Olfactory Relationships of the Diencephalon

Abstract

THE dominant part played by olfaction in the behaviour of lower mammals has long been appreciated, but it is only comparatively recently that the underlying physiological mechanisms have begun to be elucidated. There is now a considerable body of evidence implicating certain of the accepted olfactory projection sites, such as the amygdala and the pyriform cortex in emotional and reproductive behaviour^1,2, and more recent work has shown how directly the more peripheral parts of the olfactory pathway may regulate reproductive function^3,4. It has generally been assumed that the anatomical link between the olfactory system and the hypothalamus is by way of the well-defined efferent pathway from the amygdala, the stria terminalis. However, in the past few years a number of experimental neuroanatomical studies have cast doubt on the essential place of the amygdala in the olfactory system, and have led us to re-examine the primary and secondary connexions of the olfactory bulb.