Spatial plots of activity evoked by low- (50 μm) and high-amplitude (400 μm) stimulation. The schematic at the top-left indicates the anatomical orientation of the cortex: A-anterior, M-medial, P-posterior, L-lateral. Absorbances were measured within the boxel shown in the top-middle panel. The schematic (top-right) shows how each frame is spatially represented with respect to the boxel of interest. Both stimulus amplitudes are mapped 1, 5 and 10 seconds after stimulus onset. Absorbance values at each pixel (x, y location) are represented two fold: both by their height along the z-axis, and by their color.