Chapter 8. General Principles of Sensory Processing, Touch, and Pain
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by Hal Hodson CAN YOU imagine feeling Earth's magnetic field on the tip of your tongue? Strangely, this is now possible, using a device that converts the tongue into a "display" for output from environmental sensors. Gershon Dublon of the Massachusetts Institute of Technology devised a small pad containing electrodes in a 5 × 5 grid. Users put the pad, which Gershon calls Tongueduino, on their tongue. When hooked up to an electronic sensor, the pad converts signals from the sensor into small pulses of electric current across the grid, which the tongue "reads" as a pattern of tingles. Dublon says the brain quickly adapts to new stimuli on the tongue and integrates them into our senses. For example, if Tongueduino is attached to a sensor that detects Earth's magnetic field, users can learn to use their tongue as a compass. "You might not have to train much," he says. "You could just put this on and start to perceive." Dublon has been testing Tongueduino on himself for the past year using a range of environmental sensors. He will now try the device out on 12 volunteers. Blair MacIntyre at the Georgia Institute of Technology in Atlanta says a wireless version of Tongueduino could prove useful in augmented reality applications that deliver information to users inconspicuously, without interfering with their vision or hearing. "There's a need for forms of awareness that aren't socially intrusive," he says. Even Google's much-publicised Project Glass will involve wearing a headset, he points out. © Copyright Reed Business Information Ltd.
The latest bionic superhero is a rat: its brain hooked up to an infrared detector, it's become the first animal to be given a sixth sense. Developed by Miguel Nicolelis and colleagues at Duke University in Durham, North Carolina, the system connects a head-mounted sensor to a brain region that normally processes touch sensations from whiskers. As shown in this video, the rat's brain is tricked when infrared light is detected, giving it a new sense organ. "Instead of seeing, the rats learned how to touch the light," says Nicolelis. Even though the touch-processing brain area acquires a new role, the team found that it continues to process touch sensations from whiskers, somehow dividing its time between both types of signal. "The adult brain is a lot more plastic than we thought," says Nicolelis. The finding could lead to new brain prostheses that restore sight in humans with a damaged visual cortex. By bypassing the damaged part of the brain altogether, it might be possible to wire up a video camera to a part of the brain that processes touch, letting people "touch" what the camera sees. According to Nicolelis, it could also lead to superhero powers for humans. "It could be X-rays, radio waves, anything," he says. "Superman probably had a prosthetic device that nobody knew of." © Copyright Reed Business Information Ltd.
By Laura Sanders Some nerve fibers seem to love a good rubdown. These tendrils, which spread across skin like upside-down tree roots, detect smooth, steady stroking and send a feel-good message to the brain, researchers report in the Jan. 31 Nature. Although the researchers found these neurons in mice, similar cells in people may trigger massage bliss. The results are the latest to emphasize the strong and often underappreciated connection between emotions and the sensation of touch, says study coauthor David Anderson, a Howard Hughes Medical Institute investigator at Caltech. “It may seem frivolous to be studying massage neurons in mice, but it raises a profound issue — why do certain stimuli feel a certain way?” he says. It’s no surprise that many people find a caress pleasant. Earlier studies in people suggested that a particular breed of nerve fibers detects a caress and carries that signal to the brain. But scientists hadn’t been able to directly link this type of neuron to good feelings, either in people or in animals. “The beauty of this paper is that it goes one step further and adds behavioral elements,” says cognitive neuroscientist Francis McGlone of Liverpool John Moores University in England. Directly linking these neurons with pleasure clarifies the importance of touch, McGlone says. “Skin is a social organ,” he says. A growing number of studies show that the sensation of touch, particularly early in life, profoundly sculpts the brain. Young animals deprived of touch grow up with severe behavioral abnormalities. Babies fare better when they are held and touched frequently. And touch sensation can be altered in certain disorders. People with autism, for instance, often dislike caresses. © Society for Science & the Public 2000 - 2013
