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

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Laurel Hamers Scientists have traced the sensation of itch to a place you can’t scratch. The discomfort of a mosquito bite or an allergic reaction activates itch-sensitive nerve cells in the spinal cord. Those neurons talk to a structure near the base of the brain called the parabrachial nucleus, researchers report in the Aug. 18 Science. It’s a region that’s known to receive information about other sensations, such as pain and taste. The discovery gets researchers one step closer to finding out where itch signals ultimately end up. “The parabrachial nucleus is just the first relay center for [itch signals] going into the brain,” says study coauthor Yan-Gang Sun, a neuroscientist at the Chinese Academy of Sciences in Shanghai. Understanding the way these signals are processed by the brain could someday provide relief for people with chronic itch, Sun says. While the temporary itchiness of a bug bite is annoying, longer term, “uncontrollable scratching behavior can cause serious skin damage.” Previous studies have looked at the way an itch registers on the skin or how neurons convey those sensations to the spinal cord. But how those signals travel to the brain has been a trickier question, and this research is a “major step” toward answering it, says Zhou-Feng Chen, director of the Center for the Study of Itch at Washington University School of Medicine in St. Louis. |© Society for Science & the Public 2000 - 2017.

Keyword: Pain & Touch
Link ID: 23972 - Posted: 08.18.2017

Researchers from the National Institutes of Health have identified a class of sensory neurons (nerve cells that electrically send and receive messages between the body and brain) that can be activated by stimuli as precise as the pulling of a single hair. Understanding basic mechanisms underlying these different types of responses will be an important step toward the rational design of new approaches to pain therapy. The findings were published in the journal Neuron. “Scientists know that distinct types of neurons detect different types of sensations, such as touch, heat, cold, pain, pressure, and vibration,” noted Alexander Chesler, Ph.D., lead author of the study and principal investigator with the National Center for Complementary and Integrative Health’s (NCCIH) Division of Intramural Research (DIR). “But they know more about neurons involved with temperature and touch than those underlying mechanical pain, like anatomical pain related to specific postures or activities.” In this study, Chesler and his colleagues used a novel strategy that combined functional imaging (which measures neuronal activity), recordings of electrical activity in the brain, and genetics to see how neurons respond to various stimuli. The scientists focused on a class of sensory neurons that express a gene called Calca, as these neurons have a long history in pain research. The scientists applied various stimuli to the hairy skin of mice cheeks, including gentle mechanical stimuli (air puff, stroking, and brushing), “high-threshold” mechanical stimuli (hair pulling and skin pinching), and temperature stimulation. They found that the target neurons belong to two broad categories, both of which were insensitive to gentle stimulation. The first was a well-known type of pain fiber—a polymodal nociceptor—that responds to a host of high intensity stimuli such as heat and pinching. The second was a unique and previously unknown type of neuron that responded robustly to hair pulling. They called this previously undescribed class of high-threshold mechanoreceptors (HTMRs) “circ-HTMRs,” due to the unusual nerve terminals these neurons made in skin. They observed that the endings of the fibers made lasso-like structures around the base of each hair follicle.

Keyword: Pain & Touch
Link ID: 23970 - Posted: 08.17.2017

By DAVID C. ROBERTS Five years ago, I still lived a double life. I was 35, looking out over the Gulf of Thailand and a few weathered beach tenders. Inside, where dark suits filled the conference room, I could feel the eyes of my fellow diplomats. No doubt they were wondering why I was sitting on my briefcase. I joked to no one in particular “My nuclear codes,” trying to deflect awkwardness. The case actually concealed an orthotic sitting cushion that muffled the pain in my lower back; without it, silent shrieking was all I heard. Or maybe they had noticed I was the only one sweating. The air-conditioning tempered the tropical heat, but it was no match for the corset heat wrap that lay discreetly under my tailored suit. Over the previous decade I had become adept at hiding the unexplained pain that racked my back and joints. To all appearances, I was a fit 6-foot-3 man with an easy gait. No one in that conference room knew my suit pants disguised a lace-up ankle brace and a strap velcroed around my left knee. Nor did they know that during breaks I would sneak back to my hotel room where my wife, an artist who moonlighted as my one-person pit crew, waited to press my quadratus lumborum muscle back into submission. I lasted through that meeting as I had through countless others. But in the months that followed, sitting and walking became increasingly difficult. I started to stand during meetings, avoid plane travel, and take motorcycle taxis to go just a couple of buildings’ distance. Eventually, I let the doctors at the embassy in on my secret. They deemed me unfit for work and medevac’ed me from Bangkok back to the United States for treatment. I left quickly, without awkward explanations or goodbyes. © 2017 The New York Times Company

