It is controversial whether the STN or the GPi, the main targets of DBS therapy in patients with Parkinson's disease, is the appropriate target. We select GPi-DBS in patients judged by our cognitive function test battery to be at high-risk for cognitive decline after STN-DBS. While DBS surgery is usually performed under local anesthesia for the precise placement of DBS electrodes, general anesthesia might be useful in patients intolerant of long-lasting surgical stress. Our monkey experiments revealed that the most medial part of the STN receives direct input from the limbic cortex, suggesting that the spread of stimulation to these limbic territories may elicit adverse emotional effects. Other monkey experiments on the physiological mechanism of DBS suggest that high-frequency GPi stimulation disrupts information flow through the GPi.