Recent progress in deep brain stimulation offers the unique opportunity to modulate neural activity of the subthalamic nucleus with unprecedented spatial and temporal precision. To leverage these advances, it is central to understand how changes in neural activity reflect behavioral adjustments and how this can be altered by stimulation. This chapter summarizes how subthalamic deep brain stimulation can be applied as a translational tool to better understand the processes underlying decision-making and motor control in patients with Parkinson’s disease and how this tool might be used to improve treatment in the future.