Localization of odor-induced oscillations in the bumblebee antennal lobe

Odor-induced oscillatory signals have been reported in odor discrimination in various insects. To understand dynamic olfactory coding in the first order olfactory center, the antennal lobe, localization of oscillatory signals was investigated using an optical recording technique with a voltage-sensitive dye. We present here the first report of visualization of the spatial distribution pattern of odor-induced oscillations in the bumblebee antennal lobe. Analysis of the odor-induced optical responses by a maximum entropy method allowed visualization of oscillatory regions in the antennal lobe. The oscillatory signals were usually localized to regions corresponding to a single or several glomerular structures. Our results suggest that glomerular structures may be functional units of odor processing from the viewpoint of odor-induced population responses, the oscillations.