Cracking the Chemical Code

Michael Leon
Department of Neurobiology and Behavior
University of California, Irvine

Abstract: Our strategy to understand the olfactory code has involved four approaches. In the first, we determined whether the system encodes odorants in their entirety, or whether it encodes odorants by representing combinations of molecular features that add together to comprise a neural picture of each odorant. We found evidence for both mechanisms. Our second strategy examined the ways that such features are represented in the olfactory system. We stimulated rats with odorants that differed greatly in their molecular structure to be able to identify a set of odorant feature response domains. Our third approach asked how odorants with very small differences in molecular structure are coded, and we found systematic differences in the representation of such features within response domains. Finally, we were able to predict odor perception from the neural representations of odorants that differed in only a single aspect of their structure.

Johnson, B.A., Woo, C.C. and Leon, M. Spatial coding of odorant features in the glomerular layer of the rat olfactory bulb. Journal of Comparative Neurology, 1998, 393, 457-471.

Johnson, B.A., Woo, C.C., Hingco, E.E., Pham, K.L. and Leon, M. Multidimensional chemotopic responses to n-aliphatic acid odorants in the rat olfactory bulb. Journal of Comparative Neurology, 1999, 409, 529-548.

Johnson, B.A. and Leon, M. Modular glomerular representations of odorants in the rat olfactory bulb and the effects of stimulus concentration. Journal of Comparative Neurology, 2000, 422, 496-509.

Johnson, B.A. and Leon, M. Odorant molecular length: One aspect of the olfactory code. Journal of Comparative Neurology, 2000, 426, 330-338.

Linster, C., Johnson, B.A., Morse, A., Yue, E., Xu, Z., Hingco, E.E., Choi, Y., Choi, M., Messiha, A. and Leon, M. Perceptual correlates of neural representations evoked by odorant enantiomers. Journal of Neuroscience, 2001, 21, 9837-9843.

Johnson, B.A., Ho, S., Xu, Z., Yihan, J.S., Yip, S., Hingco, E.E. and Leon, M. Functional mapping of the rat olfactory bulb using diverse odorants reveals modular responses to functional groups and hydrocarbon structural features. Journal of Comparative Neurology, 2002, 449, 180-194.

Linster C. Johnson, B.A., Morse, A., Yue, E. and Leon, M. Spontaneous vs. reinforced olfactory discriminations, Journal of Neuroscience, 2002, 22, 6842-6845.


Lab web site: http://leonlab.bio.uci.edu/

Department web site: http://neurobiology.uci.edu