Persons with Parkinson’s disease increasingly lose their mobility over time and are eventually unable to walk. Hope for these patients rests on deep brain stimulation, also known as a brain pacemaker. In a current study, researchers investigated whether and how stimulation of a certain region of the brain can have a positive impact on ambulatory ability and provide patients with higher quality of life. To do this, the researchers used a technique in which the nerve cells are activated and deactivated via light.