Chapter 11. Motor Control and Plasticity
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by Catherine de Lange Why wait for the doctor to see you? A smart patch attached to your skin could diagnose health problems automatically – and even administer drugs. Monitoring movement disorders such as Parkinson's disease or epilepsy relies on video recordings of symptoms and personal surveys, says Dae-Hyeong Kim at the Seoul National University in South Korea. And although using wearable devices to monitor the vital signs of patients is theoretically possible, the wearable pads, straps and wrist bands that can do this are often cumbersome and inflexible. To track the progression of symptoms and the response to medication more accurately would require devices that monitor cues from the body, store recorded data for pattern analysis and deliver therapeutic agents through the human skin in a controlled way, Kim says. So Kim and his team have developed an adhesive patch that is flexible and can be worn on the wrist like a second skin. The patch is 1 millimetre thick and made of a hydrocolloid dressing – a type of thin flexible bandage. Into it they embedded a layer of silicon nanoparticles. These silicon nanomembranes are often used for flexible electronics, and can pick up the bend and stretch of human skin and convert these into small electronic signals. The signals are stored as data in separate memory cells made from layers of gold nanoparticles. The device could be used to detect and treat tremors in people who have Parkinson's disease, or epileptic seizures, says Kim. If these movements are detected, small heaters in the patch trigger the release of drugs from silicon nanoparticles. The patch also contains temperature sensors to make sure the skin doesn't burn during the process. © Copyright Reed Business Information Ltd.
By JAMES GORMAN There are lots of reasons scientists love fruit flies, but a big one is their flying ability. These almost microscopic creatures, with minimalist nervous systems and prey to every puff of wind, must often execute millisecond aerial ballets to stay aloft. To study fly flight, scientists have to develop techniques that are almost as interesting as the flies. At Cornell University, for instance, researchers have been investigating how the flies recover when their flight is momentarily disturbed. Among their conclusions: a small group of fly neurons is solving calculus problems, or what for humans are calculus problems. To do the research, the members of Cornell team — Itai Cohen and his colleagues, including Z. Jane Wang, John Guckenheimer, Tsevi Beatus and Leif Ristroph, who is now at New York University — glue tiny magnets to the flies and use a magnetic pulse to pull them this way or that. In the language of aeronautics, the scientists disturb either the flies’ pitch (up or down), yaw (left or right) or roll, which is just what it sounds like. The system, developed by Dr. Ristroph as a graduate student in Dr. Cohen’s lab, involves both low and high tech. On the low end, the researchers snip bits of metal bristle off a brush to serve as micromagnets that they glue to the flies’ backs. At the high end, three video cameras record every bit of the flight at 8,000 frames per second, and the researchers use computers to merge the data from the cameras into a three-dimensional reconstruction of the flies’ movements that they can analyze mathematically. © 2014 The New York Times Company
Link ID: 19388 - Posted: 03.20.2014
Helen Shen For Frank Donobedian, sitting still is a challenge. But on this day in early January, he has been asked to do just that for three minutes. Perched on a chair in a laboratory at Stanford University in California, he presses his hands to his sides, plants his feet on the floor and tries with limited success to lock down the trembling in his limbs — a symptom of his Parkinson's disease. Only after the full 180 seconds does he relax. Other requests follow: stand still, lie still on the floor, walk across the room. Each poses a similar struggle, and all are watched closely by Helen Bronte-Stewart, the neuroscientist who runs the lab. “You're making history,” she reassures her patient. “Everybody keeps saying that,” replies the 73-year-old Donobedian, a retired schoolteacher, with a laugh. “But I'm not doing anything.” “Well, your brain is,” says Bronte-Stewart. Like thousands of people with Parkinson's before him, Donobedian is being treated with deep brain stimulation (DBS), in which an implant quiets his tremors by sending pulses of electricity into motor areas of his brain. Last October, a team of surgeons at Stanford threaded the device's two thin wires, each with four electrode contacts, through his cortex into a deep-seated brain region known as the subthalamic nucleus (STN). But Donobedian's particular device is something new. Released to researchers in August 2013 by Medtronic, a health-technology firm in Minneapolis, Minnesota, it is among the first of an advanced generation of neurostimulators that not only send electricity into the brain, but can also read out neural signals generated by it. On this day, Bronte-Stewart and her team have temporarily turned off the stimulating current and are using some of the device's eight electrical contacts to record abnormal neural patterns that might correlate with the tremors, slowness of movement and freezing that are hallmarks of Parkinson's disease. © 2014 Nature Publishing Group,
