Chapter 11. Motor Control and Plasticity
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Maggie Fox NBC News Walking is an almost magic elixir, doctors like to say. It can reverse diabetes, lower blood pressure, and help people keep the fat off. Now a study shows it can also help people with Parkinson’s disease. Parkinson’s patients who walked just three times a week felt less tired, less depressed and they found their Parkinson’s symptoms improved, also. “The results of our study suggest that walking may provide a safe and easily accessible way of improving the symptoms of Parkinson’s disease and improve quality of life,” Dr. Ergun Uc of the University of Iowa and the Veterans Affairs Medical Center of Iowa City, who led the study. The findings would only apply to Parkinson’s patients who can still walk easily. Parkinson’s is caused by the loss of brain cells that produce a message carrying-chemical, or neurotransmitter, that is important for movement. Symptoms can start with a barely noticeable trembling but worsen to difficulty walking and talking, depression and other disability. There’s no cure and the drugs used to treat the condition usually stop helping over time. Some people have trouble walking. But for those who don’t, the study found, walking can help their symptoms. And other research suggests that regular exercise can help slow down the progression of Parkinson’s. Various programs show that dancing,cycling, Pilates and even boxing can help. But walking has a big advantage – people can do it anywhere, without special equipment, and on their own schedules.
Link ID: 19786 - Posted: 07.03.2014
Simon Makin Running helps mice to recover from a type of blindness caused by sensory deprivation early in life, researchers report. The study, published on 26 June in eLife1, also illuminates processes underlying the brain’s ability to rewire itself in response to experience — a phenomenon known as plasticity, which neuroscientists believe is the basis of learning. More than 50 years ago, neurophysiologists David Hubel and Torsten Wiesel cracked the 'code' used to send information from the eyes to the brain. They also showed that the visual cortex develops properly only if it receives input from both eyes early in life. If one eye is deprived of sight during this ‘critical period’, the result is amblyopia, or ‘lazy eye’, a state of near blindness. This can happen to someone born with a droopy eyelid, cataract or other defect not corrected in time. If the eye is opened in adulthood, recovery can be slow and incomplete. In 2010, neuroscientists Christopher Niell and Michael Stryker, both at the University of California, San Francisco (UCSF), showed that running more than doubled the response of mice's visual cortex neurons to visual stimulation2 (see 'Neuroscience: Through the eyes of a mouse'). Stryker says that it is probably more important, and taxing, to keep track of the environment when navigating it at speed, and that lower responsiveness at rest may have evolved to conserve energy in less-demanding situations. “It makes sense to put the visual system in a high-gain state when you’re moving through the environment, because vision tells you about far away things, whereas touch only tells you about things that are close,” he says. © 2014 Nature Publishing Group
By Jim Tankersley COLUMBUS, Ohio — First they screwed the end of the gray cord into the metal silo rising out of Ian Burkhart’s skull. Later they laid his right forearm across two foam cylinders, and they wrapped it with thin strips that looked like film from an old home movie camera. They ran him through some practice drills, and then it was time for him to try. If he succeeded at this next task, it would be science fiction come true: His thoughts would bypass his broken spinal cord. With the help of an algorithm and some electrodes, he would move his once-dead limb again — a scientific first. “Ready?” the young engineer, Nick Annetta, asked from the computer to his left. “Three. Two. One.” Burkhart, 23, marshaled every neuron he could muster, and he thought about his hand. 1 of 14 The last time the hand obeyed him, it was 2010 and Burkhart was running into the Atlantic Ocean. The hand had gripped the steering wheel as he drove the van from Ohio University to North Carolina’s Outer Banks, where he and friends were celebrating the end of freshman year. The hand unclenched to drop his towel on the sand. Burkhart splashed into the waves, the hand flying above his head, the ocean warm around his feet, the sun roasting his arms, and he dived. In an instant, he felt nothing. Not his hand. Not his legs. Only the breeze drying the saltwater on his face.
