Fantana Antoniu L, Soucy Edward R, Meister Markus
Molecular and Cellular Biology Department and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
Neuron. 2008 Sep 11;59(5):802-14. doi: 10.1016/j.neuron.2008.07.039.
Center-surround receptive fields are a fundamental unit of brain organization. It has been proposed that olfactory bulb mitral cells exhibit this functional circuitry, with excitation from one glomerulus and inhibition from a broad field of glomeruli within reach of the lateral dendrites. We investigated this hypothesis using a combination of in vivo intrinsic imaging, single-unit recording, and a large panel of odors. Assuming a broad inhibitory field, a mitral cell would be influenced by >100 contiguous glomeruli and should respond to many odors. Instead, the observed response rate was an order of magnitude lower. A quantitative model indicates that mitral cell responses can be explained by just a handful of glomeruli. These glomeruli are spatially dispersed on the bulb and represent a broad range of odor sensitivities. We conclude that mitral cells do not have center-surround receptive fields. Instead, each mitral cell performs a specific computation combining a small and diverse set of glomerular inputs.
中心-周边感受野是脑组织的基本单位。有人提出嗅球的二尖瓣细胞呈现出这种功能回路，即一个肾小球的兴奋以及来自侧枝树突可及范围内广泛肾小球区域的抑制。我们结合体内固有成像、单单位记录以及大量气味组合对这一假说进行了研究。假设存在广泛的抑制区域，一个二尖瓣细胞会受到超过100个相邻肾小球的影响，并且应该对多种气味做出反应。然而，观察到的反应率要低一个数量级。一个定量模型表明，二尖瓣细胞的反应仅由少数几个肾小球就能解释。这些肾小球在球状体上呈空间分散分布，代表了广泛的气味敏感性。我们得出结论，二尖瓣细胞没有中心-周边感受野。相反，每个二尖瓣细胞通过组合一小部分多样的肾小球输入来执行特定的计算。
