Olfaction

Abstract

Olfaction is the sense of smell, which is mediated by specialized sensory cells in the nasal cavity. Many vertebrate species, including most mammalian species, possess two distinct anatomically different olfactory systems: the main olfactory system and the accessory olfactory system. The main olfactory system is generally thought to be important in the detection and processing of airborne chemicals whereas the accessory olfactory system is mainly used in the detection and processing of water-soluble chemicals. In particularly, the main olfactory system is thought to be important for the detection of more general, environmentally or food-related odors, whereas the accessory olfactory system has evolved for the detection of odors, better known as pheromones which are important for reproduction. The current knowledge on the behavioral, physiological, and molecular aspects of odor detection in mammals, including humans, is presented in this chapter.