Effects of excitatory inputs on antidromic activation with electrode placed at (a) position I, (b) position II, and (c) position III during cathodic stimulation. Somatic (top) and axonal (bottom) firing rate as a function of gexc and fpulse. gexc = 0 nS (no excitatory inputs), 0.03 nS, 0.06 nS, and 0.12 nS. (d) Voltage responses recorded in the soma and node15 at three positions. There were recurrent orthodromic spikes in the axon. (e) Voltage responses recorded in the soma and node15 at three positions. The axon failed to respond to 100% of the stimulus. Each synaptic input was a 20 Hz Poisson train. Pulse amplitude was 1.2Ith, and pulse width was 0.1 ms.