Dendritic relationship between starburst amacrine cells and direction-selective ganglion cells in the rabbit retina

We investigated the dendritic relationship between starburst amacrine cells (SAs) and morphologically and physiologically characterized ON and ON-OFF direction-selective ganglion cells (DSGCs) in the rabbit retina. ON and ON-OFF DSGCs were found to exhibit tight dendritic cofasciculation with the SA plexus, visualized by immunolabelling of the vesicular acetylcholine transporter (VAChT). The degree of cofasciculation of both types of DSGC dendrites and SA plexus was found to be significant, unlike the relationship between non-DS cells and the SA plexus, which was close to chance distribution. No difference in the degree of cofasciculation in different regions of the DS dendritic field was observed. Individual SAs intracellularly injected both on the 'preferred' and 'null' side of the DSGCs showed the same degree of cofasciculation with the DSGCs. Therefore, the computation of motion direction is unlikely to result from apparent asymmetry in geometric proximity between SAs and DSGCs. Highly selective synaptic connections between SAs and DSGCs are necessary.

我们研究了兔视网膜中星爆无长突细胞（SAs）与在形态和生理上具有特征的给光（ON）和给光 - 撤光（ON - OFF）方向选择性神经节细胞（DSGCs）之间的树突关系。通过对囊泡乙酰胆碱转运体（VAChT）进行免疫标记可见，给光和给光 - 撤光方向选择性神经节细胞与星爆无长突细胞丛呈现紧密的树突共束。发现这两种类型的方向选择性神经节细胞树突与星爆无长突细胞丛的共束程度是显著的，这与非方向选择性细胞和星爆无长突细胞丛之间的关系不同，后者接近随机分布。在方向选择性神经节细胞树突区域的不同部位未观察到共束程度的差异。在方向选择性神经节细胞的“偏好”侧和“无效”侧进行细胞内注射的单个星爆无长突细胞与方向选择性神经节细胞显示出相同的共束程度。因此，运动方向的计算不太可能是由星爆无长突细胞和方向选择性神经节细胞之间几何邻近性的明显不对称导致的。星爆无长突细胞和方向选择性神经节细胞之间高度选择性的突触连接是必要的。