Odor maps

Schaefer, M.L., Yamazaki, K., Osada, K., Restrepo, D. and Beauchamp, G.K. (2002) Olfactory fingerprints for major histocompatibility complex-determined body odors II relationship among odor maps, genetics, odor composition, and behavior. J. Neurosci. 22, 9513-9521. 

If a spatial olfactory code underlies a subsequent identification of an odor, then we would expect concentration-dependent variations of odor maps to have an impact on the perceived odor quality. Stimulus concentration can indeed influence perception of odor quality and behavior of insects. For example, olfactory responses of the fruit fly, Drosophia melanogaster, shifted from attraction to repulsion as the concentration increased (Siddiqi, 1983 Stensmyr et al., 2003). Future studies should thus involve correlations of behavior with glomerular activity at different concentrations. 

Dynamic odor maps 24.4.2.3.1 Spatio-temporal representations... 

Uchida N., Takahashi Y. K., Tanifuji M. and Mori K. (2000) Odor maps in the mammalian olfactory bulb domain organization and odorant structural features. Nat. Neurosci. 3(10), 1035-1043. 

Strotmann J, Wanner I, Krieger J, Raming K, Breer H (1992) Expression of odorant receptors in spatially restricted subsets of chemosensory neurones. Neuroreport 3(12) 1053—1056 Strotmann J, Conzelmann S, Beck A, Feinstein P, Breer H, Mombaerts P (2000) Local permutations in the glomerular array of the mouse olfactory bulb. J Neurosci 20(18) 6927-6938 Strotmann J, Levai O, Fleischer J, Schwarzenbacher K, Breer H (2004) Olfactory receptor proteins in axonal processes of chemosensory neurons. J Neurosci 24(35) 7754-7761 Taniguchi M, Nagao H, Takahashi YK, Yamaguchi M, Mitsui S, Yagi T, Mori K, Shimizu T (2003) Distorted odor maps in the olfactory bulb of semaphorin 3A-deficient mice. J Neurosci 23(4) 1390-1397... 

Fig. 4 Odor map in the zebrafish olfactory bulb. Amino acids and nucleotides are received mostly by V2R-type olfactory receptors on microvillous OSNs and are represented in the lateral region of the OB. In contrast, bile acids are received by OR-type olfactory receptors on ciliated OSNs and are represented in the medial region of the OB. LOT lateral olfactory tract, MOT medial olfactory tract...

Meister M, Bonhoeffer T (2001) Tuning and topography in an odor map on the rat olfactory bulb. J Neurosci 21 1361-1360... 

Nagayama S, Takahashi YK, Yoshihara Y, Mori K. 2004. Mitral and tufted cells differ in the decoding manner of odor maps in the rat olfactory bulb. J Neurophysiol 91 2532-2540. 

Due to the complex structure of odor space, it is an extremely interesting and challenging question whether the olfactory system has a correlate of retinotopic maps in vision or frequency maps in audition. And if it does, what would be the organizing principle of such an odor map Furthermore, can we learn from this organization of biological olfactory systems to build artificial chemosensor systems that perform at levels comparable to the performance of the former in general olfactory sensing tasks ... 

Fig. 6.2. Illustration of chemotopic convergence the relative response to three analytes (labeled A, B and C) is used to define the wavenumbers affinities (shown as a colorbar). IR wavenumbers with similar affinities project to the same SOM node as a result of chemotopic convergence. Activity across the SOM lattice can be considered as an artificial odor map.

To generate artificial odor maps, a population of 4,000 pseudo-sensors generated from the IR spectrum is projected chemotopically onto a 10x10 SOM lattice (100 nodes). The odor images are then low-pass filtered using a 5x5 Gaussian kernel. 

Fig. 6.3. Odor maps generated from the IR spectrum using the chemotopic convergence model...

Fig. 6.3. shows the odor maps for ten different smell percepts from the IR database. The following observations can be made based on the odor images obtained from their IR absorption spectrum ... 

Fig. 6.4. Odor maps obtained in the rat olfactory bulb for the same ten smell percepts...

A database of odor maps from the rat olfactory bulb is available at http //leonlab.bio.uci.edu/... 

Spatial odor images for these compounds in the dorsal part of rat OB are shown in Figure 6.4. These odor maps were obtained using optical imaging techniques involving... 

Sweat and Cheese descriptors overlap similar to the IR-generated odor maps. Minty smelling Methyl salicylate and Menthol produced distinct odor maps. 

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