Parkinson's disease (PD) is a progressive neurodegenerative disease affecting over 10 million people world-wide. It can be a debilitating disorder and although studied for decades, the physiological changes in the basal ganglia thalamocortical (BGTC) circuit that underlie its development remain under debate. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and internal globus pallidus (GPi) has been a highly effective therapy for many patients with PD, however, the results have been highly variable and may be associated with cognitive compromise in some patients. To advance DBS therapies for PD we require a deeper understanding of the local and network-wide circuit dynamics and their relationship to motor signs and cognitive function. This understanding will provide the rationale for optimizing STN and GPi DBS, targeting specific regions within the STN and GPi, and development of patient-specific DBS based on the patients' motor signs and cognitive profile