The phenomenology of limbic kindling

Kindling is a model of epilepsy whereby repeated administration of brief low-intensity trains of electrical stimulation come to elicit electrographic and behavioral manifestations of seizure. In the absence of overt tissue damage, an animal that has been kindled is rendered in a permanent state of increased susceptibility to seizures. A number of persistent biochemical and physiological alterations in function accompany kindling, some of which may impact upon behavior of the organism for a long period of time despite the absence of further seizure activation. The sensitivity of limbic structures to kindling may contribute to the behavioral categories of cognition and affect that are particularly impacted by the kindling process. The increased proclivity for seizure disorders that characterizes kindling is not restricted to the initial kindling stimulus, but generalizes to other agents with convulsive properties. This paper provides an overview of the phenomenology of kindling, describes some of the conditions necessary for its induction, and some of the functional alterations that accompany its development and endure when overt convulsive behavior has subsided. Finally, a series of studies in our laboratory is presented which provides evidence of chemically induced kindling by repeated low-level exposure to some pesticides, namely those of the chlorinated hydrocarbon class.