Whole-cell perforated patch recordings were performed on SCZD (n=30) and control (n=20) three-month-old hiPSC neurons cocultured with wildtype human astrocytes (Sciencell) on acid-etched coverslips and typically transduced with LV-SYNP-GFP. The recording micropipettes (tip resistance 3–6 MÙ) were tip-filled with internal solution composed of 115mM K-gluconate, 4mM NaCl, 1.5mM MgCl2, 20 mM HEPES, and 0.5mM EGTA (pH 7.4) and then back-filled with the same internal solution containing 200µg/ml amphotericinB (Calbiochem). Recordings were made using Axopatch 200B amplifier (Axon Instruments). Signals were sampled and filtered at 10kHz and 2kHz, respectively. The whole-cell capacitance was fully compensated, whereas the series resistance was uncompensated but monitored during the experiment by the amplitude of the capacitive current in response to a 5mV pulse. The bath was constantly perfused with fresh HEPES-buffered saline composed of 115mM NaCl, 2mM KCl, 10mM HEPES, 3mM CaCl2, 10mM glucose and 1.5mM MgCl2 (pH 7.4). For voltage-clamp recordings, cells were clamped at −60 to −80mV; Na+ currents and K+ currents were stimulated by voltage step depolarizations. Command voltage varied from −50 to +20mV in 10mV increments. For current-clamp recordings, induced action potentials were stimulated with current steps from −0.2 to + 0.5nA. All recordings were performed at room temperature.
