Fig. 1.

Stimulus generation. A, Electrodes E1 and E2 near the animal's head and tail measured the normal electric organ discharge waveform,H-T EOD, and a sinusoidal Stimulus waveform was synchronized to the zero crossings of theH-T EOD (dotted lines). The stimulus waveform was presented to the animal with two different geometries. With global geometry the stimuli were applied via electrodesG1 and G2, resulting in relatively homogeneous stimulation of the body surface. With local geometry a stimulus dipole applied the stimulus to localized regions of the body surface. B, C, Period histograms of the responses of a p-receptor afferent to sinusoidal amplitude-modulated stimuli showing that, with correct calibration, global and local stimuli result in similar electroreceptor afferent responses.