Glomerular input patterns in the mouse olfactory bulb evoked by retronasal odor stimuli
Glomerular input patterns in the mouse olfactory bulb evoked by retronasal odor stimuli
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DOI：
10.1186/1471-2202-14-45
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发表时间：
2013-04-08
期刊：
影响因子：
2.4
通讯作者：
Lowe, Graeme
中科院分区：
文献类型：
--
作者：
Furudono, Yuichi;Cruz, Ginny;Lowe, Graeme
背景：气味刺激可以通过外鼻孔吸入，或通过口腔反向气流从鼻后进入嗅觉上皮。有证据表明，通过这两种途径感知到的气味在质量和强度上可能有所不同。我们很好奇这种差异是否可能在气味编码的外围机制中具有神经基础。为了探索这种可能性，我们比较了鼻前和鼻后刺激引起的背侧嗅球中肾小球的嗅觉受体输入。通过对嗅神经末梢中表达突触前活性荧光报告基因突触氢 (spH) 的转基因小鼠进行光学成像，获得肾小球反应图。结果：我们发现鼻后递送的气味剂能够激活背侧嗅球多个肾小球的输入。对于以相当的浓度和流速递送的气味剂，鼻后反应小于鼻前反应，并且它们表现出更高的阈值和右移的剂量反应曲线。鼻前和鼻后反应的肾小球图通常有很好的重叠，鼻后图中肾小球的总数较少。然而，阈值处的地图可能非常不同，几乎没有重叠。鼻后反应也更窄地调整为不同碳链长度的同源脂肪族气味剂系列，链较长、疏水性更强的化合物在可比较的蒸气水平下很少或没有引起反应。结论：鼻后嗅觉的几个特征可能与观察到的肾小球气味反应的特性有关。鼻后反应比口鼻反应更弱、更稀疏的发现与心理物理学研究一致，显示阈值和阈上测试中鼻后嗅觉的敏感性较低。阈上浓度下鼻前和鼻后气味图的相似性和重叠与通过这两种途径施用的相同气味刺激的总体相似的感知质量一致。然而，接近阈值的地图的分歧是鼻前嗅觉和鼻后嗅觉之间感知差异的潜在因素。鼻后反应的较窄调整表明它们可能较少受到色谱吸附效应的影响。
Background: Odorant stimuli can access the olfactory epithelium either orthonasally, by inhalation through the external nares, or retronasally by reverse airflow from the oral cavity. There is evidence that odors perceived through these two routes can differ in quality and intensity. We were curious whether such differences might potentially have a neural basis in the peripheral mechanisms of odor coding. To explore this possibility, we compared olfactory receptor input to glomeruli in the dorsal olfactory bulb evoked by orthonasal and retronasal stimulation. Maps of glomerular response were acquired by optical imaging of transgenic mice expressing synaptopHluorin (spH), a fluorescent reporter of presynaptic activity, in olfactory nerve terminals.Results: We found that retronasally delivered odorants were able to activate inputs to multiple glomeruli in the dorsal olfactory bulb. The retronasal responses were smaller than orthonasal responses to odorants delivered at comparable concentrations and flow rates, and they displayed higher thresholds and right-shifted dose-response curves. Glomerular maps of orthonasal and retronasal responses were usually well overlapped, with fewer total numbers of glomeruli in retronasal maps. However, maps at threshold could be quite distinct with little overlap. Retronasal responses were also more narrowly tuned to homologous series of aliphatic odorants of varying carbon chain length, with longer chain, more hydrophobic compounds evoking little or no response at comparable vapor levels.Conclusions: Several features of retronasal olfaction are possibly referable to the observed properties of glomerular odorant responses. The finding that retronasal responses are weaker and sparser than orthonasal responses is consistent with psychophysical studies showing lower sensitivity for retronasal olfaction in threshold and suprathreshold tests. The similarity and overlap of orthonasal and retronasal odor maps at suprathreshold concentrations agrees with generally similar perceived qualities for the same odorant stimuli administered by the two routes. However, divergence of maps near threshold is a potential factor in perceptual differences between orthonasal and retronasal olfaction. Narrower tuning of retronasal responses suggests that they may be less influenced by chromatographic adsorption effects.