Activa Parkinson's Control Therapy, which has been approved in the United States since January 2002 and in Canada, Europe and Australia since 1998, extends the use of Medtronic's brain stimulation technology to benefit patients with advanced, levodopa-responsive Parkinson's disease. Activa Parkinson's Control Therapy targets the subthalamic nucleus (STN) or the globus pallidus interna (GPi) to suppress some of the disabling symptoms of Parkinson's disease