Johnson Brett A, Xu Zhe, Pancoast Paige, Kwok Jennifer, Ong Joan, Leon Michael
Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697-4550, USA.
J Comp Neurol. 2006 Nov 1;499(1):1-16. doi: 10.1002/cne.21093.
As part of our ongoing effort to relate stimulus to response in the olfactory system, we tested the hypothesis that the unique chemical structures and odors of various cyclic odorants would be associated with unique spatial response patterns in the glomerular layer of the rat olfactory bulb. To this end, rats were exposed to sets of odorants, including monocyclic hydrocarbons, bicyclic compounds, and various heterocyclic structures containing oxygen or nitrogen in the ring. Relative activity across the entire layer was assessed by mapping uptake of 2-deoxyglucose into anatomically standardized data matrices. Whereas monocyclic hydrocarbons evoked patterns similar to those evoked by open-chained hydrocarbon odorants, a set of bicyclic compounds with structures and odors similar to camphor evoked uptake in paired ventral domains not previously associated with any other odorant chemical structures. Despite their unique odors as judged by humans, heterocyclic odorants either evoked uptake in previously characterized areas corresponding to their functional groups or stimulated weak or patchy patterns involving isolated glomeruli. Although the patchiness of the patterns may be partially related to the rigidity of the compounds, which would be expected to restrict their interactions to only a few receptors, the weakness of the patterns suggests the possibility of species-specific odorant representations. We conclude that, whereas some of the novel cyclic structures indeed were represented by unique patterns in the rat bulb, other unique structures were poorly represented, even when they evoked intense and unique odors in humans.
作为我们在嗅觉系统中持续探索刺激与反应关系的一部分，我们检验了这样一个假设：各种环状气味剂独特的化学结构和气味会与大鼠嗅球肾小球层独特的空间反应模式相关联。为此，我们让大鼠接触了多组气味剂，包括单环烃、双环化合物以及环中含有氧或氮的各种杂环结构。通过将2-脱氧葡萄糖的摄取情况映射到解剖学标准化数据矩阵中，评估了整个层面的相对活性。单环烃引发的模式与开链烃气味剂引发的模式相似，而一组结构和气味与樟脑相似的双环化合物在成对的腹侧区域引发了摄取，这些区域以前与任何其他气味剂化学结构都没有关联。尽管人类认为杂环气味剂具有独特气味，但它们要么在先前根据其官能团特征描述的区域引发摄取，要么刺激涉及孤立肾小球的微弱或零散模式。尽管模式的零散可能部分与化合物的刚性有关，刚性预计会将它们的相互作用限制在少数受体上，但模式的微弱表明存在物种特异性气味剂表征的可能性。我们得出结论，虽然一些新型环状结构确实在大鼠嗅球中由独特模式表示，但其他独特结构的表示却很差，即使它们在人类中引发强烈且独特的气味。
