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

Follow us on Facebook or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 1465

By Gina Kolata The Food and Drug Administration approved a new medication Thursday to treat pain from an injury or surgery. It is expensive, with a list price of $15.50 per pill. But unlike opioid pain medicines, it cannot become addictive. That is because the drug, suzetrigine, made by Vertex Pharmaceuticals and to be sold as Journavx, works only on nerves outside the brain, blocking pain signals. It cannot get into the brain. Researchers say they expect it to be the first of a new generation of more powerful nonaddictive drugs to relieve pain. To test the drug, Vertex, which is based in Boston, conducted two large clinical trials, each with approximately 1,000 patients who had pain from surgery. They were randomly assigned to get a placebo; to get the opioid sold as Vicodin, a widely used combination pain medicine of acetaminophen (Tylenol) and hydrocodone; or to get suzetrigine. In one trial, patients had an abdominoplasty, or tummy tuck. In the other, they had a bunionectomy. Side effects of suzetrigine reported by patients were similar to the ones reported by those taking the placebo. The company also submitted data from a 250-person study that assessed the drug’s safety and tolerability in patients with pain from surgery, trauma or accidents. Suzetrigine eased pain as much as the combination opioid. Both were better than the placebo at relieving pain. Suzetrigine’s price, though, is much higher than that of acetaminophen plus hydrocodone. Patients are expected to take two pills a day, for a total cost of $31 a day. The older drug, said Dr. John D. Loeser, an emeritus pain expert at the University of Washington, is “dirt cheap” at pennies per pill. But suzetrigine does not have opioids’ unpleasant side effects like nausea and drowsiness, and it is nonaddictive. © 2025 The New York Times Company

Keyword: Pain & Touch; Drug Abuse
Link ID: 29653 - Posted: 02.01.2025

By Laura Sanders Scratching an itch can bring a contradictory wave of pleasure and misery. A mouse study on scratching, reported in the Jan. 31 Science, fleshes out this head-scratching paradox and could point out ways to better curb pernicious itch in people. First, the bad news: Scratching itchy ears led to a round of inflammation. Itch-provoking substances, such as the oil in poison ivy, activate mast cells, immune sentries that release itch signals and kick off inflammation. But so does scratching, the new study suggests. “The act of scratching is actually triggering the inflammation by synergizing with mast cells to make them more effective,” says study coauthor Daniel Kaplan, a dermatologist and immunologist at the University of Pittsburgh. Mice that couldn’t scratch their itchy ears, thanks to tiny cones of shame, had less inflammation than mice that scratched. The same was true for mice that didn’t sense the itch, the researchers report. Kaplan relates the results to a mosquito bite. “Most of the time, it’ll go away in five, 10 minutes,” he says. “But if you start scratching it, now, you get a really big, inflamed, itchy lesion on your skin that can stick around for several days. It’s a lot worse. And I think this could be a mechanism that explains why.” Now onto the good news: Scratching lessened the amount of potentially harmful bacteria (Staphylococcus aureus) on mice’s skin, perhaps through the heightened immune reaction it prompts. “That was a clear demonstration that scratching can have a benefit in the context of an acute infection,” Kaplan says. But too much scratching can rip the skin and usher in more bacteria, he cautions. “In that sense, scratching, through a different mechanism, also makes things even worse.” © Society for Science & the Public 2000–2025.

