Functional Characteristics of the Antennal Lobe

Abstract

Odour molecules are recognised by specific receptor proteins associated with the dendritic membranes of olfactory receptor neurons (ORNs; Buck and Axel 1991; Chap. 2). The olfactory signal is then transmitted through ORN axons to the primary processing centre in the CNS: the olfactory bulb (OB) in vertebrates, the olfactory lobe (OL) in crustaceans, the antennal lobe (AL) in insects. In the ALs, the axon terminals of ORNs synapse onto the dendrites of a variety of interneurons associated with the first-order olfactory neuropil (Chap. 4). The AL is thus the level in the insect olfactory system where the molecular information associated with the odour stimulus is first processed, and where the temporal and spatial features of odours can be accentuated or attenuated. Neural processing in this neuropil involves not only excitatory and inhibitory synaptic and intrinsic membrane currents, but may also involve more complex circuit phenomena such as network oscillations, as more fully described in Chap. 6.