Chapter 5. The Sensorimotor System
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By Sheena Goodyear, A brain implant the size of a paper-clip might one day help paralyzed people regain the ability to use their arms and legs via a wireless connection that will transmit their thoughts to an exoskeleton. It's not the first technology to allow paralyzed people to operate mechanical limbs with signals from their brain, but it has the potential to revolutionize the field because it's minimally invasive and totally wireless. It's made possible because of a matchstick-sized implant called a stentrode, crafted from nitinol, an alloy that is commonly used in brassiere underwires and eyeglass frames, according to a study published in the journal Nature Biotechnology. "It's really a new method for getting brain data out of the brain without performing brain surgery," Thomas Oxley, a neurologist at the University of Melbourne who designed the device, told CBC News. "Part of the reason that brain-machine interfaces have not been successful to this point is because they get rejected by the body, and the reason they get rejected is because they all require direct implantation into the brain. And to do that you have to take off the skull — you have to perform a craniotomy." ©2016 CBC/Radio-Canada.
Link ID: 21886 - Posted: 02.11.2016
Jo Marchant The brain cells of people with Parkinson’s disease can be trained to reliably respond to placebo drugs, Italian neuroscientists report. The training wears off after 24 hours but the effect shows it may be possible to reduce the medication needed to treat Parkinson’s by interspersing real drugs with inert injections or pills, says placebo researcher Fabrizio Benedetti at the University of Turin, Italy, who led the work. A few people with Parkinson’s disease do respond dramatically to placebos, but most do not1. People with the condition suffer characteristic tremors and stiff muscles because their dopamine-producing brain cells are gradually dying off. They alleviate their symptoms by taking drugs such as apomorphine, which activate receptors for dopamine. For some conditions — such as pain and immune disorders — trials have shown2 that it is possible to train people to respond to placebos, although this practice hasn’t made its way into clinical care. Benedetti and his colleagues wondered whether the same effect might be possible for neurological disorders. They studied 42 people with advanced Parkinson’s disease who were having electrodes implanted into their brains for a therapy called deep brain stimulation, which eases symptoms by stimulating affected brain areas directly. That surgery gave Benedetti’s team a rare opportunity to measure the activity of individual neurons in the thalamus, a brain region known to be inhibited by lack of dopamine in people with Parkinson's. © 2016 Nature Publishing Grou
Link ID: 21884 - Posted: 02.10.2016
Colombia says three people have died after contracting the Zika virus and developing a rare nerve disorder. Health Minister Alejandro Gaviria said there was a "causal connection" between Zika, the Guillain-Barre disorder and the three deaths. Earlier, Brazilian scientists said they had detected for the first time active samples of Zika in urine and saliva. However, it is not clear whether the virus can be transmitted through bodily fluids. Zika, a mosquito-borne disease, has been linked to cases of babies born in Brazil with microcephaly - underdeveloped brains. "We have confirmed and attributed three deaths to Zika," said the head of Colombia's National Health Institute, Martha Lucia Ospina. "In this case, the three deaths were preceded by Guillain-Barre syndrome." Guillain-Barre is a rare disorder in which the body's immune system attacks part of the nervous system. It isn't normally fatal. Ms Ospina said another six deaths were being investigated for possible links to Zika. "Other cases (of deaths linked to Zika) are going to emerge," she said. "The world is realising that Zika can be deadly. The mortality rate is not very high, but it can be deadly." Mr Gaviria said one of the fatalities took place in San Andres and the other two in Turbo, in Antioquia department. UK virologist Prof Jonathan Ball, of the University of Nottingham, told the BBC: "We have been saying Zika has been associated with Guillain-Barre. One of the complications of that could be respiratory failure. But it is still probably a very rare event." Although Zika usually causes mild, flu-like symptoms, it has been linked to thousands of suspected birth defects. However, it has not yet been proved that Zika causes either microcephaly or Guillain-Barre. © 2016 BBC
Rare ‘allergy’ to vibrations tied to faulty gene By Kelly Servick If you have the rare condition known as vibratory urticaria, you may be wary of handling lawnmowers and electric mixers. Rubbing or vibration against your skin—even from drying off with a towel—can cause you to break out in hives, make your face flush, give you headaches, or produce the sensation of a metallic taste. The condition, which runs in families, is so rare that the researchers who work on it have only tracked down a few cases over years of searching. But a genetic study on three such unique families has revealed a potential mechanism for the strange symptoms. Research published online today in the New England Journal of Medicine describes a mutation in a gene called ADGRE2, found in 22 people with vibratory urticaria, but not in 14 of their unaffected relatives. The gene codes for a receptor protein that was found on the surface of mast cells—immune cells in the skin that dump out inflammatory molecules such as histamines that increase blood flow to an area and can cause hives. The researchers observed that shaking mast cells in a dish breaks apart two subunits of this receptor protein, which prompts histamine release. In people with the newly discovered mutation, the receptor is more prone to breakage, which causes this protective immune response at the site of physical trauma to run amok. © 2016 American Association for the Advancement of Science.
