Figure 5. Current-voltage relationship of external electrically evoked responses.

A, Raw traces recorded under voltage-clamp conditions stepping the holding potential from -105mV to 30mV in 15mV steps. External electrical stimulation is delivered at t=500ms during the voltage step. Traces show the observed currents immediately following the stimulus artifact, inset box: 200ms, 700pA. B, Current-voltage relationship for n=6 wild-type INL cells displayed an n-shaped response type to external electrical stimulation with a peak ~ 50mV. Response was measured as the difference between the current immediately preceding, and the peak of the current following, the stimulus artifact. C, Current-voltage relationship displayed in B was replicated in n=3 wild-type INL cells using the voltage-clamp by the addition of an 100µs, 100mV internal step, delivered at successive holding potentials, instead of the external electrical stimulation.