Effect of some brain lesions on intracranial self-stimulation in the rat

Abstract

Lesions were placed in the preoptic area, the area of the mamillothalamic tract, the area of the postcommissural fornix, or the area of the interpeduncular and ventral tegmental nuclei in rats self-stimulating to stimuli in the posterior lateral hypothalamus. Effective lesions caused a reduction, but not an abolition, of response rates, usually with partial to complete recovery with time. The results indicate that at least 4 ipsilateral areas (a region in the anterior preoptic area, the mamillothalamic tract, a region anterior to the interpeduncular nucleus, and an area involving either the habenulo-interpeduncular tract or the mamillotegmental tract) are involved in, but not essential to, the self-stimulation response originating in the posterior lateral hypothalamus. The fornix does not appear to be involved. The system underlying the self-stimulation response contains both redundancy and a significant capacity for reorganization.