I _h in wild-type vestibular neuron cell bodies and calyx terminals. (A–C) I_h is activated in response to voltage steps between −144 and −64 mV in 10-mV increments in cell bodies (HP: −84 mV) and both peripheral and central dimorphic terminals (HP: −64 mV). (D–F) Activation curves generated from tail currents at −74 mV. Cell bodies displayed smaller maximum conductance than calyx terminals, but showed no differences in half-activation voltage or slope factor. (G–I) Traces recorded at −144, −124, and −104 mV from A, B, and C normalized for amplitude and fit with double exponential functions. (J–L) Fast and slow activation time constants were similar among the three populations. The number of samples is shown inside the bars for each condition. Error bars indicate mean ± SEM.