Synaptic transmission was assessed during and immediately after sustained stimulation in autaptic excitatory munc18-1 neurons expressing M18WT or M18Y473D.(E) Quantification of RRP and Pves (EPSC charge / RRP charge * 100) from C-D. Average RRP size M18WT (naive: 1.73 ± 0.69 nC, after HFS: 1.34 ± 0.54 nC, n=12, paired t-test, p = 0.0557). Average RRP size M18Y473D (Naive: 0.061 ± 0.019 nC, after HFS: 0.207 ± 0.050 nC, n=9, paired t-test, p = 0.0246). Average Pves M18WT (naive: 7.07 ± 0.76 %, after HFS: 10.6 ± 1.6 %, n=12, paired t-test, p = 0.0201). Average Pves M18Y473D (naive: 0.27 ± 0.22 %, after HFS: 10.8 ± 2.2%, n=9, paired t-test, p = 0.0012). 