Electrodes offer amputees, paralyzed people new hope

Published: Tuesday, June 30 2009 12:00 a.m. MDT

University of Utah neurosurgeon Paul A. House led a study involving the new, long-lasting microelectrodes.

Kelly Johnson

Spencer Kellis headed into his doctoral program at the University of Utah thinking he'd be using computers to perform architectural analysis, but over a lunch with researchers last summer, his focus changed.

The result now has the potential of changing lives.

"The human interaction and human aspect provides more motivation," the electrical engineering student said Monday. "It makes it easier to crunch numbers knowing that there are people who will benefit from the research we do."

Kellis was one of a number of students, researchers and others involved in a new study revealing that amputees and paralyzed people can do without brain poking to move various parts of their body. Kellis was responsible for generating preliminary graphs used to make conclusions on how brain signals power the rest of the human body.

Electrode arrays were placed on the brains of two patients at the U. hospital who were already undergoing brain surgery for severe epilepsy. The trials revealed optimal spacing of the electrodes and allowed researchers to further help in movement of immobile limbs.

Until now, such patients have used computers connected to electrodes within the brain, and other experimental devices to control bionic limbs and prosthetics. The study, published Tuesday in the journal Neurological Focus, shows that brain signals controlling arm movements can be detected accurately using new microelectrodes that sit on the brain but don't penetrate it.

"The unique thing about this technology is that it provides lots of information out of the brain without having to put the electrodes into the brain," said Bradley Greger, an assistant professor of bioengineering at the U. and co-author of the study. "That lets neurosurgeons put this device under the skull but over brain areas where it would be risky to place penetrating electrodes such as areas that control speech, memory and other cognitive functions."

Paralyzed people with an inability to communicate may someday benefit from the findings, allowing the electrodes surrounding the brain to send signals to a computer that would convert the thoughts to audible words. The same would be true for people who have lost a limb or complete function of their arms or legs, as the new device would give them a broader range of control over a prosthetic or computer interface, enabling "amputees or people with severe paralysis to interact with their environment," Greger said.

U. neurosurgeon Paul A. House, the study's lead author, said the new research represents "a modest step" in assisting people with disabilities.

The technology, which uses the microelectrodes to convert the thoughts of amputees and paralyzed people into signals that control artificial body parts, is expected within a few years at the earliest. Further research and fine tuning on the computer software is being done to possibly interpret brain signals resulting in actual movement of a prosthetic limb.

The findings are not the first in the realm of microelectrodes being placed on the surface of the brain. A Massachusetts study explored similar technologies, but U. researchers expanded the array of electrodes to include 100 brain readers, making them smaller and able to read larger surface areas of the brain, Kellis said. He said he's astounded at the impact a single processing unit can have in a person's life.

Newer, smaller versions can detect many of the discrete nerve impulses that control body movements. The spacing of the microelectrodes is also critical.

The nonpenetrating electrodes may allow a longer life for devices that will help disabled people use their own thoughts to control computers, robotic limbs or other machines. The longer lifespan has yet to be proven, "but we are very optimistic that by being less invasive, it certainly should last longer and provide a more durable interface with the brain," House said.

E-MAIL: wleonard@desnews.com

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