Sight

How information gets from the eye to the brain.

Look at the lovely diagram, then read the similarly lovely explanation:

1. Objects seen in a visual field are detected on the opposite retinal side – eg the left temporal field is detected on the left nasal retina.
2. The axons of the ganglion cells of the retina form the optic nerve. This passes through the optic canal to the base of the brain, where the two nerves meet in the optic chiasm.
3. In the optic chiasm, the temporal visual fields swap to the opposite side of the brain from their side of origin – eg. The left temporal field passes to the right lateral geniculate nucleus.
4. The LGN sends action potentials to the visual cortex, in the occipital lobe. The different types of visual information are processed simultaneously in different parts of the cerebral cortex before they are reintegrated to produce our sight, and perceptions/reflexes based on it.

Obviously, its way more complex than this, and bits and pieces are processed in completely different places as well, but it’ll do.