Links for Keyword: Biomechanics

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By Katherine Harmon With a juicy insect dinner perched on a leaf above the water, what is a hungry little archer fish down below to do? Knock it down with a super-powered, super-precise jet of water that packs six times the power the fish could generate with its own muscles, according to new findings published online October 24 in PLoS ONE. The stunning spitting power of the amazing archer fish (Toxotes jaculatrix) was first described in the 18th century. The creature lives in mostly in mangrove forests and estuaries where insects are prevalent—above water, that is. And these tasty treats are not easily knocked off of the plants that hang over the archer fish’s territory. The insects, such as grasshoppers, can hang on with a force some 10 times their own body weight. So the archer fish has developed an impressive strategy for fetching food that not many other fish can reach. Its water jet can target and dislodge a single insect so that it falls into the water for the fish to eat. Just how the fish manages to do this—and in less than a second—had remained a mystery. Many scientists figured that the source must be a special organ in the fish’s body. “The origin of the effectiveness of the jet squirted by the archer fish has been searched for inside of the fish for nearly 250 years,” Alberto Vailati, a physicist at the University of Milan and co-author of the new paper, said in a prepared statement. © 2012 Scientific American

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 17429 - Posted: 10.27.2012

By Nick Bascom Superstar athletes are revered for their physical prowess, not for what goes on between their ears. And most postgame interviews do little to challenge the notion that athletes have more brawn than brains. But brainpower has a vital role in elite sports performance, recent research shows. “Brawn plays a part, but there’s a whole lot more to it than that,” says John Milton, a neuroscientist at the Claremont Colleges in California. Whether on the court, field or course, the body depends on the brain for direction. But the brain is a busy taskmaster, with duties beyond guiding motion, making it difficult to focus on that particular job. Like chess masters and virtuoso musicians, superior athletes are better than novices at turning on just the parts of the brain relevant to the desired task, Milton’s work reveals. “In professionals, the overall brain activation is much lower, but certain connections are enhanced,” he says. In other words, experts employ only the finely tuned neural regions that help enhance performance, without getting bogged down by extraneous information. Elite athletes’ ability to focus the brain might even explain their struggle to eloquently describe performance after the game. Like a starship captain diverting power from life support to bolster shields in a battle, professional athletes temporarily shut down the memory-forming regions of the brain so as to maximize activity in centers that guide movement. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 16198 - Posted: 12.31.2011

Using muscle tissue from tarantulas, an HHMI international research scholar and his colleagues have figured out the detailed structure and arrangement of the miniature molecular motors that control movement. Their work, which takes advantage of a new technique for visualizing tissues in their natural state, provides new insights into the molecular basis of muscle relaxation, and perhaps its activation too. “We have solved the structure of the array of miniature motors that form our muscles and found out how they are switched off,” said Ral Padrn, a HHMI international research scholar in the Department of Structural Biology at the Venezuelan Institute for Scientific Research (Instituto Venezolano de Investigaciones Cientficas or IVIC) in Caracas, Venezuela. The findings are reported in the August 25, 2005, issue of the journal Nature. Padrn and his colleagues focused their studies on striated muscle—the type of muscle that controls skeletal movement and contractions of the heart. Striated muscles are made of long cylindrical cells called muscle fibers. Within the fibers, millions of units known as sarcomeres give rise to movement of skeletal muscles. Sarcomeres are composed mainly of thick filaments of myosin, the most common protein in muscle cells, responsible for their elastic and contractile properties. The thick filaments are arranged in parallel with thin filaments of another muscle protein, actin. When the actin and myosin filaments slide along one another, the muscle contracts or relaxes. © 2005 Howard Hughes Medical Institute.

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 7795 - Posted: 06.24.2010

Jumbos' bouncy legs help them pack a pace. HELEN R. PILCHER Its official: elephants can run. Biomechanics researchers have done their sums and decided that the springy steps of an angry elephant at full charge count as running - not ambling or trotting. As their speed rises past 16 kilometres per hour, elephants adopt "more of a bouncing motion", explains John Hutchinson of Stanford University in California. Technically, this makes them runners. Hutchinson and his colleagues organized a 30-metre track event with 42 healthy, adult Asian elephants1. The elephants, from tourist parks and conservation camps in Lampang, Thailand, ran one at a time along the track, five to ten times a day, with rests, over several days. © Nature News Service / Macmillan Magazines Ltd 2003

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 3645 - Posted: 06.24.2010

Learn if you are salmon or sole. By Eric Haseltine Have you ever pondered why salmon meat is red and filet of sole white? For that matter, what makes chicken thighs darker than chicken breasts? The answer is that there are roughly two types of muscle fibers: reddish tissue that has lots of endurance (due to heavy concentrations of dark, oxygen bearing myoglobin) and pale fibers that have pitifully little myoglobin and stamina, but enormous speed and strength. This division of labor makes sense when you consider that sometimes, like when you're taking a long hike, your muscles need endurance, while other times -for instance when you're removing large boulders from the garden-you must summon short bursts of explosive strength. Although all muscles contain a mixture of both fiber types, certain muscle groups tend to have more of one fiber category than the other because of their unique functions. For instance, leg muscles that keep you standing for long periods tend to be darker, while those active in short spurts (like the breast muscles chickens use to flap their wings) tend to be lighter. Reddish fibers are sometimes called "slow twitch" because they contract up to 10 times more slowly than their whiter cousins. Salmon, who must swim long distances over many days have primarily red, slow muscles because staying power is much more important to their lifestyle than speed. Sole, on the other hand, don't need much endurance because they lounge around on the sea bottom. But when sole do have to move, say, when a predator gets too interested in them, they have to move in a hurry. © Copyright 2001 The Walt Disney Company.

