Fig. 2. Division of log-ISIHs into component peaks. Thetop four panels are the responses of different neurons to the m-sequence stimulus. Log-ISIHs consist of 200 bins spaced logarithmically between 0.1 msec and 2 sec, so that each bin is 5.1% larger than the previous one. Each log-ISIH is divided, by eye, into its component peaks, which are then color-coded according to the position of the maximum (black for <3 msec,light gray for 3–38 msec, and dark grayfor >38 msec). Top, Same simple cell as in Figure 1; three peaks. Second panel, Simple cell (38/6), 5.9 spikes/sec, 11,343 ISIs; two peaks (short and long). Third panel, Simple cell (34/12t), 5.2 spikes/sec, 9,997 ISIs; two peaks (medium and long). Fourth panel, complex cell, 29.9 spikes/sec, 57,943 ISIs; one peak (medium). The boundary positions across 66 neurons are collected into a log-ISIH (bottom panel), which reveals a tightly clustered, bimodal distribution.