Keyword: Pain & Touch
Link ID: 23908 - Posted: 08.02.2017

Ashlie Stevens Ah, the brain freeze — the signature pain of summer experienced by anyone who has eaten an ice cream cone with too much enthusiasm or slurped down a slushie a little too quickly. But have you ever stopped mid-freeze to think about why our bodies react like this? Well, researchers who study pain have, and some, like Dr. Kris Rau of the University of Louisville in Kentucky, say it's a good way to understand the basics of how we process damaging stimuli. But first, a lesson in terminology. "There's a scientific medical term for ice cream headaches which is sphenopalatine ganglion neuralgia," Rau says. Try breaking that out at your next ice cream social. Anyway, to understand how brain freeze happens, it helps to think of your body and brain as a big computer where everything is hooked together. In this case, you see an ice cream truck. You get some ice cream. And then your brain gives you the go-ahead and you dive face-first into a double-scoop of mint chocolate chip. "Now on the roof of your mouth there are a lot of little blood vessels, capillaries," Rau says. "And there's a lot of nerve fibers called nociceptors that detect painful or noxious stimuli." The rush of cold causes those vessels to constrict. "And when that happens, it happens so quickly that all of those little pain fibers in the roof of your mouth — they interpret that as being a painful stimulus," Rau says. A message is then shot up to your brain via the trigeminal nerve, one of the major nerves of the facial area. The brain itself doesn't have any pain sensing fibers, but its covering — called the meninges — does. © 2017 npr

Keyword: Pain & Touch
Link ID: 23901 - Posted: 08.01.2017

By Natalie Grover (Reuters) - A handful of drugmakers are taking their first steps toward developing marijuana-based painkillers, alternatives to opioids that have led to widespread abuse and caused the U.S. health regulator to ask for a withdrawal of a popular drug this month. The cannabis plant has been used for decades to manage pain and there are increasingly sophisticated marijuana products available across 29 U.S. states, as well as in the District of Columbia, where medical marijuana is legal. There are no U.S. Food and Drug Administration (FDA)-approved painkillers derived from marijuana, but companies such as Axim Biotechnologies Inc, Nemus Bioscience Inc and Intec Pharma Ltd have drugs in various stages of development. The companies are targeting the more than 100 million Americans who suffer from chronic pain, and are dependent on opioid painkillers such as Vicodin, or addicted to street opiates including heroin. Opioid overdose, which claimed celebrities including Prince and Heath Ledger as victims, contributed to more than 33,000 deaths in 2015, according to the Centers for Disease Control and Prevention. Earlier this month, the FDA asked Endo International Plc to withdraw its Opana ER painkiller from the market, the first time the agency has called for the removal of an opioid painkiller for public health reasons. The FDA concluded that the drug's benefits no longer outweighed its risks. Multiple studies have shown that pro-medical marijuana states have reported fewer opiate deaths and there are no deaths related to marijuana overdose on record.(http://reut.rs/2r74Sbe) © 2017 Scientific American

