Chapter 5. The Sensorimotor System
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By Lisa Sanders, M.D On Thursday we challenged Well readers to solve the difficult case of twin sisters who, in the prime of youth, developed a weakness that forced them to use their arms to rise from a chair. Nearly 300 of you wrote in with thoughts on this difficult case. Many of you recognized that this was likely to be a genetic disorder, though I greatly admired the “House”-ian thinking that led to a host of possible reasons why two sisters, living in different states, might develop the same symptoms independent of their shared DNA. It took this patient, Katie Buryk, four years to get her answer, which was: Late onset Tay-Sachs disease Although several of you made this difficult diagnosis, the first to do so was George Bonadurer, a second year medical student at Mayo Medical School in Rochester, Minn. He says he recently read about this disease in a book of unusual cases that had come to the Mayo clinic for help. This is actually Mr. Bonadurer’s second win of this contest. Strong work! Tay-Sachs disease was first identified by two physicians, independently, in the 1880s. Dr. Warren Tay was an ophthalmologist in London. Dr. Bernard Sachs was a neurologist in New York City. Each described a disease in infants that caused profound weakness, blindness and, usually by age 4, death. Careful consideration of cases over the following decades showed that the disease was inherited and often seen in children of Ashkenazi descent. Studying the patterns of inheritance, it became clear that both parents had to have the abnormal gene and that each of their children would have a one in four chance of being born with the disease. The terrible manifestations of the disease derive from an inherited inability to make an essential protein in the brain. This protein acts to break down discarded components of the cells. Without this protein, these discarded cell parts accumulate, interrupting normal nerve and brain cell functioning. This mechanism and the missing protein was identified in 1969, allowing for the development of a test for carriers. Since the development of this test, the incidence of Tay-Sachs in the United States has dropped by 90 percent. © 2015 The New York Times Company
Andrew Griffin Companies are taking out a huge amount of patents related to reading brainwaves, according to analysis, with a range of different applications. Fewer than 400 neuro-technology related patents were filed between 2000-2009. But in 2010 alone that reached 800, and last year 1,600 were filed, according to research company SharpBrains. The patents are for a range of uses, not just for the healthcare technology that might be expected. The company with the most patents is market research firm Nielsen, which has 100. Microsoft also has 89 related patents. Other uses of the technology that have been patented include devices that can change the thoughts of feelings of those that they are used on. But there are still medical uses — some of those patents awarded include technology to measure brain lesions and improve vision. The volume and diversity of the patents shows that we are at the beginning of “the pervasive neurotechnology age”, the company’s CEO Alvaro Fernandez said. "Neurotech has gone well beyond medicine, with non-medical corporations, often under the radar, developing neurotechnologies to enhance work and life," said Fernandez.
Roger Dobson Tapping your fingers on the table is usually a sign of boredom or irritation. But not all tappers are equal, it seems. Men drum their digits slightly faster than women and people in their twenties tap substantially faster than people twice their age. The results of the first study into finger-tapping speeds also found that smokers tap a little faster than non-smokers and fit people tap faster than those who avoid exercise. The research, carried out by scientists at two universities in Istanbul – Bogazici University and Fatih University – examined the tapping rates and “finger load capacities” of 148 people aged between 18 and 85. Each participant was asked to perform a one-minute tapping exercise on a keyboard at “maximum volitional tempo”. Researchers found that the index finger on the right hand of both men and women was the fastest digit, achieving a tapping rate of up to five beats a second among those in their twenties. The middle finger was almost as nifty as the index finger, but the little finger – the slowest digit in the bunch – was capable only of a sluggish 3.8 taps a second among people in the same age group. At first glance, the study might appear to be rather frivolous. But a deeper understanding of finger tapping could aid the design of computer keyboards and musical instruments. It may also aid researchers who use finger-tapping tests for medical assessment of neurological conditions such as Parkinson’s disease, schizophrenia and Alzheimer’s.
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.
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
Scientists have raised hopes that they may be able to create a vaccine to block the progress of Parkinson’s disease. They believe new research provides evidence that an abnormal protein may trigger the condition. If the theory is correct, researchers say it might be possible to prime a person’s immune system – using a special vaccine – so it is ready to attack the rogue protein as it passes through the body. In this way, the protein would be prevented from destroying a person’s dopamine-manufacturing cells, where the disease inflicts its greatest damage. This new vision of Parkinson’s has been arousing excitement among researchers. “It has transformed the way we see Parkinson’s,” said Roger Barker, professor of clinical neurosciences at Cambridge University. Parkinson’s does not usually affect people until they are over 50. However, researchers have uncovered recent evidence that suggests it may be caused by an event occurring 10 to 20 years before its main symptoms – tremors, rigidity and slowness of movement – manifest themselves. “If you ask Parkinson’s patients if, in the past, they have experienced loss of sense of smell or suffer from disturbed sleep or have problems with their bowels, very often they reply they have,” said Barker, whose work is backed by the charity Parkinson’s UK, whose Parkinson Awareness week ends on Sunday. “Frequently these patients manifest symptoms several years before it becomes apparent they have the disease. We now believe there is a link.” © 2015 Guardian News and Media Limited
Link ID: 20855 - Posted: 04.28.2015
By Emily Dwass In the frightening world of brain tumors, “benign” is a good word to hear. But even a nonmalignant tumor can be dangerous — especially if, as in my case, it goes undetected, becoming a stealth invader. “Anecdotally, we often hear about women who were originally misdiagnosed — sometimes for years,” said Tom Halkin, a spokesman for the patient advocacy nonprofit National Brain Tumor Society. When I developed tingling in my limbs 12 years ago, two Los Angeles neurologists diagnosed Guillain-Barré syndrome, a disorder in which the immune system attacks the nervous system. The symptoms of numbness and weakness ebbed and flowed for three years. Then one day, I couldn’t slide my right foot into a flip-flop. This got me a ride in a magnetic resonance imaging machine, which revealed a brain mass the size of a tennis ball. It was a benign meningioma, a tumor that grows in the membranes surrounding the brain and spinal cord. After the diagnosis, I consulted with Los Angeles surgeons. “We’re going to cut your head open like a pumpkin,” one told me. I chose someone else, who had a stellar reputation, who was compassionate, and who did not compare my skull to a squash. “You’re cured,” he said as I awoke in the operating room. Recovery took about six weeks and went smoothly, except for my right foot, which remains partly numb. I relearned to walk and to drive with my left foot, using adaptive equipment. Had my tumor been diagnosed earlier, I might have avoided a large craniotomy and permanent foot issues. “It’s critical to find these tumors when they are small, when radiosurgery is an option, rather than when they are very big or produce a lot of symptoms, at which point it’s not optimal to treat them without doing open surgery,” said Dr. Susan Pannullo, the director of neuro-oncology and neurosurgical radiosurgery at NewYork-Presbyterian Hospital and Weill Cornell Medical College. © 2015 The New York Times Company
Keyword: Movement Disorders
Link ID: 20854 - Posted: 04.28.2015
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