By Gary Marcus and Christof Koch What would you give for a retinal chip that let you see in the dark or for a next-generation cochlear implant that let you hear any conversation in a noisy restaurant, no matter how loud? Or for a memory chip, wired directly into your brain's hippocampus, that gave you perfect recall of everything you read? Or for an implanted interface with the Internet that automatically translated a clearly articulated silent thought ("the French sun king") into an online search that digested the relevant Wikipedia page and projected a summary directly into your brain? Science fiction? Perhaps not for very much longer. Brain implants today are where laser eye surgery was several decades ago. They are not risk-free and make sense only for a narrowly defined set of patients—but they are a sign of things to come. Unlike pacemakers, dental crowns or implantable insulin pumps, neuroprosthetics—devices that restore or supplement the mind's capacities with electronics inserted directly into the nervous system—change how we perceive the world and move through it. For better or worse, these devices become part of who we are. Neuroprosthetics aren't new. They have been around commercially for three decades, in the form of the cochlear implants used in the ears (the outer reaches of the nervous system) of more than 300,000 hearing-impaired people around the world. Last year, the Food and Drug Administration approved the first retinal implant, made by the company Second Sight. ©2014 Dow Jones & Company, Inc.
Link ID: 19371 - Posted: 03.17.2014
By Neuroskeptic A neuroscience paper published before Christmas drew my eye with the expansive title: “How Thoughts Give Rise to Action“ Subtitled “Conscious Motor Intention Increases the Excitability of Target-Specific Motor Circuits”, the article’s abstract was no less bold, concluding that: These results indicate that conscious intentions govern motor function… until today, it was unclear whether conscious motor intention exists prior to movement, or whether the brain constructs such an intention after movement initiation. The authors, Zschorlich and Köhling of the University of Rostock, Germany, are weighing into a long-standing debate in philosophy, psychology, and neuroscience, concerning the role of consciousness in controlling our actions. To simplify, one school of thought holds that (at least some of the time), our intentions or plans control our actions. Many people would say that this is what common sense teaches us as well. But there’s an alternative view, in which our consciously-experienced intentions are not causes of our actions but are actually products of them, being generated after the action has already begun. This view is certainly counterintuitive, and many find it disturbing as it seems to undermine ‘free will’. That’s the background. Zschorlich and Köhling say that they’ve demonstrated that conscious intentions do exist, prior to motor actions, and that these intentions are accompanied by particular changes in brain activity. They claim to have done this using transcranial magnetic stimulation (TMS), a way of causing a localized modulation of brain electrical activity.
Link ID: 19370 - Posted: 03.17.2014
New findings reveal how a mutation, a change in the genetic code that causes neurodegeneration, alters the shape of DNA, making cells more vulnerable to stress and more likely to die. The particular mutation, in the C9orf72 gene, is the most common cause for amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease), and frontotemporal degeneration (FTD), the second most common type of dementia in people under 65. This research by Jiou Wang, Ph.D., and his colleagues at Johns Hopkins University (JHU) was published in Nature and was partially funded by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke (NINDS). In ALS, the muscle-activating neurons in the spinal cord die, eventually causing paralysis. In FTD neurons in particular brain areas die leading to progressive loss of cognitive abilities. The mutation may also be associated with Alzheimer’s and Huntington’s diseases. DNA contains a person’s genetic code, which is made up of a unique string of bases, chemicals represented by letters. Portions of this code are divided into genes that provide instructions for making molecules (proteins) that control how cells function. The normal C9orf72 gene contains a section of repeating letters; in most people, this sequence is repeated two to 25 times. In contrast, the mutation associated with ALS and FTD can result in up to tens of thousands of repeats of this section.
