Optic Nerve & Optical Chiasm
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 Optic nerves send electrical signals from each eye meet in the brain
at the optic chiasm. Here, the left visual from one eye is combined with the other eye
and the same goes for the right visual. Now the singals split again. The right visual
heads for the left brain and the left visual mamkes its way to the right side of the brain.
This way, visual messages from both eyes will reach both halves of the visual cortex. The
brain then merges the image into one image which you are looking out at the world with. This
parital crossing of the nerve fibers at the optic chiasm is the reason why we humans have
stereoscopic sight, also known as a field of depth. |
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| Lateral Geniculate
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From the optic chiasm, the signals reach the lateral geniculate, twin relay stations deep
in each hemisphere of the brain. There are some theories surrounding this area of the brain.
Some scientists think that the lateral geniculate does some coordination with other
sensory information since other sensory organs send signals to this destination as well.
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| Visual Cortex
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Most visual impulses will travel directly from the lateral geniculate nuclei to the
primiary visual cortex, also known as the striate cortex due to its many layers
forming a striped appearance. In the striate cortex lies our ability to detect
spatial organization of a scene, the shape of objects and their tone of shading.
THen from the striate cortex, some more nerve fiibers connect it to the prestriate,
also known as the secondary visual, cotex. It is believed that this area of the brain
decodes visual messages a a higher level than the striate's. The patterns, i.e. a
flower as a flower. From the prestriate cortex, visual signals enter the temporal lobes,
located near the side of the head, for further and perhaps even more sophisticated
processing. Any damage done to the visual sites in the temporal lobe can inhibit
visual learning. |
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