In insects, the
olfactory pathway starts at the antennae (though in some insects like
Drosophila there are olfactory sensory neurons in other parts of the body) from where the sensory neurons carry the information about the
odorant molecules impinging on the antenna to the antennal lobe. The number and identities of glomeruli are species specific; most species contain 40 to 160 individually identifiable glomeruli within the antennal lobe. 43 glomeruli in the
fruit fly antennal lobe, and 203 glomeruli in
cockroach. The local neurons, which are primarily inhibitory, have their
neurites restricted to the antennal lobe. Projection neurons, which generally receive information from a single glomerulus, project to higher brain centers such as the
mushroom body and the
lateral horn. The interaction between the
olfactory receptor neurons, local neurons and projection neurons reformats the information input from the sensory neurons into a spatio-temporal code before it is sent to higher brain centers. ==References==