(B-G) Munc18-1 null hippocampal neurons were rescued with wildtype Munc18-1a or a Munc18-1 mutant, Y473A, in which Y473 was replaced with alanine.(F) Top: example traces of spontaneous release of single vesicles (mEPSCs). Average mEPSC frequency (M18WT: 20.18 ± 5.18 Hz, n=15; M18Y473A: 0.48 ± 0.15 Hz, n=20, t-test with Welch correction, p = 0.0019), amplitude (M18WT: 26.0 ± 1.7 pA, n=15; M18Y473A: 24.5 ± 1.6 pA, n=20, t-test, p = 0.5334) and decay time (M18WT: 1.98 ± 0.10 ms, n=15; M18Y473A: 2.13 ± 0.17 ms, n=20, t-test with Welch correction, p = 0.4499). 