The mammalian olfactory system is mainly composed of the olfactory epi
theluim which contains the receptor cells, the olfactory bulb which co
ntains the relay cells, and the olfactory paleocotex which is the proj
ection site of the bulb. All studies until now have failed to reveal a
cellular selectivity at these three levels. By contrast, lots of data
show that odorants could induce spatio-temporal maps in each of these
structures.