Keyword: Pain & Touch
Link ID: 29648 - Posted: 02.01.2025

By Jennifer Kahn Here’s a strange story: One day two summers ago, I woke up because my arms — both of them — hurt. Not the way they do when you’ve slept in a funny position, but as if the tendons in my forearms and hands were moving through mud. What felt like sharp electric shocks kept sparking in my fingers and sometimes up the inside of my biceps and across my chest. Holding anything was excruciating: a cup, a toothbrush, my phone. Even doing nothing was miserable. It hurt when I sat with my hands in my lap, when I stood, when I lay flat on the bed or on my side. The slightest pressure — a bedsheet, a watch band, a bra strap — was intolerable. It was August, and every doctor seemed to be away on vacation. The ones I did manage to see were politely stumped. It wasn’t carpal tunnel, tennis elbow or any other injury they could identify. I did nothing unusual the day before: an hour of work on my laptop, followed by a visit with a friend. We sat in her backyard and talked. For the first few weeks, I could barely sleep. Over the following months, I lost weight — almost a pound a week. I couldn’t drive, or cook, or use my laptop for work, or even hold a book or a pen. I would have been bored, except the pain was so tiring that I could barely function. I spent the days shuffling around the house listening to audiobooks and doing voice-to-text searches for “nerve pain arms” with my phone flat on the table, then carefully, painfully, scrolling through the results. I think we’re past the point where I have to explain that chronic pain is not the result of imbalanced humors or a wandering uterus or possession by demons. But for more modern skeptics, this is where I should add that chronic pain also isn’t just “all in your head” or “not really that bad” — or any of the other ways in which people who suffer from it are still regularly gaslit and dismissed. Personally, I never had to contend with not being believed, almost certainly because I’m an otherwise healthy, reasonably well-off white woman with a clean medical history and no significant record of anxiety or depression. Instead, I was taken seriously. A whole gamut of tests was run. My wrists were X-rayed. I had an M.R.I. on my cervical spine. Each new doctor ordered new blood tests: some for vitamin deficiencies, others for autoimmune diseases like rheumatoid arthritis. © 2025 The New York Times Company

Keyword: Pain & Touch
Link ID: 29628 - Posted: 01.15.2025

By Lisa Sanders, M.D. The 62-year-old woman shifted in her seat. The flight to Honolulu was full, the mood a little giddy. The unbroken ocean and sky filled the window. She and her daughter were four hours into the trip from Los Angeles to the wedding of a close family friend; it was going to be a great week. Then, she caught herself scratching lightly at a place on her forearm, just below the crease of her elbow. She lifted her arm to look at the spot. Nothing there. Immediately she was filled with dread. She reached over her head to touch the call button. She needed ice, lots of ice, and she needed it right away. The mild itch had already exploded into spasms of an intense sensation — it seemed wrong to call it an itch; surely there was a better word for it. The fierce intensity of the feeling shocked her. It was a feeling that insisted she scratch. Except scratching never helped. And she had the scars to prove it. She had suffered episodes of itching like this a few times in the past couple of years, though never quite as bad as it was on this flight. Her doctor back home had no idea what caused the crazy itch or what more she might do about it. These attacks came out of nowhere but immediately brought life to a standstill as she tried to ease the unbearable sensation. A bout could last for hours and almost always ended with her arm a bloody mess. When her daughter first saw her mother raking her nails over the invisible injury and the distress she felt fighting this unwinnable battle, she had offered her a Valium. And it helped. The itch was still there but the intensity somehow lessened. On the flight, the woman retrieved the pills she now carried with her all the time. The little bags of ice brought by the flight attendant melted slowly, numbing the hand that pressed them against her arm and easing the itch. She knew from experience that as soon as the ice was removed, the itch would roar back. The attendant brought an ice bucket. But within the hour, she needed more ice. More Valium. She was drenched with the condensation. Her clothes were dotted with blood. She didn’t care. She just had to get through it. © 2024 The New York Times Company

Keyword: Pain & Touch
Link ID: 29583 - Posted: 12.04.2024

Heather Margonari The opioid crisis remains a significant public health challenge in the United States. In 2022, over 2.5 million American adults had an opioid use disorder, and opioids accounted for nearly 76% of overdose deaths. Some patients are fearful of using opioids after surgery due to concerns about dependence and potential side effects, even when appropriately prescribed by a doctor to manage pain. Surgery is often the first time patients receive an opioid prescription, and their widespread use raises concerns about patients becoming long-term users. Leftover pills from a patient’s prescriptions may also be misused. Researchers like us are working to develop a personalized and comprehensive surgical experience that doesn’t use opioids. Our approach to opioid-free surgery addresses both physical and emotional well-being through effective anesthesia and complementary pain-management techniques. What is opioid-free anesthesia? Clinicians have used morphine and other opioids to manage pain for thousands of years. These drugs remain integral to anesthesia. Help us raise up the voices of experts. Most surgical procedures use a strategy called balanced anesthesia, which combines drugs that induce sleep and relax muscles with opioids to control pain. However, using opioids in anesthesia can lead to unwanted side effects, such as serious cardiac and respiratory problems, nausea and vomiting, and digestive issues. Concerns over these adverse effects and the opioid crisis have fueled the development of opioid-free anesthesia. This approach uses non-opioid drugs to relieve pain before, during and after surgery while minimizing the risk of side effects and dependency. Studies have shown that opioid-free anesthesia can provide similar levels of pain relief to traditional methods using opioids. Copyright © 2010–2024, The Conversation US, Inc.

