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Chelsea Wald The sailfish’s sword-like bill looks as if it was made to slash at prey. But a study published today in Proceedings of the Royal Society B1 reveals that the bill is actually a multifunctional killing tool, enabling the fish to perform delicate, as well as swashbuckling, manoeuvres. By following throngs of predatory birds off the coast of Cancún, Mexico, the study’s authors were able to track Atlantic sailfish (Istiophorus albicans) hunting sardines, says co-author Alexander Wilson, a behavioural ecologist now at Carleton University in Ottawa, Canada. He and his colleagues made high-speed, high-resolution films in the open ocean over six days in 2012. Sailfish hunt in groups, taking turns to approach the ball of schooling fish. Their bodies darken and sometimes flash stripes and spots, perhaps to confuse the prey, or to signal to each other. “It’s a very orderly process,” Wilson says. “They don’t want to risk breaking their bills.” Although sailfish are among the fastest creatures in the ocean — they have been documented to swim at more than 110 kilometres per hour, or 60 knots — the new research shows that their strategy is to approach their prey slowly from behind and gently insert their bills into the school, without eliciting an evasive manoeuvre from the sardines. Then, by whipping their heads in powerful, sudden jerks, they can slash their bills left and right, with their upright fins providing stability. In fact, their bill tips slash with about the same acceleration as the tip of a swinging baseball bat, even in the water, says co-author Paolo Domenici, an environmental physiologist at the Institute for the Marine and Coastal Environment of Italy's National Research Council in Torregrande, on the island of Sardinia. The result is a scene of fishy carnage, as the surrounding water fills with iridescent fragments of sardine skin. © 2014 Nature Publishing Group,

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 5: The Sensorimotor System
Link ID: 19523 - Posted: 04.23.2014

By Ella Davies Reporter, BBC Nature The whales are known for their tusks which can reach 2.6m (9ft) in length, earning them comparisons with mythological unicorns. The tusk is an exaggerated front tooth and scientists have discovered that it helps the animals sense changes in their environment. Dr Martin Nweeia from the Harvard School of Dental Medicine, US, undertook the study alongside an international team of colleagues. Through the years, many theories have tried to explain the function of the narwhal's impressive tusk. "People have said it's everything from an ice pick to an acoustic probe, but this is the first time that someone has discovered sensory function and has the science to show it," said Dr Nweeia. More recently, experts have agreed that the tusk is a sexual characteristic because it is more often exhibited by males and they appear to use them during fights to assert their social hierarchy. But because the animals are rarely seen, the exact function of the tusk has remained a mystery. Previous studies have revealed that the animals have no enamel on their tusk - the external layer of the tooth that provides a barrier in most mammal teeth. Dr Nweeia and the team's analysis revealed that the outer cementum layer of the tusk is porous and the inner dentin layer has microscopic tubes that channel in towards the centre. In the middle of the tusk lies the pulp, where nerve endings which connect to the narwhal's brain are found. BBC © 2014

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 8: Hormones and Sex
Link ID: 19374 - Posted: 03.18.2014

Daniel Cressey Researchers have called for a common method of killing zebrafish used in laboratories to be abandoned amid growing evidence that it causes unnecessary suffering. The anaesthetic MS-222, which can be added to tanks to cause overdose, seems to distress the fish, two separate studies have shown. The studies’ authors propose that alternative anaesthetics or methods should be used instead. “These two studies — carried out independently — use different methodologies to reach the same conclusion: zebrafish detect and avoid MS-222 in the water,” says Stewart Owen, a senior environmental scientist at AstraZeneca’s Brixham Environmental Laboratory in Brixham, UK, and a co-author of one of the studies. “As this is a clear aversive response, as a humane choice, one would no longer use this agent for routine zebrafish anaesthesia.” The use of zebrafish (Danio rerio) in research has skyrocketed in recent years as scientists have sought alternatives to more controversial animal models, such as mammals. The fish are cheap and easy to keep, and although no firm data on numbers have been collected, millions are known to be housed in laboratories around the world. Nearly all will eventually be killed. MS-222 (ethyl 3-aminobenzoate methane­sulphate, also known as TMS) is one of the agents most frequently used to kill the creatures. It is listed as an acceptable method of euthanasia by many institutions, and also by societies such as the American Veterinary Medical Association. But the study by Owen and his co-authors, published last year (G. D. Readman et al. PLoS ONE 8, e73773; 2013), and the second study, published earlier this month by Daniel Weary and his colleagues at the University of British Columbia in Vancouver, Canada (D. Wong et al. PLoS ONE 9, e88030; 2014), show that zebrafish seem to find the chemical distressing. The research should fundamentally change the practice, say the authors of both papers. © 2014 Nature Publishing Group

