Electrophysiological properties of human induced pluripotent stem cell (hiPSC) differentiated neurons. (A): Representative example (upper panel) of currents evoked by depolarizing voltage steps indicated above the traces (see scheme of the protocol in 4B, insert); expanded from dashed lines (insert), rectangular traces of fast-activating, fast-inactivating inward currents evoked by depolarizing voltage steps, as indicated; example (bottom traces) of currents evoked by the same set of depolarizing voltage steps as indicated above after 1-minute preapplication of TTX (1 μM) plus TEA (20 mM). Note the strong inhibition of both inward and outward components. (B): Current-voltage relations of outward K+ (▪) and inward Na+ (▴) in control conditions and after 1-minute application of 1 μM TTX + 20 mM TEA (●); scheme of depolarizing protocol (insert) for recording current-voltage relations. In the different tests, pulse protocol was the same. (C): Examples of single traces illustrating separate inhibition of voltage-gated Na+ currents by 1 μM TTX (left) and K currents by 20 mM TEA (right). Note different time scales. Abbreviations: TEA, tetraethylammonium; TTX, tetrodotoxin.