Bilateral synchronous spike wave electrographic patterns in the cat. Interaction of bilateral cortical foci in the intact, the bilateral cortical-callosal, and adiencephalic preparation.

THE PRECISE and constant location of origin of the bilateral, symmetrical patterns of electrical discharge as they occur in man with "idiopathic" or "essential epilepsy" ("petit mal" and "grand mal") has not yet been completely defined. The characteristic electroencephalographic patterns which accompany the "absence" seizure of petit mal have not yet been exactly reproduced in animals. The most distinctive electroencephalographic pattern of idiopathic epilepsy in childhood is the 2.5 to 3.5 cycle-per-second (cps) spike wave associated with the "absence" seizure. This discharge is abrupt in onset, bilateral, nearly synchronous, and of nearly equal amplitude in the two hemisphere. It is often precipitated by hyperventilation and photic stimulation. Two distinct categories of hypotheses of the location of the lesion responsible for originating the bilateral grouped discharges of idiopathic epilepsy, especially in petit mal, have emerged: (1) The "centrencephalic" hypothesis of exclusive origin of the process giving rise to the spike