By Anne Pycha Future doctors may ask us to say more than “Ahhh.” Several groups of neuroscientists, psychiatrists and computer scientists are now investigating the extent to which patients' language use can provide diagnostic clues—before a single laboratory test is run. Increased computing power and new methods to measure the relation between behavior and brain activity have advanced such efforts. And although tests based on the spoken word may not be as accurate as gene sequencing or MRI scans, for diseases lacking clear biological indicators, language mining could help fill the gap. Psychiatrists at Columbia University interviewed 34 young adults at risk for psychosis, a common sign of schizophrenia that includes delusions and hallucinations. Two and a half years later five of the subjects had developed psychosis, and the remaining 29 remained free of the disorder. A specially designed algorithm combed the initial interviews collectively to look for language features that distinguished the two groups and found that psychosis correlated with shorter sentences, loss of flow in meaning from one sentence to the next and less frequent use of the words “that,” “what” and “which.” When later tested on each individual interview, the computer program predicted who did and who did not develop psychosis with 100 percent accuracy. The results were recently published in Schizophrenia, and a second round of testing with another group of at-risk subjects is now under way. Parkinson's Disease Twenty-seven subjects in a study at Favaloro University in Argentina listened to recorded sentences containing verbs associated with specific hand shapes (such as “applaud” or “punch”). As soon as they understood the sentence, participants pressed a button while keeping both hands in either a flat or clenched-fist position. © 2016 Scientific American
Videos just discovered show the first people ever to be treated for the symptoms of Parkinson’s disease. The footage, hidden for half a century, shows Chilean miners with severe movement problems improving on daily doses of L-dopa. The videos were filmed by George Cotzias at Brookhaven National Laboratory in Upton, New York. In 1963, while studying the toxic effects of manganese in human tissues, Cotzias learned of four workers in the Corral del Quemado mine in Andacollo, Chile, who had developed a syndrome called manganism – which resembled Parkinson’s – through inhaling manganese dust. Cotzias travelled to Chile to include the miners in a trial of leva-dopa, a chemical building block that the body converts into dopamine, low levels of which cause uncontrolled movements in people with Parkinson’s. L-dopa was being tested in Parkinson’s patients around the same time but with little success – even small amounts caused adverse side-effects that prevented a high enough dose reaching the brain. The footage clearly shows the severe problems with walking and turning miners had before treatment. After several months of receiving a daily dose of L-dopa, they were able to feed themselves, shave, tie their shoelaces, and run. “It’s a very important part of the history of neurology,” says Marcelo Miranda, a researcher at Clinica Las Condes in Santiago, Chile, who found the footage, some of which was shown at a conference in the 1960s, but hasn’t been seen since. “It’s the only available document of that period that shows the first patients with Parkinson’s symptoms treated with L-dopa and their extraordinary response.” © Copyright Reed Business Information Ltd.
Link ID: 21811 - Posted: 01.23.2016
A map for other people’s faces has been discovered in the brain. It could help explain why some of us are better at recognising faces than others. Every part of your body that you can move or feel is represented in the outer layer of your brain. These “maps”, found in the motor and sensory cortices (see diagram, below), tend to preserve the basic spatial layout of the body – neurons that represent our fingers are closer to neurons that represent our arms than our feet, for example. The same goes for other people’s faces, says Linda Henriksson at Aalto University in Helsinki, Finland. Her team scanned 12 people’s brains while they looked at hundreds of images of noses, eyes, mouths and other facial features and recorded which bits of the brain became active. This revealed a region in the occipital face area in which features that are next to each other on a real face are organised together in the brain’s representation of that face. The team have called this map the “faciotopy”. The occipital face area is a region of the brain known to be involved in general facial processing. “Facial recognition is so fundamental to human behaviour that it makes sense that there would be a specialised area of the brain that maps features of the face,” she says. © Copyright Reed Business Information Ltd.
