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Schlagwörter:
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Zusammenfassung:
How features are extracted from chemical stimuli by the sense of smell still is not clear. Presumably many more odors can be distinguished than there are receptors in the large family of odorant receptor molecules. Thus, perception of odorants seems to require a combinatorial coding strategy. We have used zebrafish, Danio rerio, as a model system to analyse the neural representation of odorants at the molecular, connectional, and physiological level. Zebrafish possess a well-developed sense of smell that governs a variety of behaviors. We find that the family of odorant receptor genes and the number of modules in the olfactory bulb (glomeruli) are about an order of magnitude smaller than those of mammals. We observe spatial patterning of odorant receptor gene expression, of glomeruli and of odorant-induced responses in the olfactory bulb, all of which are reproducible between individuals. Response to odorants, as inferred from odorant receptor gene expression, is broadly distributed within the sensory surface. In contrast, representation of odorants is much more localized at the input level of the olfactory bulb. Classes and subclasses of odorants are represented chemotopically, whereas closely related odorants are distinguished by combinatorial encoding on the basis of broadly tuned glomerular modules.