By Sandra G. Boodman Still clutching his discharge instructions from a suburban Maryland emergency room, Brian Harms struggled to make sense of what the neurosurgeon was saying. The ER staff had told Harms, admitted hours earlier, that his diagnoses were headache and vertigo and that he should go home and rest. A CT scan had found a benign cyst in his brain, but the staff didn’t convey any urgency about treating it. As the 29-year-old College Park resident was gathering his things, a neurosurgeon rushed in, telling Harms he would not be going home. “I need to get this information to you quickly,” Harms remembers the specialist telling him on the morning of Sept. 28, 2011. “You are in a lot of trouble, and you need surgery as soon as possible.” The neurosurgeon had been trying to arrange a transfer to Johns Hopkins Hospital in Baltimore, but doctors were worried that he might die en route. “I highly suggest you trust me and let me do this procedure here,” Harms remembers the surgeon telling him, but the decision was his. For Harms, who had seen several doctors for headaches and other symptoms during the previous 18 months, the news was beyond shocking. “It felt like the floor dropped out beneath me,” he recalled. “I was scared witless.” Only later would Harms, a University of Maryland doctoral candidate in geochemistry, learn how lucky he was to have survived both a series of misdiagnoses and a test, performed hours before his emergency surgery, that could have killed him. © 1996-2013 The Washington Post
Keyword: Pain & Touch
Link ID: 17727 - Posted: 01.29.2013
By Ashutosh Jogalekar G Protein-Coupled Receptors (GPCRs) are the messengers of the human body, key proteins whose ubiquitous importance was validated by the 2012 Nobel Prize in chemistry. As I mentioned in a post written after the announcement of the prize, GPCRs are involved in virtually every physiological process you can think of, from sensing colors, flavors and smells to the action of neurotransmitters and hormones. In addition they are of enormous commercial importance, with something like 30% of marketed drugs binding to these proteins and regulating their function. These drugs include everything from antidepressants to blood-pressure lowering medications. But GPCRs are also notoriously hard to study. They are hard to isolate from their protective lipid cell membrane, hard to crystallize and hard to coax into giving up their molecular secrets. One reason the Nobel Prize was awarded was because the two researchers – Robert Lefkowitz and Brian Kobilka – perfected techniques to isolate, stabilize, crystallize and study these complex proteins. But there’s still a long way to go. There are almost 800 GPCRs, out of which ‘only’ 16 have been crystallized during the past decade or so. In addition all the studied GPCRs are from the so-called Class A family. There’s still five classes left to decipher, and these contain many important receptors including the ones involved in smell. Clearly it’s going to be a long time before we can get a handle on the majority of these important proteins. Fortunately there’s something important that GPCR researchers have realized; it’s the fact that many of these GPCRs have amino acid sequences that are similar. If you know what experimental conditions work for one protein, perhaps you can use the same conditions for another similar GPCR. © 2013 Scientific American
Link ID: 17692 - Posted: 01.17.2013
By KENNETH CHANG Mosquito bite? Poison ivy? Dry skin? Fuzzy sweater? Everyone has an itch to scratch. Why we and other animals itch remains something of a mystery. But now researchers at Johns Hopkins and Yale in the United States and several universities in China have found a key piece of the puzzle, identifying sensory neurons in mice that are dedicated to relaying itchy sensations from the top layers of skin to the spinal cord. “Our study, for the first time, shows the existence of itch-specific nerves,” said Xinzhong Dong, a professor of neuroscience at the Johns Hopkins University School of Medicine and the senior author of a paper about the findings in the journal Nature Neuroscience. Scientists have debated for decades whether separate circuitry existed for itchiness or whether its signals passed through the same nerves used to transmit pain. Earlier data — suppressing pain with morphine can cause chronic itching, for example — indicated some overlap between the two sensations. But the fact that evolution also produced dedicated itch nerves in mice — and almost certainly in people as well — suggests that itching serves an important role in survival and is not just a byproduct of the pain nerves. © 2013 The New York Times Company
Keyword: Pain & Touch
Link ID: 17660 - Posted: 01.08.2013
A strong family history of seizures could increase the chances of having severe migraines, says a study in Epilepsia journal. Scientists from Columbia University, New York, analysed 500 families containing two or more close relatives with epilepsy. Their findings could mean that genes exist that cause both epilepsy and migraine. Epilepsy Action said it could lead to targeted treatments. Previous studies have shown that people with epilepsy are substantially more likely than the general population to have migraine headaches, but it was not clear whether that was due to a shared genetic cause. The researchers found that people with three or more close relatives with a seizure disorder were more than twice as likely to experience 'migraine with aura' than patients from families with fewer individuals with seizures. Migraine with aura is a severe headache preceded by symptoms such as seeing flashing lights, temporary visual loss, speech problems or numbness of the face. Dr Melodie Winawer, lead author of the study from Columbia University Medical Centre, said the findings had implications for epilepsy patients. "Our study demonstrates a strong genetic basis for migraine and epilepsy, because the rate of migraine is increased only in people who have close (rather than distant) relatives with epilepsy." BBC © 2013
