Firing properties of neurons derived from FA iPS cells.

<p>(<b>A</b>–<b>B</b>). Patch-clamp recordings were made from iPS cells displaying an ovoid soma and bipolar processes. (<b>C</b>). 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). (<b>D</b>). Negative current injection resulted in membrane hyperpolarisation, without the addition of a depolarizing sag or rebound action potentials at stimulus offset. (<b>E</b>). Action potentials were blocked by addition of the sodium channel antagonist TTX (gray). (<b>F</b>). In voltage-clamp recordings, the transient inward current observed during membrane depolarization (black) was abolished in the presence of TTX (gray). (<b>G</b>). I–V curve demonstrating the voltage-dependence of the TTX-sensitive sodium current.