Mice and rats immobilized with Parkinson's-like symptoms were able to scurry around normally after researchers stimulated their spinal cords with electricity.

Researchers plan to start testing the technique on primates in a few months. If successful, they hope to begin human trials in 2010.

'It's something that has definitely got some scientific traction to it.'— Dr. Walter Koroshetz

Parkinson's is a degenerative brain disorder that can leave people incapacitated with tremors, slowed movements, stiff limbs and gait or balance problems.

Spinal cord stimulators are already implanted in people with chronic pain to block painful signals from being sent to and from the brain.

The estimated 1.5 million Americans and 100,000 Canadians with Parkinson's gradually lose brain cells that produce dopamine — a chemical that help controls muscle movement.

When researchers turned the device on, the slow, stiff movements in the dopamine-depleted animals were replaced with the active behaviour of healthy mice and rats.

"We see an almost immediate and dramatic change in the animal's ability to function when the device stimulates the spinal cord," said the study's senior investigator, Dr. Miguel Nicolelis of Duke University in Durham, N.C.

"Moreover, it is easy to use, significantly less invasive than other alternatives to medication, such as deep brain stimulation, and has the potential for widespread use in conjunction with medications typically used to treat Parkinson's disease."

When animals were given the device without a replacement for dopamine called L-dopa, they were 26 times more active. When zapped along with the drug, two doses were needed to restore movement, compared with five doses when only the drug was used, the researchers found.

How does it work?

In healthy people, neurons fire to different muscles at different moments.

Research suggests that in Parkinson's, neurons all start firing at once, like excited preschoolers all talking at the same time instead of raising their hands to be called on one at a time.

Spinal cord stimulation appears to send a signal up to the brain to interrupt the pattern of misfiring, said Dr. Walter Koroshetz, deputy director of the U.S. National Institute of Neurological Disorders and Stroke, which helped fund the work.

More work needs to be done to done, such as testing whether the effects last long enough to be helpful for patients, but "it's something that has definitely got some scientific traction to it," Koroshetz said.

Deep brain stimulation explored

A second Parkinson's-related study appearing in the same issue looked at deep brain stimulation, a more invasive, pacemaker-like approach used to treat the disease.

In deep brain stimulation, pulses of electricity are applied to electrodes on the brain's subthalamic region. The shocks seem to calm the abnormal behaviour in the brain.

Researchers at Stanford University Medical Center in California found rodents with Parkinson-like symptoms showed the most benefits when the primary motor cortex, a movement-control region on the surface of the brain, was targetted.

Previously, it was thought that turning off neurons in the subthalamic nucleus was more important for controlling symptoms.

With files from Associated Press