Molecular basis for the secondary neural circuit formation in the mouse olfactory system

在小鼠嗅觉系统中，地图拓扑结构主要是通过嗅觉感觉神经元（OSN）的轴突-轴突相互作用建立的。然而，为了使地图发挥作用，OSN必须与二尖瓣/簇状（M/T）细胞建立适当的连接。那么，M/T细胞树突如何找到它们的伙伴肾小球与OSN轴突形成突触呢？肾小球的气味受体特异性是否在M/T细胞树突与OSN轴突的匹配中起指导作用？为了解决这些问题，我们分析了树突选择和突触形成的二尖瓣细胞在各种突变小鼠，其中肾小球形成受到干扰。我们还研究了成年肾小球中的突触重建。我们目前的研究结果支持“邻近模型”，即二尖瓣细胞倾向于连接初级树突最近的相邻肾小球，无论或特异性。肾小球的地图位置或地址码在匹配二尖瓣细胞与其伴侣肾小球中起着关键作用。

In the mouse olfactory system, map topography is largely established by axon-axon interactions of olfactory sensory neurons (OSNs). However, to make the map functional, the OSNs must make proper connections to the mitral/tufted (M/T) cells. Then, how do the M/T cell dendrites find their partner glomeruli for synapse formation with OSN axons? Does the odorant receptor (OR) specificity of glomeruli play an instructive role in matching M/T cell dendrites with OSN axons? To address these questions, we analyzed dendrite selection and synapse formation of mitral cells in various mutant mice in which glomerular formation was perturbed. We also studied synapse reconstitution in adult glomeruli. Our present results support the "proximity model", whereby mitral cells tend to connect primary dendrites to the nearest neighboring glomeruli regardless of OR specificity. The map location or address code of glomeruli plays a key role in matching mitral cells with their partner glomeruli.