Fig. 3. Extracellular recordings of spontaneous action potential firing in slices from wild type (  A ) and β³(N265M) mutant mice (  B ). Effect of 0.2 μm etomidate on the occurrence of episodes of ongoing activity (EOA, left section) and action potential firing within an EOA (right section). The number of EOAs was not changed by etomidate. Within a single EOA etomidate reduces action potential firing in the mutant to a lesser degree than in the wild type.