Fig. 7. Response of the neuron in figures 3 and 6to increasing doses of the GABA^Aantagonist bicuculline at 0 and 1 MAC halothane. When the increase in neuronal frequency had reached a plateau, the bicuculline dose rate was increased at least one more step to ascertain that the bicuculline effect was saturated, i.e. , that all GABA^Areceptors were blocked.