Fig. 2: Comparison of vesicular release kinetics in wild type (WT) and Syt1^−/− neurons.

a Average time courses of evoked vesicular release in WT and Syt1^−/− (quanta per frame). The traces were obtained by first averaging in each imaged bouton the number of quanta detected in individual frames following each of 51 action potentials in the train (frames 0 to 50, 4 ms/frame). This was followed by calculating the cell-averaged responses (range 21 – 162 boutons per cell) and finally the mean responses across all recorded neurons (shaded areas represent SEM among the recoded cells). Based on the distinct biphasic time-course of vesicular release in wild-type neurons, the time threshold between synchronous and asynchronous release events was set at 10 ms after the somatic action potential (i.e. at the border between 2nd and 3rd frames, see main text for details). b Comparison of synchronous, asynchronous and total release in wild type and Syt1^−/− neurons during the 5 Hz stimulation train. Left, traces represent the average number of vesicular quanta released at each action potential in a single presynaptic bouton (mean ± SEM, shaded area). Right, distributions of mean synchronous, asynchronous and total release efficacies at the steady state (between action potentials 20 and 51) among the recorded cells (mean ± SEM). (a, b) Wild type, N = 16 cells from 5 culture preparations; Syt1^−/−, N = 11 cells from 4 culture preparations ** p < 0.01, *** p < 0.001, ns p = 0.09, two-tailed Mann–Whitney U test (for exact p values and for further details of statistical analysis see SourceData.xlsx file).