Abstract: Mammals have two distinct , well-developed olfactory systems : the main olfactory system (MOS) and the vomeronasal system (VS). The former is specialized for the discrimination of volatile chemical. The latter is used to recognize pheromones. In this review , we unraveled coding patterns of two olfactory systems for information recognition at three levels : olfactory receptor , olfactory bulb and higher brain region beyond the olfactory bulb. The vomeronasal organ use narrow tuning range to recognize pheromones components , differing significantly from coding scheme used by the olfactory epithelium in which odors are recognized through distributed combinations of different receptors. Information is integrated by domains of glomeruli that receive the same receptors inputs in the accessory olfactory bulb differ from specific combinations of glomeruli modules in the main olfactory bulb. Pheromones signals exert their effects on hypothalamic areas through which pheromones elicit specific behavior and neuroendocrine effects in VS; In contrast , the olfactory cortex likely use temporal pattern to encode neuron populations , and perception of odor is related to different region of brain in MOS. In conclusion , the coding of olfactory information is likely to be far simpler in VS than in MOS due to VS fulfilling fewer functions.

Key words: Mammals, Main olfactory system, Vomeronasal system, Pheromones, Coding, Receptor

摘要： 哺乳动物具有两套嗅觉系统, 即主要嗅觉系统和犁鼻系统。前者对环境中的大多数挥发性化学物质进行识别, 后者对同种个体释放的信息素进行识别。本文从嗅觉感受器、嗅球、嗅球以上脑区三个水平综述了这两种嗅觉系统对化学信息识别的编码模式。犁鼻器用较窄的调谐识别信息素成分, 不同于嗅上皮用分类性合并受体的方式识别气味; 副嗅球以接受相同受体输入的肾丝球所在区域为单位整合信息, 而主嗅球通过对肾丝球模块的特异性合并编码信息; 在犁鼻系统, 信息素的信号更多地作用于下丘脑区域, 引起特定的行为和神经内分泌反应。而在主要嗅觉系统, 嗅皮层可能采用时间模式编码神经元群, 对气味的最终感受与脑的不同区域有关。犁鼻系统较主要嗅觉系统的编码简单, 可能与其执行的功能较少有关。

关键词: 哺乳动物, 主要嗅觉系统, 犁鼻系统, 信息素, 编码, 受体