Fig. 4. Modulation of behavior of Pinsky–Rinzel model of CA3 hippocampal neurons by increasing concentrations of halothane during application of the relatively low somal injection current (I^S= 0.75 μA/cm²) used to generate Fig. 3A. It is assumed that halothane modulates Ca²⁺conductance by decreasing the peak Ca²⁺conductance according to the Hill equation where a halothane concentration of 0.85 mm deceases Ca²⁺conductance by 50%, and with a Hill coefficient of 1.5. A modest increase in burst frequency and duration is produced when halothane concentration is 0.10 mm (A ). This becomes more pronounced for a halothane concentration of 0.20 mm (B ). Sustained spike activity appears with halothane concentrations of 0.33 mm (C ) and greater (not shown). For each case, a segment near the end of the panel on the left is shown in greater detail on the right.