Figure 2.

Idealized traces showing elementary Ca²⁺ channel currents. (A) The traces show the activity of five Ca²⁺ channels each opening with a P_o of 0.2 (a value similar to the average P_o found in cell-attached recordings at −20 mV in adult IHCs: Zampini et al., 2013). (B) The activity of five Ca²⁺ channels with one opening with a P_o of 0.8 (gating mode 2; top trace) and 4 channels opening with a P_o of 0.05. Note that in this case the average P_o for the 5 channel group is 0.2, as it is in (A). In both (A) and (B) the vertical dashed lines indicate time points at which no Ca²⁺ channels are open (see text). Note that the simultaneous occurrence of no openings in all 5 channels is clearly more frequent in (A) than in (B). By convention, the inward current is indicated by the downward deflection of the trace; “c” is closed, “o” is open.