Chapter 8. General Principles of Sensory Processing, Touch, and Pain
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By ABIGAIL ZUGER, M.D. I hadn’t seen Larry in a dozen years when he reappeared in my office a few months ago, grinning. We were both grinning. I always liked Larry, even though he was a bit of a hustler, a little erratic in his appointments, a persistent dabbler in a variety of illegal substances. But he was always careful to avoid the hard stuff; he said he had a bad problem as a teenager and was going to stay out of trouble. It was to stay out of trouble that he left town all those years ago, and now he was back, grayer and thinner but still smiling. Then he pulled out a list of the medications he needed, and we both stopped smiling. According to Larry’s list, he was now taking giant quantities of one of the most addictive painkillers around, an immensely popular black-market drug most doctors automatically avoid prescribing except under the most exceptional circumstances. “I got a bad back now, Doc,” Larry said. Doctors hate pain. Let me count the ways. We hate it because we are (mostly) kindhearted and hate to see people suffer. We hate it because it is invisible, cannot be measured or monitored, and varies wildly and unpredictably from person to person. We hate it because it can drag us closer to the perilous zones of illegal practice than any other complaint. And we hate it most of all because unless we specifically seek out training in how to manage pain, we get virtually none at all, and wind up flying over all kinds of scary territory absolutely solo, without a map or a net. Copyright 2013 The New York Times Company
Roberta Kwok Sitting motionless in her wheelchair, paralysed from the neck down by a stroke, Cathy Hutchinson seems to take no notice of the cable rising from the top of her head through her curly dark hair. Instead, she stares intently at a bottle sitting on the table in front of her, a straw protruding from the top. Her gaze never wavers as she mentally guides a robot arm beside her to reach across the table, close its grippers around the bottle, then slowly lift the vessel towards her mouth. Only when she finally manages to take a sip does her face relax into a luminous smile. This video of 58-year-old Hutchinson illustrates the strides being taken in brain-controlled prosthetics1. Over the past 15 years, researchers have shown that a rat can make a robotic arm push a lever2, a monkey can play a video game3 and a person with quadriplegia — Hutchinson — can sip from a bottle of coffee1, all by simply thinking about the action. Improvements in prosthetic limbs have been equally dramatic, with devices now able to move individual fingers and bend at more than two dozen joints. But Hutchinson's focused stare in that video also illustrates the one crucial feature still missing from prosthetics. Her eyes could tell her where the arm was, but she could not feel what it was doing. Nor could she sense when the grippers touched the bottle, or whether it was slipping out of their grasp. Without this type of sensory feedback, even the simplest actions can be slow and clumsy, as Igor Spetic of Madison, Ohio, knows well. Fitted with a prosthetic after his right hand was crushed in an industrial accident in 2010, Spetic describes breaking dishes, grabbing fruit too hard and bruising it and dropping a can when trying to pick it up at the local shop. Having a sense of touch would be “tremendous”, he says. “It'd be one step closer to having the hand back.” © 2013 Nature Publishing Group,
By Stephani Sutherland Itching is not the only sensation to arise from unique neurons. A team at the California Institute of Technology has identified neurons that transmit the pleasurable sensations of massage, at least in mice. The cells responded to gentle rubbing but not to pinching or poking. Activation of the cells requires “a pressure component,” says lead investigator David Anderson, a neuroscientist at Caltech, “much like you would apply if you were stroking your cat.” The team first identified the mysterious cells several years ago by an unusual protein on their surface called MrgprB4—closely related to the receptor expressed by the newly identified itch cells. The rare sensory cells make up only about 2 percent of the body's peripheral neurons that respond to external stimuli, but they seem to cover about half the skin's surface with large, branching nerve endings. Whereas sensory neurons that transmit pain have been intensely studied, this is the first demonstration in live animals of a sensory cell that gives pleasure. After the scientists activated those neurons with a designer drug, the mice came to favor the place where they received the drug, according to the paper published January 31 in Nature. © 2013 Scientific American
Keyword: Pain & Touch
Link ID: 18092 - Posted: 04.30.2013
