Antennal Lobe Structure

Abstract

Primary olfactory brain centres are unique in anatomical organisation throughout the animal kingdom and can be easily recognised by their spheroidal neuropilar subcompartments termed olfactory glomeruli. This chapter reviews the anatomical organisation of the first-order olfactory brain areas in insects, the antennal lobes (ALs). The ALs are part of the deutocerebrum of the insect brain. They receive receptor neuron input from olfactory sensilla on the antennae and other appendages, whereas antennal mechanoreceptive neurons project to a separate neuropil in the deutocerebrum, the antennal mechanosensory and motor centre (AMMC; Fig. 1). The anatomical organisation of the AL will be described and will be compared between different insect species. Cellular elements and synaptic connections in the AL will be characterised at the light-microscopic and ultrastructural level, and the anatomical features will be discussed in relation to functional aspects. The presented data from insects will, finally, be compared with findings from other invertebrates and from vertebrate species.