This video illustrates the dynamic changes in brain oxygenation in response to whisker stimulation in a head-restrained mouse under light isoflurane anesthesia. Imaging is performed through a 3 mm diameter glass window that replaces the skull and dura, offering a clear view of the superficial layers of the barrel cortex. The barrel cortex, specifically activated by whisker stimulation, corresponds in daily function to the human sensory area responsible for tactile information, such as touch. Each frame represents a subtraction image, showcasing the difference in light reflectance at approximately 665 nm (deep red light) before and after whisker stimulation. Frames are captured every 20 seconds during a 20-second trial. Black regions signify decreased oxygenation in response to stimulation, indicating areas of heightened computational demand and oxygen consumption within the cortex. This high-precision imaging method utilizes the differential reflectance of blood with and without oxygen at this wavelength, enabling the visualization of localized cortical activity in response to sensory input, and providing insight into the neural and vascular dynamics of sensory processing.