Cannabis makes pain more bearable rather than actually reducing it, a study from the University of Oxford suggests. Using brain imaging, researchers found that the psychoactive ingredient in cannabis reduced activity in a part of the brain linked to emotional aspects of pain. But the effect on the pain experienced varied greatly, they said. The researchers' findings are published in the journal Pain. The Oxford researchers recruited 12 healthy men to take part in their small study. Participants were given either a 15mg tablet of THC (delta-9-tetrahydrocannabinol) - the ingredient that is responsible for the high - or a placebo. The volunteers then had a cream rubbed into the skin of one leg to induce pain, which was either a dummy cream or a cream that contained chilli - which caused a burning and painful sensation. Each participant had four MRI scans which revealed how their brain activity changed when their perception of the pain reduced. Dr Michael Lee, lead study author from Oxford University's Centre for Functional Magnetic Resonance Imaging of the Brain, said: "We found that with THC, on average people didn't report any change in the burn, but the pain bothered them less." BBC © 2012
By Liz Kowalczyk Health officials investigating the national fungal meningitis outbreak caused by tainted steroid injections had thought that the worst was over. The number of new cases was dwindling. Then came patients like Anna Adair. An avid gardener and dog-breeder, Adair was rolled into a Michigan emergency room in a wheelchair Nov. 15. She had been bedridden for days, and that morning a bolt of pain in her lower back had caused her to tumble to the bathroom floor. Doctors quickly reached a disturbing realization: An infection caused by black mold had infiltrated her spine, near where she had received an injection made by a Massachusetts pharmacy, and spread into the bone. It was not the meningitis that sickened hundreds of others in late summer and early fall, but part of a frightening second wave of fungal infections caused by contaminated drugs. Dozens more people have now been diagnosed with excruciating abscesses or inflamed nerves in their backs that are proving formidable to cure. In a health alert issued Thursday, the federal Centers for Disease Control and Prevention said it is worried that some patients with spinal infections may not even be aware of their condition because the symptoms mimic the very back pain they originally sought to treat with steroids. The agency is now recommending that doctors consider performing MRI scans to screen all patients who have persistent back pain and received steroids from one of three contaminated batches. Previously, it advised scanning just those with new or worsening pain. © 2012 NY Times Co.
Keyword: Pain & Touch
Link ID: 17631 - Posted: 12.22.2012
By ANAHAD O'CONNOR Chronic sleep loss has many downsides, among them weight gain, depression and irritability. But now scientists have found a new one: It also weakens your tolerance for pain. In recent studies, researchers have shown that losing sleep may disrupt the body’s pain signaling system, heightening sensitivity to painful stimuli. Though it is not clear why, one theory is that sleep loss increases inflammation throughout the body. Catching up on sleep if you are behind may reduce inflammation. Scientists believe this could have implications for people with chronic pain. It could also have an impact on the effects of painkillers, which appear to be blunted after chronic sleep loss. In one study published in the journal Sleep, scientists at the sleep disorders and research center at Henry Ford Hospital in Detroit recruited 18 healthy adults and split them into two groups. One was allowed to sleep for an average of nine hours, while the other averaged two fewer hours of sleep each night. To assess pain thresholds, the researchers measured how long the subjects were able to hold a finger to a source of radiant heat. After four nights, the group that was allowed to sleep the longest was able to withstand the painful stimuli much longer, by about 25 percent on average. Several studies in the past have had similar findings, including one in 2006 that showed that one night of cutting sleep in half could significantly reduce a person’s threshold for physical pain. Copyright 2012 The New York Times Company