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19294 - Posted: 02.26.2014

By Michelle Roberts Health editor, BBC News online Doctors have devised a new way to treat amputees with phantom limb pain. Using computer-generated augmented reality, the patient can see and move a virtual arm controlled by their stump. Electric signals from the muscles in the amputated limb "talk" to the computer, allowing real-time movement. Amputee Ture Johanson says his pain has reduced dramatically thanks to the new computer program, which he now uses regularly in his home. He now has periods when he is free of pain and he is no longer woken at night by intense periods of pain. Mr Johanson, who is 73 and lives in Sweden, lost half of his right arm in a car accident 48 years ago. After a below-elbow amputation he faced daily pain and discomfort emanating from his now missing arm and hand. Over the decades he has tried numerous therapies, including hypnosis, to no avail. Within weeks of starting on the augmented reality treatment in Max Ortiz Catalan's clinic at Chalmers University of Technology, his pain has now eased. "The pain is much less now. I still have it often but it is shorter, for only a few seconds where before it was for minutes. BBC © 2014

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 14: Attention and Consciousness
Link ID: 19293 - Posted: 02.26.2014

By DENISE GRADY The experiment was not for the squirmish. Volunteers were made to itch like crazy on one arm, but not allowed to scratch. Then they were whisked into an M.R.I. scanner to see what parts of their brains lit up when they itched, when researchers scratched them and when they were finally allowed to scratch themselves. The scientific question was this: Why does it feel so good to scratch an itch? “It’s quite intriguing to see how many brain centers are activated,” said Dr. Gil Yosipovitch, chairman of dermatology at the Temple University School of Medicine and director of the Temple Center for Itch (he conducted the experiment while working at Wake Forest School of Medicine). “There is no one itch center. Everyone wants that target, but it doesn’t work in real life like that.” Instead, itching and scratching engage brain areas involved not only in sensation, but also in mental processes that help explain why we love to scratch: motivation and reward, pleasure, craving and even addiction. What an itch turns on, a scratch turns off — and scratching oneself does it better than being scratched by someone else. The study results were published in December in the journal PLOS One. Itching was long overshadowed by pain in both research and treatment, and was even considered just a mild form of pain. But millions of people suffer from itching, and times have changed. Research has found nerves, molecules and cellular receptors that are specific for itching and set it apart from pain, and the medical profession has begun to take it seriously as a debilitating problem that deserves to be studied and treated. Within the last decade, there has been a flurry of research into what causes itching and how to stop it. Along with brain imaging, studies have begun to look at gene activity and to map the signals that flow between cells in the skin, the immune system, the spinal cord and the brain. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19264 - Posted: 02.18.2014

