title: Topographic mapping--the olfactory system.
abstract: Sensory systems must map accurate representations of the external world in the brain. Although the physical senses of touch and vision build topographic representations of the spatial coordinates of the body and the field of view, the chemical sense of olfaction maps discontinuous features of chemical space, comprising an extremely large number of possible odor stimuli. In both mammals and insects, olfactory circuits are wired according to the convergence of axons from sensory neurons expressing the same odorant receptor. Synapses are organized into distinctive spherical neuropils--the olfactory glomeruli--that connect sensory input with output neurons and local modulatory interneurons. Although there is a strong conservation of form in the olfactory maps of mammals and insects, they arise using divergent mechanisms. Olfactory glomeruli provide a unique solution to the problem of mapping discontinuous chemical space onto the brain.
authors.affiliation: The University of Tokyo, Graduate School of Science, Department of Biophysics and Biochemistry, Yayoi 2-11-16, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imai
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakano
authors.forename: Leslie B
authors.initials: LB
authors.lastname: Vosshall
mesh_terms: D000818:Animals; D019521:Body Patterning; D001931:Brain Mapping; D004330:Drosophila; D005260:Female; D006801:Humans; D007395:Interneurons / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D008967:Molecular Biology; D018034:Olfactory Receptor Neurons / Q000502:physiology; D018035:Receptors, Odorant / Q000502:physiology*; D012903:Smell / Q000502:physiology*
chemical_list: D018035:Receptors, Odorant