ABSTRACT
Chemicals that dissolve in liquid stimulate both olfactory and taste receptors in a similar way. The perception of food flavor is dependent upon the close interaction between the olfactory and gustatory (taste) systems. The olfactory system detects, recognizes, and finely discriminate airborne odorants. This special visceral sensation becomes functional at birth and effectively operates even at low molecular concentration of the odorants. Odorants bind reversibly to the receptor membrane proteins in the olfactory epithelium, generating depolarization and action potentials through a series of interactions. Propagated action potentials converge on the olfactory bulb and course through the olfactory tract and the striae to the pyriform cortex. Association cortices also receive olfactory projection indirectly from the pyriform cortex via the thalamus. Olfaction is considered one of the oldest systems that directly influences feeding behavior, emotion, social attitude, protective reaction, and sexual desire. This is achieved through extensive connections to diverse areas of the brain including the septal area, entorhinal cortex, and amygdala. Pheromones can elicit responses that affect the reproductive cycles, possibly through a hypothalamic connection; however, the precise mechanism that underlies the processing of these chemosensory signals and the role of the vomeronasal organ (VNO) remain at best preliminary.
