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

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By Andrea Alfano There are many types of touch. A cold splash of water, the tug of a strong breeze or the heat and heft of your coffee mug will each play on your skin in a different way. Within your skin is an array of touch sensors, each associated with nerve fibers that connect to the central nervous system. These sensors comprise specialized nerve endings and skin cells. Along with the fibers, they translate our physical interactions with the world into electrical signals that our brain can process. They help to bridge the gap between the physical act of touching and the cognitive awareness of tactile sensation. Even a simple stroke across the forearm engages several distinct nerve fibers. Three types—A-beta, A-delta and C fibers—have subtypes that are specialized for sensing particular types of touch; other subtypes carry information related to pain. The integration of information from these fibers is what allows us to gain such rich sensory experiences through our skin, but it has also made it more challenging for researchers to understand the fibers’ individual roles. Although these fibers do not act in isolation, the examples that follow highlight the primary nerve fibers engaged by different types of touch. © 2015 Scientific American

Keyword: Pain & Touch
Link ID: 21066 - Posted: 06.18.2015

by Laura Sanders The motor homunculus is a funny-looking fellow with a hulking thumb, delicate toes and a tongue that wags below his head. His body parts and proportions stem from decades-old experiments that mapped brain areas to the body parts they control. Now, a new study suggests that the motor homunculus’ neck was in the wrong place. Hyder Jinnah of Emory University in Atlanta and colleagues used fMRI to scan the brains of volunteers as they activated their head-turning neck muscles. (Pads held participants’ heads still, so the muscles fired but heads didn’t move.) This head turn was accompanied by activity in part of the brain that controls movement. The exact spot seems to be between the brain areas that control the shoulder and the trunk — not between the areas responsible for moving the thumb and the top of the head as earlier motor homunculi had suggested, the team reports in the June 17 Journal of Neuroscience. © Society for Science & the Public 2000 - 2015.

Keyword: Pain & Touch
Link ID: 21060 - Posted: 06.17.2015

Joe Palca Scientists found a molecule crucial to perceiving the sensation of itching. It affects how the brain responds to serotonin, and may explain why anti-depressants that boost serotonin make some itch. JOE PALCA, BYLINE: How do you go about discovering what makes us itch? Well, if you're Diana Bautista at the University of California, Berkeley, you ask what molecules are involved. DIANA BAUTISTA: We say OK, what are the possible molecular players out there that might be contributing to itch or touch? PALCA: Bautista says it turns out itch and touch, and even pain, all seem to be related - at least in the way our brains makes sense of these sensations. But how to tell which molecules are key players? Bautista says basically you try everything you can. BAUTISTA: We test a lot of candidates. And if we're really lucky, one of our candidates - we can prove that it plays a really important role. PALCA: And now she thinks she's found one. Working with colleagues at the Buck Institute for Research on Aging, she's found a molecule that's made by a gene called HTR7. When there's less of this molecule, animals with itchy skin conditions, like eczema, do less scratching. When there's more of it, itching gets worse. The way this molecule works is kind of interesting. It changes how sensitive brain cells are to a chemical called serotonin. Now, serotonin is a chemical that's related to depression. So Bautista's research might explain why certain antidepressant drugs that boost serotonin have a peculiar side effect. For some people, the drugs make them itch. Bautista says the new research is certainly not the end of the story when it comes to understanding itch. © 2015 NPR

