Ictal patterns in experimental models of epilepsy.

The goal of this article is to review many of the animal models that have been used for epilepsy research. The intent is to present the behavioral and electrographic patterns observed in these models and to relate those patterns to human epilepsy. This review is organized into three sections. The first section deals with the methods used in the study of epilepsy. These methods range from in vivo preparations, through in vitro brain slice preparations and neural grafting methods, to computer simulation methods. The second section of the review deals with agents capable of inducing epilepsy. Some of the agents include chemical convulsants, ionic changes in the tissue, changes in osmolarity, and withdrawal from drugs. The effects of these agents are reviewed with their relation to the mechanisms of action. Finally, the methods used to control epilepsy are reviewed. These methods include the application of anticonvulsants, changes in the osmolarity, neuronal grafts and electrical currents. Examples of epileptiform activity obtained from animal models published in the literature are shown in several figures for comparison to human patterns. It is clear from this review that animal models are capable of reproducing many of the seizure types found in clinical situations. Although we have some understanding of the mechanisms underlying the abnormal behavior in these animal models, we are unable to explain the mechanisms underlying human epilepsy. However, the combination of existing animal models, in vitro human tissue experiments, and computer stimulation should allow us to advance rapidly toward a solution.