by Bethany Brookshire There are times when science is a painful experience. My most excruciating moment in science involved a heated electrode placed on my bare leg. This wasn’t some sort of graduate school hazing ritual. I was a volunteer in a study to determine how we process feelings of pain. As part of the experiment I was exposed to different levels of heat and asked how painful I thought they were. When the electrode was removed, I eagerly asked how my pain tolerance compared with that of others. I secretly hoped that I was some sort of superwoman, capable of feeling pain that would send other people into screaming fits and brushing it off with a stoic grimace. It turns out, however, that I was a bit of a wuss. Ouch. I figured I could just blame my genes. About half of our susceptibility to pain can be explained by genetic differences. The other half, however, remains up for grabs. And a new study published February 4 in Nature Communications suggests that part of our susceptibility to pain might lie in chemical markers on our genes. These “notes” on your DNA, known as epigenetic changes, can be affected by environment, behavior and even diet. So the findings reveal that our genetic susceptibility to pain might not be our destiny. Tim Spector and Jordana Bell, genetic epidemiologists at King’s College London, were interested in the role of the epigenome in pain sensitivity. Epigenetic changes such as the addition (or subtraction) of a methyl group on a gene make that gene more or less likely to be used in a cell by altering how much protein can be made from it. These differences in proteins can affect everything from obesity to memory to whether you end up like your mother. © Society for Science & the Public 2000 - 2013.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 13: Memory, Learning, and Development
Link ID: 19243 - Posted: 02.12.2014

by Douglas Heaven We have the world at our fingertips. A sense of touch can sometimes be as important as sight, helping us to avoid crushing delicate objects or ensuring that we hold on firmly when carrying hot cups of coffee. Now, for the first time, a person who lost his left hand has had a near-natural sense of touch restored thanks to a prosthesis. "I didn't realise it was possible," says Dennis Aabo Sørensen, who is so far the only person to have been fitted with the new prosthesis. "The feeling is very close to the sensation you get when you touch things with your normal hand." To restore Sørensen's sense of touch, Silvestro Micera at the Swiss Federal Institute of Technology in Lausanne and his colleagues implanted tiny electrodes inside the ulnar and median nerve bundles in Sørensen's upper arm. Between them, the ulnar nerve – which runs down to the little finger and ring finger – and the median nerve – which runs down to the index and middle fingers – carry sensations from most of the hand, including the palm. The team then connected the electrodes to pressure sensors on the fingertips and palm of a robotic prosthetic hand via cables running down the outside of Sørensen's arm. When he used the hand to grasp an object, electrical signals from the pressure pads were fired directly into the nerves, providing him with a sense of touch. Getting to grips The electrical signals were calibrated so that Sørensen could feel a range of sensation, from the slightest touch to firm pressure just below his pain threshold, depending on the strength of his grip. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19215 - Posted: 02.06.2014

by Andy Coghlan If you flinch where others merely frown, you might want to take a look at your lifestyle. That's because environmental factors may have retuned your genes to make you more sensitive to pain. "We know that stressful life events such as diet, smoking, drinking and exposure to pollution all have effects on your genes, but we didn't know if they specifically affected pain genes," says Tim Spector of King's College London. Now, a study of identical twins suggests they do. It seems that epigenetic changes – environmentally triggered chemical alterations that affect how active your genes are – can dial your pain threshold up or down. This implies that genetic tweaks of this kind, such as the addition of one or more methyl groups to a gene, may account for some differences in how our senses operate. Spector and his colleagues assessed the ability of hundreds of pairs of twins to withstand the heat of a laser on their skin, a standard pain test. They selected 25 pairs who showed the greatest difference in the highest temperature they could bear. Since identical twins have the same genes, any variation in pain sensitivity can be attributed to epigenetic differences. Pain thermostat The researchers screened the twins' DNA for differences in methylation levels across 10 million gene regions. They found a significant difference in nine genes, most of which then turned out to have been previously implicated in pain-sensitivity in animal experiments. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 13: Memory, Learning, and Development
Link ID: 19208 - Posted: 02.05.2014

by Kat Arney Next time you struggle to resist an itchy rash or insect bite, you could find relief in the mirror. Perception of our own bodies can be easily manipulated using tricks such as the rubber hand illusion, which fools people into thinking a rubber hand is their own. Reflecting someone's limb in a mirror has also been used to treat phantom limb pain. Now Christoph Helmchen and his colleagues at the University of Lübeck in Germany have shown that a similar mirror illusion can fool people into feeling relief from an itch, even when they scratch the wrong place. The team injected the right forearms of 26 male volunteers with itch-inducing chemical histamine. Because the injection creates a red spot, they painted a corresponding dot on the opposite arm so both looked identical. One of the researchers then scratched each arm in turn. Unsurprisingly, scratching the itchy arm produced relief, while scratching the other one did not. Next, they placed a large vertical mirror in front of the itchy arm, blocking off the subject's view of their right arm and reflecting back the non-itchy one in its place . They asked the volunteers to look only at the reflected limb in the mirror, whilst a member of the team again scratched each arm. This time the participants felt relief when the unaffected, reflected arm was scratched. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 14: Attention and Consciousness
Link ID: 19178 - Posted: 01.28.2014

