Figure 8. Bushy cells of the aVCN also possess an I_h.

A, inward currents recorded from a bushy cell evoked by 500 ms hyperpolarizing voltage steps from -60 to -140 mV (in -10 mV increments, holding potential was -60 mV). Data are not leak subtracted; dashed line indicates the zero current level and arrows indicate latency of measurements for the current-voltage (I-V) relationship. I_i, instantaneous current; I_ss, steady state at 500 ms. B, I-V relationship for the data in A, measured as the difference (▪) between the instantaneous current (I_i, ○) and the current measured at 500 ms (I_ss, •). C, the mean I_h activation curve obtained from 15 bushy cells. The normalised tail current magnitude is plotted against the test potential and fitted to a Boltzmann function (continuous line) with half-activation (V_1/2) of -94 mV and with a slope factor of 13 mV. Vertical bars are ±s.d. D, a different bushy neurone under current clamp, in response to a 200 ms hyperpolarizing current stimulus. Increasing hyperpolarizing current injection causes a slow time-dependent relaxation of the voltage trace, which can trigger action potentials at the end of the pulse. A dashed line indicates zero voltage level and current steps are plotted below. The resting membrane potential was -58 mV.