Targeting of olfactory neurons

Olfactory sensory neurons detect an enormous variety of small volatile mole cules with extremely high sensitivity and specificity. The actual recogniti on and discrimination of odorous compounds is accomplished by specific rece ptor proteins located in the ciliary membrane of the sensory neurons. Axona l connections into the olfactory bulb, the first relay station for odor pro cessing in the brain, are organized such that all neurons expressing the sa me odorant receptor converge their axone onto common glomeruli which are lo cated at similar positions in all individuals from one species. For the est ablishment of this precise targeting of olfactory axons to their appropriat e glomeruli, combinatorial functions of axon-associated cell adhesion molec ules and odorant receptor proteins appear to be required. Odorants that sti mulate distinct receptor cell populations will thereby activate a specific combination of glomeruli in the bulb; this characteristic activity pattern may be used by the system to encode the quality of a particular odorant.