The coding of odour-intensity in the honeybee antennal lobe: local computation optimizes odour representation.
We investigated strategies involved in odour intensity coding by the primary olfactory centre of insects, the antennal lobe (AL), the structural and functional analogue of the olfactory bulb. Using calcium imaging in the honeybee, we simultaneously measured the projection neuron output responses and a compound signal dominated by receptor neuron input in identified olfactory glomeruli to odours spanning seven log units of concentration. A comparison of the two processing levels indicates that the intercellular computation within the AL modulates and contrast-enhances the primary olfactory signals. As a result the AL network optimizes the olfactory code: odour representation is improved at lower concentrations, the relative activity of olfactory glomeruli allows encoding odour quality over up to four log-unit concentrations, and odour-intensity is reliably represented in the overall excitation across AL.
Sachse
Silke
S
Institut für Biologie - Neurobiologie, Freie Universität Berlin, Königin-Luise Str. 28-30, 14195 Berlin, Germany.
Galizia
C Giovanni
CG
D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D001516:Bees; D002118:Calcium / Q000378:metabolism; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods; D004056:Differential Threshold / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes / Q000378:metabolism; D000441:Hexanols / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D009433:Neural Inhibition / Q000187:drug effects; D000442:Octanols / Q000494:pharmacology; D009812:Odorants; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D009833:Olfactory Pathways / Q000187:drug effects / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000187:drug effects / Q000502:physiology*; D012679:Sense Organs / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical
D000447:Aldehydes; D005456:Fluorescent Dyes; D000441:Hexanols; D000442:Octanols; C008664:nonanal; D002118:Calcium