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

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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

Linda Geddes Four scientists who discovered a key mechanism that causes migraines, paving the way for new preventive treatments, have won the largest prize for neuroscience in the world, sharing £1.1m. The Lundbeck Foundation in Denmark announced on Thursday that the British researcher Peter Goadsby, Michael Moskowitz of the US, Lars Edvinsson of Sweden and Jes Olesen of Denmark had won the Brain prize. Speaking at a press briefing ahead of the announcement, Goadsby, a professor of neurology at King’s College London, said: “I’m excited that migraine research is getting this award and that migraine – this disabling problem that is a brain disorder – is being recognised in an appropriate way.” Formally known as the Grete Lundbeck European brain research prize, the annual award recognises highly original and influential advances in any area of brain research. The award ceremony will take place in Copenhagen on 25 October, where the prize will be presented by Crown Prince Frederik of Denmark. The prize-winning research revolves around unpicking the neural basis of migraine, a crippling neurological condition characterised by episodes of throbbing head pain, as well as nausea, vomiting, dizziness, extreme sensitivity to sound, light, touch and smell. It affects about one in seven people globally and is about three times more common in women than men. In the UK, it is estimated that migraines result in the loss of 25m work or school days each year at an economic cost of £2.3bn. © 2021 Guardian News & Media Limited

Keyword: Pain & Touch
Link ID: 27717 - Posted: 03.06.2021

By Cara Giaimo Platypuses do it. Opossums do it. Even three species of North American flying squirrel do it. Tasmanian devils, echidnas and wombats may also do it, although the evidence is not quite so robust. And, breaking news: Two species of rabbit-size rodents called springhares do it. That is, they glow under black light, that perplexing quirk of certain mammals that is baffling biologists and delighting animal lovers all over the world. Springhares, which hop around the savannas of southern and eastern Africa, weren’t on anyone’s fluorescence bingo card. Like the other glowing mammals, they are nocturnal. But unlike the other creatures, they are Old World placental mammals, an evolutionary group not previously represented. Their glow, a unique pinkish-orange the authors call “funky and vivid,” forms surprisingly variable patterns, generally concentrated on the head, legs, rear and tail. Fluorescence is a material property rather than a biological one. Certain pigments can absorb ultraviolet light and re-emit it as a vibrant, visible color. These pigments have been found in amphibians and some birds, and are added to things like white T-shirts and party supplies. But mammals, it seems, don’t tend to have these pigments. A group of researchers, many associated with Northland College in Ashland, Wis., has been chasing down exceptions for the past few years — ever since one member, the biologist Jonathan Martin, happened to wave a UV flashlight at a flying squirrel in his backyard. It glowed eraser pink. © 2021 The New York Times Company

Keyword: Vision; Evolution
Link ID: 27697 - Posted: 02.19.2021

By Isobel Whitcomb It began with a pulled muscle. Each day after school, as the sun sank dusky purple over the hills of my hometown, I’d run with my track teammates. Even on our easy days, I’d bound ahead, leaving them behind. It wasn’t that I thought myself better than them—it’s that when I ran fast, and focused on nothing but the cold air burning my lungs and my feet pounding, my normally anxious thoughts turned to white noise. Until, one day, something popped in my leg. I stopped. I limped a little, and then tried running again: sharp, hot pain radiated down my thigh. Panic flooded me, as I imagined weeks without running: weeks without a predictable break from my own thoughts, weeks immersed in adolescent loneliness. I was 14. Pain was about to define a decade of my life. Advertisement First, I took a break from the sport—five months of stretching, icing, and waiting for the leg to heal. I returned to running, but soon after, I developed a throbbing pain in my back. The cycle repeated. Less than a year later, the pain showed up again, this time in my foot. My focus on healing my body became singular: I tried physical therapy and massage and acupuncture. I researched conditions that could lead to repeat injury. Maybe I had a rare soft-tissue disorder, I thought, or maybe early-onset rheumatoid arthritis. I let an osteopath stick a giant needle into my spinal ligaments, and inject me with sugar water, which is just as painful as it sounds. After a chiropractor recommended an anti-inflammatory diet, I subsisted on only meat and vegetables. I’d get a few good months—a joyful summer, a successful cross-country season. Then the pain would return again. As I prepared to leave home for college, my knees and ankles throbbed. For several months, my hip hurt so badly I dreaded even walking to the dining hall. Then, while scrambling to finish my senior thesis, neck spasms prevented me from leaving my bed for days. When I saw doctors, I hoped that they would discover something terribly wrong. They never did. “Have you tried psychotherapy?” one asked me. I had. I’d been in therapy for years. © 2021 The Slate Group LLC.

