An experimental study of the fornix and hypothalamo‐tegmental tracts in the cat

Single electrolytic lesions were placed at various levels of the hippocampus, septum, and amygdala to elicit fiber degeneration from these structures in order to determine their efferent pathways to the hypothalamus. The Nauta silver Impregnation method for degenerated axons was used in this study. Fornix fibers of hippocampal origin were traced to the preoptic, dorsomedial, and posterior hypothalamic areas. Fornix fibers of septal origin were traced to preoptic, paraventricular, and ventromedial hypothalamic nuclei. Degenerated fibers from the baso‐lateral amygdaloid nuclei were traced to the preoptic and ventromedial hypothalamic nuclei through the stria terminalis. Lesions were also placed in the anterior hypothalamic area, the dorsal hypothalamic area, the dorsomedial nucleus, the ventromedial nucleus, the paraventricular nucleus, and the posterior hypothalamic area. Degenerated fibers were traced from these nuclei to the midbrain tegmentum through the hypothalamo‐tegmental tracts. The hypothalamus, then can be considered a way station for impulses from the limbic lobe to lower brain stem centers.