(Press-News.org) Researchers at Case Western Reserve University have developed a computer modeling method to accurately predict how a peripheral nerve axon responds to electrical stimuli, slashing the complex work from an inhibitory weeks-long process to just a few seconds.
The method, which enables efficient evaluation of a nerve's response to millions of electrode designs, is an integral step toward building more accurate and capable electrodes to stimulate nerves and thereby enable people with paralysis or amputated limbs better control of movement.
To increase the accuracy of the results, the researchers included a key parameter overlooked in past mathematical approaches that were equally fast, but inaccurate. With the new techniques, electrode design can be optimized using advanced algorithms based on natural genetics.
An explanation of the work, which the team hopes others in the field will freely use, and a second method that was simpler and faster but proved less effective, are now available online in the Journal of Neural Engineering.
"We believe this will allow the next generation of computer-aided development of electrodes," said Dustin Tyler, associate professor of biomedical engineering at Case School of Engineering and senior author of the paper.
Since his graduate school days, Tyler has been developing electrodes to stimulate nerves in paralyzed patients and amputees. Taking the large step from animal models to human clinical trials can be improved with better computer modeling, he said.
"Finding the optimal way to stimulate a nerve is kind of like the 'travelling salesman' trying to figure out which is the most efficient route through a group of cities," Tyler said.
Mapping each possible route and figuring the time spent on the road is very difficult to do with a simple equation.
But, using a complex mathematical formula called a genetic algorithm to simultaneously consider all the routes, or in Tyler's predicament electrode designs, and determining the best requires that each design be evaluated in fractions of seconds. This was not possible previously.
The genetic algorithm mimics the process of natural selection, gene recombination and mutation seen in nature. Or, in this case, takes into account which portions of a neuron to stimulate, how much, with how many points of contact, and more variables.
By adding a variable: the magnitude of the voltage outside the cell produced by the electrode, Tyler's group raised the accuracy beyond current techinques.
They used the free-online nerve simulation environment NEURON developed at Yale University. The data the team used is included in the supplemental materials of their paper and may be downloaded for free, said Erik Petersen, a PhD student at Case Western Reserve and lead author. The third author is Oliver Izad, a former master's student in Tyler's lab.
Their method was developed specifically for peripheral motor nerve axons. Nerves cells with different structures, such as those in the brain, spinal cord, or organs are still being investigated.
The researchers are now developing parameters that would take into account these variations in structure to extend the method to work for all of them, further cutting time needed to develop accurate models.
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MINNEAPOLIS / ST. PAUL (July 20, 2011) – University of Minnesota Medical School and College of Biological Sciences researchers have made a key discovery showing that male sex must be maintained throughout life.
The research team, led by Drs. David Zarkower and Vivian Bardwell of the U of M Department of Genetics, Cell Biology and Development, found that removing an important male development gene, called Dmrt1, causes male cells in mouse testis to become female cells.
The findings are published online today in Nature.
In mammals, sex chromosomes (XX in female, XY ...
BUFFALO, N.Y. -- A University at Buffalo-led research team has developed a mathematical framework that could one day form the basis of technologies that turn road vibrations, airport runway noise and other "junk" energy into useful power.
The concept all begins with a granular system comprising a chain of equal-sized particles -- spheres, for instance -- that touch one another.
In a paper in Physical Review E this June, UB theoretical physicist Surajit Sen and colleagues describe how altering the shape of grain-to-grain contact areas between the particles dramatically ...
COLUMBUS, Ohio – Instead of calming fears, the death of Osama bin Laden actually led more Americans to feel threatened by Muslims living in the United States, according to a new nationwide survey.
In the weeks following the U.S. military campaign that killed bin Laden, the head of the terrorist organization Al Qaeda, American attitudes toward Muslim Americans took a significant negative shift, results showed.
Americans found Muslims living in the United States more threatening after bin Laden's death, positive perceptions of Muslims plummeted, and those surveyed were ...
DURHAM, N.C. – Esses are everywhere.
From economic trends, population growth, the spread of cancer, or the adoption of new technology, certain patterns inevitably seem to emerge. A new technology, for example, begins with slow acceptance, followed by explosive growth, only to level off before "hitting the wall."
When plotted on graph, this pattern of growth takes the shape of an "S."
While this S-curve has long been recognized by economists and scientists, a Duke University professor believes that a theory he developed explains the reason for the prevalence of this ...
Los Angeles, (July 2011) — Despite helping to push Hosni Mubarak and his regime from power, Egypt's liberals and pro-democracy activists are having trouble moving from revolution to politics, according to a recent article in the World Policy Journal (published by SAGE).
In this in-depth look at the Egyptian political landscape, the article's author, Jenna Krasjeki, examines various groups vying for influence and public support in the run-up to elections this fall. One common characteristic that Krasjeski notes is the lack of organization in the groups of young, liberal ...
A simple cut to the skin unleashes a complex cascade of chemistry to stem the flow of blood. Now, scientists at Washington University School of Medicine in St. Louis have used evolutionary clues to reveal how a key clotting protein assembles. The finding sheds new light on common bleeding disorders.
The long tube-shaped protein with a vital role in blood clotting is called von Willebrand Factor (VWF). Made in cells that form the inner lining of blood vessels, VWF circulates in the blood seeking out sites of injury. When it finds them, its helical tube unfurls to catch ...
Flooding along the Missouri River continues as shown in recent Landsat satellite images of the Nebraska and Iowa border. Heavy rains and snowmelt have caused the river to remain above flood stage for an extended period.
A Landsat 5 image of the area from May 5, 2011 shows normal flow. In contrast, a Landsat 7 image from July 17 depicts flood conditions in the same location.
A national overview map of streamflow provided by U.S. Geological Survey (USGS) WaterWatch graphically portrays the immense geographic extent of flooding in the Missouri River basin.
Monitoring ...
In the fight to improve global health, alleviate hunger, raise living standards and empower women in the developing world, chickens have an important role to play.
Jagdev Sharma, a researcher at the Center for Infectious Diseases and Vaccinology at Arizona State University's Biodesign Institute has been investigating the advantages of a more productive species of chicken for villagers in rural Uganda. He reports his findings this week at the American Veterinary Medical Association Meeting in Saint Louis, Missouri.
The star of this developing story is a type of chicken ...
Scientists of the CDF collaboration at the Department of Energy's Fermi National Accelerator Laboratory announced the observation of a new particle, the neutral Xi-sub-b. This particle contains three quarks: a strange quark, an up quark and a bottom quark (s-u-b). While its existence was predicted by the Standard Model, the observation of the neutral Xi-sub-b is significant because it strengthens our understanding of how quarks form matter. Fermilab physicist Pat Lukens, a member of the CDF collaboration, presented the discovery at Fermilab on Wednesday, July 20.
The ...
The GOES-13 satellite captured a triple-header in the tropics today when it captured three tropical cyclones in one image in the Northern Hemisphere.
A visible image taken from the GOES-13 satellite on July 20 at 14:45 UTC (10:45 a.m. EDT) and shows a consolidating low pressure area called System 99L in the eastern North Atlantic Ocean, Tropical Storm Bret several hundred miles east of South Carolina, and a large Hurricane Dora off the west coast of Mexico. The image was created by the NASA/NOAA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md.
System ...
