FIG. 3.

Supra- and subthreshold membrane behavior of motoneurons. A: ionic currents underlying the action potential waveform. B: ionic currents underlying subthreshold membrane behavior, in this case, elicited by a short-lasting depolarizing/hyperpolarizing square current pulse. C: different phases of adaptation during repetitive firing and postdischarge hyperpolarization after a long-lasting current pulse. Unless noted, currents are activated at times indicated. For definitions, see Table 1 and section iiC.