Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stimulating nerve cells with laser precision

27.10.2004


Researchers devise optical method to safely, effectively stimulate neurons



Biomedical engineers and physicians at Vanderbilt University have brought the day when artificial limbs will be controlled directly by the brain considerably closer by discovering a method that uses laser light, rather than electricity, to stimulate and control nerve cells.

The researchers have discovered that low-intensity infrared laser light can spark specific nerves to life, exciting a leg or even individual toes without actually touching the nerve cells. “This technique brings nerve stimulation out of the Dark Ages,” said Vanderbilt Assistant Professor of Biomedical Engineering and Neurological Surgery Anita Mahadevan-Jansen. “Much work is going on around the world trying to make electric nerve stimulation better, but the technique is inherently limited. Using lasers instead, we can simultaneously excite and record the responses of nerve fibers with much greater precision, accuracy and effectiveness.”


The method was developed by Mahadevan-Jansen; her husband Duco Jansen, associate professor of biomedical engineering and neurological surgery; Dr. Peter Konrad and Dr. Chris Kao of Vanderbilt Neurological Surgery, both assistant professors of neurological surgery; and biomedical engineering doctoral student Jonathon Wells.

In an experiment with rats, the scientists used a laser to stimulate the sciatic nerve and to control muscles in the animal’s hind leg and individual toes, demonstrating accuracy beyond the limitations of electrical stimulation. Immediately following the experiment, the rats regained full use of their legs with no signs of weakness or damage.

Konrad, who is also director of the Vanderbilt Functional Neurosurgery program, points out that neurostimulation is ideally done cell by cell. “The problem with the conventional electrical method is that we have a large zone around our target neuron that also is affected simply because of the way electricity travels throughout the tissue. Using light to stimulate neurons, we can pick off a single neuron without affecting the other neurons around it.”

In a matter of months, Kao says, a machine could be created that helps guide neurosurgeons to the target nerves during rhizotomy, a procedure that frees someone from a spastic or seemingly frozen muscle, as when someone’s head is stuck in a tortuous position. Currently, once the proper neural region is selected, surgeons pinpoint the individual nerves by a process of elimination, striking nerves with an electric probe while the patient is awake to ensure that the right nerve has been located.

But electrical probes create a halo of electrical activity in surrounding neurons, creating a "blind spot" and other inaccurate data in the recording and analysis of the procedure, making it tedious and difficult to locate the exact nerve. Optics, on the other hand, can deliver laser precision by stimulating only the nerve cell of interest.

The idea of optical stimulation started as the scientists questioned whether they could accurately detect the movement through the brain of an electrical impulse from a nerve cell. Konrad suggested using light to trace the activity, and Mahadevan-Jansen thought of using laser light to stimulate nerves and to actually generate this activity.

Vanderbilt’s W.M. Keck Foundation Free Electron Laser Center was the perfect facility to give it a try. The Department of Defense-funded FEL, one of only a handful in the world and the only one equipped to perform medical experimental research, was used to see if the idea worked and to determine the optimal settings for the laser.

Now that the research team has shown that the process works and that it is safe, they are turning their attention to studying the exact mechanisms behind the stimulation effects. The most likely candidates, Jansen and Wells say, include a photothermal or mechanical effect or perhaps a combination of the two.

The scientists are beginning experiments in the central nervous system.

Mahadevan-Jansen said the technique, which is pending patent approval, is not the only novel aspect of this work. "This research results from the marriage of biomedical engineering, optical science and neurological research," Mahadevan-Jansen said. "Some programs are working on optics, and some are working on neurological stimulation, but nobody has put them together."

Imagining future applications, Konrad said he can envision an array of fiber optic threads that runs directly from the brain or spinal cord to a prosthetic arm or leg, creating the ultimate man-machine interface.

Vivian Cooper-Capps | EurekAlert!
Further information:
http://www.vanderbilt.edu

More articles from Life Sciences:

nachricht Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung

nachricht Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>