Fig. 9.

The interburst hyperpolarization is actively generated. A, Intracellular injection of a short depolarizing current pulse in a chattering cell generates either one or two action potentials with an increase in the duration of the pulse. Following the action potentials is a hyperpolarization that lasts for ∼20–30 msec. B, Block of transmembrane Ca²⁺ currents with low Ca²⁺ and raised Mn²⁺ does not block the interburst AHP.C, Block of action potentials with tetrodotoxin reveals how the interburst AHP depends on the generation of a burst of action potentials.