OLFACTORY INPUT TO THE LATERAL HYPOTHALAMUS IN THE MONKEY

Abstract

Responses to eight odors of the lateral hypothalamic (LHA) neurons were studied in unanesthetized monkeys. It was proved that LHA neurons have as highly developed ability in odor discrimination as the lateroposterior portion of the orbitofrontal cortex (LPOF). Next, by means of horseradish peroxidase (HRP) and evoked potential methods, olfactory pathways to LHA were studied. Labeled neurons were found mainly in the septum (Spt) and partly in other areas, but scarcely in the prepyriform-amygdaloid areas and olfactory tubercle. Then, olfactory input to Spt area was proved electrophysiologically. Consequently, it was supposed very probable that olfactory impulses come to Spt through the medial olfactory tract directly and / or through the lateral olfactory tract and the olfactory tubercle indirectly, before reaching LHA.