Scientists have stumbled upon a new way to help patients with Parkinson's to move more easily.
Writing in this week's Science, Duke University researcher Miguel Nicolelis and his colleagues have used experimental animals to show how a simple nerve stimulation technique can overcome the symptoms of the disease.
Patients with Parkinson's, which is caused by the loss of brain cells that produce the transmitter chemical dopamine, characteristically develop symptoms of slow movements and also find movements hard to initiate. The symptoms can be partially overcome with drugs including L-DOPA, which works by boosting brain dopamine levels, although the treatment tends to become less effective with time and can also cause significant side effects. In recent years scientists have been able to provide some relief to sufferers by implanting stimulating electrodes deep within the brain to increase the activity in the neural circuits that control movements. However, this surgery is highly invasive and therefore risky. Instead Nicolelis and his team took a different approach. They implanted epidural stimulators in the main sensory pathway of the spinal cord and found that animals previously paralysed by the disease showed a remarkable improvement in symptoms. "We see an almost immediate and dramatic change in the animal's ability to function," says Nicolelis. The team think that the approach, which is much simpler and safer than implanting electrodes deep in the brain, works by blocking abnormal patterns of brain activity seen in the disease. The team think that waves of nerve activity caused by the synchronous firing of many different nerve cells build up and make it very difficult for the brain's motor circuits to initiate movements. But stimulating the sensory pathways three hundred times per second disrupts these neurological oscillations resulting in Parkinsonian animals showing twenty-six times more spontaneous movement than untreated controls.
"Following stimulation the neurons desynchronise resembling the firing pattern you would see in a healthy mouse is continuously moving," says study co-author Per Petersson.