Chapter 5. The Sensorimotor System
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By Jerry Adler Smithsonian Magazine | In London, Benjamin Franklin once opened a bottle of fortified wine from Virginia and poured out, along with the refreshment, three drowned flies, two of which revived after a few hours and flew away. Ever the visionary, he wondered about the possibility of incarcerating himself in a wine barrel for future resurrection, “to see and observe the state of America a hundred years hence.” Alas, he wrote to a friend in 1773, “we live in an age too early . . . to see such an art brought in our time to its perfection.” If Franklin were alive today he would find a kindred spirit in Ken Hayworth, a neuroscientist who also wants to be around in 100 years but recognizes that, at 43, he’s not likely to make it on his own. Nor does he expect to get there preserved in alcohol or a freezer; despite the claims made by advocates of cryonics, he says, the ability to revivify a frozen body “isn’t really on the horizon.” So Hayworth is hoping for what he considers the next best thing. He wishes to upload his mind—his memories, skills and personality—to a computer that can be programmed to emulate the processes of his brain, making him, or a simulacrum, effectively immortal (as long as someone keeps the power on). Hayworth’s dream, which he is pursuing as president of the Brain Preservation Foundation, is one version of the “technological singularity.” It envisions a future of “substrate-independent minds,” in which human and machine consciousness will merge, transcending biological limits of time, space and memory. “This new substrate won’t be dependent on an oxygen atmosphere,” says Randal Koene, who works on the same problem at his organization, Carboncopies.org. “It can go on a journey of 1,000 years, it can process more information at a higher speed, it can see in the X-ray spectrum if we build it that way.”
By Brady Dennis In recent months, Pasadena-based Genervon has galvanized many patients with ALS by repeatedly touting the results of 12-week, 12-person trial involving the company's drug, GM604. The company asserted its early results were “statistically significant,” “very robust” and “dramatic.” It also has said it "submitted an accelerated approval application" to the FDA which, if approved, "would allow immediate access" to patients with ALS, also known as Lou Gehrig's disease. But the Wall Street Journal reported Monday that Genervon said in an email that it is “at the point of communicating with FDA about whether [the agency] would accept our formal application” for accelerated approval. In other words, the company has not yet submitted a New Drug Application, a step needed to officially set the FDA approval process in motion. The company's acknowledgement that it has not filed an NDA appears to contradict earlier press releases and statements made by the firm's owners, Winston and Dorothy Ko -- or at least to have sown confusion about the actual status of GM604. In one February press release, for example, the company said that in a meeting with the FDA, "three times during the one-hour meeting we requested that the FDA grant GM604 accelerated approval." Asking, however, is not the same as filing the necessary paperwork and the accompanying data required for the FDA to accept it as sufficient. The difference might seem to be a matter of semantics. But the real-world consequence is that, if Genervon has no application pending at the FDA, there is no imminent decision for the FDA to make about approving GM604.
Keyword: ALS-Lou Gehrig's Disease
Link ID: 20833 - Posted: 04.22.2015
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
Carl Zimmer In 1998, Dr. Philip A. Starr started putting electrodes in people’s brains. A neurosurgeon at the University of California, San Francisco, Dr. Starr was treating people with Parkinson’s disease, which slowly destroys essential bits of brain tissue, robbing people of control of their bodies. At first, drugs had given his patients some relief, but now they needed more help. After the surgery, Dr. Starr closed up his patients’ skulls and switched on the electrodes, releasing a steady buzz of electric pulses in their brains. For many patients, the effect was immediate. “We have people who, when they’re not taking their meds, can be frozen,” said Dr. Starr. “When we turn on the stimulator, they start walking.” First developed in the early 1990s, deep brain stimulation, or D.B.S., was approved by the Food and Drug Administration for treating Parkinson’s disease in 2002. Since its invention, about 100,000 people have received implants. While D.B.S. doesn’t halt Parkinson’s, it can turn back the clock a few years for many patients. Yet despite its clear effectiveness, scientists like Dr. Starr have struggled to understand what D.B.S. actually does to the brain. “We do D.B.S. because it works,” said Dr. Starr, “but we don’t really know how.” In a recent experiment, Dr. Starr and his colleagues believe they found a clue. D.B.S. may counter Parkinson’s disease by liberating the brain from a devastating electrical lock-step. The new research, published on Monday in Nature Neuroscience, may help scientists develop better treatments for Parkinson’s disease. It may also help researchers adapt D.B.S. for treatment of such brain disorders as depression and obsessive compulsive disorder. © 2015 The New York Times Company
Link ID: 20817 - Posted: 04.18.2015
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
by Jessica Hamzelou An exoskeleton that enables movement and provides tactile feedback has helped eight paralysed people regain sensation and move previously paralysed muscles "I FELT the ball!" yelled Juliano Pinto as he kicked off the Football World Cup in Brazil last year. Pinto, aged 29 at the time, lost the use of his lower body after a car accident in 2006. "It was the most moving moment," says Miguel Nicolelis at Duke University in North Carolina, head of the Walk Again Project, which developed the thought-controlled exoskeleton that enabled Pinto to make his kick. Since November 2013, Nicolelis and his team have been training Pinto and seven other people with similar injuries to use the exoskeleton – a robotic device that encases the limbs and converts brain signals into movement. The device also feeds sensory information to its wearer, which seems to have partially reawakened their nervous system. When Nicolelis reassessed his volunteers after a year of training, he found that all eight people had regained sensations and the ability to move muscles in their once-paralysed limbs. "Nobody expected it at all," says Nicolelis, who presented the results at the Brain Forum in Lausanne, Switzerland, on 31 March. "When we first saw the level of recovery, there was not a single person in the room with a dry eye." When a person's spinal cord is injured, the connection between body and brain can be damaged, leaving them unable to feel or move parts of their body. If a few spinal nerves remain, people can sometimes regain control over their limbs, although this can involve years of rehabilitation. © Copyright Reed Business Information Ltd.
