with one eye closed, how does both sides of the brain receive visual information of what you’re seeing?
I know at a high level that the two hemispheres are connected and exchange information. But what internal mechanism of of the brain achieves this?
In: Biology
[Here’s](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Human_visual_pathway.svg/1200px-Human_visual_pathway.svg.png) a good diagram of the visual pathway. The nerve fibers on the left side of the right eyeball (the side closer to the nose) sees the right half of the visual field, while the fibers on the right side (the side closer to the ear) sees the left half of the visual field. These fibers travel together until they reach a structure called the optic chiasm, where the fibers seeing the right half of the visual field cross over to the left hemisphere, while the fibers seeing the left half continue to the right hemisphere. The overall result is that your left hemisphere only processes fibers that see the right field of your vision, and vice versa.
Basically all neural pathways cross over in this way and are processed on the opposite side; it’s thought to be an evolutionary remnant from when we evolved to have our spinal cords run along our backs instead of our bellies like bugs do. Some people already posted this, but there’s a structure called the corpus callosum that’s literally just made of nerve fibers crossing between the hemispheres of your brain.
You get some pretty funky symptoms if this structure is damaged — for example, if you closed your eyes and picked up a fork in your left hand, you wouldn’t be able to name it, because the right hemisphere processes sensation from the left side of the body, but the language center of the brain is in the left hemisphere. So you’d be able to feel that you had a metal object with tines in your hand, and you’d know that a metal object with tines is called a fork, but you wouldn’t be able to put the word and the sensation together.
First you have a misconception: Both sides of the brain get information from both eyes. The issue is that the sides of the *visual field* are split between halves of the brain.
The other part of the answer is that the two hemispheres communicate via the corpus callosum.
If I understand you correctly you’re asking about the corpus callosum. Its a nerve structure in your brain that bridges between the two hemispheres. If that is severed its actually possible to teach one side of the brain something and not the other.
L&R Optic nerves meet at the optic chiasm. At this point some of the nerve fibers from each eye (or nerve more accurately) cross over (some continue on w/o crossing) and supply both sides of the brain.
[https://en.wikipedia.org/wiki/Optic_chiasm](https://en.wikipedia.org/wiki/Optic_chiasm)
Latest Answers