Fig. 6.

Human ESC-derived neurons functionally mature in vitro. (A) A phase-contrast image of a neuronal culture during patch clamp recordings. (B) Action potentials are elicited upon a 20 pA current injection in neurons differentiated for 12 weeks in vitro. (C) Inward and outward currents are elicited upon voltage steps (−50 mV to 50 mV) in a 12-week-old neuron (i). Application of 1 μM tetrodotoxin (ii) completely eliminated inward currents (i,ii, arrows) that are characteristic of Na⁺ currents (iii). (D) In the ventrally patterned neuronal population, spontaneous postsynaptic currents were recorded from 10-week-old neurons (i) and application of 50 μM bicucculine completely inhibited postsynaptic currents (ii). (E) Immunostaining showed the expression of TBR1 by a biocytin-labeled neuron after patch clamping. Scale bar: 50 μm.