Keyword: Pain & Touch
Link ID: 29575 - Posted: 11.27.2024

Terry Gross We've all had bug bites, or dry scalp, or a sunburn that causes itch. But what if you felt itchy all the time — and there was no relief? Journalist Annie Lowrey suffers from primary biliary cholangitis (PBC), a degenerative liver disease in which the body mistakenly attacks cells lining the bile ducts, causing them to inflame. The result is a severe itch that doesn't respond to antihistamines or steroids. "It feels like being trapped inside your own body," Lowrey says of the disease. "I always describe it as being like a car alarm. Like, you can't stop thinking about it." PBC is impacts approximately 80,000 people in the U.S., the majority of whom are women. At its worst, Lowrey says, the itch caused her to dig holes in her skin and scalp. She's even fantasized about having limbs amputated to escape the itch. Lowrey writes about living with PBC in the Atlantic article, "Why People Itch and How to Stop It." She says a big part of her struggle is coming to terms with the fact that she may never feel fully at ease in her skin. "I talked to two folks who are a lot older than I was, just about like, how do you deal with it? How do you deal with the fact that you might itch and never stop itching? … And both of them were kind of like, 'You put up with it, stop worrying about it and get on with your life,'" she says. "I think I was mentally trapped ... and sometimes it's like, OK, ... go do something else. Life continues on. You have a body. It's OK." © 2024 npr

Keyword: Pain & Touch
Link ID: 29556 - Posted: 11.13.2024

By Miryam Naddaf When a dog shakes water off its fur, the action is not just a random flurry of movements — nor a deliberate effort to drench anyone standing nearby. This instinctive reflex is shared by many furry mammals including mice, cats, squirrels, lions, tigers and bears. The move helps animals to remove water, insects or other irritants from hard-to-reach places. But underlying the shakes is a complex — and previously mysterious — neurological mechanism. Now, researchers have identified the neural circuit that triggers characteristic ‘wet dog’ shaking behaviour in mice — which involves a specific class of touch receptors, and neurons that connect the spinal cord to the brain. Their findings were published in Science on 7 November1. “The touch system is so complex and rich that [it] can distinguish a water droplet from a crawling insect from the gentle touch of a loved one,” says Kara Marshall, a neuroscientist at Baylor College of Medicine in Houston, Texas. “It’s really remarkable to be able to link a very specific subset of touch receptors to this familiar and understandable behaviour.” The hairy skin of mammals is packed with more than 12 types of sensory neuron, each with a unique function to detect and interpret various sensations. Study co-author Dawei Zhang, a neuroscientist then at Harvard Medical School in Boston, Massachusetts, and his colleagues focused on a type of ultra-sensitive touch detecting receptors called C-fibre low-threshold mechanoreceptors (C-LTMRs), which wrap around hair follicles. In humans, these receptors are associated with pleasant touch sensations, such as a soft hug or a soothing stroke. But in mice and other animals, they serve a protective role: alerting them to the presence of something on their skin, whether it’s water, dirt or a parasite. When these stimuli cause hairs on the skin to bend it activates the C-LTMRs, says Marshall, “extending the sensibility of the skin beyond just the surface”. © 2024 Springer Nature Limited

Keyword: Pain & Touch; Evolution
Link ID: 29551 - Posted: 11.09.2024

By Amber Dance For Cherise Irons, chocolate, red wine and aged cheeses are dangerous. So are certain sounds, perfumes and other strong scents, cold weather and thunderstorms. Stress and lack of sleep, too. She suspects all of these things can trigger her migraine attacks, which manifest in a variety of ways: pounding pain in the back of her head, exquisite sensitivity to the slightest sound, even blackouts and partial paralysis. Irons, 48, of Coral Springs, Florida, once worked as a school assistant principal. Now, she’s on disability due to her migraine. Irons has tried so many migraine medications she’s lost count — but none has helped for long. Even a few of the much-touted new drugs that have quelled episodes for many people with migraine have failed for Irons. Though not all are as impaired as Irons, migraine is a surprisingly common problem, affecting 14 percent to 15 percent of people. Yet scientists and physicians remain largely in the dark about how triggers like Irons’s lead to attacks. They have made progress nonetheless: The latest drugs, inhibitors of a body signaling molecule called CGRP, have been a blessing for many. For others, not so much. And it’s not clear why. The complexity of migraine probably has something to do with it. “It’s a very diverse condition,” says Debbie Hay, a pharmacologist at the University of Otago in Dunedin, New Zealand. “There’s still huge debate as to what the causes are, what the consequences are.”