Keyword: Pain & Touch; Drug Abuse
Link ID: 23774 - Posted: 06.26.2017

By STEPH YIN European eels are born and die in the North Atlantic Ocean, but spend most of their lives in rivers or estuaries across Europe and North Africa. In between, they traverse thousands of miles of ocean, where it’s often unclear which way is up or down. Scientists have therefore long suspected that these critically endangered fish use magnetism to help guide them. A study published Friday in Science Advances shows, for the first time, that European eels might link magnetic cues with the tides to navigate. Studying juveniles during the crucial stage when they move toward land from open ocean, the authors found that eels faced different directions based on whether the tide was flowing in (flood tide) or out (ebb tide). Changing orientation might help eels take advantage of tides to travel from the ocean to the coast, and into fresh water, more efficiently, said Alessandro Cresci, a graduate student at the University of Miami and lead author of the study. Previous studies have shown that eels can detect magnetic fields, but how they use this sixth sense “has remained a matter of speculation” until now, said Michael J. Miller, an eel biologist at Nihon University in Japan who was not involved in the study. When transitioning from sea to coast, European eels are in a stage of their lives where they are about the size of a finger and transparent along their bodies, thus the name “glass eels.” Mr. Cresci’s group studied glass eels from the coast of Norway, observing the animals in the field by putting 54 slippery, see-through eels, one by one, in a drifting chamber equipped with cameras and compasses. When the tide ebbed, these animals generally faced south, but when it flowed in, they showed no consistent orientation. The researchers then studied 49 of the same eels in laboratory tanks. They subjected some of the eels to reoriented magnetic fields, rotating magnetic north to the east, south or west. © 2017 The New York Times Company

Keyword: Animal Migration
Link ID: 23728 - Posted: 06.12.2017

Rob Stein The Food and Drug Administration requested Thursday that the drugmaker Endo Pharmaceuticals stop selling Opana ER — its extended-release version of Opana. The FDA says the move marks the first time the agency has taken steps to remove an opioid from the market because of "public health consequences of abuse." An increasing number of people, the FDA says, are abusing the powerful prescription pills by crushing, dissolving and injecting them. The sharing of needles by these drug users has fueled an outbreak of associated infectious diseases — HIV, hepatitis C and another serious blood disorder. "We are facing an opioid epidemic — a public health crisis, and we must take all necessary steps to reduce the scope of opioid misuse and abuse," says Dr. Scott Gottlieb, the FDA's commissioner, in announcing the move. "We will continue to take regulatory steps when we see situations where an opioid product's risks outweigh its benefits, not only for its intended patient population but also in regard to its potential for misuse and abuse," Gottlieb says. Dangers Of Opana Opioid Painkiller Outweigh Benefits, FDA Panel Says In a written statement, Endo says the company is "reviewing the request and is evaluating the full range of potential options as we determine the appropriate path forward." The company defended its drug, a version of the medicine oxymorphone hydrochloride, citing the opioid's effectiveness in alleviating pain and Endo's efforts to prevent abuse. © 2017 npr

Keyword: Drug Abuse; Pain & Touch
Link ID: 23725 - Posted: 06.09.2017

By NICHOLAS BAKALAR Chronic pain may be linked to an increasing risk for dementia. Researchers interviewed 10,065 people over 62 in 1998 and 2000, asking whether they suffered “persistent pain,” defined as being often troubled with moderate or severe pain. Then they tracked their health through 2012. After adjusting for many variables, they found that compared with those who reported no pain problems, people who reported persistent pain in both 1998 and 2000 had a 9 percent more rapid decline in memory performance. Moreover, the probability of dementia increased 7.7 percent faster in those with persistent pain compared with those without. The study, in JAMA Internal Medicine, does not prove cause and effect. But chronic pain may divert attention from other mental activity, leading to poor memory, and some studies have found that allaying pain with opioids can lead to cognitive improvements. Still, the lead author, Dr. Elizabeth L. Whitlock, an anesthesiologist at the University of California at San Francisco, acknowledged that treatment with opioids is problematic, and that safely controlling chronic pain is a problem that so far has no satisfactory solution. “I’d encourage clinicians to be aware of the cognitive implications of a simple report of pain,” she said. “It’s a simple question to ask, and the answer can be used to identify a population at high risk of functional and cognitive problems.” © 2017 The New York Times Company

