Cortical inhibition processes and the anticonvulsant action of benzodiazepine derivatives.

A comparative study of the effect of various benzodiazepine derivatives (clonazepam, lorazepam, diazepam, and medazepam) on the recovery cycle of the interzonal response in the motor cortex of unanesthetized immobilized cats showed that these substances selectively depress the testing potential within the interval of 20-100 msec between conditioning and testing stimuli, evidence of the potentiation of GABA-ergic inhibition in the cortex. Clear correlation was shown between the degree of protective action of the various benzodiazepine derivatives against convulsions due to the GABA deficiency and their ability to induce depression of the test response. It is suggested that the GABA-positive action of the benzodiazepines plays a significant role in the mechanism of their anticonvulsant activity.