Figure 13. Effect of varying amplitude of Na_P on the rate of rise of input required for repetitive firing.

In the model motoneuron, varying the rate constant O_off (see Fig. 1) from 0.015 (reduced Na_P model) to 0.03 (standard model) decreased the rate of rise of a linear current ramp needed to generate repetitive firing. The minimal rate of rise that produced at least five spikes is plotted versus Na_P expressed as a percentage of Na_T for a step from −120 mV to −10 mV.