The Chamorro people of the Pacific island of Guam know it as lytigo-bodig. For decades, they have been struck down by a mysterious illness that resembles the muscle-wasting disease amyotrophic lateral sclerosis (ALS), Parkinson’s disease and Alzheimer’s-like dementia. It now looks like we have a clue that could point to a way of slowing its development. Lytigo-bodig is a progressive disease. ALS symptoms arrive when people are in their mid-40s and early 50s. By the time they reach their 60s, they also have the shaking and lack of coordination that characterises Parkinson’s, before the cognitive problems associated with dementia also set in. “Initially they stumble a bit, but as their muscles wither, they need help with eating and going to the toilet, as well as having difficulty swallowing and breathing,” says Paul Cox of the Institute for Ethnomedicine in Wyoming. For a long time, a chemical called BMAA, found in the cycad seeds that the Chamorro grind up to make flour, has been suspected as the cause of the disease. The toxin builds up in the cyanobacteria that grow in the roots of cycad plants. It also accumulates in the tissue of seed-eating flying foxes, which the Chamorro hunt and eat. To see if they could confirm BMAA as the culprit, Cox fed fruit spiked with the toxin to vervet monkeys for 140 days. They estimated this was equivalent to the dose a typical islander might get over a lifetime. Although they didn’t show cognitive problems, the animals did develop brain abnormalities called tau tangles and deposits of amyloid plaque. The density and placement of these abnormalities were similar to those seen in the islanders. “The structure of the pathology is almost identical,” says Cox. “We were stunned.” © Copyright Reed Business Information Ltd.
By Ralph G. Neas In mid-February of 1979, I started experiencing tingling sensations in my feet and fingers. I told myself I was only feeling some residual effects from a bout with the flu several weeks before, and I caught the afternoon plane to Minneapolis to join my new boss, U.S. Sen. David Durenberger (R-Minn.), for several days of political meetings. That was on Sunday. On Tuesday, midway through a presentation, I began slurring my words and I found it hard to swallow. A local doctor, on hearing I’d had the flu, told me to go to my hotel room, take a couple of aspirin and call him in the morning. I spent the night moving from the bed to the couch to the chair to the floor, seeking relief from pain that was affecting more and more of my body. Just before dawn, I noticed that the right side of my face was paralyzed. On my way to the ER, the left side became paralyzed. I wasn’t having a recurrence of the flu. A spinal tap confirmed doctors’ suspicions that I’d come down with Guillain-Barré syndrome, or GBS, a rare neurological disorder that can cause total paralysis. Within 10 days I was so weakened by the spreading paralysis in my legs and arms that I could not get out of my bed at St. Mary’s, the Minneapolis hospital where I was being treated. Within three weeks, doctors performed a tracheostomy — connecting a mechanical respirator to my windpipe — because my ability to breathe was getting so poor.
Laura Sanders Pain can sear memories into the brain, a new study finds. A full year after viewing a picture of a random, neutral object, people could remember it better if they had been feeling painful heat when they first saw it. “The results are fun, they are interesting and they are provocative,” says neuroscientist A. Vania Apkarian of Northwestern University in Chicago. The findings “speak to the idea that pain really engages memory.” Neuroscientists G. Elliott Wimmer and Christian Büchel of University Medical Center Hamburg-Eppendorf in Germany reported the results in a paper online at BioRxiv.org first posted December 24 and revised January 6. The findings are under review at a journal, and Wimmer declined to comment on the study until it is accepted for publication. Wimmer and Büchel recruited 31 brave souls who agreed to feel pain delivered by a heat-delivering thermode on their left forearms. Each person’s pain sensitivity was used to calibrate the amount of heat they received in the experiment, which was either not painful (a 2 on an 8-point scale) or the highest a person could endure multiple times (a full 8). While undergoing a functional MRI scan, participants looked at a series of pictures of unremarkable household objects, such as a camera, sometimes feeling pain and sometimes not. Right after seeing the images, the people took a pop quiz in which they answered whether an object was familiar. Pain didn’t influence memory right away. Right after their ordeal, participants remembered about three-quarters of the previously seen objects, regardless of whether pain was present, the researchers found. © Society for Science & the Public 2000 - 2015.