Keyword: Alzheimers; Pain & Touch
Link ID: 23719 - Posted: 06.08.2017

By Matthew Hutson The life of a sheep is not as cushy as it looks. They suffer injury and infection, and can’t tell their human handlers when they’re in pain. Recently, veterinarians have developed a protocol for estimating the pain a sheep is in from its facial expressions, but humans apply it inconsistently, and manual ratings are time-consuming. Computer scientists at the University of Cambridge in the United Kingdom have stepped in to automate the task. They started by listing several “facial action units” (AUs) associated with different levels of pain, drawing on the Sheep Pain Facial Expression Scale. They manually labeled these AUs—nostril deformation, rotation of each ear, and narrowing of each eye—in 480 photos of sheep. Then they trained a machine-learning algorithm by feeding it 90% of the photos and their labels, and tested the algorithm on the remaining 10%. The program’s average accuracy at identifying the AUs was 67%, about as accurate as the average human, the researchers will report today at the IEEE International Conference on Automatic Face and Gesture Recognition in Washington, D.C. Ears were the most telling cue. Refining the training procedure further boosted accuracy. Given additional labeled images, the scientists expect their method would also work with other animals. Better diagnosis of pain could lead to quicker treatment. © 2017 American Association for the Advancement of Science. A

Keyword: Pain & Touch
Link ID: 23694 - Posted: 06.02.2017

Laurel Hamers Last year, Joan Peay slipped on her garage steps and smashed her knee on the welcome mat. Peay, 77, is no stranger to pain. The Tennessee retiree has had 17 surgeries in the last 35 years — knee replacements, hip replacements, back surgery. She even survived a 2012 fungal meningitis outbreak that sickened her and hundreds of others, and killed 64. This knee injury, though, “hurt like the dickens.” When she asked her longtime doctor for something stronger than ibuprofen to manage the pain, he treated her like a criminal, Peay says. His response was frustrating: “He’s known me for nine years, and I’ve never asked him for pain medicine other than what’s needed after surgery,” she says. She received nothing stronger than over-the-counter remedies. A year after the fall, she still lives in constant pain. Just five years ago, Peay might have been handed a bottle of opioid painkillers for her knee. After all, opioids — including codeine, morphine and oxycodone — are some of the most powerful tools available to stop pain. Hitting opioid receptors in the peripheral nervous system keeps pain messages from reaching the brain. But opioids can cause problems by overstimulating the brain’s reward system and binding to receptors in the brain stem and gut. But an opioid addiction epidemic spreading across the United States has soured some doctors on the drugs. Many are justifiably concerned that patients will get hooked or share their pain pills with friends and family. And even short-term users risk dangerous side effects: The drugs slow breathing and can cause constipation, nausea and vomiting. |© Society for Science & the Public 2000 - 2017

Keyword: Pain & Touch; Drug Abuse
Link ID: 23686 - Posted: 05.31.2017

Patients who are told their medication can have certain side-effects may report these symptoms more often than patients who aren't aware their treatment carries these risks, a study of popular cholesterol pills suggests. Researchers focused on what they dubbed the "nocebo" effect, or the potential for people to complain of treatment-related side-effects when they think they're taking a specific drug but are actually given a placebo, or dummy pill, without any active ingredients. "It has been recognized for many years that when patients are warned about possible adverse reactions to a drug, they are much more likely to complain of these side effects than when they are unaware of the possibility that such side-effects might occur," said senior study author Dr. Peter Sever, a researcher at Imperial College London. To test this "nocebo" effect, researchers first randomly assigned about 10,000 trial participants in the UK, Ireland and Scandinavia to take either a statin pill to lower cholesterol or a placebo, then followed people for around three years to see how often they complained of four known statin side-effects: Patients on statins and on placebo pills reported similar rates of muscle aches and erectile dysfunction, the study found. People taking placebo also reported higher rates of sleep difficulties than patients on statins. ©2017 CBC/Radio-Canada.

