Fig. 5. The reduced efficiency of electrical pulses in eliciting a normal-sized post-pause novelty response was not due to insufficient intensity (A) or temporal patterning (B). (A) One cycle of a 1 kHz sinewave was delivered at one of the set field strengths indicated on the abscissa (0.9-235 mV cm^-1 peak-to-peak). Different symbols relate to three fish, gc1 (circles), gc2 (squares) and gc3 (triangles), and show (100), average efficiencies 100 electric organ discharges (EODs) after a pause. Measurements were obtained after 220 pauses. The number of pauses for each fish, given in order from low to high intensity, was: gc1, 20, 20, 7, 53; gc2, 10, 30, 10, 30; gc3, 10 each). The steady-state response strengths increased with increasing intensity but so did the post-pause strengths, leaving their ratio constant. (B) The post-pause efficiency (100) did not differ when either a single pulse or an extended series of pulses was given as stimulus. Means + S.E.M. are shown, obtained in experiments with two fish, gc1 (dark grey columns) and gc2 (light grey columns). The different time courses of the stimuli are illustrated schematically below the columns. Stimuli were a single cycle of a 1-kHz sine wave, a group of six such pulses with 20 ms silent intervals separating successive pulses or a continuous wave of 100 cycles. All stimuli had the same intensity (235 mV cm^-1 peak-to-peak).

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