AWAKE CRANIOTOMY COHORT  Inclusion Criteria:  Age 18+ Ability to understand a written informed consent document, and the willingness to sign it Radiographic evidence of tumor on MRI (i.e. non-enhancing) invading primary motor cortex in the non-dominant hemisphere. Karnofsky performance status (KPS) ≥ 70 Normal or near normal motor strength (i.e., at least 3/5 in relevant areas) Normal or near normal speech (Can consistently name at least 4/5 cards) Free of other illness, in the judgment of the investigator, that may shorten life expectancy Willing and able to participate in all aspects of the study  Exclusion Criteria:  Presence of other malignancy not in remission Evidence of bi-hemispheric or widespread tumor involvement Medically high-risk surgical candidate History of recent scalp or systemic infection Presence of other implants or foreign bodies in the head Inability to receive an MRI for any reason Inability to receive cortical stimulation for any reason Presence of implanted cardiac device (such as a pacemaker or defibrillator)  HEALTHY VOLUNTEER COHORT  Inclusion Criteria:  Age 18+ Ability to understand a written informed consent document, and the willingness to sign it Normal or near normal motor strength (i.e., 5/5 in relevant areas) Normal or near normal speech (Can consistently name at least 4/5 cards) Free of other illness, in the judgment of the investigator, that may shorten life expectancy Willing and able to participate in all aspects of the study  Exclusion Criteria:  History or presence of malignancy within the last 3 years, except subjects who have been treated successfully with no recurrence for > 1 year of basal cell or squamous cell carcinoma of the skin or in-situ cervical cancer Decreased motor strength (i.e. 4/5 or in relevant areas). Atypical form of the hand interfering with their ability to perform the actions requested by the study team Any other significant pre-existing medical conditions that, in the judgment of the Investigator, may increase the risks associated with study participation, or would preclude successful participation in the study.