Keyword: Pain & Touch
Link ID: 21042 - Posted: 06.13.2015

Fergus Walsh Medical correspondent Scientists in Austria have created an artificial leg which allows the amputee to feel lifelike sensations from their foot. The recipient, Wolfang Rangger, who lost his right leg in 2007, said: "It feels like I have a foot again. It's like a second lease of life." Prof Hubert Egger of the University of Linz, said sensors fitted to the sole of the artificial foot, stimulated nerves at the base of the stump. He added it was the first time that a leg amputee had been fitted with a sensory-enhanced prosthesis. How it works Surgeons first rewired nerve endings in the patient's stump to place them close to the skin surface. Six sensors were fitted to the base of the foot, to measure the pressure of heel, toe and foot movement. These signals were relayed to a micro-controller which relayed them to stimulators inside the shaft where it touched the base of the stump. These vibrated, stimulating the nerve endings under the skin, which relayed the signals to the brain. Prof Egger said: "The sensors tell the brain there is a foot and the wearer has the impression that it rolls off the ground when he walks." Wolfgang Ranger, a former teacher, who lost his leg after a blood clot caused by a stroke, has been testing the device for six months, both in the lab and at home. He says it has given him a new lease of life He said: "I no longer slip on ice and I can tell whether I walk on gravel, concrete, grass or sand. I can even feel small stones." © 2015 BBC.

Keyword: Pain & Touch; Robotics
Link ID: 21028 - Posted: 06.09.2015

Mo Costandi Being unable to feel pain may sound appealing, but it would be extremely hazardous to your health. Pain is, for most of us, a very unpleasant feeling, but it serves the important evolutionary purpose of alerting us to potentially life-threatening injuries. Without it, people are more prone to hurting themselves and so, because they can be completely oblivious to serious injuries, a life without pain is often cut short. Take 16-year-old Ashlyn Blocker from Patterson, Georgia, who has been completely unable to sense any kind of physical pain since the day she was born. As a newborn, she barely made a sound, and when her milk teeth started coming out, she nearly chewed off part of her tongue. Growing up, she burnt the skin off the palm of her hands on a pressure washer that her father had left running, and once ran around on a broken ankle for two whole days before her parents noticed the injury. She was once swarmed and bitten by hundreds of fire ants, has dipped her hands into boiling water, and injured herself in countless other ways, without ever feeling a thing. Ashlyn is one of a tiny number of people with congenital insensitivity to pain. The condition is so rare, in fact, that the doctor who diagnosed her in 2006 told her parents that she may be the only one in the world who has it. But later that year, a research team led by Geoffrey Woods of the University of Cambridge, identified three distinct mutations in the SCN9A gene, all of which cause the same condition in members of three large families in northern Pakistan, and in 2013, Ashlyn’s doctor Roland Staud and his colleagues reported that her condition is the result of two other mutations in the same gene. Now, Woods and his colleagues have discovered yet more mutations that cause congenital insensitivity to pain. © 2015 Guardian News and Media Limited

Keyword: Pain & Touch; Genes & Behavior
Link ID: 20981 - Posted: 05.26.2015

by Jessica Hamzelou Painful needle heading your way? A sharp intake of breath might be all that is needed to make that injection a little more bearable. When you are stressed, your blood pressure rises to fuel your brain or limbs should you need to fight or flee. But your body has a natural response for calming back down. Pressure sensors on blood vessels in your lungs can tell your brain to bring the pressure back down, and the signals from these sensors also make the brain dampen the nervous system, leaving you less sensitive to pain. This dampening mechanism might be why people with higher blood pressures appear to have higher pain thresholds. Gustavo Reyes del Paso at the University of Jaén in Spain wondered whether holding your breath – a stress-free way of raising blood pressure and triggering the pressure sensors – might also raise a person's pain threshold. To find out, he squashed the fingernails of 38 people for 5 seconds while they held their breath. Then he repeated the test while the volunteers breathed slowly. Both techniques were distracting, but the volunteers reported less pain when breath-holding than when slow breathing. Reyes del Paso thinks holding your breath might be a natural response to the expectation of pain. "Several of our volunteers told us they already do this when they are in pain," he says. But he doesn't think the trick will work for a stubbed toe or unexpected injury. You have to start before the pain kicks in, he says, for example, in anticipation of an injection. © Copyright Reed Business Information Ltd