Keyword: Pain & Touch
Link ID: 29519 - Posted: 10.16.2024

By Laura Sanders CHICAGO — Big news for fighting sisters: Scientists have found the sensors that signal the painful zing of a hair pull. And this pain message can rip along a nerve fiber at about 100 miles an hour, placing it among the fastest known pain signals. The discovery, presented October 8 at the annual meeting of the Society for Neuroscience, offers insight into the diverse ways our bodies sense and respond to different sorts of pain. Pain can come from many catastrophes — cuts, jabs, pinches, cramps, bites, slaps, stubbing a toe in the dark. And while our bodies can generally tell these insults apart thanks to a variety of biological pathways, they all hurt. “It’s not surprising that we have figured out many, many ways to make [pain] happen,” says neuroscientist Gregory Dussor of the University of Texas at Dallas. “Because when it doesn’t, we don’t live.” Laboratory tests showed a hair pull to be about 10 times as painful as a pinprick, neuroscientist Emma Kindström of Linköping University in Sweden and colleagues found. The pain of the pull relies on a large, propeller-shaped protein called PIEZO2, further tests showed. That sensor was known to detect mechanical forces, including light touches, but wasn’t thought to detect acute pain signals. People who lack this protein don’t feel hair-pull pain. A hair-pull signal moves along nerve fibers much faster than other sorts of pain, Kindström says, traveling in bursts along an insulated conduit called an Aβ nerve fiber. Other kinds of pain signals, such as a burn from a hot stove, travel more slowly along different kinds of fibers. © Society for Science & the Public 2000–2024.

Keyword: Pain & Touch
Link ID: 29512 - Posted: 10.12.2024

By Cassandra Willyard Megan Hodge’s first bout of intense pain arrived when she was in her mid-20s. Hodge and her husband were getting ready to visit family for Thanksgiving. Though Hodge had been dealing with a variety of chronic health issues, her workout had gone well that morning and she finally felt like she was getting a handle on her health. Hodge began packing. As she reached into her closet to grab a sweater, her back gave out. The pain was excruciating, so intense that she felt light-headed and thought she might vomit. As the years passed, Hodge had more frequent and more severe bouts of back pain. Any small movement could be a trigger — grabbing a towel from the linen closet, picking up a toy off the floor, sneezing. In 2021, Hodge experienced a particularly bad flare-up. None of the strategies she had previously used to help her manage seemed to be working. She was afraid to make any movement. She felt hopeless. “I just could not regain footing, metaphorically and physically,” she says. “I truly felt frozen in my chronic pain and chronic health journey.” Hodge is far from alone. In the United States, chronic pain affects tens of millions of people — about 1 in 5 adults and nearly 1 in 3 people ages 65 and older. “The amount of suffering from arthritis and aging that I’ve seen in my pain clinic, it’s overwhelming to me as a pain doctor,” says Antje Barreveld, an anesthesiologist at Mass General Brigham’s Newton-Wellesley Hospital in Massachusetts. What’s more, the mainstay therapy for severe acute and chronic pain — prescription opioids — has helped fuel an epidemic that kills tens of thousands of people each year. “We have to have some better alternatives,” she says. So researchers have doubled down in their quest to find new pain treatments that aren’t as addictive as opioids. “The pain field has really made very rapid and tremendous progress in the last decade,” says D.P. Mohapatra, a former pain scientist who now oversees research at the National Institute of Neurological Disorders and Stroke in Bethesda, Md. © Society for Science & the Public 2000–2024.

