How deep brain stimulation relieves Parkinson’s symptoms

New York Times : For more than a decade, deep brain stimulation (DBS) has been used to treat patients with Parkinson’s disease. In DBS, electrodes implanted in the patient’s brain act as a sort of pacemaker to send electrical impulses to specific parts of the brain and help restore a person’s ability to control his or her movements. Why the treatment is effective, however, was not entirely understood. To find out, Philip Starr of the University of California, San Francisco, and his colleagues conducted a series of experiments in which they added a strip of sensors to the motor cortex of DBS patients and then studied the signals emitted by the brain’s neurons. Parkinson’s disease appears to affect the brain’s beta rhythms by causing them to become so tightly synchronized that the brain’s motor cortex becomes phase locked. DBS disrupts that oversynchronization, allowing the motor cortex to function normally. The researchers say that although the finding is important, Parkinson’s is a complicated disease and DBS relieves just some of its symptoms. DBS could, however, be used to treat other conditions as well, including depression and obsessive compulsive disorder.