The neuroimaging technique utilized is Phosphorus-31 Magnetic Resonance Spectroscopy (31P-MRS). 31P-MRS is a non-invasive method with no exposure to ionizing radiation. At the magnetic field strength utilized (3 Tesla), magnetic resonance imaging is FDA-approved and is not associated with irreversible or serious adverse events. Furthermore, 31P-MRS is the only in vivo method for in vivo quantification of phosphorus energy metabolism, in living human brain.