more. Those cues cause patterns of neural activity, which the central nervous system interprets so we can tell if something is smooth or rough, wet or dry, moving or still. © Society for Science & the Public 2000–2021.

Keyword: Pain & Touch; Robotics
Link ID: 27787 - Posted: 04.24.2021

By Lisa Sanders, M.D. It was dark by the time the 41-year-old woman was able to start the long drive from her father’s apartment in Washington, D.C., to her home in Westchester County, N.Y. She was eager to get back to her husband and three children. Somewhere after she crossed the border into Maryland, the woman suddenly developed a terrible itch all over her body. She’d been a little itchy for the past couple of weeks but attributed that to dry skin from her now-faded summertime tan. This seemed very different: much stronger, much deeper. And absolutely everywhere, all at the same time. The sensation was so intense it was hard for the woman to pay attention to the road. She found herself driving with one hand on the steering wheel and the other working to respond to her skin’s new need. There was no rash — or at least nothing she could feel — just the terrible itch, so deep inside her skin that she felt as if she couldn’t scratch hard enough to really get to it. By the light of the Baltimore Harbor Tunnel she saw that her nails and fingers were dark with blood. That scared her, and she tried to stop scratching, but she couldn’t. It felt as if a million ants were crawling all over her body. Not on her skin, but somehow under it. The woman had gone to Washington to help her elderly father move. His place was a mess. Many of his belongings hadn’t been touched in years. She figured that she was having a reaction to all the dust and dirt and who knows what else she encountered while cleaning. As soon as she got home, she took a long shower; the cool water soothed her excoriated skin. She lathered herself with moisturizer and sank gratefully into her bed. But the reprieve didn’t last, and from that night on she was tormented by an itch that no scratching could satisfy. © 2021 The New York Times Company

Keyword: Pain & Touch; Hormones & Behavior
Link ID: 27775 - Posted: 04.17.2021

By Kathryn Schulz One of the most amazing things I have ever witnessed involved an otherwise unprepossessing house cat named Billy. This was some years ago, shortly after I had moved into a little rental house in the Hudson Valley. Billy, a big, bad-tempered old tomcat, belonged to the previous tenant, a guy by the name of Phil. Phil adored that cat, and the cat—improbably, given his otherwise unenthusiastic feelings about humanity—returned the favor. On the day Phil vacated the house, he wrestled an irate Billy into a cat carrier, loaded him into a moving van, and headed toward his new apartment, in Brooklyn. Thirty minutes down I-84, in the middle of a drenching rainstorm, the cat somehow clawed his way out of the carrier. Phil pulled over to the shoulder but found that, from the driver’s seat, he could neither coax nor drag the cat back into captivity. Moving carefully, he got out of the van, walked around to the other side, and opened the door a gingerly two inches—whereupon Billy shot out, streaked unscathed across two lanes of seventy-mile-per-hour traffic, and disappeared into the wide, overgrown median. After nearly an hour in the pouring rain trying to make his own way to the other side, Phil gave up and, heartbroken, continued onward to his newly diminished home. Some weeks later, at a little before seven in the morning, I woke up to a banging at my door. Braced for an emergency, I rushed downstairs. The house had double-glass doors flanked by picture windows, which together gave out onto almost the entire yard, but I could see no one. I was standing there, sleep-addled and confused, when up onto his hind legs and into my line of vision popped an extremely scrawny and filthy gray cat. I gaped. Then I opened the door and asked the cat, idiotically, “Are you Billy?” He paced, distraught, and meowed at the door. I retreated inside and returned with a bowl each of food and water, but he ignored them and banged again at the door. Flummoxed, I took a picture and texted it to my landlord with much the same question I had asked the cat: “Is this Billy?” © 2021 Condé Nast.

Keyword: Animal Migration
Link ID: 27752 - Posted: 03.31.2021

By Veronique Greenwood There’s nothing quite like the peculiar, bone-jarring reaction of a damaged tooth exposed to something cold: a bite of ice cream, or a cold drink, and suddenly, that sharp, searing feeling, like a needle piercing a nerve. Researchers have known for years that this phenomenon results from damage to the tooth’s protective outer layer. But just how the message goes from the outside of your tooth to the nerves within it has been difficult to uncover. On Friday, biologists reported in the journal Science Advances that they have identified an unexpected player in this painful sensation: a protein embedded in the surface of cells inside the teeth. The discovery provides a glimpse of the connection between the outer world and the interior of a tooth, and could one day help guide the development of treatments for tooth pain. More than a decade ago, Dr. Katharina Zimmerman, now a professor at Friedrich-Alexander University in Germany, discovered that cells producing a protein called TRPC5 were sensitive to cold. When things got chilly, TRPC5 popped open to form a channel, allowing ions to flow across the cell’s membrane. Ion channels like TRPC5 are sprinkled throughout our bodies, Dr. Zimmerman said, and they are behind some surprisingly familiar sensations. For instance, if your eyes start to feel cold and dry in chilly air, it’s a result of an ion channel being activated in the cornea. She wondered which other parts of the body might make use of a cold receptor such as TRPC5. And it occurred to her that “the most sensitive tissue in the human body can be teeth” when it comes to cold sensations. © 2021 The New York Times Company

