Combined Effects of Drugs and Electrical Excitation of Cortical Motor Area in Cats. ∗

Abstract

It was shown that, following the method of Frangois-Franck, 1 between 35 and 55 clonic convulsions could be elicited in cats by stimulating the cortical motor area with the induced tetanizing current before the animals succumbed. 2 Wortis, Coombs and Pike 3 observed that from about 5 to 10 clonic convulsions can be induced by the administration of convulsant drugs such as camphor mono-bromide before respiration fails and blood pressure falls to base line. 4

In this series, which first developed as a set of controls in another group of experiments, I wished to see whether a combination of both methods would be more or less effective in prolonging or curtailing the number of convulsions and the resistance of the animal, than the use of one method alone.

Two methods of procedure were carried out.

1. In a series of 10 cats, the motor area was exposed under ether, and the anesthetic then intermitted. After recovery from ether, the cortex was stimulated with a mild induced tetanizing current as previously described. When the cortex had been stimulated from 25 to 40 times, with the usual clonic convulsions, a dose of camphor monobromide which corresponded to about the estimated minimal convulsive dose for the weight of the animal, was injected intravenously. In most cases, it proved fatal. Respiration failed and the animal usually died in tonic extension without the usual typical clonic convulsion, or with only a few clonic twitches.

2. In another series of 12 cats, after exposure of the motor area under anesthesia, with one electrical excitation to make sure the clonic convulsive response was readily elicitable, the estimated minimal convulsive dose of camphor monobromide or absinth was administered.