Figure 4: Development of spontaneous excitatory synaptic activity.

(a) Example traces of spontaneous excitatory synaptic currents from control (CTR), AS and UBE3A KO neurons at 3–8, 9–14 and 15–20 weeks in culture. Scale bar for top CTR, AS and UBE3A KO, 10 pA, 5 s. Scale bar for bottom CTR traces, 10 pA, 100 ms. (b) Frequency of spontaneous synaptic currents for neurons derived from all CTR and AS subjects during development (for both groups, n>40 cells at each time point). (c) Percent of synaptically active neurons (event frequency >0.2 Hz) derived from CTR (4 subjects, n>60 cells at every time point), AS subjects (3 subjects, n>40 cells at every time point) and UBE3A KO (1 line; n>40 cells at every time point) during development. *P<0.05 for significant differences between CTR and AS. ^#P<0.05 for significant differences between CTR and UBE3A KO line (χ² test). (d) Mean frequency of spontaneous synaptic events for active neurons derived from CTR (4 subjects, n>40 cells at every time point), AS subjects (3 subjects, n>35 cells at every time point) and UBE3A KO (1 line; n>15 cells at every time point). (e) Mean amplitude of spontaneous synaptic events for neurons plotted in d. *P<0.05 for differences between CTR and AS. ^#P<0.05 for differences between CTR and UBE3A KO line (two-way analysis of variance (ANOVA)). (f) Synaptic frequency and (g) amplitude for (left to right) CTR neurons treated with UBE3A ASOs at 6 weeks in culture (6 coverslips per condition, 15 cells per coverslip), CTR neurons treated with UBE3A ASOs at 18 weeks in culture (4 coverslips per condition, 15 cells per coverslip), AS neurons treated with 1 μM topotecan (2–4 coverslips per condition, 15 cells per coverslip), 10 mM KCl-treated CTR neurons from 4 CTR subjects (1 coverslip for both vehicle and KCl for each CTR line, 15 cells per coverslip). *P<0.05, Student’s t-test. Error bars represent mean ±s.e.m.