Keyword: Pain & Touch
Link ID: 27748 - Posted: 03.27.2021

By Karen J. Bannan Hayley Gudgin of Sammamish, Wash., got her first migraine in 1991 when she was a 19-year-old nursing student. “I was convinced I was having a brain hemorrhage,” she says. “There was no way anything could be that painful and not be really serious.” She retreated to her bed and woke up feeling better the next day. But it wasn’t long until another migraine hit. And another. Taking a pill that combines caffeine with the pain relievers acetaminophen and codeine made life manageable until she got pregnant and had to stop taking her medication. After her son was born, the migraines came back. She started taking the drugs again, but they didn’t work and actually made her attacks worse. By the time Gudgin gave birth to her second son in 1997, she was having about 15 attacks a month. Her symptoms worsened over time and included severe pain, nausea, sensitivity to light, swollen hands, difficulty speaking, vomiting and diarrhea so intense she often wound up dehydrated in the emergency room. “It hit me [that] I had to do something when I was vomiting in the toilet, and my 3-year-old came and pulled my hair back,” she says. “It was no way to live — and not just because of the pain. You go to sleep every night not knowing how you’re going to wake up. You make plans knowing you might have to cancel them.” A headache specialist prescribed several preventive medicines, but each caused side effects for Gudgin, including weight gain and kidney stones. Then, in 2018, Gudgin read about a new type of treatment for frequent migraine sufferers. Her neurologist agreed it was worth a try. After much wrangling with her insurance company — the drug is costly, and she had to prove that two other drugs had failed to help her — she got approval to take it. © Society for Science & the Public 2000–2021.

Keyword: Pain & Touch
Link ID: 27743 - Posted: 03.23.2021

Ariana Remmel A gene-silencing technique based on CRISPR can relieve pain in mice, according to a study1. Although the therapy is still a long way from being used in humans, scientists say it is a promising approach for squelching chronic pain that lasts for months or years. Chronic pain is typically treated with opioids such as morphine, which can lead to addiction. “It’s a real challenge that the best drugs we have to treat pain give us another disease,” says Margarita Calvo, a pain physician at the Pontifical Catholic University of Chile, in Santiago, who wasn’t involved in the research. That’s why the CRISPR-based technique is exciting, she says. Scientists are already evaluating CRISPR therapies that edit a person’s genome as treatments for blood diseases and some forms of hereditary blindness. The new version of CRISPR doesn’t edit genes directly — it stops them from being expressed — and so shouldn’t cause permanent changes, although it’s unclear how long its effects last for. Some studies estimate that a large proportion of the population in Europe and the United States — as high as 50% — experiences chronic pain2,3. This pain can become debilitating over time by limiting a person’s activity and having a negative effect on their mental health. Despite the prevalence of the condition, few options exist for providing long-term relief without side effects. Even so, doctors have been moving away from prescribing opioids owing to addiction risk, and that has pared down their options even further.

Keyword: Pain & Touch; Genes & Behavior
Link ID: 27728 - Posted: 03.13.2021

By Kelly Servick Swallowing an oxycodone pill might quiet nerves and blunt pain, but the drug makes other unwanted visits in the brain—to centers that can drive addiction and suppress breathing. Now, a study in mice shows certain types of pain can be prevented or reversed without apparent side effects by silencing a gene involved in pain signaling. If the approach weathers further testing, it could give chronic pain patients a safer and longer lasting option than opioids. “It’s a beautiful piece of work,” says Rajesh Khanna, a neuroscientist who studies pain mechanisms and potential treatments at the University of Arizona. Despite successes of gene therapy against rare and life-threatening disorders, few teams have explored genetic approaches to treating pain, he says. That’s in part because of reluctance to permanently change the genome to address conditions that, although disabling, aren’t always permanent or fatal. But the new approach doesn’t alter the DNA sequence itself and is theoretically reversible, Khanna notes. “I think this study is going to be our benchmark.” A prick of the finger or a punch in the gut causes pain because nerves branching through our bodies reach into the spinal cord to relay messages to the brain. Those messages can persist even after the initial injury has healed, causing chronic pain. To fire their electrical signals, pain-sensing nerves rely on the flow of ions across protein channels in their membranes. One such channel, called Nav1.7, stands out for the remarkable pain disorders that arise when it malfunctions. People with genetic mutations that make Nav1.7 overactive are prone to attacks of burning pain. Those with mutations that deactivate Nav1.7 feel no pain at all. © 2021 American Association for the Advancement of Science.

Keyword: Pain & Touch
Link ID: 27726 - Posted: 03.11.2021

By Erin Garcia de Jesus A whiff of catnip can make mosquitoes buzz off, and now researchers know why. The active component of catnip (Nepeta cataria) repels insects by triggering a chemical receptor that spurs sensations such as pain or itch, researchers report March 4 in Current Biology. The sensor, dubbed TRPA1, is common in animals — from flatworms to people — and responds to environmental irritants such as cold, heat, wasabi and tear gas. When irritants come into contact with TRPA1, the reaction can make people cough or an insect flee. Catnip’s repellent effect on insects — and its euphoric effect on felines — has been documented for millennia. Studies have shown that catnip may be as effective as the widely used synthetic repellent diethyl-m-toluamide, or DEET (SN: 9/5/01). But it was unknown how the plant repelled insects. So researchers exposed mosquitoes and fruit flies to catnip and monitored the insects’ behavior. Fruit flies were less likely to lay eggs on the side of a petri dish that was treated with catnip or its active component, nepetalactone. Mosquitoes were also less likely to take blood from a human hand coated with catnip. Insects that had been genetically modified to lack TRPA1, however, had no aversion to the plant. That behavior — coupled with experiments in lab-grown cells that show catnip activates TRPA1 — suggests that insect TRPA1 senses catnip as an irritant. Puzzling out how the plant deters insects could help researchers design potent repellents that may be easier to obtain in developing countries hit hard by mosquito-borne diseases. “Oil extracted from the plant or the plant itself could be a great starting point,” says study coauthor Marco Gallio, a neuroscientist at Northwestern University in Evanston, Ill. © Society for Science & the Public 2000–2021

Keyword: Pain & Touch; Evolution
Link ID: 27719 - Posted: 03.06.2021