title: Weaker ligands can dominate an odor blend due to syntopic interactions.
abstract: Most odors in natural environments are mixtures of several compounds. Perceptually, these can blend into a new "perfume," or some components may dominate as elements of the mixture. In order to understand such mixture interactions, it is necessary to study the events at the olfactory periphery, down to the level of single-odorant receptor cells. Does a strong ligand present at a low concentration outweigh the effect of weak ligands present at high concentrations? We used the fruit fly receptor dOr22a and a banana-like odor mixture as a model system. We show that an intermediate ligand at an intermediate concentration alone elicits the neuron's blend response, despite the presence of both weaker ligands at higher concentration, and of better ligands at lower concentration in the mixture. Because all of these components, when given alone, elicited significant responses, this reveals specific mixture processing already at the periphery. By measuring complete dose-response curves we show that these mixture effects can be fully explained by a model of syntopic interaction at a single-receptor binding site. Our data have important implications for how odor mixtures are processed in general, and what preprocessing occurs before the information reaches the brain.
authors: Neurobiology, University of Konstanz, D-78457 Konstanz, Germany. daniel.muench@uni-konstanz.de
authors: Daniel
authors: D
authors: Münch
authors: Benjamin
authors: B
authors: Schmeichel
authors: Ana F
authors: AF
authors: Silbering
authors: C Giovanni
authors: CG
authors: Galizia
mesh_terms: D000818:Animals; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D009812:Odorants / Q000032:analysis; D018034:Olfactory Receptor Neurons / Q000378:metabolism*; D010476:Perfume / Q000378:metabolism*; D018035:Receptors, Odorant / Q000378:metabolism*; D012903:Smell
chemical_list: D029721:Drosophila Proteins; C496847:OR22a protein, Drosophila; D010476:Perfume; D018035:Receptors, Odorant