Deep brain stimulation (DBS) surgery is currently a standard procedure for advanced Parkinson’s disease (PD). It involves inserting an electrode into a small nucleus in the basal ganglia and results in drastic improvements in the motor symptoms of PD. In order to correctly place the electrode, many medical centers keep the patient fully awake during this part of the surgery as electrode localization is based on the electrical signals of the awake brain. To enable DBS to be performed under sedation we looked at the electrical characteristics of the basal ganglia and the cortex in two non-human primates when they were given different types of sedatives: propofol, ketamine or interleaved propofol-ketamine. These characteristics were observed while the primates were healthy and while they had experimentally-induced Parkinsonism. Finally, we compared the electrical signals under these three sedative states to those while the primates were naturally sleeping. We found that propofol and ketamine have opposing effects on the electrical activity such that ketamine mimics rapid eye movement (REM) sleep, propofol mimics non-REM (NREM) sleep and the interleaved propofol-ketamine protocol mimics the NREM-REM sleep cycle. Further, ketamine’s effects do not disrupt the signals that are used for DBS electrode localization. These promising findings are a first step in enabling DBS surgery to be safely and accurately performed under sedation.
