Figure 1. Firing properties of neurons derived from FA iPS cells.

(A–B). Patch-clamp recordings were made from iPS cells displaying an ovoid soma and bipolar processes. (C). Action potentials were activated in response to membrane depolarization. In the example shown here, multiple action potentials are observed at threshold (gray), whilst a single spike occurs in response to supra threshold stimulation (black). (D). Negative current injection resulted in membrane hyperpolarisation, without the addition of a depolarizing sag or rebound action potentials at stimulus offset. (E). Action potentials were blocked by addition of the sodium channel antagonist TTX (gray). (F). In voltage-clamp recordings, the transient inward current observed during membrane depolarization (black) was abolished in the presence of TTX (gray). (G). I–V curve demonstrating the voltage-dependence of the TTX-sensitive sodium current.