By LISA SANDERS, M.D. On Thursday, we challenged Well readers to puzzle their way through the case of a 25-year-old elephant trainer who developed “the worst headache of his life.” The case was made more confusing by the fact that he had been head-butted by a zebra several years earlier. Turns out the zebra was a bit of a red herring – for the doctors at the time, and for many of you. The correct diagnosis is… Herpes zoster, commonly known as shingles The internist assigned to the case, Dr. Bilal Ahmed, was able to make the diagnosis because when he examined the patient the next day, he saw the characteristic zoster rash above the patient’s right eye that had developed overnight. Nearly 200 people wrote in with their thoughts on what Dr. Ahmed might have seen to reveal the diagnosis when he looked at the patient. The first person to guess the correct diagnosis was Lotty Fulkerson of Massachusetts, a licensed practical nurse who has seen a lot of zoster. It was the combination of the patient’s terrible pain and the fact that the doctor saw something that told him the diagnosis that made her think it was probably shingles. Only three other readers guessed correctly. Herpes zoster, also known as shingles, is caused by the re-emergence of the herpes virus that is the source of the childhood illness chickenpox. The term “shingles” comes from the Latin word “cingulum,” which means belt or girdle; the rash of herpes zoster often appears in a band or belt-like pattern. When the original chickenpox infection resolves, the virus doesn’t die but instead takes refuge in branches of the nerves just outside the spinal cord, where it will reside for decades. In up to a third of patients who have had chickenpox, it re-emerges, causing pain and a rash and sometimes more. Why these survivor viruses re-emerge is unclear, but it may be linked to a weakened immune system. Copyright 2012 The New York Times Company
Keyword: Pain & Touch
Link ID: 17556 - Posted: 12.01.2012
By JUSTIN HECKERT The girl who feels no pain was in the kitchen, stirring ramen noodles, when the spoon slipped from her hand and dropped into the pot of boiling water. It was a school night; the TV was on in the living room, and her mother was folding clothes on the couch. Without thinking, Ashlyn Blocker reached her right hand in to retrieve the spoon, then took her hand out of the water and stood looking at it under the oven light. She walked a few steps to the sink and ran cold water over all her faded white scars, then called to her mother, “I just put my fingers in!” Her mother, Tara Blocker, dropped the clothes and rushed to her daughter’s side. “Oh, my lord!” she said — after 13 years, that same old fear — and then she got some ice and gently pressed it against her daughter’s hand, relieved that the burn wasn’t worse. “I showed her how to get another utensil and fish the spoon out,” Tara said with a weary laugh when she recounted the story to me two months later. “Another thing,” she said, “she’s starting to use flat irons for her hair, and those things get superhot.” Tara was sitting on the couch in a T-shirt printed with the words “Camp Painless But Hopeful.” Ashlyn was curled on the living-room carpet crocheting a purse from one of the skeins of yarn she keeps piled in her room. Her 10-year-old sister, Tristen, was in the leather recliner, asleep on top of their father, John Blocker, who stretched out there after work and was slowly falling asleep, too. The house smelled of the homemade macaroni and cheese they were going to have for dinner. A South Georgia rainstorm drummed the gutters, and lightning illuminated the batting cage and the pool in the backyard. Without lifting her eyes from the crochet hooks in her hands, Ashlyn spoke up to add one detail to her mother’s story. “I was just thinking, What did I just do?” she said. © 2012 The New York Times Company
Keyword: Pain & Touch
Link ID: 17507 - Posted: 11.19.2012
Women with migraines did not appear to experience a decline in cognitive ability over time compared to those who didn’t have them, according to a nine-year follow up study funded by the National Institutes of Health. The study also showed that women with migraine had a higher likelihood of having brain changes that appeared as bright spots on magnetic resonance imaging (MRI), a type of imaging commonly used to evaluate tissues of the body. "The fact that there is no evidence of cognitive loss among these women is good news," said Linda Porter, Ph.D., pain health science policy advisor in the Office of the Director at the National Institute of Neurological Disorders and Stroke (NINDS), which provided funding for the study. "We’ve known for a while that women with migraine tend to have these brain changes as seen on MRI. This nine-year study is the first of its kind to provide long-term follow-up looking for associated risk." "An important message from the study is that there seems no need for more aggressive treatment or prevention of attacks," said Mark C. Kruit, M.D., Ph.D., one of the principal investigators, and a neuroradiologist from Leiden University Medical Center, the Netherlands, which led the study. Dr. Kruit and associates evaluated MRIs for changes in the white matter, brainstem, and cerebellum that appeared on the scans as bright spots known as hyperintensities. Previous studies have shown an association between such hyperintensities and risk factors for atherosclerotic disease, increased risk of stroke and cognitive decline.
