DSI-evoked enhancement and depotentiation differ in their integration times. A, The effect of holding the duration of a DSI spike train constant and varying spike frequency (i). The magnitudes of both the transient enhancement (ii) and the depotentiation (iii) increased with frequency (or number) of DSI spikes (ii, F(4,33) = 20.4, p < 0.001; iii, F(4,19) = 48.2, p < 0.001, by one-way ANOVA). B, The effect of holding the number of DSI spikes constant and varying spike frequency (i). The magnitudes of the transient enhancement (ii) increased with DSI spike frequency (F(4,44) = 27.9, p < 0.001, by one-way ANOVA). The extent of the DSI-evoked depotentiation (iii) also increased with increasing spike frequency (F(4,17) = 153.6, p < 0.001, by one-way ANOVA), but a significant change from control was seen even at low spike frequencies (0–2 Hz, p < 0.05 by pairwise multiple comparison by Student–Newman–Keuls method). No further increase in the extent of depotentiation was seen at higher DSI spike frequencies (2–10 Hz, p > 0.23 by pairwise multiple comparison by Student–Newman–Keuls method).