By James Gallagher Health and science reporter, BBC News US doctors are warning of an emerging polio-like disease in California where up to 20 people have been infected. A meeting of the American Academy of Neurology heard that some patients had developed paralysis in all four limbs, which had not improved with treatment. The US is polio-free, but related viruses can also attack the nervous system leading to paralysis. Doctors say they do not expect an epidemic of the polio-like virus and that the infection remains rare. Polio is a dangerous and feared childhood infection. The virus rapidly invades the nervous system and causes paralysis in one in 200 cases. It can be fatal if it stops the lungs from working. There have been 20 suspected cases of the new infection, mostly in children, in the past 18 months, A detailed analysis of five cases showed enterovirus-68 - which is related to poliovirus - could be to blame. In those cases all the children had been vaccinated against polio. Symptoms have ranged from restricted movement in one limb to severe weakness in both legs and arms. Dr Emanuelle Waubant, a neurologist at the University of California, San Francisco, told the BBC: "There has been no obvious increase in the pace of new cases so we don't think we're about to experience an epidemic, that's the good news. BBC © 2014
Keyword: Movement Disorders
Link ID: 19283 - Posted: 02.24.2014
by Clare Wilson A monkey controlling the hand of its unconscious cage-mate with its thoughts may sound like animal voodoo, but it is a step towards returning movement to people with spinal cord injuries. The hope is that people who are paralysed could have electrodes implanted in their brains that pick up their intended movements. These electrical signals could then be sent to a prosthetic limb, or directly to the person's paralysed muscles, bypassing the injury in their spinal cord. Ziv Williams at Harvard Medical School in Boston wanted to see if sending these signals to nerves in the spinal cord would also work, as this might ultimately give a greater range of movement from each electrode. His team placed electrodes in a monkey's brain, connecting them via a computer to wires going into the spinal cord of an anaesthetised, unconscious monkey. The unconscious monkey's limbs served as the equivalent of paralysed limbs. A hand of the unconscious monkey was strapped to a joystick, controlling a cursor that the other monkey could see on a screen. Williams's team had previously had the conscious monkey practise the joystick task for itself and had recorded its brain activity to work out which signals corresponded to moving the joystick back and forth. Through trial and error, they deduced which nerves to stimulate in the spinal cord of the anaesthetised monkey to produce similar movements in that monkey's hand. When both parts were fed to the computer, the conscious monkey was able to move the "paralysed" monkey's hand to make the cursor hit a target. © Copyright Reed Business Information Ltd.
Link ID: 19266 - Posted: 02.19.2014
by Clare Wilson SOMETIMES you find out more about how something works by turning it off. That seems to be true for mirror neurons, the brain cells implicated in traits ranging from empathy and learning to language acquisition. Mirror neurons are said to help us interpret other people's behaviour, but this has yet to be shown convincingly in experiments. Now a study that briefly disabled these cells might give a better idea of what they do. Mirror neurons were discovered in the 1990s when an Italian team was measuring electrical activity in the brains of monkeys. In the region that controls movement, some of the neurons that fire to carry out a particular action – such as grasping an apple – also fired when the monkey saw another animal do the same thing. The tempting conclusion was that these neurons help interpret others' behaviour. Further work suggested that people also have this system, and some researchers claimed that conditions where empathy is lacking, such as autism or psychopathy, could arise from defective mirror neurons. Yet there has been little evidence to back this up and critics argued that mirror neuron activity could just be some sort of side effect of witnessing action. Powerful magnetic fields are known to temporarily disrupt brain cell activity, and a technique called transcranial magnetic stimulation (TMS) is increasingly used in the lab to dampen specific areas of the brain. © Copyright Reed Business Information Ltd.
|By Carl Erik Fisher After 22 years of failed treatments, including rehabilitation, psychotherapy and an array of psychiatric medications, a middle-aged Dutch man decided to take an extraordinary step to fight his heroin addiction. He underwent an experimental brain surgery called deep brain stimulation (DBS). At the University of Amsterdam, researchers bored small holes in his skull and guided two long, thin probes deep into his head. The ends of the probes were lined with small electrodes, which were positioned in his nucleus accumbens, a brain area near the base of the skull that is associated with addiction. The scientists ran the connecting wires under his scalp, behind his ear and down to a battery pack sewn under the skin of his chest. Once turned on, the electrodes began delivering constant electrical pulses, much like a pacemaker, with the goal of altering the brain circuits thought to be causing his drug cravings. At first the stimulation intensified his desire for heroin, and he almost doubled his drug intake. But after the researchers adjusted the pulses, the cravings diminished, and he drastically cut down his heroin use. Neurosurgeries are now being pursued for a variety of mental illnesses. Initially developed in the 1980s to treat movement disorders, including Parkinson's disease, DBS is today used to treat depression, dementia, obsessive-compulsive disorder, substance abuse and even obesity. Despite several success stories, many of these new ventures have attracted critics, and some skeptics have even called for an outright halt to this research. © 2014 Scientific American
