Imaging plasticity in the honeybee antennal lobe

The olfactory system of the honeybee, Apis mellifera, is a well-established model for studying the anatomical bases of odor coding and olfactory memory. The bee primary olfactory centers, the antennal lobes (ALs), are organized in a fixed arrangement of spheroidal neuropil units, the glomeruli. These structures receive inputs from the bee olfactory receptor neurons (ORNs), are modulated by local interneurons (LINs), and send outputs to higher brain centers through the projection neurons (PNs). The spatio-temporal pattern of activation of the glomeruli is odor-specific, thus, imaging of intracellular calcium of the PNs may provide maps of odor representation. Such maps have been demonstrated to vary upon olfactory conditioning (i.e. through enhancement of the discrimination of a rewarded odor against an unrewarded one), but the underlying mechanisms for this plasticity are not known. The aim of this study is to investigate plastic changes following odor conditioning and, in particular, possible variations in number and morphology of the synapses involved in the ALs circuitry