Correlation maps for stimulus amplitudes of 50 (left) and 400 (right) microns. The schematic at top-right indicates the anatomical orientation of the OIS image as well as all maps: A-anterior, M-medial, P-posterior, L-lateral. Color bars show coefficient of determination values for each map. The correlated signal, obtained from averaging of absorbance values within the ROI (encircled in the image at top-left) at each frame, is shown under each map (time course in solid red). Only the portion of the signal enclosed within the dashed lines (corresponding to the stimulus duration, green-on, red-off) is correlated. r values describe the degree of similarity between a given pixel's time course and the corrselated signal. Negative r values indicate that absorbance decreases to below-background levels. Thus, the signal in solid red represents the time course that would be observed in a pixel with an r value of +1 and the dotted blue line indicates the time course that would be observed in a pixel with an r value of -1.