By Michelle Roberts Health editor, BBC News online A magnet device can be used to treat some types of migraine, new UK guidance advises. The watchdog NICE says although there is limited evidence, transcranial magnetic stimulation (TMS) may help ease symptoms in some patients. It says that the procedure is still relatively new and that more data is needed about its long-term safety and efficacy. But it may be useful for patients for whom other treatments have failed. Migraine is common - it affects about one in four women and one in 12 men in the UK. There are several types - with and without aura and with or without headache - and several treatment options, including common painkillers, such as paracetamol. Although there is no cure for migraine, it is often possible to prevent or lessen the severity of attacks. NICE recommends various medications, as well as acupuncture, and now also TMS, under the supervision of a specialist doctor - although it has not assessed whether it would be a cost effective therapy for the NHS. TMS involves using a portable device that is placed on the scalp to deliver a brief magnetic pulse. NICE says doctors and patients might wish to try TMS, but they should be aware about the treatment's uncertainties. Reduction in migraine symptoms may be moderate, it says. Prof Peter Goadsby, chairman of the British Association for the Study of Headache, said many migraine patients stood to benefit from trying TMS. BBC © 2014

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19158 - Posted: 01.22.2014

Things are heating up in the world of genetics. The hot pepper (Capsicum annuum) is one of the most widely grown spice crops globally, playing an important role in many medicines, makeups, and meals worldwide. Although the plant’s so-called capsaicin chemical is well known for spicing things up, until now the genetic spark responsible for the pepper’s pungency was unknown. A team of scientists recently completed the first high-quality reference genome for the hot pepper. Comparing the pepper’s genome with that of its tame cousin, the tomato, the scientists discovered the gene responsible for fiery capsaicin production appeared in both plants. While the tomato carried four nonfunctioning copies of the gene, the hot pepper carried seven nonfunctioning copies and one functioning copy, the team reports online today in Nature Genetics. The researchers believe the pepper’s capsaicin-creating gene appeared after five mutations occurred during DNA replication, with the final mutation creating a functional copy. The mouth-burning chemicals likely protected the mutant pepper’s seeds from grazing land animals millions of years ago, giving the mutant a reproductive advantage and helping the mutant gene spread. The team says the finding could help breeders boost the pepper’s heat, nutrition, and medicinal properties. One researcher even suggests that geneticists could activate one of the tomato’s dormant genes, enabling capsaicinoid production and creating a plant that makes ready-made salsa. © 2014 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19151 - Posted: 01.20.2014

-- Bats and other animals use ultrasound to their advantage. Now a new study of humans suggests ultrasound can alter brain activity to boost people's sensory perception. First, researchers placed an electrode on the wrist of volunteers to stimulate the nerve that runs down the arm and into the hand. Before stimulating the radial nerve, they delivered ultrasound to the head -- to an area of the cerebral cortex that processes sensory information received from the hand. The participants' brain responses were recorded using electroencephalography (EEG). The ultrasound decreased the EEG signal and weakened the brain waves responsible for processing sensory input from the hands, according to the study published online Jan. 12 in the journal Nature Neuroscience. The Virginia Tech researchers then conducted two common neurological tests. One measures a person's ability to distinguish whether two pins placed close together and touching the skin are actually two distinct contact points. The other test measures sensitivity to the frequency of a series of air puffs. The scientists were surprised to discover that when they received ultrasound, the participants showed significant improvements in their ability to distinguish pins at closer distances and to identify small differences in the frequency of successive air puffs. The ultrasound may have changed the balance of inhibition and excitation between neighboring neurons within the cerebral cortex, resulting in a boost in sensory perception, explained study leader William Tyler, an assistant professor at Virginia Tech's Carilion Research Institute. © 2014 HealthDay

