THE EFFECT OF STRYCHNINE SULPHATE ON THE EMOTIONAL MIMETIC FUNCTIONS OF THE HYPOTHALAMUS OF THE CAT

¹ From the Division of Psychiatry and the Otho S. A. Sprague Memorial Institute, University of Chicago

By means of original modifications of the Horsley-Clarke stereotaxic technique forty-three cats were prepared in series of acute and recovery experiments so that the vegetative and emotional mimetic responses of the hypothalamus to various faradic stimuli could be studied before and after the intraperitoneal administration of strychnine sulphate or the injection of a solution of this drug directly into the diencephalon. The results of these experiments may be summarized as follows:

1. Faradic stimulation of the hypothalamus in a recovery preparation produces vegetative and peripheral muscular responses characteristic of rage and fear, i.e.: mydriasis, piloerection, hyperpnea with vocalizations, extrusion of the claws, lashing of the tail and clawing and fighting movements followed after the termination of the stimulus by precipitate flight.

2. The intraperitoneal injection of from 0.14 to 0.16 mgm. per kilogram of strychnine sulphate in a recovery preparation causes hyperesthesia and increased emotional irritability but does not consistently lower the threshold or increase the intensity of the reactions of the animal to faradic stimulation of the hypothalamus. The injection of from 0.07 to 0.15 mgm. of strychnine sulphate in from 0.05 to 0.1 cc. of saline directly into the hypothalamus of a recovery preparation, however, causes marked pseudo-affective behavior and a definite increase in the vegetative and other reactions of the hypothalamus.

3. Strychnine also facilitates the electrical reactivity of the hypothalamus in lightly etherized animals, in which it is possible to observe that the vasomotor and respiratory responses are increased, particularly when the drug is injected directly into the hypothalamus.

4. The results of our experiments are therefore in accord with the findings of others as to the action of strychnine on the nervous system and confirm the thesis that the hypothalamus has an integrative and regulatory function in controlling the various physiological mechanisms of emotional expression.