Link ID: 19770 - Posted: 06.25.2014
THE star of the World Cup may not be able to bend it like Beckham, but they might be able to kick a ball using the power of their mind. If all goes to plan, a paralysed young adult will use an exoskeleton controlled by their thoughtsMovie Camera to take the first kick of the football tournament in Thursday's opening ceremony in São Paulo, Brazil. The exoskeleton belongs to the Walk Again Project, an international collaboration using technology to overcome paralysis. Since December, the project has been training eight paralysed people to use the suit, which supports the lower body and is controlled by brain activity detected by a cap of electrodes placed over the head. The brain signals are sent to a computer, which converts them into movement. Lead robotic engineer Gordon Cheng, at the Technical University of Munich, Germany, says that there is a phenomenal amount of technology within the exoskeleton, including sensors that feed information about pressure and temperature back to the arms of the user, which still have sensation. The team hopes this will replicate to some extent the feeling of kicking a ball. The exoskeleton isn't the only technology on show in Brazil. FIFA has announced that fans will decide who is man of the match by voting for their favourite player on Twitter during the second half of each game using #ManOfTheMatch. © Copyright Reed Business Information Ltd.
Link ID: 19720 - Posted: 06.12.2014
by Laura Sanders Transplanted cells can flourish for over a decade in the brain of a person with Parkinson’s disease, scientists write in the June 26 Cell Reports. Finding that these cells have staying power may encourage clinicians to pursue stem cell transplants, a still-experimental way to counter the brain deterioration that comes with Parkinson’s. Penelope Hallett of Harvard University and McLean Hospital in Belmont, Mass., and colleagues studied postmortem brain tissue from five people with advanced Parkinson’s. The five had received stem cell transplants between four and 14 years earlier. In all five people’s samples, neurons that originated from the transplanted cells showed signs of good health and appeared capable of sending messages with the brain chemical dopamine, a neurotransmitter that Parkinson’s depletes. Results are mixed about whether these transplanted cells are a good way to ease Parkinson’s symptoms. Some patients have shown improvements after the new cells stitched themselves into the brain, while others didn’t benefit from them. The cells can also cause unwanted side effects such as involuntary movements. P. J. Hallett et al. Long-term health of dopaminergic neuron transplants in Parkinson’s disease patients. Cell Reports. Vol. 7, June 26, 2014. doi: 10.1016/j.celrep.2014.05.027. © Society for Science & the Public 2000 - 2013
By Kelly Servick During the World Cup next week, there may be 1 minute during the opening ceremony when the boisterous stadium crowd in São Paulo falls silent: when a paraplegic young person wearing a brain-controlled, robotic exoskeleton attempts to rise from a wheelchair, walk several steps, and kick a soccer ball. The neuroscientist behind the planned event, Miguel Nicolelis, is familiar with the spotlight. His lab at Duke University in Durham, North Carolina, pioneered brain-computer interfaces, using surgically implanted electrodes to read neural signals that can control robotic arms. Symbolically, the project is a homecoming for Nicolelis. He has portrayed it as a testament to the scientific progress and potential of his native Brazil, where he founded and directs the International Institute of Neuroscience of Natal. The press has showered him with attention, and the Brazilian government chipped in nearly $15 million in support. But scientifically, the project is a departure. Nicolelis first intended the exoskeleton to read signals from implanted electrodes, but decided instead to use a noninvasive, EEG sensor cap. That drew skepticism from Nicolelis’s critics—and he has a few—that the system wouldn’t really be a scientific advance. Others have developed crude EEG-based exoskeletons, they note, and it will be impossible to tell from the demo how this system compares. A bigger concern is that the event could generate false hope for paralyzed patients and give the public a skewed impression of the field’s progress. © 2014 American Association for the Advancement of Science
Link ID: 19698 - Posted: 06.06.2014