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19147 - Posted: 01.18.2014

By NICHOLAS BAKALAR Both acupuncture and sham acupuncture were effective in reducing menopausal symptoms in women being treated with aromatase inhibitors for breast cancer, a small randomized trial found. Joint and muscle pain, hot flashes and night sweats are common side effects of those estrogen-lowering drugs. The trial, published online in Cancer, randomized 47 breast cancer patients to eight weekly sessions of either real or sham acupuncture. Those assigned to real acupuncture received treatment with needles in recognized acupoints believed to be helpful in relieving menopausal symptoms. The controls got non-penetrating needles placed in sham acupuncture points. Patients and researchers did not know which patients had received which treatment. The patients kept daily diaries or filled out several questionnaires on the frequency and severity of hot flashes and other symptoms. Patient-reported symptoms, especially hot flashes, improved significantly after both sham and real treatment. There was no statistically significant difference between the two groups. The results may be attributable to a placebo effect, but the scientists suggest that the slight pricking of the skin could cause physiological changes. In any case, the lead author, Dr. Ting Bao, a medical oncologist at the University of Maryland, Baltimore, said there is no harm in trying acupuncture. “Acupuncture as a medical procedure has been practiced for thousands of years,” she said. “It has a minimal risk and potentially significant benefits.” Copyright 2013 The New York Times Company

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 19074 - Posted: 12.28.2013

By RONI CARYN RABIN Women are more likely than men to die after a heart attack, and some researchers have suggested a reason: Doctors may be misdiagnosing women more often because their symptoms differ from those experienced by men. But a study published Monday indicates that too much has been made of gender differences in chest pain, the hallmark symptom of heart disease. Although the researchers found some distinctions, no pattern was clearly more characteristic of women or could be used to improve heart attack diagnosis in women, the authors concluded. “We should stop treating women differently at the emergency room when they present with chest pain and discomfort,” said Dr. Maria Rubini Gimenez, a cardiologist at University Hospital Basel and lead author of the new study, published in JAMA Internal Medicine. Instead, she said, all patients with acute chest pain must be evaluated for heart attack with appropriate diagnostics, including an electrocardiogram and blood tests. Roughly 80 percent of people who have chest pain and discomfort are suffering from indigestion, acid reflux or another relatively benign condition, said Dr. John G. Canto, director of the chest pain center at Lakeland Regional Medical Center in Lakeland, Fla., who has researched heart attack diagnosis. “The trick is, how do you figure out the 15 to 20 percent actually having a heart attack?” he said. The new research confirms “that there is a lot of overlap in symptoms between patients who are having a heart attack and those who aren’t, and there is a lot of overlap in symptoms between men and women.” The new study examined 2,475 patients, including 796 women, who reported to emergency rooms at nine hospitals in Switzerland, Spain and Italy complaining of acute chest pain between April 21, 2006, and Aug. 12, 2012. Copyright 2013 The New York Times Company

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 8: Hormones and Sex
Link ID: 18972 - Posted: 11.26.2013

by Simon Makin "The only thing we have to fear is fear itself," said Franklin D. Roosevelt. He might have been onto something: research suggests that the anticipation of pain is actually worse than the pain itself. In other words, people are happy to endure a bit more pain, if it means they spend less time waiting for it. Classical theories of decision-making suppose that people bring rewards forward and postpone punishments, because we give far-off events less weight. This is called "temporal discounting". But this theory seems to go out the window when it comes to pain. One explanation for this is that the anticipation of pain is itself unpleasant, a phenomenon that researchers have appropriately termed "dread". To investigate how dread varies with time, Giles Story at University College London, and his colleagues, hooked up 33 volunteers to a device that gave them mild electric shocks. The researchers also presented people with a series of choices between more or less mildly painful shocks, sooner or later. During every "episode" there was a minimum of two shocks, which could rise to a maximum of 14, but before they were given them, people had to make a choice such as nine extra shocks now or six extra shocks five episodes from now. The number of shocks they received each time was determined by these past choices. Although a few people always chose to experience the minimum pain, 70 per cent of the time, on average, participants chose to receive the extra shocks sooner rather than a smaller number later. By varying the number of shocks and when they occurred, the team was able to figure out that the dread of pain increased exponentially as pain approached in time. Similar results occurred in a test using hypothetical dental appointments. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18959 - Posted: 11.23.2013