Keyword: Pain & Touch
Link ID: 23665 - Posted: 05.27.2017

Laura Beil Even though a sprained ankle rarely needs an opioid, a new study of emergency room patients found that about 7 percent of patients got sent home with a prescription for the potentially addictive painkiller anyway. And the more pills prescribed, the greater the chance the prescription would be refilled, raising concerns about continued use. The research adds to evidence that it’s hard for some people to stop taking the pills even after a brief use. State officials in New Jersey recently enacted a law limiting first-time prescriptions to a five-day supply, and other states should consider similar restrictions, says Kit Delgado, an assistant professor of Emergency Medicine and Epidemiology at the University of Pennsylvania. “The bottom line is that we need to do our best not to expose people to opioids,” Delgado says. “And if we do, start with the smallest quantity possible.” The research was presented May 17 at the Society for Academic Emergency Medicine’s annual meeting in Orlando. Previous research has found that the more opioids such as hydrocodone and oxycodone are prescribed, the more likely patients are to keep taking them. But previous studies have been too broad to account for differences in diagnoses — for instance, whether people who received refills kept taking the drug simply because they still were in pain, Delgado says. He and colleagues limited their study to prescriptions written after ankle sprains to people who had not used an opioid in the previous six months. Usually, those injuries aren’t serious and don’t require opioids. |© Society for Science & the Public 2000 - 2017

Keyword: Drug Abuse; Pain & Touch
Link ID: 23638 - Posted: 05.20.2017

By Roman Liepelt and Jack Brooks An amputee struggles to use his new prosthetic limb. A patient with a frontal-lobe brain lesion insists that her left hand has a mind of its own. The alleged criminal claims in court that he did not fire the gun, even though several eyewitnesses watched him do it. Each of these individuals is grappling with two elements of the mind-body connection: ownership, or an ability to separate ourselves from the physical and social environments, and agency, a conviction that we have control over our limbs. We are quick to investigate a sticker placed on our forehead when looking in a mirror, recognizing the foreign object as abnormal. The human brain typically handles these phenomena by comparing neural signals encoding the intended action with those signals carrying sensory feedback. When we are born, we make erratic reaching and kicking movements to map our body and to calibrate our sensorimotor system. During infancy, these movements solidify our self-awareness, and around the time we first walk, we are quick to investigate a sticker placed on our forehead when looking in a mirror, recognizing the foreign object as abnormal. By the age of four, our brains are proficient at distinguishing self and other. In the amputee, the brain lesion patient, and the defendant on trial, the sense of self is disrupted due to discordance between sensory feedback from the limb and the brain’s expectations of how a movement should feel. © 1986-2017 The Scientist

Keyword: Pain & Touch
Link ID: 23625 - Posted: 05.17.2017

By Moheb Costandi Pain in infants is heartbreaking for new parents, and extremely difficult to treat effectively—if at all. Every year an estimated 15 million babies are born prematurely, most of whom will then undergo numerous lifesaving but painful procedures, such as heel pricking or insertion of a thin tube known as a cannula to deliver fluids or medicine. Preterm babies in the intensive care unit are subjected to an average of 11 such “skin-breaking” procedures per day, but analgesia is only used just over one third of the time. We know that repetitive, painful procedures in early infancy can impact brain development negatively—so why is pain in infants so undertreated? One reason is the lack of standard guidelines for administering the drugs. Some analgesics given to adults are unsuitable for infants, and those that can be used often have different effects in children, making dosing a problem. What is more, newborn babies are incapable of telling us how they feel, making it impossible to determine how effective any painkiller might be. Researchers at the University of Oxford may now have overcome this latter challenge, however. They report May 3 in Science Translational Medicine having identified a pain-related brain wave signal that responds to analgesics, and could be used to measure the drugs’ efficacy. Until as recently as the 1980s, it was assumed that newborn babies do not feel pain, and that giving them analgesics would do more harm than good. Although these misconceptions have been cleared up, we still have very little understanding of infant pain, and so treating it is a huge challenge for clinicians. © 2017 Scientific American

