Functional analyses of iN cells were conducted using whole-cell patch-clamp electrophysiology as described elsewhere (88, 97). Miniature postsynaptic currents were recorded at a holding potential of −70 mV in the presence of 1 μM tetrodotoxin. Cs-based solution was used, which consisted of 40 mM CsCl, 3.5 mM KCl, 10 mM Hepes, 0.05 mM EGTA, 90 mM K-gluconate, 1.8 mM NaCl, 1.7 mM MgCl2, 2 mM adenosine 5′-triphosphate (ATP)–magnesium, 0.4 mM guanosine 5′-triphosphate–sodium, and 10 mM phosphocreatine. The recording batch solution contained 140 mM NaCl, 5 mM KCl, 10 mM Hepes, 2 mM CaCl2, 2 mM MgCl2, and 10 mM glucose (pH 7.4). All cell culture recordings were conducted at room temperature.
