Deep brain stimulation (DBS) of the basal ganglia has been used as effective treatments for advanced Parkinson's disease and dystonia. However, the mechanism of its therapeutic effect is not well understood. In this book, Dr. Tsang presents his research findings where movement-related activities were recorded from the basal ganglia and the pedunculopontine nucleus region from patients with Parkinson's disease and dystonia after they received implants of DBS electrodes. This work provides an overview of current treatment protocols including medications and surgery for movement disorders. It advances our understanding of the mechanism of DBS therapy and implies on its future application for the treatments of these disorders.