Computation of molecular information in mammalian olfactory systems.

The olfactory system is unique in that the sensory input is in the form of molecular information carried in odour molecules and that a huge variety of compounds can function as odour molecules. The mammalian olfactory system has neuronal networks that can process and integrate the molecular information for discrimination of odour molecules and for perception of olfactory images of objects. Recent rapid advances have begun to provide new insights into the functional logic employed by the main olfactory system for odour discrimination, for odour classification and for olfactory perception of objects. This review discusses how the odour molecule information is encoded, transmitted, processed and decoded at distinct anatomical structures (sensory epithelium, olfactory bulb and olfactory cortex) of the olfactory nervous system. We also discuss the functional network in the accessory olfactory system with regard to the processing of pheromonal information.