Keyword: Pain & Touch
Link ID: 20930 - Posted: 05.14.2015

Patricia Neighmond Terri Bradford has suffered debilitating headache pain all her life. Some days the pain is so bad, she says, "By 11 o'clock in the morning, I'm on the couch in a darkened room with my head packed in ice." Over the years, Bradford, who is 50 years old and lives in Bedford, Mass., has searched desperately for pain relief. She's been to the doctor countless times for countless tests. "Everything I've had, I've had twice," she says. "I've had two spinal taps; I've had so many nerve blocks I've lost count." Bradford is not alone. It's estimated that every year 12 million Americans go to the doctor seeking help for headaches. Nearly one quarter of the population suffers from recurrent severe tension headaches or migraines. People who go to the doctor for headache pain are more likely to be sent for advanced testing and treatment, a study finds. That testing is expensive, it may not be necessary and could even be harmful, says lead researcher Dr. John Mafi of Beth Israel Deaconess Medical Center in Boston. Mafi looked at the rates of advanced imaging like CT scans and MRIs in people with headaches, as well as referrals to other doctors, presumably specialists. He found that from 1999 to 2010, the number of diagnostic tests rose from 6.7 percent of all doctor visits to 13.9 percent. At the same time, referrals to other doctors increased from 6.9 percent to 13.2 percent. So almost double what it was a decade ago. Mafi says this isn't because more people are suffering headaches. The headache rate has remained virtually the same over the past decade. But what has changed is supply and demand. Today there are a lot more advanced diagnostic machines than there were a decade ago, and more patients are asking to be tested. © 2015 NPR

Keyword: Parkinsons; Stress
Link ID: 20906 - Posted: 05.11.2015

by Helen Thomson Giving people the illusion of teleporting around a room has revealed how the brain constructs our sense of self. The findings may aid treatments for schizophrenia and asomatognosia – a rare condition characterised by a lack of awareness of a part of one's body. As we go about our daily lives, we experience our body as a physical entity with a specific location. For instance, when you sit at a desk you are aware of your body and its rough position with respect to objects around you. These experiences are thought to form a fundamental aspect of self-consciousness. Arvid Guterstam, a neuroscientist at the Karolinska Institute in Stockholm, Sweden, and his colleagues wondered how the brain produces these experiences. To find out, Guterstam's team had 15 people lie in an fMRI brain scanner while wearing a head-mounted display. This was connected to a camera on a dummy body lying elsewhere in the room, enabling the participants to see the room – and themselves inside the scanner - from the dummy's perspective. A member of the team then stroked the participant's body and the dummy's body at the same time. This induced the out-of-body experience of owning the dummy body and being at its location. The experiment was repeated with the dummy body positioned in different parts of the room, allowing the person to be perceptually teleported between the different locations, says Guterstam. All that was needed to break the illusion was to touch the participant's and the dummy's bodies at different times. © Copyright Reed Business Information Ltd.

Keyword: Pain & Touch; Attention
Link ID: 20874 - Posted: 05.02.2015

by Jacob Aron Now that's an in-flight meal. To snatch a mealworm in mid-air, the bat in this video performs impressive aerial acrobatics aided by a unique cluster of touch sensors on its wings. Bats are known to use echolocation to identify their dinner, steering towards prey by listening for reflected sounds. It turns out that their sense of touch plays a key role as well. Ellen Lumpkin of Columbia University, New York, and her colleagues have discovered that bats have a special arrangement of hairs and touch-sensitive receptors across their wings that detect changes in airflow to help stabilise flight. The team also found that sensory neurons arranged in a pattern on bat wings (pictured) send signals to the lower spinal cord, which is unusual for a mammal. This part of the spinal cord usually receives messages from an animal's torso. The bizarre circuitry reflects the embryonic origins of bat wings, which form when their front limbs, torso and hind limbs fuse together. Journal reference: Cell Reports, DOI: 10.1016/j.celrep.2015.04.001 © Copyright Reed Business Information Ltd