By MICHAEL BEHAR One morning in May 1998, Kevin Tracey converted a room in his lab at the Feinstein Institute for Medical Research in Manhasset, N.Y., into a makeshift operating theater and then prepped his patient — a rat — for surgery. A neurosurgeon, and also Feinstein Institute’s president, Tracey had spent more than a decade searching for a link between nerves and the immune system. His work led him to hypothesize that stimulating the vagus nerve with electricity would alleviate harmful inflammation. “The vagus nerve is behind the artery where you feel your pulse,” he told me recently, pressing his right index finger to his neck. The vagus nerve and its branches conduct nerve impulses — called action potentials — to every major organ. But communication between nerves and the immune system was considered impossible, according to the scientific consensus in 1998. Textbooks from the era taught, he said, “that the immune system was just cells floating around. Nerves don’t float anywhere. Nerves are fixed in tissues.” It would have been “inconceivable,” he added, to propose that nerves were directly interacting with immune cells. Nonetheless, Tracey was certain that an interface existed, and that his rat would prove it. After anesthetizing the animal, Tracey cut an incision in its neck, using a surgical microscope to find his way around his patient’s anatomy. With a hand-held nerve stimulator, he delivered several one-second electrical pulses to the rat’s exposed vagus nerve. He stitched the cut closed and gave the rat a bacterial toxin known to promote the production of tumor necrosis factor, or T.N.F., a protein that triggers inflammation in animals, including humans. “We let it sleep for an hour, then took blood tests,” he said. The bacterial toxin should have triggered rampant inflammation, but instead the production of tumor necrosis factor was blocked by 75 percent. “For me, it was a life-changing moment,” Tracey said. What he had demonstrated was that the nervous system was like a computer terminal through which you could deliver commands to stop a problem, like acute inflammation, before it starts, or repair a body after it gets sick. “All the information is coming and going as electrical signals,” Tracey said. For months, he’d been arguing with his staff, whose members considered this rat project of his harebrained. “Half of them were in the hallway betting against me,” Tracey said. © 2014 The New York Times Company
Link ID: 19649 - Posted: 05.23.2014
A drug to treat a particular form of Duchenne muscular dystrophy has been given the green light by the European Medicines Agency and could be available in the UK in six months. Translarna is only relevant to patients with a 'nonsense mutation', who make up 10-15% of those affected by Duchenne. The EMA decided not to pass the drug in January, but they have since re-examined the evidence. A campaign group said the drug must reach the right children without delay. There are currently no approved therapies available for this life-threatening condition. The patients who will benefit the most are those aged five years and over who are still able to walk, the EMA said. Duchenne muscular dystrophy is a genetic disease that gradually causes weakness and loss of muscle function. Patients with the condition lack normal dystrophin, a protein found in muscles, which helps to protect muscles from injury. In patients with the disease, the muscles become damaged and eventually stop working. There are 2,400 children in the UK living with muscular dystrophy, but only those whose condition is caused by a particular 'nonsense mutation' - namely 200 children - are suitable to use Translarna. The drug, ataluren, will be known by the brand name of Translarna in the EU. It was developed by PTC Therapeutics. The next step will see the European Commission rubberstamp the EMA's scientific 'green light' within the next three months and authorise the drug to be marketed in the European Union. At that point, individual member states, including the UK, must decide how it will be funded. The Muscular Dystrophy Campaign is calling for urgent meetings with National Institute of Health of Clinical Excellence (NICE) and NHS England to discuss how Translarna can be cleared for approval and use in the UK. It said families in the UK could have access to the drug by spring 2015. Robert Meadowcroft, chief executive of the campaign, said: "This decision by the EMA is fantastic news. BBC © 2014