If you were stung by a bark scorpion, the most venomous scorpion in North America, you’d feel something like the intense, painful jolt of being electrocuted. Moments after the creature flips its tail and injects venom into your skin, the intense pain would be joined by a numbness or tingling in the body part that was stung, and you might experience a shortness of breath. The effect of this venom on some people—small children, the elderly or adults with compromised immune systems—can even trigger frothing at the mouth, seizure-like symptoms, paralysis and potentially death. Based solely on its body size, the four-inch-long furry grasshopper mouse should die within minutes of being stung—thanks to the scorpion’s venom, which causes temporary paralysis, the muscles that allow the mouse to breathe should shut down, leading to asphyxiation—so you’d think the rodent would avoid the scorpions at all costs. But if you put a mouse and a scorpion in the same place, the rodent’s reaction is strikingly brazen. If stung, the four-inch-long rodent might jump back for a moment in surprise. Then, after a brief pause, it’ll go in for the kill and devour the scorpion piece by piece: This predatory behavior isn’t the result of remarkable toughness. As scientists recently discovered, the mouse has evolved a particularly useful adaptation: It’s immune to both the pain and paralytic effects that make the scorpion’s venom so toxic. Although scientists long knew that the mouse, native to the deserts of the American Southwest, preys upon a range of non-toxic scorpions, “no one had ever really asked whether they attack and kill really toxic scorpions,” says Ashlee Rowe of Michigan State University, who led the new study published today in Science.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 18839 - Posted: 10.28.2013

Who would win in a fight: a bark scorpion or a grasshopper mouse? It seems like an easy call. The bark scorpion (Centruroides sculpturatus) delivers one of the most painful stings in the animal kingdom—human victims have compared the experience to being branded. The 25-gram grasshopper mouse (Onychomys torridus) is, well, a mouse. But as you can see in the video above, grasshopper mice routinely kill and eat bark scorpions, blissfully munching away even as their prey sting them repeatedly (and sometimes right in the face). Now, scientists have discovered why the grasshopper mice don’t react to bark scorpion stings: They simply don’t feel them. Evolutionary neurobiologist Ashlee Rowe at the University of Texas, Austin, has been studying the grasshopper mice’s apparent superpower since she was in graduate school. For the new study, she milked venom from nearly 500 bark scorpions and started experimenting. When she injected the venom into the hind paws of regular laboratory mice, the mice furiously licked the site for several minutes. But when she injected the same venom into grasshopper mice, they licked their paws for just a few seconds and then went about their business, apparently unfazed. In fact, the grasshopper mice appeared to be more irritated by injections of the saline solution Rowe used as a control. Rowe knew that grasshopper mice weren’t entirely impervious to pain—they reacted to injections of other painful chemicals such as formalin, just not the bark scorpion venom. To find out what was going on, she and her team decided to determine how the venom affects the grasshopper mouse’s nervous system, in particular the parts responsible for sensing pain. © 2013 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 18838 - Posted: 10.26.2013