Keyword: Pain & Touch; Drug Abuse
Link ID: 29470 - Posted: 09.07.2024

By Marla Broadfoot When doctors ask Sara Gehrig to describe her pain, she often says it is indescribable. Stabbing, burning, aching—those words frequently fail to depict sensations that have persisted for so long they are now a part of her, like her bones and skin. “My pain is like an extra limb that comes along with me every day.” Gehrig, a former yoga instructor and personal trainer who lives in Wisconsin, is 44 years old. At the age of 17 she discovered she had spinal stenosis, a narrowing of the spinal cord that puts pressure on the nerves there. She experienced bursts of excruciating pain in her back and buttocks and running down her legs. That pain has spread over the years, despite attempts to fend it off with physical therapy, anti-inflammatory injections and multiple surgeries. Over-the-counter medications such as ibuprofen (Advil) provide little relief. And she is allergic to the most potent painkillers—prescription opioids—which can induce violent vomiting. Today her agony typically hovers at a 7 out of 10 on the standard numerical scale used to rate pain, where 0 is no pain and 10 is the most severe imaginable. Occasionally her pain flares to a 9 or 10. At one point, before her doctor convinced her to take antidepressants, Gehrig struggled with thoughts of suicide. “For many with chronic pain, it’s always in their back pocket,” she says. “It’s not that we want to die. We want the pain to go away.” Gehrig says she would be willing to try another type of painkiller, but only if she knew it was safe. She keeps up with the latest research, so she was interested to hear earlier this year that Vertex Pharmaceuticals was testing a new drug that works differently than opioids and other pain medications. That drug, a pill called VX-548, blocks pain signals before they can reach the brain. It gums up sodium channels in peripheral nerve cells, and obstructed channels make it hard for those cells to transmit pain sensations. Because the drug acts only on the peripheral nerves, it does not carry the potential for addiction associated with opioids—oxycodone (OxyContin) and similar drugs exert their effects on the brain and spinal cord and thus can trigger the brain’s reward centers and an addiction cycle.

Keyword: Pain & Touch; Drug Abuse
Link ID: 29445 - Posted: 08.21.2024

By Paula Span Mary Peart, 67, a retired nurse in Manchester-by-the-Sea, Mass., began taking gabapentin a year and a half ago to reduce the pain and fatigue of fibromyalgia. The drug helps her climb stairs, walk her dog and take art lessons, she said. With it, “I have a life,” she said. “If I forget to take a dose, my pain comes right back.” Jane Dausch has a neurological condition called transverse myelitis and uses gabapentin as needed when her legs and feet ache. “It seems to be effective at calming down nerve pain,” said Ms. Dausch, 67, a retired physical therapist in North Kingstown, R.I. Amy Thomas, who owns three bookstores in the San Francisco Bay Area, takes gabapentin for rheumatoid arthritis. Along with yoga and physical therapy, “it’s probably contributing to it being easier for me to move around,” Ms. Thomas, 67, said. All three are taking the non-opioid pain drug for off-label uses. The only conditions for which gabapentin has been approved for adult use by the Food and Drug Administration are epileptic seizures, in 1993, and postherpetic neuralgia, the nerve pain that can linger after a bout of shingles, in 2002. But that has not stopped patients and health care providers from turning to gabapentin (whose brand names include Neurontin) for a startling array of other conditions, including sciatica, neuropathy from diabetes, lower back pain and post-surgery pain. Also: Agitation from dementia. Insomnia. Migraines. Itching. Bipolar disorder. Alcohol dependence. Evidence of effectiveness for these conditions is all over the map. The drug appears to provide relief for some patients with diabetic neuropathy but not with some other kinds of neuropathic pain. Several small studies indicate that gabapentin can reduce the itching associated with kidney failure. But the data for its effectiveness against low back pain or a number of psychiatric disorders are limited and show no meaningful impact. “It’s crazy how many indications it’s used for,” said Dr. Michael Steinman, a geriatrician at the University of California, San Francisco, and a co-director of the U.S. Deprescribing Research Network. “It’s become a we-don’t-know-what-else-to-do drug.” © 2024 The New York Times Company