By JAMES GORMAN If an exercise wheel sits in a forest, will mice run on it? Every once in a while, science asks a simple question and gets a straightforward answer. In this case, yes, they will. And not only mice, but also rats, shrews, frogs and slugs. True, the frogs did not exactly run, and the slugs probably ended up on the wheel by accident, but the mice clearly enjoyed it. That, scientists said, means that wheel-running is not a neurotic behavior found only in caged mice. They like the wheel. Two researchers in the Netherlands did an experiment that it seems nobody had tried before. They placed exercise wheels outdoors in a yard garden and in an area of dunes, and monitored the wheels with motion detectors and automatic cameras. They were inspired by questions from animal welfare committees at universities about whether mice were really enjoying wheel-running, an activity used in all sorts of studies, or were instead like bears pacing in a cage, stressed and neurotic. Would they run on a wheel if they were free? Now there is no doubt. Mice came to the wheels like human beings to a health club holding a spring membership sale. They made the wheels spin. They hopped on, hopped off and hopped back on. “When I saw the first mice, I was extremely happy,” said Johanna H. Meijer at Leiden University Medical Center in the Netherlands. “I had to laugh about the results, but at the same time, I take it very seriously. It’s funny, and it’s important at the same time.” Dr. Meijer’s day job is as a “brain electrophysiologist” studying biological rhythms in mice. She relished the chance to get out of the laboratory and study wild animals, and in a way that no one else had. © 2014 The New York Times Company
Dr. Mark Saleh Bell's palsy is a neurological condition frequently seen in emergency rooms and medical offices. Symptoms consist of weakness involving all muscles on one side of the face. About 40,000 cases occur annually in the United States. Men and women are equally affected, and though it can occur at any age, people in their 40s are especially vulnerable. The facial weakness that occurs in Bell's palsy prevents the eye of the affected side from blinking properly and causes the mouth to droop. Because the eyelid doesn't close sufficiently, the eye can dry and become irritated. Bell's palsy symptoms progress fairly rapidly, with weakness usually occurring within three days. If the progression of weakness is more gradual and extends beyond a week, Bell's palsy may not be the problem, and other potential causes should be investigated. Those with certain medical conditions, such as diabetes or pregnancy, are at greater risk of developing Bell's palsy, and those who have had one episode have an 8 percent chance of recurrence. Bell's palsy is thought to occur when the seventh cranial (facial) nerve becomes inflamed. The nerve controls the muscles involved in facial expression and is responsible for other functions, including taste perception, eye tearing and salivation. The cause of the inflammation is unknown, although the herpes simplex virus and autoimmune inflammation are possible causes. © 2014 Hearst Communications, Inc.
Keyword: Movement Disorders
Link ID: 19637 - Posted: 05.20.2014
Katia Moskvitch The hundreds of suckers on an octopus’s eight arms leech reflexively to almost anything they come into contact with — but never grasp the animal itself, even though an octopus does not always know what its arms are doing. Today, researchers reveal that the animal’s skin produces a chemical that stops the octopus’s suckers from grabbing hold of its own body parts, and getting tangled up. “Octopus arms have a built-in mechanism that prevents the suckers from grabbing octopus skin,” says neuroscientist Guy Levy at the Hebrew University of Jerusalem, the lead author of the work, which appears today in Current Biology1. It is the first demonstration of a chemical self-recognition mechanism in motor control, and could help scientists to build better bio-inspired soft robots. To find out just how an octopus avoids latching onto itself, Levy and his colleagues cut off an octopus’s arm and subjected it to a series of tests. (The procedure is not considered traumatic, says Levy, because octopuses occasionally lose an arm in nature and behave normally while the limb regenerates.) The severed arms remained active for more than an hour after amputation, firmly grabbing almost any object, with three exceptions: the former host; any other live octopus; and other amputated arms. “But when we peeled the skin off an amputated arm and submitted it to another amputated arm, we were surprised to see that it grabbed the skinned arm as any other item,” says co-author Nir Nesher, also a neuroscientist at the Hebrew University. © 2014 Nature Publishing Group,
Link ID: 19623 - Posted: 05.15.2014
