Figure 6: Examples of 3 single-unit activities in awake cat’s AI in the click train paradigm. In this paradigm: (1) a single recording session lasted 10-20 min and contained hundreds of stimulus trains; (2) each stimulus train lasted 500 ms during which 1-ms-long rectangular pulses were repetitively delivered with a fixed interpulse interval ranging 1 to 480 ms; (3) the intensity of 20 successive pulses was set at 20-80 dB by 10 dB steps; (4) the data presented here were obtained at the intensity that evoked the most potent stimulus-locking responses (see Sakai et al. [1] for details). The units that exhibited excitatory responses were classified into 3 classes (A-C). Examples are shown in the 1st-3rd column, and pooled data in the 4th column. 1st column: raster dot display of discharges with the abscissa representing time (the horizontal bar at the bottom depicts 0.5-s long pulse train) and the ordinate representing pulse interval. 2nd column: “temporal modulation transfer function (temporal-MTF)” where the degree of stimulus locking (Z value of vector strength) is plotted as a function of the pulse interval. The arrow depicts the pulse interval that gave the most potent stimulus locking. The unit showing statistically-significant stimulus locking (P <0.05, Rayleigh statistics; dotted line) was classified as a “stimulus locking unit” (A and B), and the reminder as “stimulus-un-locking unit” (C). The “stimulus locking units” were divided into two subtypes according to the shape of the temporal-MTF such as “band-pass type” (A) or “low-pass type” (B). 3rd column: the amount of evoked discharges during 50-500 ms after the onset of the pulse train (responses during 0-50 ms were excluded for eliminating interval-independent onset responses). 4th column: pooled data of the temporal-MTF. For convenience of latter analysis, we specify the following 4 response region. Region a, where only onset responses are evident; Region ß, stimulus locking takes place; Region ?, discharges intermittently occurred without stimulus locking; Region d, onset responses are evident (Modified from Sakai et al. [1]).