Optical Imaging of Postsynaptic Odor Representation in the Glomerular Layer of the Mouse Olfactory Bulb
Optical Imaging of Postsynaptic Odor Representation in the Glomerular Layer of the Mouse Olfactory Bulb
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DOI：
10.1152/jn.00020.2009
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发表时间：
2009-08-01
影响因子：
2.5
通讯作者：
Chen, Wei R.
中科院分区：
文献类型：
--
作者：
Fletcher, Max L.;Masurkar, Arjun V.;Chen, Wei R.
弗莱彻ML，Masurkar AV，Xing J，Imamura F，Xiong W，Nagayama S，Mutoh H，Greer CA，Knopfel T，Chen WR.小鼠嗅球小球层突触后表达的光学成像。J Neurophysiol 102：817-830，2009.首次发表于2009年5月27日; doi：10.1152/jn.00020.2009。嗅球是第一个气味表征图出现的位点。肾小球层包括精致的局部突触电路，用于在嗅觉编码模式出现后立即处理它们。为了了解气味图是如何从传入终末传递到突触后树突的，直接监测气味诱发的肾小球突触后活动模式是必要的。在这里，我们报告使用转基因小鼠表达钙离子敏感的绿色荧光蛋白（GCaMP 2）下的Kv3.1钾通道启动子。免疫组化结果显示，GCaMP 2特异性表达在二尖瓣和簇状细胞和肾小球细胞的亚群，但在嗅神经末梢不表达。无论是在体外和体内成像结合谷氨酸受体药理学证实，气味地图报告GCaMP 2的突触后起源。因此，这些小鼠提供了一个前所未有的机会来分析空间活动模式，反映纯粹的突触后嗅觉代码。气味诱发的GCaMP 2信号具有局灶性和弥漫性空间分量。局部热点对应于单独激活的肾小球。在GCaMP 2报告的突触后气味地图，不同的气味激活不同的，但重叠的肾小球。增加气味浓度增加个别肾小球反应幅度和激活肾小球总数。此外，GCaMP 2反应显示了一个快速的时间过程，使我们能够分析在连续的嗅探周期的气味地图的时间动态。总之，与细胞特异性靶向的遗传编码的Ca 2+指标，我们已经成功地分离和表征的嗅觉神经输入和主二尖瓣/簇细胞输出之间的中间水平的气味表示。
Fletcher ML, Masurkar AV, Xing J, Imamura F, Xiong W, Nagayama S, Mutoh H, Greer CA, Knopfel T, Chen WR. Optical imaging of postsynaptic representation in the glomerular layer of the mouse olfactory bulb. J Neurophysiol 102: 817-830, 2009. First published May 27, 2009; doi:10.1152/jn.00020.2009. Olfactory glomeruli are the loci where the first odor-representation map emerges. The glomerular layer comprises exquisite local synaptic circuits for the processing of olfactory coding patterns immediately after their emergence. To understand how an odor map is transferred from afferent terminals to postsynaptic dendrites, it is essential to directly monitor the odor-evoked glomerular postsynaptic activity patterns. Here we report the use of a transgenic mouse expressing a Ca2+-sensitive green fluorescence protein (GCaMP2) under a Kv3.1 potassium-channel promoter. Immunostaining revealed that GCaMP2 was specifically expressed in mitral and tufted cells and a subpopulation of juxtaglomerular cells but not in olfactory nerve terminals. Both in vitro and in vivo imaging combined with glutamate receptor pharmacology confirmed that odor maps reported by GCaMP2 were of a postsynaptic origin. These mice thus provided an unprecedented opportunity to analyze the spatial activity pattern reflecting purely postsynaptic olfactory codes. The odor-evoked GCaMP2 signal had both focal and diffuse spatial components. The focalized hot spots corresponded to individually activated glomeruli. In GCaMP2-reported postsynaptic odor maps, different odorants activated distinct but overlapping sets of glomeruli. Increasing odor concentration increased both individual glomerular response amplitude and the total number of activated glomeruli. Furthermore, the GCaMP2 response displayed a fast time course that enabled us to analyze the temporal dynamics of odor maps over consecutive sniff cycles. In summary, with cell-specific targeting of a genetically encoded Ca2+ indicator, we have successfully isolated and characterized an intermediate level of odor representation between olfactory nerve input and principal mitral/tufted cell output.