Keyword: Pain & Touch
Link ID: 20872 - Posted: 05.02.2015

The brains of babies “light up” in a similar way to adults when exposed to the same painful stimulus, suggesting they feel pain much like adults do, researchers said on Tuesday. In the first of its kind study using magnetic resonance imaging (MRI), scientists from Britain’s Oxford University found that 18 of the 20 brain regions active in adults experiencing pain were also active in babies. Brain scans of the sleeping infants while they were subjected to mild pokes on the bottom of their feet with a special rod – creating a sensation “like being poked with a pencil” – also showed their brains had the same response to a slighter “poke” as adults did to a stimulus four times as strong, suggesting babies have a much lower pain threshold. “Obviously babies can’t tell us about their experience of pain and it is difficult to infer pain from visual observations,” said Rebeccah Slater, a doctor at Oxford’s paediatrics department who led the study. “In fact some people have argued that babies’ brains are not developed enough for them to really feel pain ... [yet] our study provides the first really strong evidence this is not the case.” Even as recently as the 1980s it was common practice for babies undergoing surgery to be given neuromuscular blocks but no pain relief medication. Last year, a review of neonatal pain management in intensive care found that although these babies experience an average of 11 painful procedures per day, 60% do not receive any kind of pain medication. © 2015 Guardian News and Media Limited

Keyword: Pain & Touch; Development of the Brain
Link ID: 20824 - Posted: 04.21.2015

Angus Chen A common pain medication might make you go from "so cute!" to "so what?" when you look at a photo of an adorable kitten. And it might make you less sensitive to horrifying things too. It's acetaminophen, the active ingredient in Tylenol. Researchers say the drug might be taking the edge off emotions – not just pain. "It seems to take off the highs of your daily highs and the lows off your daily lows," says Baldwin Way, a psychologist at Ohio State University and the principal investigator on the study, "It kind of flattens out the vicissitudes of your life." The idea that over-the-counter pain pills might affect emotions has been circulating since 2010, when two psychologists, Naomi Eisenberger and Nathan DeWall, led a study showing that acetaminophen seemed to be having both a psychological and a neurological effect on people. They asked volunteers to play a rigged game that simulated social rejection. Not only did the acetaminophen appear to be deflecting social anxieties, it also seemed to be dimming activity in the insula, a region of the brain involved in processing emotional pain. A brain that can let other thoughts bubble up despite being in pain might help its owner benefit from meditation or other cognitive therapies. "But [the insula] is a portion of the brain that seems to be involved in a lot of things," Way says. In older studies, scientists saw that people with damage in their insula didn't react as strongly to either negative or positive images. So Way and one of his students, Geoffrey Durso, figured that if acetaminophen is doing something to the insula, then it might be having a wider effect, too. © 2015 NPR

Keyword: Emotions; Pain & Touch
Link ID: 20807 - Posted: 04.16.2015

by Penny Sarchet You've got a splitting migraine. If you were offered a sugar pill, would you bother taking it? What if you were told your genetic make-up means it is very likely to make you feel better? This is one of the questions raised by the burgeoning effort to understand which genes influence the placebo effect, and how these genes – collectively known as the placebome – determine a person's susceptibility to the phenomenon. There are tremendous differences in the placebo effect between individuals, says Kathryn Hall of Harvard Medical School. "It can vary from no measurable response to someone getting significantly better." Having drawn together all the studies carried out so far, Hall says there is reasonable evidence for at least 11 genes that influence a person's susceptibility. This is enough to warrant discussing the use of genetic screening to assess how likely a person is to respond to a placebo treatment, such as a sugar pill or saline injection. The idea is that this could lead to more personalised treatments for conditions like pain syndromes, migraines, depression, irritable bowel syndrome and even Parkinson's disease, symptoms of which seem to be relieved by placebo in some individuals. It could also lead to the design of more balanced clinical trials. Your personality can help you guess whether you're among the estimated third of the population who are placebo responders. Being agreeable, extroverted and open to new experiences all appear to be associated with placebo susceptibility. Although brain imaging techniques can also indicate a person's likely susceptibility, a genetic read-out would offer a convenient, easily applicable and clearly codified measure. © Copyright Reed Business Information Ltd

