Dynamic mapping at the laminar level of odor-elicited responses in rat olfactory bulb by functional MRI.
Dynamic mapping at the laminar level of odor-elicited responses in rat olfactory bulb by functional MRI.
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DOI：
10.1073/pnas.95.13.7715
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发表时间：
1998-06
影响因子：
11.1
通讯作者：
Xiaojin Yang;R. Renken;F. Hyder;Mohamed Siddeek;Charles A. Greer;Gordon M. Shepherd;Robert G. Shulman
中科院分区：
文献类型：
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作者：
Xiaojin Yang;R. Renken;F. Hyder;Mohamed Siddeek;Charles A. Greer;Gordon M. Shepherd;Robert G. Shulman
我们应用基于血氧水平依赖（BOLD）图像对比度的功能性MRI（fMRI），以220 × 220 × 1，000 μ m和36 s的空间和时间分辨率，在层水平上绘制乙酸异戊酯（10（-2）饱和蒸汽稀释）引起的大鼠嗅球（OB）中的气味引起的嗅觉反应。OB的层状结构通过空间分辨率为110 × 110 × 1,000 μ m的高分辨率体内解剖MRI清楚地描绘。在重复的BOLD fMRI测量中，高度显著（P <0.001）的病灶位于两个OB的外层。在麻醉条件下，使用这种非侵入性方法在动物内和动物间证实了在单个肾小球或肾小球组水平的区域内发生局灶性OB活动。动态研究表明，气味引起的BOLD激活在几分钟的时间尺度上是高度可重复的，而在几十分钟内，激活有时变化缓慢。我们发现大的BOLD信号（Δ S/S = 10 - 30%）来自嗅神经层，该层没有突触，由无髓纤维和神经胶质细胞组成。我们的研究结果支持以前的研究与其他方法表明，气味引起的活动在哺乳动物OB的肾小球层域，并延长分析的时间较短的时间内在单个肾小球或肾小球组的水平。随着进一步的改进，BOLD功能磁共振成像应该是理想的系统分析的功能意义的个别肾小球的嗅觉信息编码和嗅觉系统内的时空处理。
We have applied functional MRI (fMRI) based on blood oxygenation level-dependent (BOLD) image-contrast to map odor-elicited olfactory responses at the laminar level in the rat olfactory bulb (OB) elicited by iso-amyl acetate (10(-2) dilution of saturated vapor) with spatial and temporal resolutions of 220x220x1,000 micro(m) and 36 s. The laminar structure of the OB was clearly depicted by high-resolution in vivo anatomical MRI with spatial resolution of 110x110x1,000 micro(m). In repeated BOLD fMRI measurements, highly significant (P < 0.001) foci were located in the outer layers of both OBs. The occurrence of focal OB activity within a domain at the level of individual glomeruli or groups of glomeruli was corroborated on an intra- and inter-animal basis under anesthetized conditions with this noninvasive method. The dynamic studies demonstrated that the odor-elicited BOLD activations were highly reproducible on a time scale of minutes, whereas over tens of minutes the activations sometimes varied slowly. We found large BOLD signal (DeltaS/S = 10-30%) arising from the olfactory nerve layer, which is devoid of synapses and composed of unmyelinated fibers and glial cells. Our results support previous studies with other methods showing that odors elicit activity within glomerular layer domains in the mammalian OB, and extend the analysis to shorter time periods at the level of individual glomeruli or groups of glomeruli. With further improvement, BOLD fMRI should be ideal for systematic analysis of the functional significance of individual glomeruli in olfactory information encoding and of spatiotemporal processing within the olfactory system.