Neurophysiology of epilepsy.

Epilepsy is a disorder of brain function characterized by paroxysmal stereotyped alterations in behavior associated with synchronous excessive discharge in large aggregates of neurons. It is estimated that 0.5-2% of the world's population is affected by epilepsy-perhaps as many as 80 million people. The pathogenesis of this disorder is not well understood. Because of its high incidence relative to other forms, and the ease with which it can be produced in experimental animals, focal epilepsy which results from abnormal neuronal activities in a localized brain region has been most widely studied. In this review I will examine several current hypotheses regarding the cellular neurophysiological mechanisms of focal epileptogenesis, in light of new data which require that we substantially modify previously held views. For a more extensive treatment of various aspects of this problem, the reader is referred to recent monographs and reviews (Ajmone-Marsan 1969, Jasper 1969, Jasper, Ward & Pope 1969, Purpura 1969a,b, Spencer & Kandel 1969, Ward 1969, Purpura et al 1972, Ayala et al 1973, Prince 1974, 1976). The rather narrow scope of this review inevitably does injustice to the challenge and complexity of epilepsy research, and to the significant insights into basic aspects of brain function that it has provided. As Ward and colleagues have pointed out, "An adequate model cannot be provided by examining the phenomenon of epilepsy from the parochial viewpoint of a single discipline in the neurosciences . . . . Our goal is to view . . . epilepsy from the broad base of neurobiology" (Ward, Jasper & Pope 1969).