Effects of septal lesions on electrically elicited hypothalamic rage in cats

Effects of septal lesions on thresholds of hypothalamic rage produced by electrical stimulation of the VMH were studied. Hissing and directed attack were selected from the hypothalamic rage for the threshold measurement. Hissing thresholds were measured in two situations, i.e., with provocation by the experimenter and without provocation. Those of directed attack were measured only in the former situation. The two thresholds under provocation situation lowered definitely after septal lesions in more than half cats. The most effective part for the lesion was the lateral septal area at the level of the anterior commissure and just rostral level of it. The hissing threshold under non-provocation situation was affected little. These effects disappeared in 7 or 10 days after the lesions. These findings suggest that the excitatory influence on the VMH produced by provocation was enhanced by the lateral septal lesions.