Keyword: Pain & Touch
Link ID: 17488 - Posted: 11.14.2012
by Greg Miller Seeing someone yawn or hearing someone laugh makes you likely to follow suit. The same goes for scratching an itch. Now, for the first time, researchers have investigated the neural basis of contagious itch, identifying several brain regions whose activity predicts how susceptible people are to feeling itchy when they see someone else scratch. Researchers in the United Kingdom showed volunteers video clips of people scratching an arm or a spot on their chest. Sure enough, subjects reported feeling more itchy, and most scratched themselves at least once during the experiment. When a subset of the volunteers watched the videos inside an functional magnetic resonance imaging scanner, the scans revealed activity in several of the same brain regions known to fire up in response to an itch-inducing histamine injection. Activity in three of these areas correlated with subjects' self-reported itchiness, the team reports online today in the Proceedings of the National Academy of Sciences. Personality tests suggest that the trait that best predicts susceptibility to contagious itch is neuroticism, not empathy, as some researchers have suggested. © 2010 American Association for the Advancement of Science
Kerry Grens Fewer than five percent of patients prescribed narcotics to treat chronic pain become addicted to the drugs, according to a new analysis of past research. The finding suggests that concerns about the risk of becoming addicted to prescription painkillers might be "overblown," said addiction specialist Dr. Michael Fleming at Northwestern University's Feinberg School of Medicine. "If you're a person that doesn't have a history of addiction and doesn't have any major psychiatric problems, narcotics are relatively safe as long as your doctor doesn't give you too much and uses the right medication," Fleming, who was not involved in the new study, told Reuters Health. Some recent research has concluded the same thing, but another expert remained skeptical about the new report because many of the studies it included were not considered the best quality research, and they varied widely in their results. Advertise | AdChoices "I think the jury's still out" on how worrisome prescription opioid addiction is, said Joseph Boscarino of the Geisinger Clinic in Danville, Pennsylvania, who studies pain and addiction. Opioid painkillers, which include oxycodone, fentanyl and morphine, have only recently become available for patients with chronic pain, said Boscarino, who was not part of the new study. © 2012 NBCNews.com
Why some people respond to treatments that have no active ingredients in them may be down to their genes, a study in the journal PLoS ONE suggests. The so-called "placebo effect" was examined in 104 patients with irritable bowel syndrome (IBS) in the US. Those with a particular version of the COMT gene saw an improvement in their health after placebo acupuncture. The scientists warn that while they hope their findings will be seen in other conditions, more work is needed. Edzard Ernst, a professor of complementary medicine at the University of Exeter, said: "This is a fascinating but very preliminary result. "It could solve the age-old question of why some individuals respond to placebo, while others do not. "And if so, it could impact importantly on clinical practice. "But we should be cautious - the study was small, we need independent replications, and we need to know whether the phenomenon applies just to IBS or to all diseases." Gene variants The placebo effect is when a patient experiences an improvement in their condition while undergoing an inert treatment such as taking a sugar pill or, in this case, placebo acupuncture, where the patient believes they are receiving acupuncture but a sham device prevents the needles going into their body. BBC © 2012
by Robert F. Service According to George Bernard Shaw: "The most intolerable pain is produced by prolonging the keenest pleasure." Not to be picky George, but actually both sensations result from the activity of a diverse family of proteins on the surface of cells. This year's Nobel Prize in chemistry was awarded to two Americans—Robert Lefkowitz of Duke University in Durham, North Carolina, and Brian Kobilka of Stanford University School of Medicine in Palo Alto, California—who revealed the inner workings of these proteins, which also orchestrate a variety of things such as the way we see, smell, taste, feel, and fight infections. The notion that a single family of proteins was responsible for so many different physiological processes was far from evident early on. One hint came at the end of the 19th century, when scientists studying the effects of the hormone adrenaline discovered that it had different effects in various parts of the body. It made heart rate and blood pressure increase, but it decreased digestive activity and caused pupils to relax. One idea was that proteins called receptors on different cells somehow captured adrenaline molecules and either ferried the hormone into cells or transferred a message inside to trigger a response. In the 1940s, an American biologist named Raymond Ahlquist made enough progress to conclude that there must be two types of adrenaline receptors, one that caused smooth muscle cells to contract, and the other that stimulated the heart. © 2010 American Association for the Advancement of Science
