Figure 8.

Sensitivity of the voltage-dependent rebound delay to 4-AP. A, Two-electrode current clamp records of the PD axon's responses to depolarizing steps after hyperpolarizing presteps of different amplitude. The resting membrane potential was held at −60 mV, stepped to various hyperpolarized potentials up to −90 mV for 1 s, and then to −40 mV. In control saline, more hyperpolarized presteps lead to larger delays in the onset of spiking. In 4-AP, this delay is substantially reduced. B, Plots of delay over the prestep potential for the same experiment shown in A, for control saline, 4-AP, and after 30 min wash.