A, glycinergic and GABAergic eIPSCs were pharmacologically isolated from the mixed focal eIPSCs. The data were obtained from the same bouton shown in B. B, typical traces of focal eIPSCs successively elicited from a single synapse at 0.2 Hz. Note that spontaneous mIPSCs are evoked by either glycine or GABA release or both. C, histograms of the decay time constants (τfast and τslow) of the mixed focal eIPSC in a single synapse (16 events). Bin size, 2 ms. Inset shows summary data of the averaged decay time constants of focal eIPSCs (n = 4). D, the failure rate (the frequency of failure events in the total stimuli) of focal eIPSCs was increased in the presence of bicuculline or strychnine. Each column represents the mean + s.e.m. from four neurones; **P < 0.01.