Figure 5.

A, Polarity index (PI) as a function of the difference between time-to-minimum and time-to-maximum. Dark gray and white circles indicate data from recordings exhibiting monopolar and bipolar spike waveforms, respectively. A PI of 1.6 was the criterion for separation between monopolar and bipolar waveforms. We used this value to classify the data and the results are shown in B and C. These subplots show the averaged spike waveforms for 95 stimulus datasets of 29 neurons classified as having monopolar spike waveforms (B) and for 14 datasets of three bipolar neurons (C). D, Shows distributions of first-spike latency (bin width 1 ms) for neurons classified as bipolar (white, solid line) and monopolar (dark gray, dashed line). E, Shows PSTHs, normalized per neuron (see Materials and Methods). Note the close correspondence between first-spike latency distributions (D) and the PSTHs (E). a.u., arbitrary unit.