Figure 4-5 Decerebration does not alter anesthetic requirement, as measured by the minimum alveolar concentration (MAC). Removal of brain tissue rostral to the heavy black line does not alter isoflurane MAC in rats. PAG, periaqueductal gray; RF, reticular formation; RN, red nucleus; Thl, thalamus. (Adapted from Rampil IJ, Mason P, Singh H: Anesthetic potency [MAC] is independent of forebrain structures in the rat. Anesthesiology 78:707, 1993.)