Conventional whole-cell patch-clamp recordings were made from individual iPSC-derived neurons with an EPC9 amplifier and PatchMaster software (HEKA). Preliminary experiments were conducted on dissociated monolayer cultures and showed that voltage-activated currents were present as early as 32 DIV and expression was stable out to 75 DIV. All subsequent characterization was performed on cells along the edges of the organoid preparations. Voltage- and current-clamp protocols were generated by the software used for data acquisition. Current and action potential amplitudes were measured in PatchMaster. Curve fitting and additional analysis was performed after exporting the data to Igor (Wavemetrics).
