NCBI Organism:Mus musculus, ; Cell Types:, , ;

Using a variant of miniSOG, a genetic probe for correlated light and electron microscopy (CLEM), we determined the form, fine structure and quantified the distribution of melanopsin-expressing retinal ganglion cell (ipRGC) projections within multiple brain regions. The method developed labels the entire neuron, including its axonal arbors in retinorecipient brain regions. Here the ‘synapto-projectome’ of these cells was charted in the suprachiasmatic nucleus (SCN), olivary pretectal nucleus (OPN), and subregions of the lateral geniculate. Each ipRGC axonal arbor synapsed on multiple target neurons in the SCN and OPN. Although the only direct retinal input to the OPN and SCN is from ipRGCs, the terminal arbors and boutons were different in each brain region. Also, a network of dendro-dendritic chemical synapses (DDCS) was discovered in the SCN; with ipRGC axons preferentially targeting the DDCS-linked cells. Methods used for this analysis should facilitate other CLEM studies of brain circuits at high resolution.

采用miniSOG的变体，一种关联光电子显微镜（CLEM）的遗传探针，本研究确定了黑色素细胞素表达视网膜神经节细胞（ipRGC）在多个脑区中的形态、精细结构及其分布情况。该方法对整个神经元及其在视网膜接受区脑区域中的轴突树进行了标记。在此，这些细胞的‘突触投射组’在视交叉上核（SCN）、橄榄状视顶核（OPN）和外侧膝状体亚区中得以描绘。每个ipRGC的轴突树与SCN和OPN中的多个目标神经元发生突触连接。尽管OPN和SCN的直接视网膜输入仅来自ipRGC，但每个脑区的终端树突和突触小体均有差异。此外，在SCN中发现了树突-树突化学突触网络（DDCS）；ipRGC轴突优先靶向DDCS连接的细胞。用于该分析的方法应有助于其他高分辨率脑电路CLEM研究的开展。