Properties of maximal seizures, and their alteration by anticonvulant drugs and other agents.

DESPITE the high incidence of convulsive disorders and widespread use of shock therapy in the major psychoses, relatively few investigations have dealt with the physiological properties of experimental seizures (1, 2, 3, 10, 12, 14, 16, 17). Convulsive threshold has received considerable attention, particularly in the testing of anticonvulsant drugs (11, 13, 15, 18, 21, and others), but threshold is only one of many properties which might be examined in any excitable system. Furthermore, measurements of threshold are of but limited value in the detection of antiepileptic potency (5, 6, 7, 8, 19, 20). For example, diphenylhydantoin, which has been found superior to phenobarbital in the treatment of psychomotor epilepsy and of comparable value in grand mal, is relatively ineffective in raising the threshold either for metrazol or electroshock seizures in laboratory animals. Therefore we have undertaken a series of studies on other properties of experimental seizures (7, 8, 19, 20, 23). Several new techniques for the testing of anticonvulsant drugs have already evolved from these studies (7, 8, 20, 22). The technique which to date has shown the best correlation with clinical antiepileptic efficacy is based upon the ability of certain drugs to alter the character of major seizures produced by supramaximal electroshock stimulation. The present report deals with some elementary properties of maximal seizures in normal animals, and with the effects of anticonvulsant drugs upon these properties.