Keyword: Pain & Touch; Drug Abuse
Link ID: 29438 - Posted: 08.19.2024

By Elena Kazamia It was a profound moment of connection. Carlos Casas could feel the elephant probing him, touching him with sound. The grunts emanating from the large male were of a frequency too low to hear, but Casas felt an agitation on his skin and deep inside his chest. “I was being scanned,” he says. At the time of the encounter, Casas was filming a project in Sri Lanka, and was holding a camera. But his interactions with the elephant gave the Catalonian filmmaker and installation artist an idea: What if instead of relying on images alone, he could use sound to create a physical connection between an audience of people and the subjects that fascinate him most, the animals with which we share life on this planet? Bestiari, his audio-visual project, now on display inside a former shipping warehouse at the Venice Biennale, weaves an immersive landscape for visitors. (You can explore some of the project, which was curated by Filipa Ramos, at the Instagram page for the installation.) Audio of the sounds the animals make is accompanied by video collected from remote camera traps set across national parks of Catalonia and Kenya, together with abstract film meant to capture the world as the animals see it, based on a combination of scientific research and artistic license. A series of texts serve as field guides to each animal featured in the installation. Entering the dark warehouse where Bestiari is housed, you are invited to lie on the floor, as if to fall asleep, before communing with seven different species: bees, donkeys, parakeets, snakes, bats, dolphins, and elephants. Each of the chosen species is represented by a speaker, customized to deliver the desired acoustics. Casas calls the speakers, “Trojan horses of meaning and communication.” The pitches and volumes were curated to be authentic to the original animal but perceptible by humans. For example, the echolocation chirps of bats have been slowed down to showcase the tonal progression of the sound. © 2024 NautilusNext Inc.,

Keyword: Hearing; Evolution
Link ID: 29421 - Posted: 08.03.2024

By Hannah Richter Humans aren’t the only animals that lose hearing as they grow older. Almost every mammal studied struggles to pick up some sounds as they age. Some veterinarians even fit dogs for tiny hearing aids. But at least one species of bat appears to be an exception. Reporting this month on the preprint server bioRxiv, scientists have discovered that big brown bats (Eptesicus fuscus) don’t hear any worse as they grow older, possibly because their ability to echolocate is so critical to their survival. “Hearing is kind of their superpower,” says Mirjam Knörnschild, a behavioral ecologist at the Museum of Natural History Berlin who was not involved with the work. The research, she and others say, could lead to new ways to understand—and possibly treat—hearing loss in humans. Bats actually have two superpowers. Not only can most of them echolocate—bouncing sound off objects to hunt and navigate—they also tend to be remarkably long-lived for their size. Most small mammals are short-lived, but compared with mice of similar stature, the big brown bat lives up to five times as long, sometimes topping out at 19 years old. That makes the species a fascinating target for studies of aging, says Grace Capshaw, a postdoctoral researcher at Johns Hopkins University. The bat auditory system is fundamentally the same as that of every other mammal, she says, so “bats can be a really powerful model for comparing how hearing works.” To test whether big brown bats lose their hearing over time, Capshaw and colleagues divided 23 wild-caught bats into groups of young and old, making 6 years—the mean age of the species—the dividing line. The researchers determined the bats’ ages using a precise genetic method that involves comparing each animal’s DNA with the DNA of bats with known ages. They then sedated the animals to conduct a hearing examination similar to those done on human infants.

Keyword: Hearing
Link ID: 29411 - Posted: 07.31.2024

By Miryam Naddaf About one-third of people who suffer from migraines experience a phenomenon known as aura before the headache.Credit: Tunatura/Getty For one billion people worldwide, the symptoms can be debilitating: throbbing head pain, nausea, blurred vision and fatigue that can last for days. But how brain activity triggers these severest of headaches — migraines — has long puzzled scientists. A study1 in mice, published in Science on 4 July, now offers clues about the neurological events that spark migraines. It suggests that a brief brain ‘blackout’ — when neuronal activity shuts down — temporarily changes the content of the cerebrospinal fluid, the clear liquid that surrounds the brain and spinal cord. This altered fluid, researchers suggest, travels through a previously unknown gap in anatomy to nerves in the skull where it activates pain and inflammatory receptors, causing headaches. “This work is a shift in how we think the headaches originate,” says Gregory Dussor, a neuroscientist at the University of Texas at Dallas in Richardson. “A headache might just be a general warning sign for lots of things happening inside the brain that aren’t normal.” “Migraine is actually protective in that way. The pain is protective because it’s telling the person to rest and recover and sleep,” says study co-author Maiken Nedergaard, a neuroscientist at the University of Copenhagen. The brain itself has no pain receptors; the sensation of headaches comes from areas outside the brain that are in the peripheral nervous system. But how the brain, which is not directly linked to the peripheral nervous system, triggers nerves to cause headaches is poorly understood, making them difficult to treat. © 2024 Springer Nature Limited