By R. Douglas Fields Scientists have speculated that it is a mild manifestation of pain or perhaps a malfunction of overly sensitive nerve endings stuck in a feedback loop. They have even wondered whether itching is mostly psychological (just think about bed bugs for a minute). Now a study rules out these possibilities by succeeding where past attempts have failed: a group of neuroscientists have finally isolated a unique type of nerve cell that makes us itch and only itch. In previous research, neuroscientists Liang Han and Xinzhong Dong of Johns Hopkins University and their colleagues determined that some sensory neurons with nerve endings in the skin have a unique protein receptor on them called MrgprA3. They observed under a microscope that chemicals known to create itching caused these neurons to generate electrical signals but that painful stimuli such as hot water or capsaicin, the potent substance in hot peppers, did not. In the new study published in Nature Neuroscience, the researchers used genetic engineering to selectively kill the entire population of MrgprA3 neurons in mice while leaving all the other sensory neurons intact. These mice no longer scratched themselves when exposed to itchy substances or allergens, but they showed no changes at all in responding to touch or pain-producing stimulation. The mice's behavior confirms that MrgprA3-containing neurons are essential for itch, but it does not rule out the possibility that these cells might respond to other sensations as well. To find out, the neuroscientists engineered a receptor that responds to capsaicin injected into the MrgprA3 neurons, in a type of mouse that lacks the capsaicin receptor in all its other cells. Now the only neurons that would be stimulated by capsaicin were the MrgprA3 neurons. If these cells are indeed itch-specific, injecting capsaicin into a tiny spot on the mouse's skin should make the rodent scratch instead of wincing in pain—which is exactly what happened. © 2013 Scientific American,
Keyword: Pain & Touch
Link ID: 18066 - Posted: 04.24.2013
By Sandra G. Boodman, For someone who had been such a healthy child, Nancy Kennedy couldn’t figure out how she had become the kind of sickly adult whose life revolved around visits to a seemingly endless series of doctors. Beginning in 2005, shortly after a job transfer took her from Northern Virginia to St. Louis, Kennedy, then 47, developed a string of vexing medical problems. Her white blood cell count was inexplicably elevated. Her sinuses were chronically infected, although her respiratory tract seemed unusually dry. She often felt fatigued, and her joints hurt. “It felt as though an alien had invaded my body,” said Kennedy, formerly a manager at the National Geospatial-Intelligence Agency. “I felt like I was in doctors’ offices all the time.” Tests for possible ailments — including blood disorders, cancer, multiple sclerosis and rheumatoid arthritis — were negative. For seven years. Kennedy and her primary-care physician, who said she felt as though she sent Kennedy to “every specialist that walked,” had no clear idea what might be wrong. But during a physical in January 2012, her doctor, Melissa Johnson, struck by Kennedy’s trouble walking and her accelerating deterioration, decided to check for a condition not previously considered. © 1996-2013 The Washington Post
By Gary Stix People who lose a limb often experience the sensation of still having the missing arm or leg. Phantom limbs, in fact, have spurred a whole line of independent research among neuroscientists. But it appears that all of us may be capable of these sensations, even if arms and legs remain intact. If we can conjure a phantom limb just like that, it raises all kinds of enticing questions for philosophers as well as scientists about what exactly constitutes our perception of the physical self. Karolinska Institute researchers report online in the Journal of Cognitive Neuroscience that they can induce a sensation of a phantom hand in just a short time. Watch this simple experiment here: © 2013 Scientific American
Keyword: Pain & Touch
Link ID: 18036 - Posted: 04.15.2013
by Patrick Russell Many people who have had a limb amputated report feeling sensations that appear to come from their missing arm or leg. Now researchers have found that anyone can experience having such a phantom limb. "Previous research shows that you can convince a person that a rubber hand is their own by putting it on a table in front of them and stroking it in synchrony with their real hand," explains Arvid Guterstam at the Karolinska Institute in Stockholm, Sweden, who led the study. The illusion does not work with a block of wood, he says. "But our study shows that if you take away this rubber hand, people will attribute sensations to an invisible entity." Guterstam and his colleagues made volunteers sit at a table with their right arm hidden from view behind a screenMovie Camera. An experimenter then applied brush strokes to the concealed hand and, simultaneously, to a portion of empty space in full view of each volunteer. "We discovered that most participants, within less than a minute, transfer the sensation of touch to the region of empty space where they see the paintbrush move, and experience an invisible hand in that position," says Guterstam. Mock stabbing Experimenters also mimicked stabbing the phantom hand with a kitchen knife, while monitoring volunteers' stress level. To minimise any effect related to seeing the knife for the first time, the volunteers were warned that it would be used at some point. The researchers found that during the mock stabbing, stress levels, measured using a type of sweat test, went up in about 75 per cent of the 234 participants. © Copyright Reed Business Information Ltd.
