Claudication of the action potential during fatigue-inducing stimulation. SEER ratio R(t) in a fiber subjected to the pattern of field stimuli represented at the top left. Plots labeled in upper-case letters are line averages of ratio images, sections of which are shown correspondingly labeled in lower-case letters. In the diagrams, rectangular depolarizing deflections represent trains of suprathreshold field stimuli at 70 Hz, one of which is plotted on A (bottom). The trains lasted 350 ms and were applied continuously at 2-s intervals. (A, a) R(t) and image upon the first application of the train. (B, b) The application at 1 min. (C, c) Application at 3 min. Note the alterations in signal pattern, including lower amplitude, and spatially inhomogeneous transients. (D, d) Recovery run, 10 min after stopping the stimuli. ID: 111511b_12_13_15_17.