Keyword: Pain & Touch
Link ID: 23576 - Posted: 05.05.2017

Douglas Fox Six times a day, Katrin pauses whatever she's doing, removes a small magnet from her pocket and touches it to a raised patch of skin just below her collar bone. For 60 seconds, she feels a soft vibration in her throat. Her voice quavers if she talks. Then, the sensation subsides. The magnet switches on an implanted device that emits a series of electrical pulses — each about a milliamp, similar to the current drawn by a typical hearing aid. These pulses stimulate her vagus nerve, a tract of fibres that runs down the neck from the brainstem to several major organs, including the heart and gut. The technique, called vagus-nerve stimulation, has been used since the 1990s to treat epilepsy, and since the early 2000s to treat depression. But Katrin, a 70-year-old fitness instructor in Amsterdam, who asked that her name be changed for this story, uses it to control rheumatoid arthritis, an autoimmune disorder that results in the destruction of cartilage around joints and other tissues. A clinical trial in which she enrolled five years ago is the first of its kind in humans, and it represents the culmination of two decades of research looking into the connection between the nervous and immune systems. For Kevin Tracey, a neurosurgeon at the Feinstein Institute for Medical Research in Manhasset, New York, the vagus nerve is a major component of that connection, and he says that electrical stimulation could represent a better way to treat autoimmune diseases, such as lupus, Crohn's disease and more. Several pharmaceutical companies are investing in 'electroceuticals' — devices that can modulate nerves — to treat cardiovascular and metabolic diseases. But Tracey's goal of controlling inflammation with such a device would represent a major leap forward, if it succeeds. © 2017 Macmillan Publishers Limited

Keyword: Neuroimmunology; Pain & Touch
Link ID: 23573 - Posted: 05.04.2017

Laura Sanders An electrode on top of a newborn’s scalp, near the soft spot, can measure when the baby feels pain. The method, described online May 3 in Science Translational Medicine, isn’t foolproof, but it brings scientists closer to being able to tell when infants are in distress. Pain assessment in babies is both difficult and extremely important for the same reason: Babies don’t talk. That makes it hard to tell when they are in pain, and it also means that their pain can be more easily overlooked, says Carlo Bellieni, a pediatric pain researcher at the University Hospital Siena in Italy. Doctors rely on a combination of clues such as crying, wiggling and facial grimacing to guess whether a baby is hurting. But these clues can mislead. “Similar behaviors occur when infants are not in pain, for example if they are hungry or want a cuddle,” says study coauthor Rebeccah Slater of the University of Oxford. By relying on brain activity, the new method promises to be a more objective measurement. Slater and colleagues measured brain activity in 18 newborns between 2 and 5 days old. Electroencephalography (EEG) recordings from electrodes on the scalp picked up collective nerve cell activity as babies received a heel lance to draw blood or a low-intensity bop on the foot, a touch that’s a bit like being gently poked with a blunt pencil. One electrode in particular, called the Cz electrode and perched on the top of the head, detected a telltale neural spike between 400 and 700 milliseconds after the painful event. This brain response wasn’t observed when these same babies received a sham heel lance or an innocuous touch on the heel. |© Society for Science & the Public 2000 - 2017

Keyword: Pain & Touch; Development of the Brain
Link ID: 23566 - Posted: 05.04.2017

Amber Dance Biologist Leo Smith held an unusual job while an undergraduate student in San Diego. Twice a year, he tagged along on a chartered boat with elderly passengers. The group needed him to identify two particular species of rockfish, the chilipepper rockfish and the California shortspine thornyhead. Once he’d found the red-orange creatures, the passengers would stab themselves in the arms with the fishes’ spines. Doing so, the seniors believed, would relieve their aching arthritic joints. Smith, now at the University of Kansas in Lawrence, didn’t think much of the practice at the time, but now he wonders if those passengers were on to something. Though there’s no evidence that anything in rockfish venom can alleviate pain — most fish stings are, in fact, quite painful themselves — some scientists suspect fish venom is worth a look. Studying the way venom molecules from diverse fishes inflict pain might help researchers understand how nerve cells sense pain and lead to novel ways to dull the sensation. Smith is one of a handful of scientists who are studying fish venoms, and there’s plenty to investigate. An estimated 7 to 9 percent of fishes, close to 3,000 species, are venomous, Smith’s work suggests. Venomous fishes are found in freshwater and saltwater, including some stingrays, catfishes and stonefishes. Some, such as certain fang blennies, are favorites in home aquariums. Yet stinging fishes haven’t gotten the same attention from scientists as snakes and other venomous creatures. |© Society for Science & the Public 2000 - 2017