Keyword: Pain & Touch
Link ID: 29388 - Posted: 07.11.2024

By Rodrigo Pérez Ortega It starts with blind spots, flashing lights, and blurry vision—a warning of what’s to come. About an hour later, the dreadful headache kicks in. This pairing, a shining visual experience called an aura and then a headache, happens in about one-third of people who live with migraine. But researchers haven’t been able to figure out exactly how the two are linked at the molecular level. Now, a new study in mice, published today in Science, establishes a direct mechanism: molecules traveling in the fluid that bathes the brain. The finding could lead to new targets for much-needed migraine treatments. “It’s exciting,” says Rami Burstein, a translational neuroscientist at Harvard Medical School who was not involved in the new study. “It takes a very large step into understanding how something that happened in the brain can alter sensation or perception,” he says. It may also explain why the pain of migraine is experienced only in the head, he adds. Migraine, a debilitating neurological disorder, affects about 148 million people worldwide. Recently developed medications can help reduce headaches but are not effective for everyone. Although exact causes remain elusive, research has shown migraines most likely start with a pathological burst of neural activity. During an aura before a migraine, researchers have observed a seizurelike phenomenon called cortical spreading depression (CSD), in which a wave of abnormal neural firing slowly travels throughout the brain’s outer layer, or cortex. But because the brain itself contains no pain-sensing neurons, signals from the brain would have to somehow reach the peripheral nervous system—the nerves that communicate between the body parts and the brain—to cause a headache. In particular, they’d have to get to the two lumps of neurons below the brain called the trigeminal ganglia, which innervate the two sides of our face and head. Scientists knew that pain fibers from the trigeminal ganglion were nested in the meninges—the thin, delicate membranes that envelop and protect the brain.

Keyword: Pain & Touch
Link ID: 29380 - Posted: 07.06.2024

By Claire Yuan Men and women experience pain differently, and until now, scientists didn’t know why. New research says it may be in part due to differences in male and female nerve cells. Pain-sensing nerve cells from male and female animal tissues responded differently to the same sensitizing substances, researchers report June 3 in Brain. The results suggest that at the cellular level, pain is produced differently between the sexes. The results might allow researchers “to come up with drugs that would be specific to treat female patients or male patients,” says Katherine Martucci, a neuroscientist who studies chronic pain at Duke University School of Medicine and was not involved in the study. “There’s no debate about it. They’re seeing these differences in the cells.” Some types of chronic and acute pain appear more often in one sex, but it’s unclear why. For instance, about 50 million adults in the United States suffer from chronic pain conditions, many of which are more common in women (SN: 5/22/23). Similar disparities exist for acute conditions. Such differences prompted pain researcher Frank Porreca of the University of Arizona Health Sciences in Tucson and colleagues to study nerve cells called nociceptors, which can act like alarm sensors for the body. The cells’ pain sensors, found in skin, organs and elsewhere in the body, can detect potentially dangerous stimuli and send signals to the brain, which then interprets the information as pain. In some cases, the nerve cells can become more sensitive to outside stimulation, registering even gentle sensations — like a shirt rubbing sunburned skin — as pain. © Society for Science & the Public 2000–2024.

