FIGURE 4.

Hair bundle movement induced by voltage steps. (A) Depolarization-evoked movement of unrestrained hair bundles occurred in three phases: a fast negative phase (“flick”), a subsequent positive phase (“twitch”) and a slow negative phase (slow adaptation). Stepping to +80 mV produced faster movements for the two later phases than stepping to +40mV, but did not affect the time course of the flick. (B) Short voltage steps applied to measure the flick in isolation from slower phases. Hyperpolarizations produced positive movements, whereas depolarizations caused negative movements. The dashed line is an exponential fit with a time constant τ = 165 μs. (C) Equal magnitude of the flick at the onset and offset of the voltage steps (least-squares fit: slope = −1.03, R = 0.978, N = 18 cells). (D) Voltage dependence of flick, shown as change from the holding potential of −80 mV. The flick depended linearly on voltage changes from −80 to +140 mV, but became sublinear for more positive voltages. Dashed line is a Boltzmann fit with dx = 96 mV and x₀ = −102 mV.