by Alyssa Botelho A sense of touch lets you connect with loved ones, makes your limbs feel your own, and helps you to interact with your surroundings. But people who are paraplegics or have lost limbs have to navigate the world without this most fundamental of sensory inputs. Sliman Bensmaia at the University of Chicago, Illinois, is working to change that with a new model for transmitting a sense of touch to the brain that bypasses regular routes. He hopes it will be a blueprint for constructing prosthetics that convey touch in the same way that natural limbs do. To start, Bensmaia and his colleagues trained rhesus macaques to focus their gaze in different directions depending on whether their index finger or fourth finger were being prodded. Microelectrodes were then placed in an area of the brain called the primary somatosensory cortex. This area represents an entire map of the body, with each neuron responsible for sensing when a different part of the skin is touched. Microelectrodes record the activity pattern of neurons. They can also be used in reverse – to deliver electrical stimulation to make neurons fire. Fourth finger exercise Next, the team recorded what activity occurred and where it registered in the somatosensory cortex when a monkey had its index or fourth finger poked. Then they stimulated the brain using the same pattern of activity. The monkeys reacted as if they had been touched – fixing their gaze in the direction they been taught in response to a poke. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 18789 - Posted: 10.15.2013

By Stephen L. Macknik and Susana Martinez-Conde Dennis Rogers is an unassuming guy. He's on the short side. And though muscular, he doesn't come across as the kind of towering Venice Beach, muscle-bound Arnold that you might expect from someone billed as the World's Strongest Man. Rather he has the kind of avuncular intensity you find in a great automobile mechanic—a mechanic who happens to be able to lift an engine with one hand while using the fingertips of the other hand to wrench the spark plugs out. Like it's nothing. Rogers, who has been known to keep two U.S. Air Force fighter planes from blasting away in opposite directions by holding them back with his bare hands, performed at the most recent Gathering for Gardner—a conference that celebrates the interests of one of Scientific American's greatest columnists, the late mathemagician Martin Gardner. We asked Rogers about the source of his incredible powers after the show, and we were surprised to learn that he did not know. Bill Amonette of the University of Houston–Clear Lake found that Rogers could recruit an abnormally high number of muscle fibers. But was this ability because of a freak genetic mutation? Another possibility, which Rogers thinks is more likely, is the way he processes pain when he strains those muscles. What if, instead of superpowered muscles, Rogers has a normal—though extremely well exercised—body, and his abilities arise because he can withstand more pain than most mere mortals? He claims that he does feel pain and is actually scared of dentists. In fact, during one stunt in which he held back four souped-up Harley motorbikes with straps, he bit down so hard he split a tooth from top to bottom. Rather than taking his chances at the dentist, he reached into his mouth, clamped his viselike fingertips onto the broken tooth, and extracted it, root and all. Rogers reasons that, unlike in the dentist's office—where he has no control over the pain that is inflicted on him—he has direct executive control over pain that he inflicts on himself. “I know it's coming, I have an idea of what to expect and I can decide to ignore it,” he says. © 2013 Scientific American

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18766 - Posted: 10.09.2013

By Cat Bohannon Halos, auras, flashes of light, pins and needles running down your arms, the sudden scent of sulfur—many symptoms of a migraine have vaguely mystical qualities, and experts remain puzzled by the debilitating headaches' cause. Researchers at Harvard University, however, have come at least one step closer to figuring out why women are twice as likely to suffer from chronic migraines as men. The brain of a female migraineur looks so unlike the brain of a male migraineur, asserts Harvard scientist Nasim Maleki, that we should think of migraines in men and women as “different diseases altogether.” Maleki is known for looking at pain and motor regions in the brain, which are known to be unusually excitable in migraine sufferers. In one notable study published in the journal Brain last year, she and her colleagues exposed male and female migraineurs to painful heat on the backs of their hands while imaging their brains with functional MRI. She found that the women had a greater response in areas of the brain associated with emotional processing, such as the amygdala, than did the men. Furthermore, she found that in these women, the posterior insula and the precuneus—areas of the brain responsible for motor processing, pain perception and visuospatial imagery—were significantly thicker and more connected to each other than in male migraineurs or in those without migraines. In Maleki's most recent work, presented in June at the International Headache Congress, her team imaged the brains of migraineurs and healthy people between the ages of 20 and 65, and it made a discovery that she characterizes as “very, very weird.” In women with chronic migraines, the posterior insula does not seem to thin with age, as it does for everyone else, including male migraineurs and people who do not have migraines. The region starts thick and stays thick. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 18757 - Posted: 10.08.2013