Odor maps in the brain: Spatial aspects of odor representation in sensory surface and olfactory bulb

Korsching, Sigrun I.

doi:10.1007/pl00000877

Cited by 29 publications

(13 citation statements)

References 81 publications

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“…From our olfactory bulb responses (see Fig. 1) and from comparison with other species, these may be expected to include three of the four odor groups tested here, amines, bile acids, and alcohols, aldehydes, ketones [12, 39, 40]. Amino acids are expected to mostly signal via a cAMP-independent mechanism [12, 41]; but see [11].…”

Section: Resultsmentioning

confidence: 99%

Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream

Gliem

Syed

Sansone

et al. 2012

Cell. Mol. Life Sci.

148

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In contrast to the single sensory surface present in teleost fishes, several spatially segregated subsystems with distinct molecular and functional characteristics define the mammalian olfactory system. However, the evolutionary steps of that transition remain unknown. Here we analyzed the olfactory system of an early diverging tetrapod, the amphibian Xenopus laevis, and report for the first time the existence of two odor-processing streams, sharply segregated in the main olfactory bulb and partially segregated in the olfactory epithelium of pre-metamorphic larvae. A lateral odor-processing stream is formed by microvillous receptor neurons and is characterized by amino acid responses and Gαo/Gαi as probable signal transducers, whereas a medial stream formed by ciliated receptor neurons is characterized by responses to alcohols, aldehydes, and ketones, and Gαolf/cAMP as probable signal transducers. To reveal candidates for the olfactory receptors underlying these two streams, the spatial distribution of 12 genes from four olfactory receptor gene families was determined. Several class II and some class I odorant receptors (ORs) mimic the spatial distribution observed for the medial stream, whereas a trace amine-associated receptor closely parallels the spatial pattern of the lateral odor-processing stream. Other olfactory receptors (some class I odorant receptors and vomeronasal type 1 receptors) and odor responses (to bile acids, amines) were not lateralized, the latter not even in the olfactory bulb, suggesting an incomplete segregation. Thus, the olfactory system of X. laevis exhibits an intermediate stage of segregation and as such appears well suited to investigate the molecular driving forces behind olfactory regionalization.

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Section: Resultsmentioning

confidence: 99%

Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream

Gliem

Syed

Sansone

et al. 2012

Cell. Mol. Life Sci.

148

View full text Add to dashboard Cite

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“…In zebrafish, first-order chemical features, such as molecular categories, are encoded by large glomerular domains. Second-order features, such as carbon chain length or branching, are encoded by local differences of glomerular activity patterns within chemotopical domains (Friedrich and Korsching, 1997, 1998; Fuss and Korsching, 2001; Korsching, 2001). Chemotopic maps are therefore hierarchically organized such that fine maps of secondary features are nested within coarse maps of primary features (Friedrich and Korsching, 1997, 1998).…”

Section: The Olfactory Bulb: Primary Processing Of Odor Informationmentioning

confidence: 99%

Neural circuits mediating olfactory-driven behavior in fish

Kermen¹,

Franco²,

Wyatt³

et al. 2013

Front. Neural Circuits

104

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The fish olfactory system processes odor signals and mediates behaviors that are crucial for survival such as foraging, courtship, and alarm response. Although the upstream olfactory brain areas (olfactory epithelium and olfactory bulb) are well-studied, less is known about their target brain areas and the role they play in generating odor-driven behaviors. Here we review a broad range of literature on the anatomy, physiology, and behavioral output of the olfactory system and its target areas in a wide range of teleost fish. Additionally, we discuss how applying recent technological advancements to the zebrafish (Danio rerio) could help in understanding the function of these target areas. We hope to provide a framework for elucidating the neural circuit computations underlying the odor-driven behaviors in this small, transparent, and genetically amenable vertebrate.

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“…Investigation of Drosophila OR neurons (20) also indicated that each receptor preferably responds to a specific combination of chemical features; that is, each receptor samples a specific region of ''chemical space. '' Another characteristic of olfactory systems is that OSNs expressing a specific OR make synaptic contacts with a defined subset of second-order neurons in downstream neural populations, namely the olfactory bulb of vertebrates (21) or the antennal lobe of insects (22,23). These connections are formed in spatially discrete areas, the glomeruli.…”

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confidence: 99%

Processing and classification of chemical data inspired by insect olfaction

Schmuker

Schneider

2007

Proc. Natl. Acad. Sci. U.S.A.

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The chemical sense of insects has evolved to encode and classify odorants. Thus, the neural circuits in their olfactory system are likely to implement an efficient method for coding, processing, and classifying chemical information. Here, we describe a computational method to process molecular representations and classify molecules. The three-step approach mimics neurocomputational principles observed in olfactory systems. In the first step, the original stimulus space is sampled by ''virtual receptors,'' which are chemotopically arranged by a self-organizing map. In the second step, the signals from the virtual receptors are decorrelated via correlation-based lateral inhibition. Finally, in the third step, olfactory scent perception is modeled by a machine learning classifier. We found that signal decorrelation during the second stage significantly increases the accuracy of odorant classification. Moreover, our results suggest that the proposed signal transform is capable of dimensionality reduction and is more robust against overdetermined representations than principal component scores. Our olfaction-inspired method was successfully applied to predicting bioactivities of pharmaceutically active compounds with high accuracy. It represents a way to efficiently connect chemical structure with biological activity space.bioinformatics ͉ chemical biology ͉ computational model ͉ decorrelation ͉ olfactory coding T he mechanisms that enable olfactory discrimination are remarkably similar across species and even phyla (1, 2), and several principles of organization have been observed in insects and vertebrates. One such principle is that each primary olfactory sensory neuron (OSN) specifically expresses one type of olfactory receptor (OR), as has been demonstrated, e.g., in mice (3, 4) and in Drosophila (5, 6), although exceptions to this rule exist (7,8). ORs represent the largest family of seventransmembrane G protein-coupled receptors (9-12). Several studies addressed structure-activity relationships (SARs) of . A general observation is that one odorant typically activates a number of different ORs, and each OR has rather broad ligand selectivity. Investigation of Drosophila OR neurons (20) also indicated that each receptor preferably responds to a specific combination of chemical features; that is, each receptor samples a specific region of ''chemical space. '' Another characteristic of olfactory systems is that OSNs expressing a specific OR make synaptic contacts with a defined subset of second-order neurons in downstream neural populations, namely the olfactory bulb of vertebrates (21) or the antennal lobe of insects (22,23). These connections are formed in spatially discrete areas, the glomeruli. It has long been speculated, and in part also shown, that glomeruli are chemotopically ordered, such that neighboring glomeruli receive input from OSNs that prefer ligands with similar chemical characteristics (5,(24)(25)(26)(27). There is some evidence that the spatial distance of glomeruli in the olfactory bulb is re...

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Odor maps in the brain: Spatial aspects of odor representation in sensory surface and olfactory bulb

Cited by 29 publications

References 81 publications

Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream

Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream

Neural circuits mediating olfactory-driven behavior in fish

Processing and classification of chemical data inspired by insect olfaction

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