|Rm (MΩ)||Ra (MΩ)||Cm (pF)||Vrest, I = 0(mV)||AP height (mV)||AP width (ms)||Onset potential (mV)||Threshold Iinj (pA)||Ihold (pA)|
Intracellular patch-clamp recordings on postsynaptic boutons of spike-generating afferent fibers (type I SGNs) in the cochlear explant. Rm (membrane input resistance), Ra (access resistance), and Cm (membrane capacitance) were measured with ±5–10 mV or 5–20 pA steps from −80 mV in voltage-clamp or current-clamp mode, respectively. Vrest (resting membrane potential) was defined as the mean zero-current potential. Action potential (AP) height, width, onset potential, and threshold current (Threshold Iinj.), and the mean holding current (Ihold) were measured from a baseline potential of −80 ± 2 mV. On average, AP onset potential was +16 mV relative to −80 mV. AP height was determined as the difference between the peak and the baseline potential using near-threshold current injection; AP width was measured as the full width at half-maximum amplitude; onset potential was measured as the point when the spike onset slope reached 30 mV/ms in response to ramps of depolarizing current. Threshold current was estimated with square pulses at 5–20 pA resolution. Mean and SD values are given for the number of cells (n) yielding reliable measurements.