Effect of Anticonvulsant Drugs on Cortical and Subcortical Seizure Discharges in Cats

Abstract

The mechanism by which anticonvulsant drugs prevent seizures is largely unknown. Both biochemical and electrophysiological techniques have been used to seek information regarding inhibition of convulsive discharges. In this study, after-discharges were evoked by electrical stimulation of the ectosylvian gyrus, the hippocampus, the amygdaloid nucleus, and the septal region. Threshold voltage, duration, spread, and frequency characteristics of the evoked after-discharges were studied before and after the administration of anticonvulsants. Diphenylhydantoin (Dilantin), trimethadione (Tridione), and phenobarbital were the drugs used. Methods Mature cats were anesthetized with ether administered through an endotracheal tube. Electrodes were implanted by the stereotactic method, through 3 mm. burr holes. Stainless-steel wire electrodes inserted into insulated, No. 22 needle stock were used for acute experiments. The final 0.5 mm. of the wire core was bared and separated from the uninsulated rim of the sheath by 0.3 mm. In the chronic experiments, insulated, paired strands of stainless steel