Intrinsic optical imaging of the chick visual wulst. (a) The response obtained from the right visual wulst following electrical stimulation of the left optic papilla. A vascular image of the recording area is presented in the left upper corner. The numbers in each panel indicate time (s) after stimulation. An intrinsic signal that extends from the anterior to posterior portions of the visual wulst is evoked by the electrical stimulation. (b) Decreasing light reflectance (signal intensity) plotted against recording time. The signal intensity peaks about 2 s after the onset of stimulation.