Fast prediction of axon behavior

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 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 .

"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 to stimulate nerves in paralyzed patients and . 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 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.

Related Stories

Researchers Develop Wireless Method of Brain Stimulation

Mar 16, 2009

(PhysOrg.com) -- A new, wireless method of brain stimulation has the potential to activate specific regions of the brain or restore function to damaged or cut nerves, according to a study by Case Western Reserve ...

Spinal cord bridge bypasses injury to restore mobility

Aug 17, 2006

The body's spinal cord is like a super highway of nerves. When an injury occurs, the body's policing defenses put up a roadblock in the form of a scar to prevent further injury, but it stops all neural traffic from moving ...

Breathing restored after spinal cord injury

Jul 13, 2011

Researchers at Case Western Reserve University School of Medicine bridged a spinal cord injury and biologically regenerated lost nerve connections to the diaphragm, restoring breathing in an adult rodent model of spinal cord ...

Recommended for you

Neurons in human skin perform advanced calculations

16 hours ago

Neurons in human skin perform advanced calculations, previously believed that only the brain could perform. This is according to a study from Umeå University in Sweden published in the journal Nature Ne ...

Memory in silent neurons

Aug 31, 2014

When we learn, we associate a sensory experience either with other stimuli or with a certain type of behavior. The neurons in the cerebral cortex that transmit the information modify the synaptic connections ...

Why your favourite song takes you down memory lane

Aug 28, 2014

Music triggers different functions of the brain, which helps explain why listening to a song you like might be enjoyable but a favourite song may plunge you into nostalgia, scientists said on Thursday.

User comments