In humans visual information from the right side of the visual field is represented within the left occipital lobe. However, our eyes are both pointed forward, and there is a lot of overlap in their visual fields (try looking ahead and closing one eye, then the other: you’ll notice that you still retain vision over most of your total visual field even with one eye). Since both eyes see both parts of the visual field, how are right and left sides segregated in the visual cortex?
Answer
a. The nasal retina in each eye monitors the left visual field only, while the temporal retina in each eye monitors the right visual field only.
b. The visual cortex in each hemisphere receives input from the contralateral eye only.
c. On-center retinal ganglion cells correspond to vision in the temporal retina, while off-center retinal ganglion cells correspond to vision in the nasal retina.
d. Each lateral geniculate nucleus receives input from the contralateral eye only, and this organization is preserved in projections to the visual cortex.
e. Axons from each retina segregate within the optic chiasm, so that projections from the right side of one eye are bundled with projections from the left side of the other eye, and vise-versa.