Figure 2.

ISI variability in auditory receptor neurons. A, B, Ten spike trains of an auditory receptor neuron evoked by stimulation with a 4 kHz pure tone (the cell's best frequency, schematically drawn as a slow sine wave) of 58 dB SPL (A) and 70 dB SPL (B), respectively (top). The ISIs within and across trials show high variability. The frequency of neural discharges depends on sound intensity and shows spike-frequency adaptation (bottom), data from 131 (A) and 206 (B) trials, respectively. C–E, ISI histograms of the same cell obtained for three different sound intensities I. The histograms in C and E were computed from the spike trains shown in A and B, respectively, discarding the first 200 ms as transients. The ISI variability decreases with increasing spike frequency f.