Figure 1

Response profiles for 4 representative neurons (A, B: synchronization type; C, D: non-synchronization type) in the click-train paradigm. (1st column) Raster display of spike occurrence in response to 0.5-s-long click trains (horizontal bar) at variable inter-stimulus intervals (ISI; ordinate, left) or repetition rate (ordinate, right). Regions α-δ represent qualitatively distinct response patterns as defined below. (2nd column) The "temporal modulation transfer function (tMTF)," defined as Rayleigh values as a function of ISI. The vertical bar denotes the ISI range of "region β" where statistically-significant degree of stimulus-locking responses took place (P < 0.05, Rayleigh statistics). The ISI that gives the maximal Rayleigh value is denoted as the "best ISI" (arrow). In majority of the synchronization neurons, the longer-ISI limit of region β (upper margin) was bordered with "region α" (A-1) where only the onset response was evident. (3rd column) The "rate modulation transfer function (rMTF)," defined as the mean driven rate (over 50–500 ms after the initiation of the train) as a function of ISI. The vertical bar denotes the ISI range where the mean driven rate exceeded the threshold for excitation (2*SD of spontaneous firing rate; dotted line). Among the ISI range, the one where no stimulus-locking responses took place was denominated as "region γ." In majority of the neurons examined, the shorter-ISI limit (lower margin) of region γ was bordered with "region δ" where only the onset response was evident. See text for details.