Keyword: Pain & Touch
Link ID: 20794 - Posted: 04.14.2015

|By Andrea Alfano To scratch an itch is to scratch many itches: placing nails to skin brings sweet yet short-lived relief because it often instigates another bout of itchiness. The unexpected culprit behind this vicious cycle, new research reveals, is serotonin, the so-called happiness hormone. Scientists thought itch was merely a mild form of pain until 2009, when Zhou-Feng Chen and his colleagues at the Center for the Study of Itch at Washington University in St. Louis discovered itch-specific neurons in mice. Though not identical, itch and pain are closely related; they share the same pathways in certain brain areas. Because of the doubling up, activating one suppresses the other, which is why scratching blocks the itch sensation momentarily. The act, however, also triggers the release of the chemical serotonin, which helps to alleviate pain. It is that burst that makes scratching feel good, but recent work by Chen's group showed that it exacerbates the itch-scratch cycle, too. Itch-sensing neurons have a set of receptors that facilitates pain relief and another that induces itch. Serotonin can bind only to the pain-related receptor, but because the two sets sit close to each other and physically interact, the chemical's arrival indirectly enhances the itch pathway. When Chen and his colleagues activated both receptors simultaneously in mice, the rodents scratched much more than if the itch-inducing receptor was turned on alone. In another experiment, mice lacking the cells that produce serotonin scratched less than normal mice when exposed to a skin irritant. The findings were published in the journal Neuron. © 2015 Scientific American

Keyword: Pain & Touch
Link ID: 20793 - Posted: 04.14.2015

Jon Hamilton Researchers have discovered the exact structure of the receptor that makes our sensory nerves tingle when we eat sushi garnished with wasabi. And because the "wasabi receptor" is also involved in pain perception, knowing its shape should help pharmaceutical companies develop new drugs to fight pain. The receptor, which scientists call TRPA1, is "an important molecule in the pain pathway," says David Julius, a professor of physiology at the University of California, San Francisco and an author of a paper published in this week's Nature. "A dream of mine is that some of the work we do will translate into medicines people can take for chronic pain." Julius led a team that discovered the receptor about a decade ago. Since then, researchers have shown that TRPA1 receptors begin sending distress signals to the brain whenever they encounter pungent chemical irritants, including not only wasabi but tear gas and air pollution from cars or wood fires. The receptors also become activated in response to chemicals released by the body itself when tissue becomes inflamed from an injury or a disease like rheumatoid arthritis. © 2015 NPR

Keyword: Pain & Touch
Link ID: 20780 - Posted: 04.10.2015

by Andy Coghlan Who needs sight to get around when you've got a digital compass in your head? A neuroprosthesis that feeds geomagnetic signals into the brains of blind rats has enabled them to navigate around a maze. The results demonstrate that the rats could rapidly learn to deploy a completely unnatural "sense". It raises the possibility that humans could do the same, potentially opening up new ways to treat blindness, or even to provide healthy people with extra senses. "I'm dreaming that humans can expand their senses through artificial sensors for geomagnetism, ultraviolet, radio waves, ultrasonic waves and so on," says Yuji Ikegaya of the University of Tokyo in Japan, head of the team that installed and tested the 2.5-gram implant. "Ultrasonic and radio-wave sensors may enable the next generation of human-to-human communicationMovie Camera," he says. The neuroprosthesis consists of a geomagnetic compass – a version of the microchip found in smartphones – and two electrodes that fit into the animals' visual cortices, the areas of the brain that process visual information. Whenever the rat positioned its head within 20 degrees either side of north, the electrodes sent pulses of electricity into its right visual cortex. When the rat aligned its head in a southerly direction, the left visual cortex was stimulated. The stimulation allowed blind rats to build up a mental map of their surroundings without any visual cues. During training, blind rats equipped with digital compasses improved at finding food rewards in a five-pronged maze, despite being released from one of three different arms of the maze at random each time. © Copyright Reed Business Information Ltd

