 Cortical mapping will done, which is an established procedure used to detect important areas of the brain. Usually, a nerve in the wrist is stimulated with a very small shock of electricity and a response is detected in the brain by an electrode placed on the surface. The electrical shock administered is not dangerous or painful. It will be given while asleep. For the experimental procedure used in this study, the same stimulation will be used, but the impulse detection will be performed using the speckle-contrast imaging camera. Researchers hope to see if the change in blood flow gives the same information as if the electrode was placed on the brain and used to detect the electricity. Doing both procedures is expected to take no more than 20 minutes. During this time, continual monitoring done by the surgeon and operating room staff. 