odor representation in honeybee olfactory glomeruli shows slow temporal dynamics: an optical recording study using a voltage sensitive dye
CG Galizia, A Küttner, J Joerges, R Menzel
Inst. Biologie - Neurobiologie, Fachbereich BioChemPharm, Freie Universität Berlin, D-14195 Berlin, Germany
Abstract
Stimulation with odors has been shown to elicit characteristic patterns of activated glomeruli in the antennal lobe (AL) of honeybees. In this study we show that these patterns are dynamic in a time window of 2–3 s after stimulus onset. We measured changes in the averaged membrane potential of all cells in the glomerular neuropil by optical imaging of the voltage-sensitive dye RH795 using a slow scan CCD camera (3 frames/s). The four substances 1-hexanol, hexanal, citral and clove-oil as well as the binary mixtures hexanolhexanal and hexanolcitral were used as stimuli (2 s stimulus duration). We found that: (1) every odor elicited an odor-specific activity pattern, and conversely every glomerulus had a characteristic odor response profile; (2) some glomeruli had a tonic, some a phasic-tonic, and some a slow phasic response pattern; (3) the difference between the glomerular response patterns increased within 2 s of stimulus presentation, which suggests that odor representations became more characteristic over stimulus time; and (4) the responses to odorant mixtures were complex and glomerulus-dependent: some responses correspond to the sum of the compounds’ responses, some to the response of one of the components.