Figure 2. The collicular projection as a function of retinal location.

Using the coordinates defined by the eye muscles in Figure 1D, we performed a series of retinal injections around the periphery of the retina and determined the location of their collicular target zones. A. All of the retinal injection sites (n=45) are shown in eye muscle coordinates. B. An example collicular target zone for a temporal retinal injection, with axes (white lines) used to quantify target zone location. C. A standard coordinate system, depicted here by black lines, was used to identify the location of the target zone in the superior colliculus. All target zones were measured with respect to the position of the point of divergence of the rostral superior colliculus from the midline (intersection of vertical and horizontal white lines in B). This is analogous to the ‘lambda’ point in skull coordinate systems. Shown are the positions of all the target zones from the retinal injection sites shown in A, with colors representing retinal location of injection in muscle coordinates as shown in A. Scale bar in B is 500 μm.