Keyword: Pain & Touch; Sexual Behavior
Link ID: 29366 - Posted: 06.24.2024

By Sara Reardon Specific nerve cells on the penis and clitoris detect vibrations and then become activated, causing sexual behaviours such as erections, a study in mice has revealed1. The findings could lead to new treatments for conditions such as erectile dysfunction, or for restoring sexual function in people with lower-body paralysis. Krause corpuscles — nerve endings in tightly wrapped balls located just under the skin — were first discovered in human genitals more than 150 years ago. The structures are similar to touch-activated corpuscles found on people’s fingers and hands, which respond to vibrations as the skin moves across a textured surface. But there is little research into how the genital corpuscles work and how they are involved in sex, probably because the topic is sometimes considered taboo. “It’s been hard to get people to work on this because some people have a hard time talking about it,” says David Ginty, a sensory neurobiologist at Harvard Medical School in Boston, Massachusetts, who led the team that conducted the latest research. “But I don’t, because the biology is so interesting.” Ginty and other sensory biologists have long wanted to study these mysterious neuron balls. But activating and tracking specific neurons was nearly impossible until advanced molecular techniques emerged in the past 20 years. In a 19 June paper in Nature1, Ginty and his collaborators activated the Krause corpuscles in both male and female mice using various mechanical and electrical stimuli. The neurons fired in response to low-frequency vibrations in the range of 40–80 hertz. Ginty notes that these frequencies are generally used in many sex toys; humans, it seems, realized that this was the best way to stimulate Krause corpuscles before any official experiments were published. © 2024 Springer Nature Limited

Keyword: Sexual Behavior; Pain & Touch
Link ID: 29365 - Posted: 06.24.2024

By Emily Underwood You’re driving somewhere, eyes on the road, when you start to feel a tingling sensation in your lower abdomen. That extra-large Coke you drank an hour ago has made its way through your kidneys into your bladder. “Time to pull over,” you think, scanning for an exit ramp. To most people, pulling into a highway rest stop is a profoundly mundane experience. But not to neuroscientist Rita Valentino, who has studied how the brain senses, interprets and acts on the bladder’s signals. She’s fascinated by the brain’s ability to take in sensations from the bladder, combine them with signals from outside of the body, like the sights and sounds of the road, then use that information to act — in this scenario, to find a safe, socially appropriate place to pee. “To me, it’s really an example of one of the beautiful things that the brain does,” she says. Scientists used to think that our bladders were ruled by a relatively straightforward reflex — an “on-off” switch between storing urine and letting it go. “Now we realize it’s much more complex than that,” says Valentino, now director of the division of neuroscience and behavior at the National Institute of Drug Abuse. An intricate network of brain regions that contribute to functions like decision-making, social interactions and awareness of our body’s internal state, also called interoception, participates in making the call. In addition to being mind-bogglingly complex, the system is also delicate. Scientists estimate, for example, that more than 1 in 10 adults have overactive bladder syndrome — a common constellation of symptoms that includes urinary urgency (the sensation of needing to pee even when the bladder isn’t full), nocturia (the need for frequent nightly bathroom visits) and incontinence. Although existing treatments can improve symptoms for some, they don’t work for many people, says Martin Michel, a pharmacologist at Johannes Gutenberg University in Mainz, Germany, who researches therapies for bladder disorders. Developing better drugs has proven so challenging that all major pharmaceutical companies have abandoned the effort, he adds.

Keyword: Miscellaneous
Link ID: 29337 - Posted: 06.02.2024

By Ingrid Wickelgren Ishmail Abdus-Saboor has been fascinated by the variety of the natural world since he was a boy growing up in Philadelphia. The nature walks he took under the tutelage of his third grade teacher, Mr. Moore, entranced him. “We got to interact and engage with wildlife and see animals in their native environment,” he recalled. Abdus-Saboor also brought a menagerie of creatures — cats, dogs, lizards, snakes and turtles — into his three-story home, and saved up his allowance to buy a magazine that taught him about turtles. When adults asked him what he wanted to be when he grew up, “I said I wanted to become a scientist,” he said. “I always raised eyebrows.” Abdus-Saboor did not stray from that goal. Today, he is an associate professor of biological sciences at the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia University, where he studies how the brain determines whether a touch to the skin is painful or pleasurable. “Although this question is fundamental to the human experience, it remains puzzling to explain with satisfying molecular detail,” he said. Because the skin is our largest sensory organ and a major conduit to our environment, it may hold clues for treating conditions from chronic pain to depression. To find those clues, Abdus-Saboor probes the nervous system at every juncture along the skin-to-brain axis. He does not focus on skin alone or home in on only the brain as many others do. “We merge these two worlds,” he said. That approach, he added, requires mastering two sets of techniques, reading two sets of literature and attending two sets of scientific meetings. “It gives us a unique leg up,” he said. It has led to a landmark paper published last year in Cell that laid out the entire neural circuit for pleasurable touch. © 2024 Simons Foundation.

Keyword: Pain & Touch; Emotions
Link ID: 29262 - Posted: 04.20.2024