The di-8-ANEPPS signal elicited by trains of depolarizing pulses. (A) Average of four line scan images F₂₂(x,t), obtained in a stained voltage-clamped fiber and corrected as described for Fig. 2 B. The fiber was held at −80 mV, and a train of 12 pulses (to +40 mV) was applied at a frequency of 60 Hz. The trains were repeated at 2-s intervals during 3 min. (B) The average SEER ratio R(t). Ratio traces were calculated as described in Fig. 2 from four individual images, obtained at times of 0, 1, 2, and 3 min, and averaged. The individual R(t) were similar to one another. (inset) Dark red trace, average of all transients in R (t). Black trace, command potential of individual depolarizing pulses, scaled to match the experimental record. Dots plot individual values of the command, which was updated at 1-ms intervals. ID: 111011a_23, _25, _27, and _28.