This project aims to develop and implement in vivo, label-free two-photon fluorescence lifetime imaging microscopy (2P-FLIM) for investigating the metabolic dynamics of mouse brain tissue. The approach exploits endogenous NADH autofluorescence as a sensitive optical biomarker of cellular energy metabolism. Because free and protein-bound NADH exhibit distinct fluorescence lifetimes, shifts in their relative proportions directly report changes in the balance between oxidative phosphorylation and glycolysis. By quantifying these lifetime dynamics with spatiotemporal resolution, this project seeks to elucidate the metabolic landscape of brain tissue under both physiological and hypoxic conditions.