by Helen Shen A thermometer is great for measuring a fever, but when it comes to pain, doctors must rely on the age-old question, "How bad is it?" Scientists have long struggled to find physiological signs that can reliably tell "ouch" from "@#%!" and everything in between. Now, a brain scanning study suggests that painful heat excites a specific pattern of neural activity that could hold the key to better diagnosis and treatment of all kinds of pain in the future. Functional magnetic resonance imaging (fMRI) studies have shown that certain areas of the brain—including the anterior cingulate cortex, somatosensory cortex, and thalamus—activate when people experience pain. But those same regions also light up in response to other experiences, such as painful thoughts or social rejection. In recent years, scientists have looked for a particular pattern of activity across these areas that single out the experience of physical pain. "What we're evolving towards is trying to predict quantitatively from patterns of brain activity how much an individual is feeling," says Tor Wager, a neuroscientist at the University of Colorado, Boulder. In the new study, Wager's group performed fMRI brain scans on a total of 114 healthy participants while delivering different amounts of heat to the volunteers' arms with a computer-controlled hot plate. In an initial experiment, the scientists used data from 20 people to find a brain-wide pattern of excitation and inhibition—a neural "signature"—that changed reliably as people experienced varying degrees of heat, ranging from painless to scalding. In the remainder of the study, Wager and his colleagues were able use the signature derived from the first group to predict pain responses in a completely different set of subjects—a promising sign for one day using such a model on patients suffering from unknown conditions, he says. © 2010 American Association for the Advancement of Science.
Ed Yong Every autumn, millions of monarch butterflies (Danaus plexippus) converge on a small cluster of Mexican mountains to spend the winter. They have journeyed for up to 4,000 kilometres from breeding grounds across eastern North America. And according to a study, they accomplish this prodigious migration without ever knowing where they are relative to their destination. The monarchs can use the position of the Sun as a compass, but when Henrik Mouritsen, a biologist at the University of Oldenburg in Germany, displaced them by 2,500 kilometres, he found that they did not correct their heading. “People seemed to assume that they had some kind of a map that allowed them to narrow in on a site a few kilometres across after travelling several thousands of kilometres,” he says. Now, “it is clear that they don’t”. His results are published in the Proceedings of the National Academy of Sciences1. For more than five decades, scientists have teamed up with amateurs to tag and monitor free-flying monarchs, creating a database of their migrations. When Mouritsen analysed these records, he realized that the monarchs tend to spread out over the course of their migration. Their distribution was a good fit with the predictions of a mathematical model that assumed that the monarchs were flying with just a compass, rather than a compass and a map. Mouritsen also captured 76 southwesterly flying monarchs from fields near Guelph in Ontario, Canada, and transported them 2,500 kilometres to the west, to Calgary in the Canadian province of Alberta. He placed the butterflies in a “flight simulator” — a plastic cylinder that kept them from seeing any landmarks except the sky — and tethered them to a rod that let them point in any direction without actually flying away. © 2013 Nature Publishing Group
Keyword: Animal Migration
Link ID: 18013 - Posted: 04.10.2013
by Sid Perkins The electric fields that build up on honey bees as they fly, flutter their wings, or rub body parts together may allow the insects to talk to each other, a new study suggests. Tests show that the electric fields, which can be quite strong, deflect the bees' antennae, which, in turn, provide signals to the brain through specialized organs at their bases. Scientists have long known that flying insects gain an electrical charge when they buzz around. That charge, typically positive, accumulates as the wings zip through the air—much as electrical charge accumulates on a person shuffling across a carpet. And because an insect's exoskeleton has a waxy surface that acts as an electrical insulator, that charge isn't easily dissipated, even when the insect lands on objects, says Randolf Menzel, a neurobiologist at the Free University of Berlin in Germany. Although researchers have suspected for decades that such electrical fields aid pollination by helping the tiny grains stick to insects visiting a flower, only more recently have they investigated how insects sense and respond to such fields. Just last month, for example, a team reported that bumblebees may use electrical fields to identify flowers recently visited by other insects from those that may still hold lucrative stores of nectar and pollen. A flower that a bee had recently landed on might have an altered electrical field, the