Visualizations and descriptive statistics of the observed spike times suggest two modes of behavior in the same cell class.

<p><b>1A–4A</b>: 1 second interval of spike train data for each of the four cells considered. <b>1B–4B</b>: The histogram of inter-spike intervals for cells 1–4. <b>1C–4C</b>: The spectrum of cells 1–4 (solid blue line) and its confidence intervals (dashed red lines). The dashed black line indicates the estimate of overall spiking rate where represents the total number of spikes up to time .