Figure 13.

(a) The mean spike waveforms of a putative neocortical pyramidal cell captured on 4 × 14 electrodes. The waveform with the largest peak-to-peak amplitude is colored red; (b) individual spikes (waveforms in gray color, n = 90) of the same pyramidal cell recorded by the electrode corresponding to the red waveform in panel a. The mean spike waveform is displayed in red color; (c) the autocorrelogram of the demonstrated pyramidal neuron (bin size: 1 ms). The two peaks indicate burst firing (multiple spikes fired in rapid succession); (d) Color-coded potential distribution maps corresponding to different time points of the mean spike waveform. The maps are visualized according to the layout of the 4 × 14 electrodes. The potential map corresponding to the time point of the negative peak of the mean spike waveform shown in panel b is indicated with an asterisk. Note the temporal propagation of the negative peak of the spike (red patch) from lower electrodes to upper electrodes. The spikes of the neuron were recorded in AP mode (internal reference, gain 500, high-pass 500 Hz).