Keyword: Pain & Touch; Attention
Link ID: 27693 - Posted: 02.15.2021

By Mitch Leslie Spitting cobras protect themselves by shooting jets of venom into the eyes of their attackers. A new study suggests that over the course of several million years, all three groups of spitters independently tailored the chemistry of their toxins in the same way to cause pain to a would-be predator. The work provides a novel example of convergent evolution that “deepens our understanding of this unique system” for delivering venom, says Timothy Jackson, an evolutionary toxinologist at the University of Melbourne. Like other cobras, spitting cobras will bite attackers in self-defense. Spitting is their signature move, however, and the snakes are crack shots. They can direct a stream of venom into an attacker’s face from more than 2 meters away, aiming for the eyes. The behavior is such a formidable defense that it evolved independently three times: in Asian cobras, African cobras, and a cobra cousin called the rinkhals (Hemachatus haemachatus) that lives in southern Africa. Scientists previously found the venom of some other snakes evolved to better subdue their prey. By analyzing the venoms of 17 spitting and nonspitting species—and measuring their effects—venom biologist Nicholas Casewell of the Liverpool School of Tropical Medicine and colleagues tested whether the makeup of spitting cobra venom had also changed over time to become a more effective defense. © 2021 American Association for the Advancement of Science.

Keyword: Pain & Touch; Evolution
Link ID: 27659 - Posted: 01.23.2021

By Jonathan Lambert One Volta’s electric eel — able to subdue small fish with an 860-volt jolt — is scary enough. Now imagine over 100 eels swirling about, unleashing coordinated electric attacks. Such a sight was assumed to be only the stuff of nightmares, at least for prey. Researchers have long thought that these eels, a type of knifefish, are solitary, nocturnal hunters that use their electric sense to find smaller fish as they sleep (SN: 12/4/14). But in a remote region of the Amazon, groups of over 100 electric eels (Electrophorus voltai) hunt together, corralling thousands of smaller fish together to concentrate, shock and devour the prey, researchers report January 14 in Ecology and Evolution. “This is hugely unexpected,” says Raimundo Nonato Mendes-Júnior, a biologist at the Chico Mendes Institute for Biodiversity Conservation in Brasilia, Brazil who wasn’t involved in the study. “It goes to show how very, very little we know about how electric eels behave in the wild.” Group hunting is quite rare in fishes, says Carlos David de Santana, an evolutionary biologist at the Smithsonian’s National Museum of Natural History in Washington, D.C. “I’d never even seen more than 12 electric eels together in the field,” he says. That’s why he was stunned in 2012 when his colleague Douglas Bastos, now a biologist at the National Institute of Amazonian Research in Manaus, Brazil, reported seeing more than 100 eels congregating and seemingly hunting together in a small lake in northern Brazil. © Society for Science & the Public 2000–2021.

Keyword: Evolution
Link ID: 27647 - Posted: 01.15.2021

By Krystnell A. Storr Can you tell the difference between high – and low –thread-count sheets just by touching them? Thank usherin, a protein found in a mysterious structure in your fingertips. Usherin also helps us see and hear, suggesting a deep molecular connection among our most important senses. “The work is surprising,” says Ellen Lumpkin, a neuroscientist at the University of California (UC), Berkeley, who was not involved in the study. The study, she says, points to a single protein being used over and over again in distinct ways to help us monitor the outside world. Scientists already had some hints that usherin is important for our sense of touch. A mutation in the gene that codes for it, USH2A, causes Usher syndrome—a rare, inherited disease that leads to blindness, deafness, and an inability to feel faint vibrations in the fingertips. To further explore usherin’s role in touch, researchers recruited 13 patients with a form of Usher syndrome that specifically affects touch. The team—led by Gary Lewin, a neuroscientist at the Max Delbrück Center for Molecular Medicine—measured how well each person sensed pain, temperature changes, and tiny vibrations at 10 and 125 hertz (Hz), mimicking the sensation of moving a fingertip across a rough surface. The scientists then compared the patients’ results against those of 65 healthy volunteers. People with Usher syndrome did just as well as their counterparts at sensing temperature changes and mild pain, the team found. But they were four times less likely to pick up on the 125-Hz vibrations and 1.5 times less likely to detect the 10-Hz vibrations. © 2020 American Association for the Advancement of Science.

