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The lamprey nervous system was used for the computational model  (Source: Avis Cohen and Eric D. Tytell, University of Maryland)
Studying the muscles of a fish as they swim through the water can help with better prosthetic designs

University of Maryland and Tulane University researchers have created a computational model
of a swimming fish in an effort to develop medical prosthetic limbs for humans that work more smoothly with the body's natural movements, similar to the way the muscles of a fish interact with water to produce locomotion. 

The study was led by University of Maryland researchers Eric D. Tytell and Avis Cohen along with Tulane University researchers Chia-yu Hsu and Lisa Fauci. Together, they simulated how the body of a fish "bends" with the water around it in order to understand how internal and
external forces affect locomotion. With this information, researchers hope to design medical prosthetics and robots that move fluidly with their environment. 

"When a fish moves in a fluid, muscles contract, but the fluid also moves against the body," said Tytell, a postdoctoral researcher at the University of Maryland. "So, the amount the body moves depends on the internal muscle force and the external reaction of fluids. 

"Previous studies examined body mechanics separately from fluid mechanics because it is a very hard problem to solve. This is the first time that anyone has put together a computational framework to simulate this for large, fast animals like fishes."

In this particular study, the lamprey, which is a primitive vertebrate, is being used for the simulation. The nervous system of this creature will help to design prosthetics for patients with spinal cord injuries. 

Simulations were performed with various values for different body and fluid properties. During these simulations, Tytell and Hsu found that body stiffness was an important property when determining the lamprey's ability to swim.

"Take a lamprey and a barracuda as examples," said Tytell. "If you hold a freshly dead lamprey, it just drops, because it is a very floppy fish. But if you take a fish like a barracuda, their bodies are stiffer and don't flop much. We wanted to know what difference does the floppy vs. stiff body make? If their muscles produced the same amount of force, then the floppy body, since it bends more, should accelerate more rapidly, but also expend more energy. And the stiff body should accelerate more slowly because it bends less, but once it gets going, it should use less energy."

Tytell adds that this isn't really the way it is, though. According to the study, barracudas, for the most part, accelerate more quickly than lampreys because barracuda's have stronger muscles and higher body stiffness. 

While the goal of this study is to eventually develop more fluid prosthetics and robotics, researchers also want to use this information to understand the evolution and biodiversity of fishes. According to Tytell, evolutionary biologists are looking to better understand the "selective pressures" that resulted in species having specific characteristics. Locomotion, in particular, is important because understanding how they move will help researchers understand how they find mates, escape predators and locate food. 

Researchers also want to use the computational model to figure out why fishes are shaped differently, and how they swim so smoothly through restless waters. 

"The first line of defense against external perturbations such as eddies in the water for fishes, or tripping on a rock for humans, isn't the nervous system, but rather the body's mechanics, kind of like shocks on a car," said Tytell. "If we can translate the mechanical stability that living organisms exhibit into the design of robots or prosthetics, we could really advance the technology."

"The devices may one day help people regain control over their legs and walk again," said Cohen, a professor in the Department of Biology at the University of Maryland. "We understand to first order the neural circuit that controls the muscles for swimming or walking. Now, for neuroprosthetics, we need to understand how the muscles interact with the body and the environment -- our model helps us do that."






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It's SCIENCE
By geddarkstorm on 10/19/2010 2:28:16 PM , Rating: 2
One day, you too can have prosthetic lampreys for arms.




RE: It's SCIENCE
By DEVGRU on 10/19/2010 3:50:21 PM , Rating: 2
Somewhere, there's a Japanese porn star that shares your vision!


RE: It's SCIENCE
By Smartless on 10/19/2010 5:00:36 PM , Rating: 2
Arms? Come on, they said its floppy when dead.


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