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 1200 - Posted: 06.24.2010

Drum the tip of a finger on a typewriter key quickly "eeeeee." Now, stop and type "e" take a moment, type "e," take another moment, type "e" again. The motion in both cases is exactly the same, performed by the same finger. But the brain processes that make the two different streams of 'e's are utterly different, according to a study done by a University of Southern California neural specialist and colleagues. The insight may lead to, among other things, better movement control by humanoid robots, but also new ways of movement rehabilitation. And perhaps it even offers some insight into the effect of music. Dr. Stefan Schaal, an associate professor in the computer science department of the USC Viterbi School of Engineering led the international team that used functional Magnetic Resonance Imaging (fMRI) scans to test a longstanding question regarding "rhythmic" versus "discrete" movement. "Rhythmic movements like walking, chewing or scratching are found in many organisms, ranging from insects to primates," notes Schaal in an article published in Nature Neuroscience Sept. 26. "In contrast, discrete movements like reaching and kicking are behaviors that have reached sophistication in young species, particularly in primates."

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 6159 - Posted: 09.28.2004

(Bethesda, MD) -- Motor imagery has been extensively studied with positron emissions tomography (PET) and functional magnetic resonance imaging (fMRI) techniques. Converging evidence indicates that motor imagery shares neural substrates (substances changed by enzymes) with those underlying motor execution. However, less certain are how and to what extent neural substrates are shared between the two modes of motor-related behavior. The scientific community differs regarding involvement of the primary motor cortex (M1), the region of the cerebral cortex most nearly immediately influencing movements of the face, neck and trunk, and arm and leg, during motor imagery. Some region-of-interest analyses from fMRI experiments often reveal mild activity increases in M1 during motor imagery, while group averaged analyses from fMRI and PET do not. Unfortunately, many of the fMRI studies showing M1 activity do not employ electrophysiological monitoring to exclude muscle contractions during actual scanning. In addition to the methodological differences, there has been some diversity among the behavioral tasks studied as motor imagery. Motor imagery is defined as the mental simulation of a motor act. This definition can include various concepts such as preparation for movement, passive observations of action, and mental operations of sensorimotor representations, either implicitly or explicitly.

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 3642 - Posted: 04.03.2003

Scientists from Emory University School of Medicine and the University of Pavia, Italy, have determined for the first time the three-dimensional structure of monoamine oxidase B (MAO B) ? an enzyme important in several major disease processes; particularly age-related neurological disorders. Understanding the detailed structure of the enzyme should provide a framework for designing new neuroprotective drugs. The research will be published in the January 2002 print edition of Nature Structural Biology and in the online edition on Nov. 26, 2001. Monoamine oxidases (MAO B and MAO A) are well-known targets for antidepressant drugs and for drugs used to treat neurological disorders and diseases of aging, such as Parkinson?s disease and Alzheimers disease. MAO A and MAO B are attached to the outer membrane of the mitochondria ? the energy powerhouses of cells and function to oxidize amine neurotransmitters such as dopamine and serotonin.

Related chapters from BP7e: Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 1070 - Posted: 11.28.2001

TOM CLARKE "Potassium channels underlie all our movements and thoughts," says Rod MacKinnon of Rockefeller University in New York. His team has now unravelled the molecular mechanics of these minute protein pores. Some say the work merits a Nobel Prize. Potassium (K+) channels power the transmission of nerve signals through the body and the brain by ushering K+ ions in and out of our cells. MacKinnon and his colleagues have taken high-resolution snapshots of the channels in action, revealing how, and how fast, individual K+ ions pass through1,2. It's a remarkable feat - the K+ channel's aperture is more than a hundred thousand times thinner than a sheet of paper, at under six Angstroms wide. 1.Morais-Cabral, J. H., Zhou, Y. & MacKinnon, R. Energetic optimisation of ion conduction rate by the K+ selectivity filter. Nature, 414, 37 - 42, (2001). 2.Zhou, Y., Morais-Cabral, J. H., Kaufman, A. & MacKinnon, R. Chemistry of ion hydration and coordination revealed by a K+ channel-Fab complex at 2.0 A resolution. Nature, 414, 43 - 48, (2001). 3.Doyle, D. A. et al. The structure of the potassium channel: molecular basis of K+ conduction and selectivity. Science, 280, 69 - 77, (1998). © Nature News Service / Macmillan Magazines Ltd 2001

Related chapters from BP7e: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 889 - Posted: 11.01.2001