Pete Etchells Autonomous Sensory Meridian Response, or ASMR, is a curious phenomenon. Those who experience it often characterise it as a tingling sensation in the back of the head or neck, or another part of the body, in response to some sort of sensory stimulus. That stimulus could be anything, but over the past few years, a subculture has developed around YouTube videos, and their growing popularity was the focus of a video posted on the Guardian this last week. It’s well worth a watch, but I couldn’t help but feel it would have been a bit more interesting if there had been some scientific background in it. The trouble is, there isn’t actually much research on ASMR out there. To date, only one research paper has been published on the phenomenon. In March last year, Emma Barratt, a graduate student at Swansea University, and Dr Nick Davis, then a lecturer at the same institution, published the results of a survey of some 500 ASMR enthusiasts. “ASMR is interesting to me as a psychologist because it’s a bit ‘weird’” says Davis, now at Manchester Metropolitan University. “The sensations people describe are quite hard to describe, and that’s odd because people are usually quite good at describing bodily sensation. So we wanted to know if everybody’s ASMR experience is the same, and of people tend to be triggered by the same sorts of things.” The study asked a range of questions about where, when and why people watch ASMR videos, whether there was any consistency in ASMR-triggering content, as well as whether individuals felt it had any effect on their mood. There was a remarkable consistency across participants in terms of triggering content – whispering worked for the majority of people, followed by videos involving some sort of personal attention, crisp sounds, and slow movements. For the most part, participants reported that they watched ASMR videos for relaxation purposes, or to help them sleep or deal with stress. © 2016 Guardian News and Media Limited
Keyword: Pain & Touch
Link ID: 21767 - Posted: 01.09.2016
By Emily Underwood As long as she can remember, 53-year-old Rosa Sundquist has tallied the number of days per month when her head explodes with pain. The migraines started in childhood and have gotten worse as she’s grown older. Since 2008, they have incapacitated her at least 15 days per month, year-round. Head-splitting pain isn’t the worst of Sundquist’s symptoms. Nausea, vomiting, and an intense sensitivity to light, sound, and smell make it impossible for her to work—she used to be an office manager—or often even to leave her light-proofed home in Dumfries, Virginia. On the rare occasions when she does go out to dinner or a movie with her husband and two college-aged children, she wears sunglasses and noise-canceling headphones. A short trip to the grocery store can turn into a full-blown attack “on a dime,” she says. Every 10 weeks, Sundquist gets 32 bee sting–like injections of the nerve-numbing botulism toxin into her face and neck. She also visits a neurologist in Philadelphia, Pennsylvania, who gives her a continuous intravenous infusion of the anesthetic lidocaine over 7 days. The lidocaine makes Sundquist hallucinate, but it can reduce her attacks, she says—she recently counted 20 migraine days per month instead of 30. Sundquist can also sometimes ward off an attack with triptans, the only drugs specifically designed to interrupt migraines after they start. Millions of others similarly dread the onset of a migraine, although many are not afflicted as severely as Sundquist. Worldwide, migraines strike roughly 12% of people at least once per year, with women roughly three times as likely as men to have an attack. © 2016 American Association for the Advancement of Science.
By Stephani Sutherland A technique called optogenetics has transformed neuroscience during the past 10 years by allowing researchers to turn specific neurons on and off in experimental animals. By flipping these neural switches, it has provided clues about which brain pathways are involved in diseases like depression and obsessive-compulsive disorder. “Optogenetics is not just a flash in the pan,” says neuroscientist Robert Gereau of Washington University in Saint Louis. “It allows us to do experiments that were not doable before. This is a true game changer like few other techniques in science.” Since the first papers were published on optogenetics in the mid-aughts some researchers have mused about one day using optogenetics in patients, imagining the possibility of an off-switch for depression, for instance. The technique, however, would require that a patient submit to a set of highly invasive medical procedures: genetic engineering of neurons to insert molecular switches to activate or switch off cells, along with threading of an optical fiber into the brain to flip those switches. Spurred on by a set of technical advances, optogenetics pioneer Karl Deisseroth, together with other Stanford University researchers, has formed a company to pursue optogenetics trials in patients within the next several years—one of several start-ups that are now contemplating clinical trials of the technique. Circuit Therapeutics, founded in 2010, is moving forward with specific plans to treat neurological diseases. (It also partners with pharmaceutical companies to help them use optogenetics in animal research to develop novel drug targets for human diseases.) © 2016 Scientific America
Keyword: Pain & Touch