Keyword: Vision; Robotics
Link ID: 20757 - Posted: 04.04.2015

By Catherine Saint Louis Joni Mitchell, 71, was taken to a hospital in Los Angeles on Tuesday after she was found unconscious at her Los Angeles home. In recent years, the singer has complained of a number of health problems, including one particularly unusual ailment: Morgellons disease. People who believe they have the condition report lesions that don’t heal, “fibers” extruding from their skin and uncomfortable sensations like pins-and-needles tingling or stinging. Sufferers may also report fatigue and problems with short-term memory and concentration. But Morgellons is not a medically accepted diagnosis. Scientists have struggled for nearly a decade to find a cause and have come up mostly empty-handed. Researchers at the Centers for Disease Control and Prevention studied 115 people who said they had the condition. In a report published in 2012, they said they were unable to identify an infectious source for the patients’ “unexplained dermopathy.” There was no evidence of an environmental link, and the “fibers” from patients resembled those from clothing that had gotten trapped in a scab or crusty skin. The investigators cast doubt on Morgellons as a distinct condition and said that it might be something doctors were already familiar with: delusional infestation, a psychiatric condition characterized by an unshakable but erroneous belief that one’s skin is infested with bugs or parasites. Drug use can contribute to such delusions, and the investigators noted evidence of drug use — prescription or illicit — in half of the people they examined. Of the 36 participants who completed neuropsychological testing, 11 percent had high scores for depression, and 63 percent, unsurprisingly, were preoccupied with health issues. © 2015 The New York Times Company

Keyword: Pain & Touch
Link ID: 20749 - Posted: 04.02.2015

​​The commonly-prescribed drug acetaminophen or paracetamol does nothing to help low back pain, and may affect the liver when used regularly, a large new international study has confirmed. Reporting in today's issue of the British Medical Journal researchers also say the benefits of the drug are unlikely to be worth the risks when it comes to treating osteoarthritis in the hip or knee. "Paracetamol has been widely recommended as being a safe medication, but what we are saying now is that paracetamol doesn't bring any benefit for patients with back pain, and it brings only trivial benefits to those with osteoarthritis," Gustavo Machado of The George Institute for Global Health and the University of Sydney, tells the Australian Broadcasting Corporation. "In addition to that it might bring harm to those patients." Most international clinical guidelines recommend acetaminophen as the "first choice" of treatment for low back pain and osteoarthritis of the hip and knee. However, despite a trial last year questioning the use of acetaminophen to treat low back pain, there has never been a systematic review of the evidence for this. Machado and colleagues analyzed three clinical trials and confirmed that acetaminophen is no better than placebo at treating low back pain. An analysis of 10 other clinical trials by the researchers quantified for the first time the effect acetaminophen has on reducing pain from osteoarthritis in the knee and hip. "We concluded that it is too small to be clinically worthwhile," says Machado. He says the effects of acetaminophen on the human body are not well understood and just because it can stop headaches, it doesn't mean the drug will work in all circumstances. ©2015 CBC/Radio-Canada.