By Katherine Harmon A bite from the black mamba snake (Dendroaspis polylepis) can kill an adult human within 20 minutes. But mixed in with that toxic venom is a new natural class of compound that could be used to help develop new painkillers. Named “mambalgins,” these peptides block acute and inflammatory pain in mice as well as morphine does, according to a new study. Researchers, led by Sylvie Diochot, of the Institute of Molecular and Cellular Pharmacology at Nice University, Sophia Antipolis in France, purified the peptides from the venom and profiled the compounds’ structure. They then were able to test the mambalgins in strains of mice with various genetic tweaks to their pain pathways. Diochot and her colleagues determined that the mambalgins work by blocking an as-yet untargeted set of neurological ion channels associated with pain signals. The findings were published online October 3 in Nature (Scientific American is part of Nature Publishing Group). As a bonus, mambalgins did not have the risky side effect of respiratory depression that morphine does. And the mice developed less tolerance to them over time than is typical with morphine. Experimenting with the newfound compounds should also help researchers learn more about the mechanisms that drive pain. As the researchers noted in their paper, “It is essential to understand pain better to develop new analgesics. The black mamba peptides discovered here have the potential to address both of these aims.” © 2012 Scientific American,
By PAUL CHRISTOPHER, M.D. “I’m addicted to painkillers,” J., a thickset construction worker, told me on a recent afternoon in the emergency room, his wife at his side. Two years before, after months of pain, stiffness and swelling in his hands and neck, his primary physician had diagnosed rheumatoid arthritis and had prescribed three medications: two to slow the disease and one, oxycodone, for pain. Bolstered by the painkiller, J. had felt more limber and energetic than he had in years. “I could finally keep up with the other guys,” he told me. He worked harder, and his pain worsened. His primary physician increased the oxycodone dose. Soon, J. was looking forward more to the buzz than to the relief the pills brought. He went to see two other physicians who, unaware that he was double-dipping, prescribed similar medications. When a co-worker offered to sell him painkillers directly, J.’s use spiraled out of control. By the time I saw him, he was taking dozens of pills a day, often crushing and snorting them to speed the onset of his high. With remarkable candor, he described how the drugs had marred every facet of his life — from days of missed work to increasing debt, deteriorating health and marital strain. But when I listed the treatment options that might help, J. shook his head, looked from me to his wife, and got up. “I’m all set,” he said, holding up his hands. Then he walked out of the room. Despair fell on his wife’s face. “Please,” she said, grabbing my arm, “you can’t let him leave.” Copyright 2012 The New York Times Company
By Sandra G. Boodman, The 80th birthday party for Josephine van Es marked two milestones, only one of which was apparent at the time. Held in November 2004 at her daughter’s house in Rehoboth Beach, Del., the event was a celebration of her longevity, good health and loving family. It also marked one of the last times van Es can remember feeling well and not beset by the pain that developed soon afterward and has left the inside of her mouth feeling perpetually scalded and with a constant metallic taste. “It’s awful,” said van Es, 87, who says the burning is worse than the taste, which she likens to “sucking on a penny.” Her daughter Karen van Es says that her mother’s problem has taken a toll on both their lives. For nearly eight years, she has taken time from her job at a Northern Virginia veterinary clinic to ferry her mother, who lives independently in a condominium in Lewes, Del., to doctors in Delaware, Philadelphia and Washington. She also has contacted specialists in Florida and Canada hoping one would propose an effective remedy for an ailment that took more than a year to diagnose and has so far eluded treatment. “She tells me, ‘I just feel rotten all the time,’ ” said Karen van Es, 63, an only child who speaks to her mother every day and sees her often. “My mother has lost confidence as a result of this,” Karen van Es said, adding that she often feels helpless and frustrated about not being able to do more. © 1996-2012 The Washington Post