Link ID: 21758 - Posted: 01.07.2016
By NICHOLAS WADE After decades of disappointingly slow progress, researchers have taken a substantial step toward a possible treatment for Duchenne muscular dystrophy with the help of a powerful new gene-editing technique. Duchenne muscular dystrophy is a progressive muscle-wasting disease that affects boys, putting them in wheelchairs by age 10, followed by an early death from heart failure or breathing difficulties. The disease is caused by defects in a gene that encodes a protein called dystrophin, which is essential for proper muscle function. Because the disease is devastating and incurable, and common for a hereditary illness, it has long been a target for gene therapy, though without success. An alternative treatment, drugs based on chemicals known as antisense oligonucleotides, is in clinical trials. But gene therapy — the idea of curing a genetic disease by inserting the correct gene into damaged cells — is making a comeback. A new technique, known as Crispr-Cas9, lets researchers cut the DNA of chromosomes at selected sites to remove or insert segments. Three research groups, working independently of one another, reported in the journal Science on Thursday that they had used the Crispr-Cas9 technique to treat mice with a defective dystrophin gene. Each group loaded the DNA-cutting system onto a virus that infected the mice’s muscle cells, and excised from the gene a defective stretch of DNA known as an exon. Without the defective exon, the muscle cells made a shortened dystrophin protein that was nonetheless functional, giving all of the mice more strength. The teams were led by Charles A. Gersbach of Duke University, Eric N. Olson of the University of Texas Southwestern Medical Center and Amy J. Wagers of Harvard University. © 2016 The New York Times Company
Tina Hesman Saey SAN DIEGO — Friendly ghosts help muscles heal after injury. Connective tissue sheaths that bundle muscle cells together leave behind hollow fibers when muscles are injured, Micah Webster of the Carnegie Institution for Science in Baltimore and colleagues discovered. Muscle-repairing stem cells build new tissue from inside those empty tunnels, known as ghost fibers, Webster reported December 13 at the annual meeting of the American Society for Cell Biology. Researchers previously knew that stem cells can heal muscle, but how stem cells integrate new cells into muscle fibers has been a mystery. Webster and colleagues used a special microscopy technique to watch stem cells in live mice as the cells fixed muscles damaged by snake venom. Stem cells from undamaged parts of the muscle fiber crawled back and forth through the ghostly part of the fibers and spaced themselves out evenly. Stem cells replicated themselves to reconstruct each muscle fiber inside its ghostly shell the researchers found. Stem cells didn’t move from one ghost fiber to another. The finding suggests that researchers will need to create artificial ghost fibers to repair injuries in which chunks of muscles are lost, such as in soldiers hit by explosives, Webster said. The researchers also reported the results online December 10 in Cell Stem Cell. M.T. Webster et al. Intravital imaging reveals ghost fibers as architectural units guiding muscle progenitors. Annual meeting of the American Society for Cell Biology, San Diego, December 13, 2015. M.T. Webster et al. Intravital imaging reveals ghost fibers as architectural units guiding myogenic progenitors during regeneration. Cell Stem Cell. Published online December 10, 2015. doi: 10.1016/j.stem.2015.11.005 © Society for Science & the Public 2000 - 2015
Link ID: 21704 - Posted: 12.16.2015
The clock is ticking for Ronald Cohn. He wants to use CRISPR gene editing to correct the genes of his friend’s 13-year-old son. The boy, Gavriel, has Duchenne muscular dystrophy, a genetic disease in which muscles degenerate. Breathing and heart problems often start by the time people with the condition are in their early twenties. Life expectancy is about 25 years. By the standards of science, the field of CRISPR gene editing is moving at a lightning fast pace. Although the technique was only invented a few years ago, it is already being used for research by thousands of labs worldwide to make extremely precise changes to DNA. A handful of people have already been treated using therapies enabled by the technology, and last week an international summit effectively endorsed the idea of gene editing embryos. It is too soon to try the technique out, but the summit concluded that basic research on embryos should be permitted, alongside a debate on how we should use the technology. But for people like Cohn, progress can’t come fast enough. Gavriel was diagnosed at age 4. He has already lost the use of his legs but still has some movement in his upper body, and uses a manual wheelchair. Cohn, a clinician at the Hospital for Sick Children in Toronto, estimates that he has three years to develop and test a CRISPR-based treatment if he is to help Gavriel. Muscular dystrophy is caused by a faulty gene for the protein dystrophin, which holds our muscles together. Gavriel has a duplicated version of the gene. This week, Cohn’s team published a paper describing how they grew Gavriel’s cells in a dish and used CRISPR gene-editing techniques to snip out the duplication. With the duplication removed, his cells produced normal dystrophin protein. © Copyright Reed Business Information Ltd.