By Suzanne Allard Levingston, Playing with bubble wrap is a silly activity that delights most preschoolers. But for one 21 / 2-year-old from Silver Spring, loud noises such as the pop of plastic bubbles were so upsetting that he would cover his ears and run away. Some days the sound of a vacuum cleaner would make him scream. The child so persistently avoided activities with too much noise and motion that his preschool’s administrators asked to meet with his family — and soon an assessment led to a diagnosis of sensory processing disorder, or SPD. SPD is a clinical label for people who have abnormal behavioral responses to sensory input such as sound and touch. Some children with SPD seem oversensitive to ordinary stimuli such as a shirt label’s scratching their skin. Others can be underresponsive — seemingly unaffected by the prick of a needle. A third group have motor problems that make holding a pencil or riding a bike seem impossible. Whatever the difficulty, such kids are often described as “out-of-sync,” a term popularized by Carol Stock Kranowitz’s 1998 book “The Out-of-Sync Child,” which has sold nearly 700,000 copies. As many as 16 percent of school-age kids in the United States may face sensory processing challenges. And yet there’s debate over whether these challenges constitute a discrete medical disorder. Some experts contend that SPD may be merely a symptom of some other ailment — autism, attention-deficit hyperactivity disorder, anxiety disorder or fragile X syndrome, for example — while others insist it is a separate condition that should be labeled a disorder when it interferes with daily life. The debate over how to classify SPD is not merely matter of semantics. Such discussions can affect research funding and can guide whether insurers will reimburse therapy costs. © 1996-2014 The Washington Post
by Lisa Grossman Hasta la vista, nerve damage. Experiments with bullfrog nerves show that a Terminator-style liquid metal alloy could one day be placed in the body to help severed nerves reconnect. The alloy would stay in place until the nerve has healed, before being slurped back out with a syringe. The peripheral nervous system consists of nerves that carry electrical signals from the brain to the rest of the body. Because they aren't protected by the spine or the skull, peripheral nerves are more vulnerable to injuries than those in the central nervous system. Severed nerves can reconnect if treated quickly enough, but at a rate of just 1 millimetre per day. Also, existing methodsMovie Camera for grafting nerve ends back together have serious shortcomings. For instance, most existing scaffolds for grafts must ultimately be removed, requiring risky follow-up surgery. Even more worrisome, if the nerves don't pass signals to muscles during the healing process, the muscles can atrophy to the point where they never fully recover. Liu and his colleagues wondered if liquid metal could act as a backup system for damaged nerves, helping signals pass through a graft while the nerve healed. They used an alloy of gallium, indium and selenium, which is a very good electrical conductor. The alloy is liquid at room temperature, allowing it to be removed with a syringe when it's no longer needed. © Copyright Reed Business Information Ltd.
By Julie Steenhuysen CHICAGO (Reuters) - International teams of researchers using advanced gene sequencing technology have uncovered a single genetic mutation responsible for a rare brain disorder that may have stricken families in Turkey for some 400 years. The discovery of this genetic disorder, reported in two papers in the journal Cell, demonstrates the growing power of new tools to uncover the causes of diseases that previously stumped doctors. Besides bringing relief to affected families, who can now go through prenatal genetic testing in order to have children without the disorder, the discovery helps lend insight into more common neurodegenerative disorders, such as ALS, also known as Lou Gehrig's disease, the researchers said. The reports come from two independent teams of scientists, one led by researchers at Baylor College of Medicine and the Austrian Academy of Sciences, and the other by Yale University, the University of California, San Diego, and the Academic Medical Center in the Netherlands. Both focused on families in Eastern Turkey where marriage between close relatives, such as first cousins, is common. Geneticists call these consanguineous marriages. In this population, the researchers focused specifically on families whose children had unexplained neurological disorders that likely resulted from genetic defects. Both teams identified a new neurological disorder arising from a single genetic variant called CLP1. Children born with this disorder inherit two defective copies of this gene, which plays a critical role in the health of nerve cells. Babies with the disorder have small and malformed brains, they develop progressive muscle weakness, they do not speak and they are increasingly prone to seizures.
