A, Paired recordings of EPSCs in hippocampal microisland cultures. EPSCs were induced by 20 Hz presynaptic action-potential trains. Sample recordings of presynaptic action potentials (top) and postsynaptic EPSCs (bottom) during the 1st and 10th second are shown.
B, Overlay of all EPSCs during 1st and 10th second. Note asynchronous events in the 9–10 s interval in WT neurons (arrows) that are absent in Syt7 KO neurons.
C, Summary graph of asynchronous release in the 10th second, quantified as the integrated charge transfer during 30–50 ms after a presynaptic action potential, and normalized for the overall synaptic strength by dividing the charge transfer with the average peak amplitudes during the initial 5 s. Data are means ± SEM; numbers in bars indicate number of pairs/independent cultures analyzed. Statistical significance was assessed by one-way ANOVA (** p<0.01) comparing test conditions to control.