1) To gain insight into the complex pathophysiology of epilepsy in the human brain, the synthesis of information derived from various animal models representing appropriate components of human epileptic seizure is required. For epileptic seizure propagation, the availability of anatomical pathways and their physiological connectivity according to the site of seizure origin must be considered. The reason for the notion of a preferential nature of certain pathways over others remains unknown but may be due, in part, to past history and the participation of a genetically-determined differential susceptibility. In this context, the following factors need to be considered: a) the significance of use-dependent functional/structural change of the neuronal system, b) the importance of understanding the divergent nature of neuronal connectivity, the potential role of genetic predisposition, and c) the morphological difference which exists according to ascending phylogenesis and hence the presumable functional difference across the species. 2) The corpus callosum is the major and rapid route of transhemispheric transmission of epileptic seizure in man. In the case of seizure of temporal lobe origin, its transhemispheric transmission may use the temporalipsilateral frontal through the corpus callosum to the contralateral frontal and then to the contralateral temporal limbic system. In contrast, the significance of the anterior commissure and the hippocampal commissure in man is debatable since both of these pathways have a very definite regressive tendency according to ascending phylogenesis. The specific reason why these pathways are sometimes used in a minority of temporal lobe seizure cases remains unknown.(ABSTRACT TRUNCATED AT 250 WORDS)