Abstract
The diencephalic areas have been invoked as important subcortical centers having to do with the emotions. 1 , 2 , 3 The emotional reactions of animals with hypothalamic lesions have not been differentiated as spontaneous and reflex phenomena. The former appear without provocation and vary somewhat between different subjects. The reflex emotions occur only after stimulation of one or another sensory modality. The monkey is an excellent animal for study of spontaneous emotionality. He threatens, grimaces, wiggles his ears, undergoes pilo-erection, and vocalizes either in anger or in fear. When approached he may attempt to run away or permits his anger to carry him into definite aggressions. Occasionally, in blind rage, he dashes himself against the mesh of the cage as if he meant to rend it apart. Cats show a good deal less of spontaneous emotional display than do monkeys.
Material and Method. Monkeys and cats were used in this study. In all instances, the diencephalic lesions were placed under more or less direct vision by following the stump of one optic nerve to the chiasmal region.
Observations. 1. Total destruction of the hypothalamus.
Such a lesion invariably results in stupor in which there are no spontaneous emotional demonstrations. The stupor is frequently associated with cataleptic phenomena. When the animal is painfully stimulated, there is a prompt reflex display of emotions. The threshold to such reactions is elevated but the responses are certain. One cat responded to pressure over bony prominences, with baring of claws, opening of the jaws, an awesome rumbling in his throat, and a battery of sneezes. A similar preparation in a monkey could be aroused by stimulation to adequate shows of emotions including grimacing and defense movements of all extremities.
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