Emotional behavior and arrhythmias induced in cats by hypothalamic stimulation

As the relationship between emotional behavior and electrocardiographic (ECG) change induced by hypothalamic stimulation is poorly understood, eighty-four points in various areas within the hypothalamus in conscious cats were stimulated electrically through chronically implanted electrodes, the objective being to clarify the behavior accompanying ECG changes, in particular poststimulus arrhythmias. Forty-one of 84 points elicited behavioral patterns such as defense reaction, pseudo-rage and restlessness (classified as group A), and in twenty-one (51%) of these 41 points arrhythmias occurred after cessation of stimulation. Forty-three of 84 points elicited behavioral patterns including predatory, exploratory and other behavioral responses (classified as group B), and in three (7%) of 43 points, poststimulus arrhythmias followed. Under light anesthesia, stimulations of twofold current intensity were applied at these points, and the incidences of the arrhythmias did not change in either group. The arrhythmia-inducing area in the cases of group A was found to lie dorsal and caudal to the optic chiasma and to extend caudally in the fornix. Three points in the cases of group B were located in the outer area of the aforementioned area. These studies showed that arrhythmias and group A behavior were observed mainly from stimulation of the anterior hypothalamus, whereas stimulation of other areas of the hypothalamus, including the lateral and the posterolateral hypothalamus, produced group B behavior and no arrhythmias.