A Chip to Better Control Brain Stimulators for Parkinson's

Michigan engineers are developing a closed-loop deep-brain stimulation device for Parkinson's disease that would listen to the brain while stimulating it

By Morgen E. Peck
First Published June 2008
http://www.spectrum.ieee.org/jun08/6381

19 June 2008—For more than a decade, doctors have been implanting devices called deep-brain stimulators into patients with Parkinson’s disease and stimulating a small area of their brains with low-voltage electrical pulses. So far, there’s been only one way to tell how patients are taking to the treatment: by watching. Are they walking smoothly again? Can they hold their hands in front of them without trembling? But a better way to evaluate treatment is to ask the brain directly. In such a system, neuronal feedback would direct the timing, location, and intensity of subsequent stimulation and would theoretically suppress side effects that many patients suffer today. A group of neural engineers from the University of Michigan, tackling a pivotal piece of the problem, have designed a programmable device capable of stimulating and recording from the brain simultaneously.

“It’s what a lot of people have talked about for a really long time, but nobody’s done it,” says Jerrold Vitek, a neurologist at the Cleveland Clinic, in Ohio, who treats patients with deep-brain stimulators and was not involved with the research.

Vitek describes the available technology as “first generation.” The devices, manufactured by Medtronic, electrically stimulate the subthalamic nucleus, a structure deep inside the brain, through four electrodes. When electrical impulses hit the targeted cells, the tremors associated with Parkinson’s disease subside; however, the quality of treatment greatly depends on how well surgeons implant these four electrodes. A misplaced lead could stimulate surrounding tissue and cause changes in the patient’s mood and cognition. Such a positioning error was recently found to be a leading cause of the therapy’s failure. Even with a perfect implant, patients have only one control parameter: on or off. So what you have is an inflexible system trying to control a highly variable and plastic organ.

READ BOTH PAGES (including two photos of in-brain and unit)