researchers speculated. Now, in a series of lab tests, Menzel and colleagues have studied how honey bees respond to electrical fields. In experiments conducted in small chambers with conductive walls that isolated the bees from external electrical fields, the researchers showed that a small, electrically charged wand brought close to a honey bee can cause its antennae to bend. Other tests, using antennae removed from honey bees, indicated that electrically induced deflections triggered reactions in a group of sensory cells, called the Johnston's organ, located near the base of the antennae. In yet other experiments, honey bees learned that a sugary reward was available when they detected a particular pattern of electrical field. © 2010 American Association for the Advancement of Science
By Sandra G. Boodman, A year after her daughter’s stomach problems began, Margaret Kaplow began having pains of her own. When she sat down to dinner with her family, Kaplow’s gut would clench involuntarily as she waited to see if this was one of the nights Madeline would eat a few bites before putting down her fork, pushing away from the table and announcing, “I don’t feel good.” For nearly six years, Maddie Kaplow’s severe, recurrent abdominal pain, which began shortly before her 13th birthday, was attributed to a host of ailments. Specialists in the District, Maryland and Virginia decided at various times that she had a gluten intolerance, a ruptured ovarian cyst, a diseased appendix or irritable bowel syndrome (IBS). Some were convinced that her problem was psychological and that she was a high-strung teenaged girl seeking attention. “It was a freaking nightmare,” Kaplow recalled of those years. She said she never believed her daughter was exaggerating or faking her symptoms. And each time a new diagnosis was made, Kaplow said, she felt elated that a doctor had figured out the cause of Maddie’s pain, which would turn into crushing disappointment when it recurred. It was only after she landed in a college infirmary 400 miles from her Northern Virginia home that doctors finally determined what was wrong and treated Maddie for the illness that dominated her adolescence. © 1996-2013 The Washington Post
Keyword: Pain & Touch
Link ID: 17948 - Posted: 03.26.2013
by Audrey Carlsen Plenty of us got our fill of green-colored food on St. Patrick's Day. (Green beer, anyone?) But for some people, associating taste with color is more than just a once-a-year experience. These people have synesthesia — a neurological condition in which stimulation of one sense (e.g., taste) produces experiences in a totally different sense (e.g., sight). According to researcher Sean Day, approximately one in 27 people has some form of synesthesia. We've covered this phenomenon in the past. And I'm a synesthete myself — I see letters and numbers in color, and associate sounds with shapes and textures. But only a very few people — maybe only 1 percent of synesthetes — have sensory crossovers that affect their relationship with food and drink. Jaime Smith is one of those people. He's a sommelier by trade, and he has a rare gift: He smells in colors and shapes. For Smith, who lives in Las Vegas, a white wine like Nosiola has a "beautiful aquamarine, flowy, kind of wavy color to it." Other smells also elicit three-dimensional textures and colors on what he describes as a "projector" in his mind's eye. This "added dimension," Smith says, enhances his ability to appraise and analyze wines. "I feel that I have an advantage over a lot of people, particularly in a field where you're judged on how good of a smeller you are," he says. ©2013 NPR
By LAURIE EDWARDS TO the list of differences between men and women, we can add one more: the drug-dose gender gap. Doctors and researchers increasingly understand that there can be striking variations in the way men and women respond to drugs, many of which are tested almost exclusively on males. Early this year, for instance, the Food and Drug Administration announced that it was cutting in half the prescribed dose of Ambien for women, who remained drowsy for longer than men after taking the drug. Women have hormonal cycles, smaller organs, higher body fat composition — all of which are thought to play a role in how drugs affect our bodies. We also have basic differences in gene expression, which can make differences in the way we metabolize drugs. For example, men metabolize caffeine more quickly, while women metabolize certain antibiotics and anxiety medications more quickly. In some cases, drugs work less effectively depending on sex; women are less responsive to anesthesia and ibuprofen for instance. In other cases, women are at more risk for adverse — even lethal — side effects. These differences are particularly important for the millions of women living with chronic pain. An estimated 25 percent of Americans experience chronic pain, and a disproportionate number of them are women. A review published in the Journal of Pain in 2009 found that women faced a substantially greater risk of developing pain conditions. They are twice as likely to have multiple sclerosis, two to three times more likely to develop rheumatoid arthritis and four times more likely to have chronic fatigue syndrome than men. As a whole, autoimmune diseases, which often include debilitating pain, strike women three times more frequently than men. © 2013 The New York Times Company
