Acetylcholine and the Epileptiform Activity of Chronically Isolated Cortex

Abstract

Solutions of acetylcholine were applied to the chronically isolated and the contralateral occipital cortex of cats prepared as encéphale isolé. The amounts required to produce epileptiform discharges were similar on the two sides. The spontaneous paroxysmal activity in the island was not facilitated by the application of acetylcholine but it disappeared before or at the onset of acetylcholine-induced discharges. Electrical stimulation revealed neither a decrease of the threshold for epileptiform afterdischarges nor a facilitation of spontaneous discharges on the isolated side. However, the seizure discharges in the isolated area, once induced by either acetylcholine or electrical stimulation, continued for long periods of time. The results suggest that acetylcholine acts as a convulsant stimulus without a special relationship to the intrinsic epileptiform abnormality of the isolated cortex.