Autaptic munc18-1 null hippocampal neurons were rescued with a phosphomimetic Munc18-1 mutant, Y473D or wild-type Munc18-1 as control and assessed on morphology and synaptic transmission using whole-cell patch clamp electrophysiology (F) Left: example traces of spontaneous release of single SVs (mEPSCs). Average mEPSC frequency (M18WT: 20.18 ± 5.18 Hz, n=15; M18Y473D: 0.28 ± 0.13 Hz, n=17, Mann-Whitney U test, p < 0.0001), mEPSC amplitude (M18WT: 26.0 ± 1.7 pA, n=15; M18Y473D: 27.8 ± 2.2 pA, n=17, t-test, p = 0.5372) and mEPSC decay time (M18WT: 1.98 ± 0.10 ms, n=15; M18Y473D: 2.84 ± 0.41 ms, n=17, t-test with Welch correction, p = 0.0549). 