General and Systematic Zoology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.
Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.
J Comp Neurol. 2020 Jul 15;528(11):1883-1902. doi: 10.1002/cne.24861. Epub 2020 Feb 12.
Some animals have evolved task differentiation among their eyes. A particular example is spiders, where most species have eight eyes, of which two (the principal eyes) are used for object discrimination, whereas the other three pairs (secondary eyes) detect movement. In the ctenid spider Cupiennius salei, these two eye types correspond to two visual pathways in the brain. Each eye is associated with its own first- and second-order visual neuropil. The second-order neuropils of the principal eyes are connected to the arcuate body, whereas the second-order neuropils of the secondary eyes are linked to the mushroom body. We explored the principal- and secondary eye visual pathways of the jumping spider Marpissa muscosa, in which size and visual fields of the two eye types are considerably different. We found that the connectivity of the principal eye pathway is the same as in C. salei, while there are differences in the secondary eye pathways. In M. muscosa, all secondary eyes are connected to their own first-order visual neuropils. The first-order visual neuropils of the anterior lateral and posterior lateral eyes are connected with a second-order visual neuropil each and an additional shared one (L2). In the posterior median eyes, the axons of their first-order visual neuropils project directly to the arcuate body, suggesting that the posterior median eyes do not detect movement. The L2 might function as an upstream integration center enabling faster movement decisions.
有些动物在眼睛之间已经进化出了任务分工。一个特别的例子是蜘蛛，大多数蜘蛛有 8 只眼睛，其中两只（主眼）用于物体识别，而另外三只（副眼）则用于检测运动。在栉足蛛 Cupiennius salei 中，这两种眼型对应于大脑中的两个视觉通路。每只眼睛都与自己的第一级和第二级视觉神经丛相关联。主眼的第二级神经丛与弓形体相连，而副眼的第二级神经丛则与蘑菇体相连。我们研究了跳蛛 Marpissa muscosa 的主眼和副眼视觉通路，这两种眼型的大小和视野有很大的不同。我们发现，主眼通路的连接方式与 C. salei 相同，而副眼通路则存在差异。在 M. muscosa 中，所有副眼都与自己的第一级视觉神经丛相连。前侧外侧和后侧外侧的第一级视觉神经丛分别与一个第二级视觉神经丛和一个额外的共享神经丛（L2）相连。在后部中央眼，它们的第一级视觉神经丛的轴突直接投射到弓形体，表明后部中央眼不检测运动。L2 可能作为一个上游整合中心，使运动决策更快。