Keyword: Pain & Touch; Neurotoxins
Link ID: 23515 - Posted: 04.20.2017

Laurel Hamers Earth’s magnetic field helps eels go with the flow. The Gulf Stream fast-tracks young European eels from their birthplace in the Sargasso Sea to the European rivers where they grow up. Eels can sense changes in Earth’s magnetic field to find those highways in a featureless expanse of ocean — even if it means swimming away from their ultimate destination at first, researchers report in the April 13 Current Biology. European eels (Anguilla anguilla) mate and lay eggs in the salty waters of the Sargasso Sea, a seaweed-rich region in the North Atlantic Ocean. But the fish spend most of their adult lives living in freshwater rivers and estuaries in Europe and North Africa. Exactly how eels make their journey from seawater to freshwater has baffled scientists for more than a century, says Nathan Putman, a biologist with the National Oceanic and Atmospheric Administration in Miami. The critters are hard to track. “They’re elusive,” says study coauthor Lewis Naisbett-Jones, a biologist now at the University of North Carolina at Chapel Hill. “They migrate at night and at depth. The only reason we know they spawn in the Sargasso Sea is because that’s where the smallest larvae have been collected.” |© Society for Science & the Public 2000 - 2017.

Keyword: Animal Migration
Link ID: 23492 - Posted: 04.14.2017

David Cyranoski For decades, scientists have wondered how animals can navigate huge distances using the weak signals of Earth’s magnetic field. So, interest was piqued in 2015 when two teams released papers in quick succession describing the functions of a protein found in animals that seemed to sense magnetic fields. But the claims have proved controversial, and questions have been piling up. The basic science behind the discovery was reported by Xie Can, a biophysicist at Peking University in Beijing, and his colleagues. In a paper in Nature Materials1, they claimed that a protein in animal cells forms a structure that responds to magnetic fields, and so might help in navigation. In the same year, a group led by Zhang Sheng-jia, then at Tsinghua University in Beijing, had published a paper in Science Bulletin2 reporting that the same protein could offer a powerful means of controlling brain cells. An academic battle has long raged between Xie and Zhang, but mounting evidence has cast doubt on both of their discoveries. Several researchers have challenged Xie’s claims that the protein reacts to magnetic fields. And last month, Xie co-authored a paper in Frontiers in Neural Circuits3 disputing Zhang’s work on the protein’s potential to magnetically control cells. This has all given rise to serious questions about the role of the molecule at the centre of the dispute. In their 2015 paper1, Xie and his colleagues reported that a protein called IscA1 forms a complex with another protein, Cry4, that explains how organisms pick up magnetic cues. The study found that this complex incorporates iron atoms, which gives it magnetic properties, and has a rod-like shape that aligns with an applied magnetic field. © 2017 Macmillan Publishers Limited

Keyword: Animal Migration
Link ID: 23452 - Posted: 04.05.2017

By STEPH YIN It’s a small fish, only a couple of inches long, and its bright colors make it pop in the Pacific coral reefs it calls home. The first thing that makes this fish peculiar is the striking pair of large lower canines it sports. But when attacked by a predator, this fish, part of a group called fang blennies,does something even more strange. A predator that puts this fang blenny in its mouth would experience a “violent quivering of the head,” according to George Losey, a zoologist who observed this species up close in a series of feeding experiments in the 1970s. Then the predator would open its jaws and gills. The little blenny would swim away, unscathed. A study published on Thursday in Current Biology now lays bare the details of the fish’s unusual defense mechanism: Unlike most venomous fish, which inject toxins through their fins, fang blennies deliver venom through their bite. Furthermore, fang blenny venom does not appear to produce potent pain, at least in mice. Instead, it causes a sudden drop in blood pressure, which might temporarily stupefy predators. “This is one of the most in-depth studies of how venom functions in any particular group of fish,” said Matthew Davis, an assistant professor of biology at St. Cloud State University in Minnesota, who did not participate in the research. A CT scan of Meiacanthus grammistes, a venomous fang blenny species. Anthony Romilio The authors of the study took a multipronged approach to studying venomous fang blennies. First, they imaged the jaws of fang blennies collected from around the Pacific and Indian Oceans to confirm what scientists long suspected: Not all fang blennies have venom glands at the base of their teeth. © 2017 The New York Times Company

Keyword: Pain & Touch; Neurotoxins
Link ID: 23432 - Posted: 03.31.2017