Synaptic transmission was assessed during and immediately after sustained stimulation in autaptic excitatory munc18-1 neurons expressing M18WT or M18Y473D.(C) Synaptic transmission was assessed before (naive(n)) and two seconds after (a) 40Hz stimulation. Average EPSC charge M18WT (naive: 70.9 ± 19.5 pC; after HFS: 75.4 ± 17.4 pC, n=12, paired t-test, p = 0.4049). Average EPSC charge M18Y473D (naive: 0.888 ± 0.342 pC, after HFS: 25.6 ± 9.3 pC, n=9, paired t-test, p = 0.0271). 