Lateral presynaptic inhibition mediates gain control in an olfactory circuit.
Olfactory signals are transduced by a large family of odorant receptor proteins, each of which corresponds to a unique glomerulus in the first olfactory relay of the brain. Crosstalk between glomeruli has been proposed to be important in olfactory processing, but it is not clear how these interactions shape the odour responses of second-order neurons. In the Drosophila antennal lobe (a region analogous to the vertebrate olfactory bulb), we selectively removed most interglomerular input to genetically identified second-order olfactory neurons. Here we show that this broadens the odour tuning of these neurons, implying that interglomerular inhibition dominates over interglomerular excitation. The strength of this inhibitory signal scales with total feedforward input to the entire antennal lobe, and has similar tuning in different glomeruli. A substantial portion of this interglomerular inhibition acts at a presynaptic locus, and our results imply that this is mediated by both ionotropic and metabotropic receptors on the same nerve terminal.
Olsen
Shawn R
SR
Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA.
Wilson
Rachel I
RI
D000818:Animals; D004331:Drosophila melanogaster / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D058788:GABA-B Receptor Antagonists; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009812:Odorants / Q000032:analysis; D009833:Olfactory Pathways / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010812:Physical Stimulation; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology*; D018080:Receptors, GABA-B / Q000378:metabolism; D012903:Smell / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000494:pharmacology
D058788:GABA-B Receptor Antagonists; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid