A Study to Measure the Effect of Brain Stimulation on Hand Strength and Function in Patients With Brain Tumors

AWAKE CRANIOTOMY COHORT Inclusion Criteria: 1. Age 18 - 75 2. Ability to understand a written informed consent document, and the willingness to sign it 3. Radiographic evidence of tumor on MRI (i.e. non-enhancing) invading primary motor cortex in the non-dominant hemisphere. 4. Karnofsky performance status (KPS) ≥ 70 5. Normal or near normal motor strength (i.e., at least 3/5 in relevant areas) 6. Normal or near normal speech (Can consistently name at least 4/5 cards) 7. Free of other illness, in the judgment of the investigator, that may shorten life expectancy 8. Willing and able to participate in all aspects of the study Exclusion Criteria: 1. Presence of other malignancy not in remission 2. Evidence of bi-hemispheric or widespread tumor involvement 3. Medically high-risk surgical candidate 4. History of recent scalp or systemic infection 5. Presence of other implants or foreign bodies in the head 6. Inability to receive an MRI for any reason 7. Inability to receive cortical stimulation for any reason 8. Presence of implanted cardiac device (such as a pacemaker or defibrillator)