By LAUREN BRADY When I was 18 I watched my father perform what would be his final surgery. It was the summer of 2007 and I had just returned to Colorado after surviving my freshman year of film school at New York University. One day my dad invited me to observe a vitrectomy. And while I hadn’t a clue what this would entail I immediately accepted, honored by the invitation and determined not to faint. My father’s 21 years as an ophthalmologist produced over 15,000 operations, a private practice spanning three offices, and very little vacation time. While I sensed from an early age that the long hours were taxing on him I never felt an absence. In fact, my childhood was picturesque: two loving parents, a rowdy little brother whom I pushed around until he was big enough to push back, family trips in the Jeep to the Rocky Mountains. He was the dad with the Handycam at every soccer game and school play. He worked as a surgeon, but he lived for his children. The morning of the vitrectomy we left extra early because of a limp in my dad’s right leg that had appeared a few months earlier and had gradually worsened. He suspected it was a pinched nerve and had been meaning to get it checked out. In the interim, he had started using a chair during surgery. Walking toward the hospital entrance we encountered a fellow doctor who greeted me with the familiarity of someone who’d been exposed to years of my father’s wallet photos. He asked how I liked Greenwich Village, whether I had directed any films yet and if I had tried a bialy. We walked and talked until I noticed at one point that my dad was no longer part of the conversation. Turning around I realized he was a half block back pushing himself up from the ground. © 2014 The New York Times Company
Keyword: ALS-Lou Gehrig's Disease
Link ID: 19192 - Posted: 02.01.2014
By JAMES GORMAN The question of how moles move all that dirt when they tunnel just under the surface of lawns has never attracted the extensive study that other forms of locomotion — like the flight of birds and insects, or even the jet-propulsion of jellyfish — have. But scientists at the University of Massachusetts and Brown University have recently been asking exactly how, and how hard, moles dig. Yi-Fen Lin, a graduate student at the University of Massachusetts, reported at a recent meeting of the Society for Integrative and Comparative Biology that moles seem to swim through the earth, and that the stroke they use allows them to pack a lot of power behind their shovel-like paws. Ms. Lin measured the power of hairy-tailed moles that she captured in Massachusetts and found they could exert a force up to 40 times their body weight. She also analyzed and presented X-ray videos taken of moles in a laboratory enclosure tunneling their way through a material chosen for its consistency and uniform particle size: cous cous. Angela M. Horner recorded the videos while studying the movement of Eastern moles in the lab of Thomas Roberts, a professor at Brown. One reason moles have not been studied as much as some other animals may be that they are not easy to capture or keep in a laboratory. “People said, ‘You won’t be able to catch them and you won’t be able to keep them alive,’ ” said Elizabeth R. Dumont, an evolutionary biologist who is Ms. Lin’s dissertation adviser. Ms. Lin solved the first problem by camping out in mole territory, on golf courses and farms, and marking their tunnels with sticks that she would watch for hours until movement indicated a mole on the move. © 2014 The New York Times Company
Link ID: 19179 - Posted: 01.29.2014
By Katherine Harmon Courage Unless you’ve eaten sannakji, the Korean specialty of semi-live octopus, you might never have had a squirming octopus arm in your mouth. But you’ve most likely had a very similar experience. In fact, you’re probably having one right now. Octopus arms might seem strange and mysterious, but they are remarkably similar to the human tongue. Known as muscular hydrostats, both of these appendages can easily bend, extend and change shape (remember that time you had to stretch out your tongue to lick that last bit of chocolate pudding from the bottom of the cup?). Researchers are hoping a new interdisciplinary project to look at movement in the octopus arm and the human tongue will shed light on how both of these complex structures are activated. This, in turn, could help scientists understand neurological diseases that affect speech, such as Parkinson’s. “The human tongue is a very different muscular system than the rest of the human body,” Khalil Iskarous, an assistant professor of linguistics at the University of Southern California who is helping to lead the research, said in a prepared statement. “Our bodies are vertebrate mechanisms that operate by muscle working on bone to move. The tongue is in a different muscular family, much like an invertebrate. It’s entirely muscle—it’s muscle moving muscle.” Both move by compressing fluid in one section of a muscle, creating movement in another part. But we know little about exactly how that movement is initiated and so finely controlled. © 2014 Scientific American