Chelsea Wald The sailfish’s sword-like bill looks as if it was made to slash at prey. But a study published today in Proceedings of the Royal Society B1 reveals that the bill is actually a multifunctional killing tool, enabling the fish to perform delicate, as well as swashbuckling, manoeuvres. By following throngs of predatory birds off the coast of Cancún, Mexico, the study’s authors were able to track Atlantic sailfish (Istiophorus albicans) hunting sardines, says co-author Alexander Wilson, a behavioural ecologist now at Carleton University in Ottawa, Canada. He and his colleagues made high-speed, high-resolution films in the open ocean over six days in 2012. Sailfish hunt in groups, taking turns to approach the ball of schooling fish. Their bodies darken and sometimes flash stripes and spots, perhaps to confuse the prey, or to signal to each other. “It’s a very orderly process,” Wilson says. “They don’t want to risk breaking their bills.” Although sailfish are among the fastest creatures in the ocean — they have been documented to swim at more than 110 kilometres per hour, or 60 knots — the new research shows that their strategy is to approach their prey slowly from behind and gently insert their bills into the school, without eliciting an evasive manoeuvre from the sardines. Then, by whipping their heads in powerful, sudden jerks, they can slash their bills left and right, with their upright fins providing stability. In fact, their bill tips slash with about the same acceleration as the tip of a swinging baseball bat, even in the water, says co-author Paolo Domenici, an environmental physiologist at the Institute for the Marine and Coastal Environment of Italy's National Research Council in Torregrande, on the island of Sardinia. The result is a scene of fishy carnage, as the surrounding water fills with iridescent fragments of sardine skin. © 2014 Nature Publishing Group,
Keyword: Pain & Touch
Link ID: 19523 - Posted: 04.23.2014
Muscle weakness from long-term alcoholism may stem from an inability of mitochondria, the powerhouses of cells, to self-repair, according to a study funded by the National Institutes of Health. In research conducted with rats, scientists found evidence that chronic heavy alcohol use affects a gene involved in mitochondrial repair and muscle regeneration. “The finding gives insight into why chronic heavy drinking often saps muscle strength and it could also lead to new targets for medication development,” said Dr. George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, the NIH institute that funded the study. The study is available online in the April issue of the Journal of Cell Biology. It was led by Dr. Gyorgy Hajnoczky, M.D., Ph.D., director of Thomas Jefferson University’s MitoCare Center, Philadelphia, and professor in the Department of Pathology, Anatomy and Cell Biology. Mitochondria are cellular structures that generate most of the energy needed by cells. Skeletal muscle constantly relies on mitochondria for power. When mitochondria become damaged, they can repair themselves through a process called mitochondrial fusion — joining with other mitochondria and exchanging material such as DNA. Although well known in many other tissues, the current study is the first to show that mitochondria in skeletal muscle are capable of undergoing fusion as a repair mechanism. It had been thought that this type of mitochondrial self-repair was unlikely in the packed fibers of the skeletal muscle cells, as mitochondria have little opportunity to interact in the narrow space between the thread-like structures called myofilaments that make up muscle.
By Bill Briggs A Vietnam veteran swoops his hand through a row of baby vegetables, caressing the peppers on down to the kale. The plants are aligned in tidy, military order atop his backyard fence. He could spend hours describing his first garden. But he cannot utter a word. He can’t even eat his eventual harvest. So, Bob Hoaglan, 71, simply stands and grins at the spouts behind his Oxnard, Calif., home. Then, he grabs his primary communication tool, an LCD tablet, scribbling a stylus across the screen. He displays his words with a silent chuckle: “I don’t have a green thumb.” With a button click, he erases that sentence before composing another. His daily aim is to throw his body and brain into new pursuits. The crops — fresh life for a man facing mortality — help shove his disease to the back of his mind. He admits, though, he can’t keep it there: “I try,” he writes, “Sometimes it creeps up on me.” As he shows that message, the smile vanishes. Hoaglan was diagnosed with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, nearly a year ago. Inside a malady that offers no cure or explanation, he embodies two intriguing clues that, a top researcher says, may whisper answers: Hoaglan served in the military, and he is a nice man. U.S. veterans carry a nearly 60 percent greater risk of contracting ALS than civilians, according to a white paper published in 2013 by the ALS Association, citing Harvard University research that tracked ex-service members back to 1910.