Link ID: 20805 - 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 Hal Hodson For a few days last summer, a handful of students walked through a park behind the University of Hannover in Germany. Each walked solo, but followed the same route as the others: made the same turns, walked the same distance. This was odd, because none of them knew where they were going. Instead, their steps were steered from a phone 10 paces behind them, which sent signals via bluetooth to electrodes attached to their legsMovie Camera. These stimulated the students' muscles, guiding their steps without any conscious effort. Max Pfeiffer of the University of Hannover was the driver. His project directs electrical currentMovie Camera into the students' sartorius, the longest muscle in the human body, which runs from the inside of the knee to the top of the outer thigh. When it contracts, it pulls the leg out and away from the body. To steer his test subjects left, Pfeiffer would zap their left sartorius, opening their gait and guiding them in that direction. Pfeiffer hopes his system will free people's minds up for other things as they navigate the world, allowing them to focus on their conversation or enjoy their surroundings. Tourists could keep their eyes on the sights while being imperceptibly guided around the city. Acceptance may be the biggest problem, although it is possible that the rise of wearable computing might help. Pfeiffer says the electrode's current causes a tingling sensation that diminishes the more someone uses the system. Volunteers said they were comfortable with the system taking control of their leg muscles, but only if they felt they could take control back. © Copyright Reed Business Information Ltd
Link ID: 20761 - Posted: 04.06.2015
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
By Amy Ellis Nutt and Brady Dennis For people with amyotrophic lateral sclerosis, which attacks the body’s motor neurons and renders a person unable to move, swallow or breathe, the search for an effective treatment has been a crushing disappointment. The only drug available for the disease, approved two decades ago, typically extends life just a few months. Then in the fall, a small California biotech company named Genervon began extolling the benefits of GM604, its new ALS drug. In an early-stage trial with 12 patients, the results were “statistically significant,” “very robust” and “dramatic,” the company said in news releases. Such enthusiastic pronouncements are unusual for such a small trial. In February, Genervon took an even bolder step: It applied to the Food and Drug Administration for “accelerated approval,” which allows promising treatments for serious or life-threatening diseases to bypass costly, large-scale efficacy trials and go directly to market. ALS patients responded by pleading with the FDA, in emotional videos and e-mails, to grant broad access to the experimental drug. Online forums lit up, and a Change.org petition calling for rapid approval attracted more than a half-million signatures. “Why would anyone oppose it?” asked ALS patient David Huntley in a letter read aloud in the past week at a rally on Capitol Hill. Huntley, a former triathlete, can no longer speak or travel, so his wife, Linda Clark, flew from San Diego to speak for him.
