Studying Movement Control in Parkinson's Disease Using Closed Loop Deep Brain Stimulation

Parkinson's disease is a common, disabling, progressive condition characterised by severe problems with movement for which medical treatment in the longer term can be unsatisfactory. Deep brain stimulation is a treatment, which directly stimulates the nerve cells affected inside the brain to help overcome the difficulties with movement. Classically, deep brain stimulation stimulates in a manner that is constant and independent of a patients underlying condition as reflected in their brainwave activity. Recent research has suggested that adjusting deep brain stimulation in real time using analyses of brain signals recorded from deep brain stimulation electrodes (termed closed loop deep brain stimulation) nay be better than classical deep brain stimulation in alleviating difficulties with movement. However, it remains unclear whether closed-loop deep brain stimulation also leads to fewer unwanted side effects on movement control. In order to answer this question, the investigators will analyze deep brain stimulation activity and activity recorded from the surface of the head in Parkinson's disease patients undergoing deep brain stimulation surgery. During the recordings patients will perform different movement tasks. Deep brain stimulation has been found to reduce patients' ability to suppress inappropriate movements in certain tasks and performance in these tasks will be the core point of interest. The recordings will be conducted three times: During closed loop deep brain stimulation, classical deep brain stimulation and while the stimulator is turned off. This will allow the investigators to assess putative differences in the effect of closed loop and classical deep brain stimulation with regards to wanted and unwanted effects on movement control and to elucidate their correlates in the brain.