European Journal of Neuroscience, 10:9, 2964-2974, 1998
© European Neuroscience Association
odor coding is bilaterally symmetrical in the antennal lobes of honeybees (Apis mellifera)
C. Giovanni Galizia, Karl Nägler, Bert Hölldobler1 and Randolf Menzel
Inst. Biologie - Neurobiologie, Fachbereich BioChemPharm, Freie Universität Berlin, D-14195 Berlin, Germany; 1Theodor Boveri Institut der Universität, Lehrstuhl für Verhaltensphysiologie und Soziobiologie der Universität (Zoologie II), Am Hubland, D-97074 Würzburg, Germany
Abstract
The primary olfactory neuropil, the antennal lobe (AL) in insects, is organized in glomeruli. Glomerular activity patterns are believed to represent the across-fibre pattern of the olfactory code. These patterns depend on an organized innervation from the afferent receptor cells, and interconnections of local interneurons. It is unclear how the complex organization of the AL is achieved ontogenetically. In this study, we measured the functional activity patterns elicited by stimulation with odors in the right and the left AL of the same honeybee (Apis mellifera) using optical imaging of the calcium-sensitive dye calcium green. We show here that these patterns are bilaterally symmetrical (n = 25 bees). This symmetry holds true for all odors tested, irrespective of their role as pheromones or as environmental odors, or whether they were pure substances or complex blends (n = 13 odors). Therefore, we exclude that activity dependent mechanisms local to one AL determine the functional glomerular activity. This identity is genetically predetermined. Alternatively, if activity dependent processes are involved, bilateral connections would have to shape symmetry, or, temporal constraints could lead to identical patterns on both sides due to their common history of odor exposure.