Keyword: Movement Disorders
Link ID: 19117 - Posted: 01.11.2014
Just in time for all those New Year’s resolutions to exercise more, scientists have a better idea of how the body turns pain into gain. Exertion stimulates muscles to release a molecule that modifies fat cells, turning them into calorie-burning machines, a research team has found. Exercise works the muscles but affects cells throughout the body, even in the brain. An important player in this process is a protein called PGC-1α. In exercising muscles, it activates genes that ramp up energy use. But its impact extends beyond these tissues. The protein somehow indirectly prompts, for example, white fat—the energy-storing variety that pads our hips and stomachs—to switch on genes that are characteristic of brown fat, a form that burns calories. PGC-1α doesn’t travel outside muscle cells, so researchers aren’t sure how its influence spreads, however. By sifting through the secretions of PGC-1α-making muscle cells, Robert Gerszten of Harvard Medical School in Boston and colleagues have nabbed one molecule that might be doing the protein’s bidding: β-aminoisobutyric acid (BAIBA). They found that BAIBA induces white fat cells to become more like brown fat cells, altering their gene activity patterns. And it stimulates other cell types, stoking fat metabolism in the liver, the team also reveals today in Cell Metabolism. These effects may translate into a healthier metabolism. When mice lapped up water laced with the molecule, the rodents lost weight and were better at absorbing glucose. © 2014 American Association for the Advancement of Science
Don’t worry about watching all those cat videos on the Internet. You’re not wasting time when you are at your computer—you’re honing your fine-motor skills. A study of people’s ability to translate training that involves clicking and twiddling a computer mouse reveals that the brain can apply that expertise to other fine-motor tasks requiring the hands. We know that computers are altering the way that people think. For example, using the Internet changes the way that you remember information. But what about use of the computer itself? You probably got to this story by using a computer mouse, for example, and that is a bizarre task compared with the activities that we’ve encountered in our evolutionary history. You made tiny movements of your hand in a horizontal plane to cause tiny movements of a cursor in a completely disconnected vertical plane. But with daily practice—the average computer user makes more than 1000 mouse clicks per day—you have become such an expert that you don’t even think about this amazing feat of dexterity. Scientists would love to know if that practice affects other aspects of your brain’s control of your body. The problem is finding people with no computer experience. So Konrad Kording, a psychologist at Northwestern University’s Rehabilitation Institute of Chicago in Illinois, and his former postdoc Kunlin Wei, now at Peking University in Beijing, turned to migrant Chinese workers. The country’s vast population covers the whole socioeconomic spectrum, from elite computer hackers to agricultural laborers whose lifestyles have changed little over the past century. The country’s economic boom is bringing people in waves from the countryside to cities in search of employment. © 2013 American Association for the Advancement of Science
Keyword: Learning & Memory
Link ID: 19060 - Posted: 12.21.2013
by Ashley Yeager With a little help from implanted electrodes, Parkinson's patients make fewer driving errors, at least on a computer. When steering a simulator, patients with active brain stimulators averaged 3.8 driving errors, compared with 7.5 for healthy people and 11.4 for those with Parkinson's disease who did not have implants. The Parkinson’s patients’ driving skills were also more accurate when receiving deep brain stimulation than when taking levodopa, a common treatment for the disease, researchers report December 18 in Neurology. © Society for Science & the Public 2000 - 2013
Link ID: 19054 - Posted: 12.19.2013
People with dementia who exercise improve their thinking abilities and everyday life, a body of medical research concludes. The Cochrane Collaboration carried out a systematic review of eight exercise trials involving more than 300 patients living at home or in care. Exercise did little for patients' moods, the research concluded. But it did help them carry out daily activities such as rising from a chair, and boosted their cognitive skills. Whether these benefits improve quality of life is still unclear, but the study authors say the findings are reason for optimism. Dementia affects some 800,000 people in the UK. And the number of people with the condition is steadily increasing because people are living longer. It is estimated that by 2021, the number of people with dementia in the UK will have increased to around one million. With no cure, ways to improve the lives of those living with the condition are vital. Researcher Dorothy Forbes, of the University of Alberta, and colleagues who carried out the Cochrane review, said: "Clearly, further research is needed to be able to develop best practice guidelines to enable healthcare providers to advise people with dementia living at home or in institutions. "We also need to understand what level and intensity of exercise is beneficial for someone with dementia." BBC © 2013
