Number of caudal periaqueductal gray (cPAG)-projecting retinal ganglion cells (RGCs) required to tile up the retinal surface.

The calculations are used to determine the number of cPAG-projecting RGCs that are required to cover the whole retinal surface. The size of the retinal surface area is referred from Fite’s study [11]; tiling up the whole retinal surface is generally considered as a criterion for a type of RGC, and our results indicate approximately 1300 cPAG-projecting RGCs are required to cover the whole retinal surface in this species.