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. 2019 May 14;13:35. doi: 10.3389/fncir.2019.00035

FIGURE 1.

FIGURE 1

Comparisons between primate (A,C) and rodent visual systems (B,D). Schematic diagrams in (A,B) illustrate the ocular structures and fiber tracts originating from either left (red) or right (blue) visual cortex. Labeled structures include the retina, optic nerve (ON), optic chiasm (OC), optic tract (OT), superior colliculus (SC), lateral geniculate nucleus (LGN), and visual cortex (VC). In primates, around 53% of ON fibers cross the optic chiasm and project to the contralateral hemisphere (Kupfer et al., 1967). In contrast, more than 90% of rodent ON fibers project to the contralateral hemisphere after reaching the optic chiasm, while the remaining 5–10% of fibers project to ipsilateral hemisphere (Forrester and Peters, 1967). (C,D) are the corresponding Mn-enhanced MRI (MEMRI) scans after unilateral intravitreal injection into a marmoset and a rat respectively. (C) is in 2D oblique view, whereas (D) is in 3D axial maximum intensity projected view. Note the unilateral enhancement in the eye and the ON for both primate and rodent MEMRI. In the OT, LGN and SC, primate MEMRI showed bilateral enhancement as compared to unilateral enhancement in rodent MEMRI in the contralateral hemisphere of the injected eye. (C,D) are reproduced with permissions from Yamada et al. (2008) and Chan et al. (2017).