Link ID: 18999 - Posted: 12.05.2013
At the Society for Neuroscience meeting earlier this month in San Diego, California, Science sat down with Geoffrey Ling, deputy director of the Defense Sciences Office at the Defense Advanced Research Projects Agency (DARPA), to discuss the agency’s plans for the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, a neuroscience research effort put forth by President Barack Obama earlier this year. So far, DARPA has released two calls for grant applications, with at least one more likely: The first, called SUBNETS (Systems-Based Neurotechnology for Emerging Therapies), asks researchers to develop novel, wireless devices, such as deep brain stimulators, that can cure neurological disorders such as posttraumatic stress (PTS), major depression, and chronic pain. The second, RAM (Restoring Active Memory), calls for a separate wireless device that repairs brain damage and restores memory loss. Below is an extended version of a Q&A that appears in the 29 November issue of Science. Q: Why did DARPA get involved in the BRAIN project? G.L.: It’s really focused on our injured warfighters, but it has a use for civilians who have stress disorders and civilians who also have memory disorders from dementia and the like. But at the end of the day, it is still meeting [President Obama’s] directive. Of all the things he could have chosen—global warming, alternative fuels—he chose this, so in my mind the neuroscience community should be as excited as all get-up. Q: Why does SUBNETS focus on deep brain stimulation (DBS)? G.L.: We’ve opened the possibility of using DBS but we haven’t exclusively said that. We’re challenging people to go after neuropsychiatric disorders like PTS [and] depression. We’re challenging the community to come up with something in 5 years that’s clinically feasible. DBS is an area that has really been traditionally underfunded, so we thought what the heck, let’s give it a go—in this new BRAIN Initiative the whole idea is to go after the things that there aren’t 400 R01 grants for—and let’s be bold, and boy, if it works, fabulous. © 2013 American Association for the Advancement of Science
Scientists at the National Institutes of Health have used RNA interference (RNAi) technology to reveal dozens of genes which may represent new therapeutic targets for treating Parkinson’s disease. The findings also may be relevant to several diseases caused by damage to mitochondria, the biological power plants found in cells throughout the body. “We discovered a network of genes that may regulate the disposal of dysfunctional mitochondria, opening the door to new drug targets for Parkinson’s disease and other disorders,” said Richard Youle, Ph.D., an investigator at the National Institute of Neurological Disorders and Stroke (NINDS) and a leader of the study. The findings were published online in Nature. Dr. Youle collaborated with researchers from the National Center for Advancing Translational Sciences (NCATS). Mitochondria are tubular structures with rounded ends that use oxygen to convert many chemical fuels into adenosine triphosphate, the main energy source that powers cells. Multiple neurological disorders are linked to genes that help regulate the health of mitochondria, including Parkinson’s, and movement diseases such as Charcot-Marie Tooth Syndrome and the ataxias. Some cases of Parkinson’s disease have been linked to mutations in the gene that codes for parkin, a protein that normally roams inside cells, and tags damaged mitochondria as waste. The damaged mitochondria are then degraded by cells’ lysosomes, which serve as a biological trash disposal system. Known mutations in parkin prevent tagging, resulting in accumulation of unhealthy mitochondria in the body.
by Erika Engelhaupt If you had to have a prosthetic hand, would you want it to look like a real hand? Or would you prefer a gleaming metallic number, something that doesn’t even try to look human? A new study looks at one of the issues that prosthetic designers and wearers face in making this decision: the creepy factor. People tend to get creeped out by robots or prosthetic devices that look almost, but not quite, human. So Ellen Poliakoff and colleagues at the University of Manchester in England had people rate the eeriness of various prosthetic hands. Forty-three volunteers looked at photographs of prosthetic and real hands. They rated both how humanlike (realistic) the hands were and how eerie they were, defined as “mysterious, strange, or unexpected as to send a chill up the spine.” Real human hands were rated both the most humanlike and the least eerie (a good thing for humans). Metal hands that were clearly mechanical were rated the least humanlike, but less eerie overall than prosthetic hands made to look like real hands, the team reports in the latest issue of Perception. The realistic prosthetics, like the rubber hand shown above, fell into what's known as the uncanny valley. That term, invented by roboticist Matsuhiro Mori in 1970, describes how robots become unnerving as they come to look more humanlike. The superrealistic Geminoid DK robot and the animated characters in the movie The Polar Express suffer from this problem. They look almost human, but not quite, and this mismatch between expectation and reality is one of the proposed explanations for the uncanny valley. In particular, if something looks like a human but doesn’t quite move like one, it’s often considered eerie. © Society for Science & the Public 2000 - 2013