Roscovitine increased the second uIPSC amplitude. A, Repetitive firing of presynaptic and postsynaptic FSNs (FSN1 and FSN2, respectively). Arrowheads indicate autaptic responses. B, Effects of roscovitine (Ros; 30 μm) on uIPSCs in the FSN1→FSN2 connection. C, Scaled traces before roscovitine treatment (Control), during application of roscovitine (Ros), and after washout of roscovitine. D, E, Facilitative effects of roscovitine on the second uIPSC amplitude (D) and PPR (n = 18; E). F, Repetitive firing of presynaptic and postsynaptic FSNs (FSN3 and FSN4, respectively). G, Consecutive traces and their averaged uIPSCs in control and during application of 4 mm [Ca2+]o, CgTx, and roscovitine. H, The averaged uIPSCs obtained from 10 consecutive traces shown in G were scaled to compare the PPR. I, The time course of uIPSC amplitude shown in G. J, uIPSCs under 4 mm [Ca2+]o were larger than those under application of roscovitine (n = 8). *p < 0.05; **p < 0.01, paired t test.