title: Olfactory information processing in the Drosophila antennal lobe: anything goes?
abstract: When an animal smells an odor, olfactory sensory neurons generate an activity pattern across olfactory glomeruli of the first sensory neuropil, the insect antennal lobe or the vertebrate olfactory bulb. Here, several networks of local neurons interact with sensory neurons and with output neurons--insect projection neurons, or vertebrate mitral/tufted cells. The extent and form of information processing taking place in these local networks has been subject of controversy. To investigate the role of local neurons in odor information processing we have used the calcium sensor G-CaMP to perform in vivo recordings of odor-evoked spatiotemporal activity patterns in five genetically defined neuron populations of the antennal lobe of Drosophila melanogaster: three distinct populations of local neurons (two GABAergic and one cholinergic), as well as sensory neurons and projection neurons. Odor-specific and concentration dependent spatiotemporal response patterns varied among neuron populations. Activity transfer differed along the olfactory pathway for different glomerulus-odor combinations: we found cases of profile broadening and of linear and complex transfer. Moreover, the discriminability between the odors also varied across neuron populations and was maximal in projection neurons. Discriminatory power increased with higher odor concentrations over a wide dynamic range, but decreased at the highest concentration. These results show the complexity and diversity of odor information processing mechanisms across olfactory glomeruli in the fly antennal lobe.
authors.affiliation: Institute for Neurobiology, Free University of Berlin, Berlin, Germany.
authors.forename: Ana F
authors.initials: AF
authors.lastname: Silbering
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okada
authors.forename: Kei
authors.initials: K
authors.lastname: Ito
authors.forename: C Giovanni
authors.initials: CG
authors.lastname: Galizia
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004330:Drosophila / Q000166:cytology / Q000378:metabolism*; D005260:Female; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009833:Olfactory Pathways / Q000166:cytology / Q000378:metabolism*; D018034:Olfactory Receptor Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012903:Smell / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005680:gamma-Aminobutyric Acid; D000242:Cyclic AMP; D000109:Acetylcholine