Finally, in order to investigate the shape of brain concentration-time profiles, we compared the profiles for scenarios I, II, III, and III'. Figure shows all of the plots for observed brain and simulated/predicted brain and plasma concentration-time profiles. Comparing the profiles for scenario I with those of scenarios II and III indicates scenario I provides very high predictivity as long as the brain profiles are in equilibrium with plasma: for example, ID 2, 3, 5, 6, 7, 8 (and many other instances were noted). However, in this study, we attempted to predict brain concentration-time profiles that showed non-equilibrium between the brain and plasma. For this purpose, we collected all of the relevant compounds by visual inspection of Figure . Figure shows representative non-equilibrium profiles for scenarios I/II/III, and these were separated into various types: (A) moderately slower elimination process in the brain compared with plasma, (B) much slower elimination process in the brain compared with plasma, and (C) delayed profiles in the initial phase in the brain. We identified 7 compounds (ID: 10, 13, 17, 20, 27, 31, and 45) for brain concentrations could be predicted accurately, the elimination phase could not. By contrast, for the predicted brain profiles in scenario III, both the initial concentration and elimination phase could be accurately predicted for most of the compounds (ID: 10, 13, 17, 31, and 45).