weeks after final plating (Fig. 4c). More specifically, monocultures were mainly inactive (47.4% of cells compared to only 4.5% in co-cultures) or only showed sparse activity (44.7% of cells compared to 9.1% in co-cultures). These patch clamp experiments confirm that bursts of activity increase as cultures become more mature40. Finally, the frequency of sPSC bursts is similar to the frequency of calcium oscillations in both conditions (Fig. 4d), while there is a clear difference in frequency between the two cell culture conditions (Fig. 4d). These findings strongly suggest that synaptic network activity underlies the synchronicity of the calcium oscillations in the iPSC-derived neuronal co-culture network.
