RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
1] Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 43 Vassar Street, Cambridge, Massachusetts 02139, USA [2].
Nat Commun. 2014 Apr 9;5:3639. doi: 10.1038/ncomms4639.
Chemotopic odour representations in the olfactory bulb are transferred to multiple forebrain areas and translated into appropriate output responses. However, a comprehensive projection map of bulbar output neurons at single-axon resolution is lacking in vertebrates. Here we unravel a projectome of the zebrafish olfactory bulb through genetic single-neuron tracing and image registration. We show that five major target regions receive distinct modes of projections from olfactory bulb glomeruli. The central portion of posterior telencephalon receives non-selective, interspersed inputs from all glomeruli, whereas the ventral telencephalon is diffusely innervated by axons from particular glomerular clusters. The right habenula and posterior tuberculum (diencephalic nuclei) receive convergent inputs from restricted and all glomerular clusters, respectively. The bulbar recurrent projections are coarsely topographic. Thus, the primary chemotopic organization is transformed into distinct sensory representations in higher olfactory centres. These findings provide a framework to understand general principles as well as species-specific features in decoding of odour information.
嗅球中的化学感受气味代表被传递到多个前脑区域，并转化为适当的输出反应。然而，在脊椎动物中，缺乏嗅球输出神经元的单轴突分辨率的全面投射图。在这里，我们通过遗传单神经元追踪和图像配准，揭示了斑马鱼嗅球的投射组图。我们表明，五个主要的靶区从嗅球神经球接收不同模式的投射。后端脑的中央部分接收来自所有神经球的非选择性、交错的输入，而腹侧端脑则被来自特定神经球簇的轴突广泛支配。右侧缰核和后端丘（神经核）分别接收来自受限和所有神经球簇的会聚输入。嗅球的递归投射是粗略的地形。因此，初级化学感受组织被转化为嗅觉中枢中不同的感觉代表。这些发现为理解气味信息解码的一般原则和物种特异性特征提供了一个框架。