By Stephani Sutherland Treating the brain with magnets went mainstream a few years ago, when the technique proved successful at relieving major depression. Now the procedure, repetitive transcranial magnetic stimulation (rTMS), shows promise for another mysterious, hard-to-treat disorder: chronic pain. Until now, pain seemed out of reach for rTMS because the regions involved in pain perception lie very deep within the brain. The other disorders helped by rTMS all involve brain areas close to the skull. To treat depression, for example, a single magnetic coil directs a magnetic field at the dorsolateral prefrontal cortex, a region of the brain's outer folds. When aimed at different areas of these outer folds, rTMS improves the motor symptoms of Parkinson's disease, staves off the damage of stroke, lessens the discomfort that follows nerve injury and treats obsessive-compulsive disorder. The magnetic field affects the electrical signaling used by neurons to communicate, but how exactly it improves symptoms is unclear—scientists suspect rTMS may redirect the activity of select cells or even entire brain circuits. To extend the technique's reach, David Yeomans, a neuroscientist at Stanford University, and his colleagues used four magnets rather than one and employed high-level math to steer the resulting complex fields. Their target was an area called the anterior cingulate cortex (ACC), an area active in the experience of all types of pain, regardless of its source or nature. © 2013 Scientific American
Keyword: Pain & Touch
Link ID: 17909 - Posted: 03.18.2013
By Maria Konnikova Georg Tobias Ludwig Sachs was born on April 22, 1786, in the mountain village of St. Ruprecht, Kärnthen, or Carinthia – the south of present-day Austria. From the first, he was notably different from his parents and siblings: he was an albino. (His youngest sister, eleven years his junior, would be one as well.) We don’t know if this physical distinction had any negative impact on the young Georg—but it certainly piqued his curiosity. He proceeded to embark on the scientific study of albinism at the universities in Tübingen, Altdorf, and Erlangen, and at the last of these, produced his 1812 doctoral dissertation. It was about albinism: “A Natural History of Two Albinos, the Author and His Sister.” Today, though, Sachs is remembered not for his thoughts on the nature of the albino, but rather those on another curious condition that was far less noticeable—but received a chapter of its very own in his thesis all the same: synesthesia. Georg Sachs just so happens to be the first known synesthete in the medical or psychological literature. Synesthesia means, literally, a cross-mingling of the senses, when two or more senses talk to each other in a way that is not usually associated with either sense on its own. For instance, you see color when you listen to a song on the radio. Taste shapes as you take a bite of your spaghetti. Frown at the 3 on that piece of paper because it’s giving you attitude—it seems irritable. Smile at the woman you just met because her name comes with a beautiful orange glow. The variations are many, but in every scenario, there is a sensory cross-talk that reaches to a neural level. As in, if I were to put you in a scanner while you took that bite or listened to that musical composition, the relevant areas of the brain would light up: your brain would actually be experiencing color, shape, or whatever you say you’re experiencing as if you were exposed to that very stimulus. It’s a condition that affects, by the most recent estimates, roughly 4% of the population. © 2013 Scientific American
Link ID: 17854 - Posted: 02.27.2013
by Julia Sklar IT IS a nightmare situation. A person diagnosed as being in a vegetative state has an operation without anaesthetic because they cannot feel pain. Except, maybe they can. Alexandra Markl at the Schön clinic in Bad Aibling, Germany, and colleagues studied people with unresponsive wakefulness syndrome (UWS) – also known as vegetative state – and identified activity in brain areas involved in the emotional aspects of pain. People with UWS can make reflex movements but can't show subjective awareness. There are two distinct neural networks that work together to create the sensation of pain. The more basic of the two – the sensory-discriminative network – identifies the presence of an unpleasant stimulus. It is the affective network that attaches emotions and subjective feelings to the experience. Crucially, without the activity of the emotional network, your brain detects pain but won't interpret it as unpleasant. Using PET scans, previous studies have detected activation in the sensory-discriminative network in people with UWS but their findings were consistent with a lack of subjective awareness, the hallmark of the condition. Now Markl and her colleagues have found evidence of activation in the affective or emotional network too (Brain and Behavior, doi.org/kfs). © Copyright Reed Business Information Ltd.
