[Behavioral effects of medial-dorsal thalamic, mediobasal hypothalamic and amygdaloid lesions in the rat].

Experiments were carried out to examine the effects of restricted brain lesions on activity, emotionality and aggressiveness of rats. The open-field activity test, the number of defecations test and the interspecific aggressiveness test were, respectively, employed. Lesions were placed on medial thalamus (MD), ventromedial (VM) or arcuate (ARH) hypothalamic nuclei, medial (AME) or intercalate (ICL) amygdaloid nuclei. No aggressiveness was detected in the rats under experiment, independently of the type of lesion. The open-field activity test given significant differences between control rats and animals with VM, ARH, AME or ICL lesion. Remarkable changes in the emotionality were found only between sham-operated controls and MD lesioned rats. It was concluded that hypothalamus and amygdala lesioned nuclei play a role in the neural mediation of activity, while medial thalamus influences the mediation of emotional response.