Keyword: Pain & Touch
Link ID: 20748 - Posted: 04.02.2015

By Virginia Morell Rats and mice in pain make facial expressions similar to those in humans—so similar, in fact, that a few years ago researchers developed rodent “grimace scales,” which help them assess an animal’s level of pain simply by looking at its face. But scientists have questioned whether these expressions convey anything to other rodents, or if they are simply physiological reactions devoid of meaning. Now, researchers report that other rats do pay attention to the emotional expressions of their fellows, leaving an area when they see a rat that’s suffering. “It’s a finding we thought might be true, and are glad that someone figured out how to do an experiment that shows it,” says Jeffrey Mogil, a neuroscientist at McGill University in Montreal, Canada. Mogil’s lab developed pain grimace scales for rats and mice in 2006, and it discovered that mice experience pain when they see a familiar mouse suffering—a psychological phenomenon known as emotional contagion. According to Mogil, a rodent in pain expresses its anguish through narrowed eyes, flattened ears, and a swollen nose and cheeks. Because people can read these visual cues and gauge the intensity of the animal’s pain, Mogil has long thought that other rats could do so as well. In Japan, Satoshi Nakashima, a social cognition psychologist at NTT Communication Science Laboratories in Kanagawa, thought the same thing. And, knowing that other scientists had recently shown that mice can tell the difference between paintings by Picasso and Renoir, he decided to see if rodents could also discriminate between photographs of their fellows’ expressions. He designed the current experiments as part of his doctoral research. © 2015 American Association for the Advancement of Science

Keyword: Pain & Touch; Emotions
Link ID: 20745 - Posted: 04.01.2015

Mo Costandi During the 1960s, neuroscientists Ronald Melzack and Patrick Wall proposed an influential new theory of pain. At the time, researchers were struggling to explain the phenomenon. Some believed that specific nerve fibres carry pain signals up into the brain, while others argued that the pain signals are transmitted by intense firing of non-specific fibres. Neither idea was entirely satisfactory, because they could not explain why spinal surgery often fails to abolish pain, why gentle touch and other innocuous stimuli can sometimes cause excruciating pain, or why intensely painful stimuli are not always experienced as such. Melzack and Wall’s Gate Control Theory stated that inhibitory neurons in the spinal cord control the relay of pain signals into the brain. Despite having some holes in it, the theory provided a revolutionary new framework for understanding the neural basis of pain, and ushered in the modern era of pain research. Now, almost exactly 50 years after the publication of Melzack and Wall’s theory, European researchers provide direct evidence of gatekeeper cells that control the flow of pain and itch signals from the spinal cord to the brain. The experience that we call “pain” is an extremely complex one that often involves emotional aspects. Researchers therefore distinguish it from nociception, the process by which the nervous system detects noxious stimuli. Nociception is mediated by primary sensory neurons, whose cell bodies are clumped together in the dorsal root ganglia that run alongside the spinal cord. Each has a single fibre that splits in two not far from the cell body, sending one branch out to the skin surface and the other into the spinal cord. © 2015 Guardian News and Media Limited

Keyword: Pain & Touch; Emotions
Link ID: 20744 - Posted: 04.01.2015

Claudia Dreifus Twenty-three states and the District of Columbia have legalized medical marijuana, but scientific research into its appropriate uses has lagged. Dr. Mark Ware would like to change that. Dr. Ware, 50, is the director of the Canadian Consortium for the Investigation of Cannabinoids and the director of clinical research of the Alan Edwards Pain Management Unit of McGill University Health Center. Medical marijuana has been legal in Canada for 16 years, and Dr. Ware, a practicing physician, studies how his patients take the drug and under what conditions it is effective. We spoke for two hours at the recent meeting of the American Association for the Advancement of Science and later by telephone. Our interviews have been condensed and edited for space. Q. How did you become interested in the medical possibilities of cannabis? A. In the late 1990s, I was working in Kingston, Jamaica, at a clinic treating people with sickle cell anemia. My British father and Guyanese mother had raised me in Jamaica, and I’d attended medical school there. One day, an elderly Rastafarian came for his annual checkup. I asked him, “What are your choices of medicines?” He leaned over the table and said, “You must study the herb.” That night, I went back to my office and looked up “cannabis and pain.” What I found were countless anecdotes from patients who’d obtained marijuana either legally or not and who claimed good effect with a variety of pain-related conditions. There were also the eye-opening studies showing that the nervous system had specific receptors for cannabinoids and that these receptors were located in areas related to pain. Everything ended with, “More studies are needed.” So I thought, “This is what I should be doing; let’s go!” © 2015 The New York Times Company

Keyword: Drug Abuse; Pain & Touch
Link ID: 20713 - Posted: 03.24.2015