Fig. 4. At doses below 10 µg bombykal (BAL), only action potentials of the large class were affected by the stimulus-correlated amplitude reduction. (A) Response to a 50 ms stimulus of 1 µg BAL, pseudo-highpass-filtered as in Fig. 3. The amplitudes of the large action potentials were reduced after strong bombykal stimuli and regained their original amplitude in the course of several seconds (as illustrated by the broken line). Occasionally, spontaneous small action potentials occurred during (filled arrow) or after (open arrow) the response. The reduction of the amplitude during bursts of large (shaded arrow) and small (open arrow) action potentials was reported previously (Dolzer et al., 2001). (B) Enlarged view of the marked section in A. (C) Two small and two large spontaneous action potentials recorded before the stimulation, plotted at the same amplitude scaling as in B. The small action potential during the response was of the same amplitude as the small spontaneous action potentials.