a, Quantification of IPSC charge transfer (from the same neurons as in Fig. 4a). b, Recordings of mIPSCs from cultured cortical neurons with Syt1 conditional KO and Syt7 constitutive KO infected with lentiviruses expressing ΔCre/Cre recombinase and WT Syt1 or Syt1 mutants. Left to right: sample traces, cumulative probability plot of inter-event intervals, and quantification of event frequency, amplitude, and 10–90% rise time. c, Quantification of IPSC charge transfer (from the same neurons as in Fig. 4b). d, e, mIPSCs (d) and mEPSCs (e) from cultured cortical neurons infected with lentiviruses expressing Syt1 mutants. Left to right: sample traces, cumulative probability plot of inter-event intervals, and quantification of event frequency, amplitude, and 10–90% rise time. f, Quantification of IPSC charge transfer (from the same neurons as in Fig. 4d). g, h, Recordings of mIPSCs and mEPSCs from cultured cortical neurons infected with lentiviruses expressing Syt1WT or Syt1DA, without or with lentiviruses expressing Cpx1/2 shRNAs (Cpx1/2 DKD). Left to right: sample traces, cumulative probability plot of inter-event intervals, and quantification of event frequency, amplitude, and 10–90% rise time. Shown are means ± s.e.m.; the numbers of neurons/independent cultures are indicated. Statistical significance was assessed by Student’s t-test (*P < 0.05; **P < 0.01; ***P < 0.001; NS, no significant difference) with respect to either the Cre (red) or the Cre + Syt1 group (black) in a and b, either the control (black) or the Syt1DA group (red) in c–e, and between Syt1WT and Syt1DA with or without Cpx1/2 DKD in f–h.