Figure 3.

Axonal action potentials triggered by complex spikes at different holding currents and interstimulus intervals. A, B, Somatic and axonal recordings of complex spikes evoked by a pair of climbing fiber stimulations with a 40 msec interval. A, Tonic hyperpolarizing current held the cell near -70 mV. B, no holding current. The axonal electrode was 406 μm from soma (same cell as Fig. 1). Plot of axonal signal and noise as in Figure 1. C, D, Summary of the number of somatic (solid symbols) and axonal (open symbols) spikes per climbing fiber stimulation, plotted versus interstimulus interval, with (C) (n = 7) and without (D) (n = 5) holding current. The response to the first stimulus is as labeled (rightmost symbol). E, F, Propagation efficiency for the first and second stimulations (stim), given as the ratio of the number of axonal to somatic spikes (“axon/soma ratio”) with (E) (n = 7) and without (F) (n = 5) holding current.