Willhite David C, Nguyen Katherine T, Masurkar Arjun V, Greer Charles A, Shepherd Gordon M, Chen Wei R
Department of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
Proc Natl Acad Sci U S A. 2006 Aug 15;103(33):12592-7. doi: 10.1073/pnas.0602032103. Epub 2006 Aug 8.
Olfactory sensory neurons converge onto glomeruli in the olfactory bulb (OB) to form modular information processing units. Similar input modules are organized in translaminar columns for other sensory modalities. It has been less clear in the OB whether the initial modular organization relates to a columnar structure in the deeper layers involved in local circuit processing. To probe synaptic connectivity in the OB, we injected a retrograde-specific strain of the pseudorabies virus into the rat OB and piriform cortex. The viral-staining patterns revealed a striking columnar organization that extended across all layers of the OB from the glomeruli to the deep granule cell layer. We hypothesize that the columns represent an extension of the glomerular unit. Specific patterning was observed, suggesting selective, rather than distance-dependent, center-surround connectivity. The results provide a previously undescribed basis for interpreting the synaptic connections between mitral and granule cells within the context of a columnar organization in the OB and have implications for olfactory coding and network organization.
嗅觉感觉神经元汇聚到嗅球（OB）中的肾小球，形成模块化信息处理单元。类似的输入模块以跨层柱的形式组织，用于其他感觉模态。在嗅球中，最初的模块化组织是否与参与局部回路处理的深层柱状结构相关，一直不太清楚。为了探究嗅球中的突触连接性，我们将伪狂犬病病毒的逆行特异性菌株注射到大鼠的嗅球和梨状皮层中。病毒染色模式揭示了一种显著的柱状组织，从肾小球延伸到嗅球的深层颗粒细胞层，贯穿嗅球的所有层。我们假设这些柱代表肾小球单元的延伸。观察到了特定的模式，表明是选择性的，而非距离依赖性的中心-外周连接。这些结果为在嗅球柱状组织的背景下解释二尖瓣细胞和颗粒细胞之间的突触连接提供了一个此前未描述的基础，并对嗅觉编码和网络组织具有启示意义。
