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Coding of odor molecules by neurons in mammalian olfactory bulb and cortex : Functional role of olfactory glomeruli

哺乳动物嗅球和皮层神经元对气味分子的编码：嗅觉肾小球的功能作用

基本信息

批准号：
05454684
负责人：
MORI Kensaku
金额：
$ 3.9万
依托单位：
OSAKA BIOSCIENCE INSTITUTE
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

1) Molecular receptive range properties of mitral/tufted cells in the rabbit main olfactory bulbRecording of extracellular spike responses were made from single mitral/tufted cells in various regions of the main olfactory bulb of urethane-anesthetized rabbits. Examination with an expanded panel of stimulus odor molecules that included both aromatic and aliphatic compounds indicated that single mitral/tufted cells show excitatory spike responses to a range of odor molecules (molecular receptive range) having similar conformations. These results support the hypothesis that conformational parameters of ligand odor molecules play a key role in sensory processing in the olfactory bulb. In addition, the results are in agreement with the hypothesis that sensory neurons expressing the same type of odor receptor converge on one or a few glomeruli.2) Functional role of bulbar local circuit neurons in coding of odor moleculesUsing single unit recording in rabbit main bulb, we showed that inhibitory responses are evoked in mitral/tufted cells by a defined subset of odor molecules with structures closely related to the excitatory odor molecules. Pharmacological blockade of the dendrodendritic synaptic transmission between mitral/tufted and granule cells markedly decreased the odor evoked suppression, suggesting that the inhibitory responses are evoked by lateral inhibition via the dendrodendritic synaptic pathway. The synaptic interaction s within the local circuits in the bulb, thus, greatly enhance the tuning specificity of odor responses and contribute to discrimination of odor molecule information.

1)兔主嗅球内二尖瓣/簇状细胞的分子接受范围特性用脲麻醉兔主嗅球内不同区域的单个二尖瓣/簇状细胞记录细胞外尖峰反应。用包括芳香和脂肪化合物的刺激气味分子扩展面板进行检查表明，单个二尖瓣/簇状细胞对具有相似构象的一系列气味分子（分子接受范围）表现出兴奋性尖峰反应。这些结果支持了配体气味分子的构象参数在嗅球的感觉加工中起关键作用的假设。此外，结果与表达同一类型气味受体的感觉神经元聚集在一个或几个肾小球的假设一致。2)球局部回路神经元在气味分子编码中的功能作用利用兔主球单单元记录，我们发现二尖瓣/簇状细胞中的抑制反应是由与兴奋性气味分子结构密切相关的特定气味分子亚群引起的。通过药物阻断二尖瓣/簇状细胞和颗粒细胞之间的树突突触传递，显著降低了气味引起的抑制，表明抑制反应是通过树突突触通路的侧抑制引起的。因此，球茎局部回路内的突触相互作用极大地增强了气味反应的调节特异性，并有助于气味分子信息的辨别。