Keyword: ALS-Lou Gehrig's Disease
Link ID: 20752 - Posted: 04.04.2015
Davide Castelvecchi Boots rigged with a simple spring-and-ratchet mechanism are the first devices that do not require power aids such as batteries to make walking more energy efficient. People walking in the boots expend 7% less energy than they do walking in normal shoes, the devices’ inventors report on 1 April in Nature1. That may not sound like much, but the mechanics of the human body have been shaped by millions of years of evolution, and some experts had doubted that there was room for further improvement in human locomotion, short of skating along on wheels. “It is the first paper of which I’m aware that demonstrates that a passive system can reduce energy expenditure during walking,” says Michael Goldfarb, a mechanical engineer at Vanderbilt University in Nashville, Tennessee, who develops exoskeletons for aiding people with disabilities. As early as the 1890s, inventors tried to boost the efficiency of walking by using devices such as rubber bands, says study co-author Gregory Sawicki, a biomedical engineer and locomotion physiologist at North Carolina State University in Raleigh. More recently, engineers have built unpowered exoskeletons that enable people to do tasks such as lifting heavier weights — but do not cut down the energy they expend. (Biomechanists still debate whether the running ‘blades’ made famous by South African sprinter Oscar Pistorius are more energetically efficient than human feet.2, 3) For their device, Sawicki and his colleagues built a mechanism that parallels human physiology. When a person swings a leg forward to walk, elastic energy is stored mostly in the Achilles tendon of their standing leg. That energy is released when the standing leg's foot pushes into the ground and the heel lifts off, propelling the body forwards. “There is basically a catapult in our ankle,” Sawicki says. © 2015 Nature Publishing Group
Link ID: 20750 - Posted: 04.02.2015
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
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
By Maggie Fox and Jane Derenowski A new strain of the polio-like EV-D68 may be causing the rare and mystifying cases of muscle weakness that's affected more than 100 kids across the United States, researchers reported Monday. They say they've found the strongest evidence yet that the virus caused the polio-like syndrome, but they also say it appears to be rare and might have to do with the genetic makeup of the patients. No other germ appears to be responsible, the team reports in the journal Lancet Infectious Diseases. But because most kids were tested many days after they first got sick, it may be impossible to ever know for sure. The body will have cleared the virus itself by then, said Dr. Charles Chiu of the University of California San Francisco, who helped conduct the study. "This is a virus that causes the common cold," Chiu told NBC News. "Parents don't bring their kids in until they are really sick. By that time, typically, the viral levels may be very, very low or undetectable." "Every single virus that we found in the children corresponded to new strain of the virus, called B-1." Enterovirus D68 (EV-D68) is one of about 100 different enteroviruses that infect people. They include polio but also a range of viruses that cause cold-like symptoms. Polio's the only one that is vaccinated against; before widespread vaccination it crippled 35,000 people a year in the United States.
Keyword: Movement Disorders
Link ID: 20739 - Posted: 03.31.2015
Carl Zimmer Scientists in Iceland have produced an unprecedented snapshot of a nation’s genetic makeup, discovering a host of previously unknown gene mutations that may play roles in ailments as diverse as Alzheimer’s disease, heart disease and gallstones. “This is amazing work, there’s no question about it,” said Daniel G. MacArthur, a geneticist at Massachusetts General Hospital who was not involved in the research. “They’ve now managed to get more genetic data on a much larger chunk of the population than in any other country in the world.” In a series of papers published on Wednesday in the journal Nature Genetics, researchers at Decode, an Icelandic genetics firm owned by Amgen, described sequencing the genomes — the complete DNA — of 2,636 Icelanders, the largest collection ever analyzed in a single human population. With this trove of genetic information, the scientists were able to accurately infer the genomes of more than 100,000 other Icelanders, or almost a third of the entire country. “From the technical point of view, these papers are a tour-de-force,” said David Reich, a geneticist at Harvard Medical School who was not involved in the research. While some diseases, like cystic fibrosis, are caused by a single genetic mutation, the most common ones are not. Instead, mutations to a number of different genes can each raise the risk of getting, say, heart disease or breast cancer. Discovering these mutations can shed light on these diseases and point to potential treatments. But many of them are rare, making it necessary to search large groups of people to find them. The wealth of data created in Iceland may enable scientists to begin doing that. In their new study, the researchers at Decode present several such revealing mutations. For example, they found eight people in Iceland who shared a mutation on a gene called MYL4. Medical records showed that they also have early onset atrial fibrillation, a type of irregular heartbeat. © 2015 The New York Times Company
By Kate Baggaley Mutations on a gene necessary for keeping cells clean can cause Lou Gehrig’s disease, scientists report online March 24 in Nature Neuroscience. The gene is one of many that have been connected to the condition. In amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, nerve cells that control voluntary movement die, leading to paralysis. Scientists have previously identified mutations in 29 genes that are linked with ALS, but these genes account for less than one-third of all cases. To track down more genes, a team of European researchers looked at the protein-coding DNA of 252 ALS patients with a family history of the disease, as well as of 827 healthy people. The team discovered eight mutations on a gene called TBK1 that were associated with ALS. TBK1 normally codes for a protein that controls inflammation and cleans out damaged proteins from cells. “We do not know which of these two principle functions of TBK1 is the more relevant one” to ALS, says coauthor Jochen Weishaupt, a neurologist at Ulm University in Germany. In cells with one of the eight TBK1 mutations, the protein either is missing or lacks components that it needs to interact with other proteins, the researchers found. TBK1 mutations may explain 2 percent of ALS cases that run in families, which make up about 10 percent of all incidences of the disease, Weishaupt says. © Society for Science & the Public 2000 - 2015