By Susan Milius Slight electric fields that form around flowers may lure pollinators much as floral colors and fragrances do. In lab setups, bumblebees learned to distinguish fake flowers by their electrical fields, says sensory biologist Daniel Robert at the University of Bristol in England. Combining an electrical charge with a color helped the bees learn faster, Robert and his colleagues report online February 21 in Science. Plants, a bit like lightning rods, tend to conduct electrical charges to the ground, Robert says. And bees pick up a positive charge from the atmosphere’s invisible rain of charged particles. “Anything flying through the air, whether it’s a baseball, 767 jumbo jet, or a bee, acquires a strong positive electrostatic charge due to interaction with air molecules,” says Stephen Buchmann of the University of Arizona in Tucson. Robert and his colleagues checked whether bees could choose flowers based solely on the electric fields the plants produce. Purple metal disks (encased in plastic so as not to shock bees) stood in for flowers. Half of them, wired for 30 volts, held sips of sugar water. The unwired ones offered a bitter quinine solution that bees don’t like. Bombus terrestris bumblebees learned to choose sweet, wired disks more than 80 percent of the time. When researchers unplugged the wired disks, the bees bumbled, scoring sugar only by chance. © Society for Science & the Public 2000 - 2013
Link ID: 17832 - Posted: 02.23.2013
By Sandra G. Boodman, Ian Liu’s back was killing him — and no matter what he tried, it wasn’t getting better. The 39-year-old Coast Guard officer assumed he had wrenched his back caring for his infant son, not surprising given his long history of lower back problems. But this time, the pain was much more intense and persistent, and neither physical therapy nor painkillers seemed to help. For more than a month, Liu shuttled between two Washington area military hospitals, searching for an explanation and, especially, relief. “It was the worst pain I’d ever had,” Liu recalled. A series of tests failed to explain his deteriorating condition, which stumped the medical personnel who treated him. It was only after Liu’s wife confided that he sometimes seemed disoriented that a doctor looked beyond the obvious problem and discovered the source of Liu’s pain. The cause turned out to be unrelated to his orthopedic history — and far more serious than a bad back. Liu first noticed the pain on a Friday night, Dec. 3, 2004, after he finished bathing the youngest of his three sons. “I assumed it was just from bending over the tub,” recalled Liu, who figured it would improve with time, as such problems had in the past. But the next day, his pain was worse, and as he wheeled his shopping cart around a Northern Virginia commissary, Liu was glad he had something to lean on. © 1996-2013 The Washington Post
Keyword: Pain & Touch
Link ID: 17823 - Posted: 02.19.2013
By Alan Boyle, Science Editor, NBC News BOSTON — Neuroscientists are following through on the promise of artificially enhanced bodies by creating the ability to "feel" flashes of light in invisible wavelengths, or building an entire virtual body that can be controlled via brain waves. "Things that we used to think were hoaxes or science fiction are fast becoming reality," said Todd Coleman, a bioengineering professor at the University of California at San Diego. Coleman and other researchers surveyed the rapidly developing field of neuroprosthetics in Boston this weekend at the annual meeting of the American Association for the Advancement of Science. One advance came to light just in the past week, when researchers reported that they successfully wired up rats to sense infrared light and move toward the signals to get a reward. "This was the first attempt … not to restore a function but to augment the range of sensory experience," said Duke University neurobiologist Miguel Nicolelis, the research team's leader. The project, detailed in the journal Nature Communications, involved training rats to recognize a visible light source and poke at the source with its nose to get a sip of water. Then electrodes were implanted in a region of the rats' brains that is associated with whisker-touching. The electrodes were connected to an infrared sensor on the rats' heads, which stimulated the target neurons when the rat was facing the source of an infrared beam. Then the visible lights in the test cage were replaced by infrared lights. © 2013 NBCNews.com
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.