Figure 10. Slow rise of depolarization reduces maximum rate of rise of spikes and increases the threshold in actual low-frequency NM neurons.

Spikes (upper) were induced by a rectangular current (0.5 ms duration, A) or a ramp current (1 ms duration, B). Lower traces are the time derivatives. Threshold current was larger by 11.2 ± 0.3% (n= 9, P < 0.01), threshold potential was higher by 1.5 ± 0.6 mV (n= 9, P < 0.05, arrows), and maximum rate of rise of spikes was smaller by 19.7 ± 3.1% (n= 9, P < 0.05) for the ramp current compared with the rectangular current.