Keyword: ALS-Lou Gehrig's Disease
Link ID: 19509 - Posted: 04.19.2014
Scientists may have discovered how the most common genetic cause of Parkinson’s disease destroys brain cells and devastates many patients worldwide. The study was partially funded by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke (NINDS); the results may help scientists develop new therapies. The investigators found that mutations in a gene called leucine-rich repeat kinase 2 (LRRK2; pronounced “lark two” or “lurk two”) may increase the rate at which LRRK2 tags ribosomal proteins, which are key components of protein-making machinery inside cells. This could cause the machinery to manufacture too many proteins, leading to cell death. “For nearly a decade, scientists have been trying to figure out how mutations in LRRK2 cause Parkinson’s disease,” said Margaret Sutherland, Ph.D., a program director at NINDS. “This study represents a clear link between LRRK2 and a pathogenic mechanism linked to Parkinson’s disease.” Affecting more than half a million people in the United States, Parkinson’s disease is a degenerative disorder that attacks nerve cells in many parts of the nervous system, most notably in a brain region called the substantia nigra, which releases dopamine, a chemical messenger important for movement. Initially, Parkinson’s disease causes uncontrolled movements; including trembling of the hands, arms, or legs. As the disease gradually worsens, patients lose ability to walk, talk or complete simple tasks.
Link ID: 19477 - Posted: 04.12.2014
|By Bret Stetka The data confirm it: farmers are more prone to Parkinson’s than the general population. And pesticides could be to blame. Over a decade of evidence shows a clear association between pesticide exposure and a higher risk for the second most common neurodegenerative disease, after Alzheimer's. A new study published in Neurology proposes a potential mechanism by which at least some pesticides might contribute to Parkinson’s. Regardless of inciting factors — and there appear to be many — Parkinson’s ultimately claims dopamine-releasing neurons in a small, central arc of brain called the “substantia nigra pars compacta.” The nigra normally supplies dopamine to the neighboring striatum to help coordinate movement. Through a series of complex connections, striatal signals then find their way to the motor cortex and voila, we move. But when nigral neurons die, motor function goes haywire and the classic symptoms set in, including namely tremors, slowed movements, and rigidity. Pesticides first came under suspicion as potentially lethal to the nigra in the early 1980s following a tragic designer drug debacle straight out of Breaking Bad. Patients started showing up at Northern California ERs nearly unresponsive, rigid, and tremoring — in other words, severely Parkinsonian. Savvy detective work by neurologist Dr. William Langston and his colleagues, along with the Santa Clara County police, traced the mysterious outbreak to a rogue chemist and a bad batch. He’d been trying to synthesize a “synthetic heroin” — not the snow cone flavorings he claimed — however a powder sample from his garage lab contained traces of an impurity called MPTP. MPTP, it turned out, ravages dopaminergic neurons in the nigra and causes what looks like advanced Parkinson’s. All of the newly Parkinsonian patients were heroin users who had injected the tainted product. And MPTP, it also turned out, is awfully similar in structure to the widely used herbicide paraquat, leading some neurologists to turn their attention to farms and fields. © 2014 Scientific American
by Clare Wilson A genetic tweak can make light work of some nervous disorders. Using flashes of light to stimulate modified neurons can restore movement to paralysed muscles. A study demonstrating this, carried out in mice, lays the path for using such "optogenetic" approaches to treat nerve disorders ranging from spinal cord injury to epilepsy and motor neuron disease. Optogenetics has been hailed as one of the most significant recent developments in neuroscience. It involves genetically modifying neurons so they produce a light-sensitive protein, which makes them "fire", sending an electrical signal, when exposed to light. So far optogenetics has mainly been used to explore how the brain works, but some groups are exploring using it as therapy. One stumbling block has been fears about irreversibly genetically manipulating the brain. In the latest study, a team led by Linda Greensmith of University College London altered mouse stem cells in the lab before transplanting them into nerves in the leg – this means they would be easier to remove if something went wrong. "It's a very exciting approach that has a lot of potential," says Ziv Williams of Harvard Medical School in Boston. Greensmith's team inserted an algal gene that codes for a light-responsive protein into mouse embryonic stem cells. They then added signalling molecules to make the stem cells develop into motor neurons, the cells that carry signals to and from the spinal cord to the rest of the body. They implanted these into the sciatic nerve – which runs from the spinal cord to the lower limbs – of mice whose original nerves had been cut. © Copyright Reed Business Information Ltd.
Keyword: Movement Disorders
Link ID: 19450 - Posted: 04.05.2014