By Gretchen Reynolds Physical fitness may be critical for maintaining a relatively youthful and nimble brain as we age, according to a new study of brain activation patterns in older people. For most of us, our bodies begin to lose flexibility and efficiency as we enter our 40s. Running and other movements slow down and become more awkward, and something similar seems to occur within our heads. As middle age encroaches, our thinking becomes less efficient. We don’t toggle between mental tasks as nimbly as we once did or process new information with the same aplomb and clarity. Recently, neuroscientists have begun to quantify how those cognitive changes play out in our brains, to disquieting effect. In studies comparing brain activation in young people with that of people past 40, they have found notable differences, especially during mental tasks that require attention, problem solving, decision-making and other types of high-level thinking. Such thinking primarily involves activation of the brain’s prefrontal cortex. In young people, activation in the cortex during these cognitive tasks tends to be highly localized. Depending on the type of thinking, young people’s brains light up almost exclusively in either the right or left portion of the prefrontal cortex. But in older people, studies show, brain activity during the same mental tasks requires far more brainpower. They typically display activity in both hemispheres of their prefrontal cortex. In effect, they require more of their brains’ resources to complete the same tasks that young people do with less cognitive effort. Neuroscientists coined an acronym for this phenomenon: Harold, for hemispheric asymmetry reduction in older adults. Most agree that it represents a general reorganization and weakening of the brain’s function with age. © 2015 The New York Times Company
by Chris Samoray Every fall, blackpoll warblers fly from North America to South America in what’s the longest migration route of any warbler in the Western Hemisphere. But some of the tiny songbirds take a detour before making their epic transoceanic leap. Over 40 years of data from 22,295 birds show that blackpoll warblers (Setophaga striata) living in western North America head east for a pit stop to put on weight, giving the birds the energy stores they need to cross the Atlantic Ocean, researchers report December 9 in the Auk: Ornithological Advances. For birds that breed farther west in places like Alaska, the eastern stopover means a migration distance that’s nearly twice that of their eastern U.S. counterparts, the scientists find. © Society for Science & the Public 2000 - 2015.
Keyword: Animal Migration
Link ID: 21687 - Posted: 12.10.2015
By SINDYA N. BHANOO Moderate levels of exercise may increase the brain’s flexibility and improve learning, a new study suggests. The visual cortex, the part of the brain that processes visual information, loses the ability to “rewire” itself with age, making it more difficult for adults to recover from injuries and illness, said Claudia Lunghi, a neuroscientist at the University of Pisa and one of the study’s authors. In a study in the journal Current Biology, she and her colleagues asked 20 adults to watch a movie with one eye patched while relaxing in a chair. Later, the participants exercised on a stationary bike for 10-minute intervals while watching a movie. When one eye is patched, the visual cortex compensates for the limited input by increasing its activity level. Dr. Lunghi and her colleagues tested the imbalance in strength between the participants’ eyes after the movie — a measure of changeability in the visual cortex. © 2015 The New York Times Company
Link ID: 21681 - Posted: 12.08.2015
A woman born incapable of feeling pain has been hurt for the first time – thanks to a drug normally prescribed for opioid overdoses. She was burned with a laser, and quite liked the experience. The breakthrough may lead to powerful new ways to treat painful conditions such as arthritis. Only a handful people around the world are born unable to feel pain. These individuals can often suffer a range of injuries when they are young. Babies with the condition tend to chew their fingers, toes and lips until they bleed, and toddlers can suffer an increased range of knocks, tumbles and encounters with sharp or hot objects. The disorder is caused by a rare genetic mutation that results in a lack of ion channels that transport sodium across sensory nerves. Without these channels, known as Nav1.7 channels, nerve cells are unable to communicate pain. Researchers quickly sought to make compounds that blocked Nav1.7 channels, thinking they might be able to block pain in people without the disorder. “It looked like a fantastic drug target,” says John Wood at University College London. “Pharma companies went bananas and made lots of drugs.” But while a few compounds saw some success, none brought about the total pain loss seen in people who lack the channel naturally. © Copyright Reed Business Information Ltd.