Keyword: Pain & Touch
Link ID: 27623 - Posted: 12.12.2020

By Veronique Greenwood The ibis and the kiwi are dogged diggers, probing in sand and soil for worms and other buried prey. Sandpipers, too, can be seen along the shore excavating small creatures with their beaks. It was long thought that these birds were using trial and error to find their prey. But then scientists discovered something far more peculiar: Their beaks are threaded with cells that can detect vibrations traveling through the ground. Some birds can feel the movements of their distant quarry directly, while others pick up on waves bouncing off buried shells — echolocating like a dolphin or a bat, in essence, through the earth. There’s one more odd detail in this story of birds’ unusual senses: Ostriches and emus, birds that most definitely do not hunt this way, have beaks with a similar interior structure. They are honeycombed with pits for these cells, though the cells themselves are missing. Now, scientists in a study published Wednesday in Proceedings of the Royal Society B report that prehistoric bird ancestors dating nearly as far back as the dinosaurs most likely were capable of sensing vibrations with their beaks. The birds that use this remote sensing today are not closely related to one another, said Carla du Toit, a graduate student at the University of Cape Town in South Africa and an author of the paper. That made her and her co-authors curious about when exactly this ability evolved, and whether ostriches, which are close relatives of kiwis, had an ancestor that used this sensory ability. “We had a look to see if we could find fossils of early birds from that group,” Ms. du Toit said. “And we’re very lucky.” There are very well-preserved fossils of birds called lithornithids dating from just after the event that drove nonavian dinosaurs to extinction. © 2020 The New York Times Company

Keyword: Pain & Touch; Evolution
Link ID: 27605 - Posted: 12.05.2020

Linda Geddes Many of the side-effects attributed to statins could be down to the “nocebo effect”, which occurs when someone expects to experience negative symptoms – even if the drug is a placebo – a study suggests. Statins are one of the most widely prescribed drugs in the UK, taken by nearly eight million people to reduce their risk of cardiovascular disease by lowering cholesterol levels. Yet, despite their effectiveness, up to a fifth of people stop taking them because of side-effects, such as fatigue, muscle aches, joint pain and nausea. Clinical studies have suggested, however, the incidence of side-effects is far lower. Researchers led by Frances Wood and Dr James Howard at Imperial College London recruited 60 patients who had been on statins, but stopped taking them owing to adverse effects. They were persuaded to resume treatment, and given four bottles containing atorvastatin, four bottles containing identical-looking placebo pills and four empty bottles, to be taken in a randomly prescribed order over the course of a year – including four months taking no pills. Each day, they recorded any side-effects on a smartphone, ranking their intensity from zero to 100. The researchers found 90% of symptoms experienced by the patients were present when they took placebo tablets. Also, 24 patients stopped taking tablets for at least one month of the trial, citing intolerable side-effects – amounting to 71 stoppages in total. Of these, 31 occurred during placebo months and 40 were during statin months. The results were published in the New England Journal of Medicine. © 2020 Guardian News & Media Limited

Keyword: Pain & Touch; Attention
Link ID: 27582 - Posted: 11.16.2020

By Carolyn Wilke Fish fins aren’t just for swimming. They’re feelers, too. The fins of round gobies can detect textures with a sensitivity similar to that of the pads on monkeys’ fingers, researchers report November 3 in the Journal of Experimental Biology. Compared with landlubbers, little is known about aquatic animals’ sense of touch. And for fish, “we used to only think of fins as motor structures,” says Adam Hardy, a neuroscientist at the University of Chicago. “But it’s really becoming increasingly clear that fins play important sensory roles.” Studying those sensory roles can hint at ways to mimic nature for robotics and provide a window into the evolution of touch. The newfound parallels between primates and fish suggest that limbs that sense physical forces emerged early, before splits in the vertebrate evolutionary tree led to animals with fins, arms and legs, says Melina Hale, a neurobiologist and biomechanist also at the University of Chicago. “These capabilities arose incredibly early and maybe set the stage for what we can do with our hands now and what fish can do with their fins in terms of touch.” Hardy and Hale measured the activity of nerves in the fins of bottom-dwelling round gobies (Neogobius melanostomus) to get a sense of what fish learn about texture from their fins. In the wild, round gobies brush against the bottom surface and rest there on their large pectoral fins. “They’re really well suited to testing these sorts of questions,” Hardy says. Working with fins from six euthanized gobies, the researchers recorded electrical spikes from their nerves as a bumpy plastic ring attached to a motor rolled lightly above each fin. A salt solution keeps the nerves functioning as they would if the nerves were in a live fish, Hardy says. © Society for Science & the Public 2000–2020

Keyword: Pain & Touch; Evolution
Link ID: 27564 - Posted: 11.04.2020