© 2018 by Janelle E. Letzen, PhD

 
Vision
What is the visual system?
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The visual system is quite a sight 👀. It's a group of cortical and subcortical brain regions, as well as our eyes, that allows us to receive and process sensory information in our environment in order to create our visual perception.

What are the parts of the visual system?

Let's start off with our visual field, or the total area that can be seen when we focus our eyes on a specific point. In this case, our eyes are focused on a distant mountain view. 

If we cut the mountain view down the middle, we have our left and right hemifields. Hemifields actually span about 170 degrees, giving you peripheral vision. 

The pieces of starfruit on the optic nerve represent information from your left hemifield. Ultimately, this information gets processed in the right side of your brain. Stimuli in your right hemifield (orange pepper) get processed in your left hemisphere.

 

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As visual information enters the retinas and passes through the optic nerve, information that initially enter through your "nasal retina" (i.e., nerves closer to your nose) cross at the optic chiasm. 

The signals then remain on their respective sides as they travel through the optic tract, thalamus (lateral geniculate nucleus), optic radians, and finally into visual cortex.

References

[1] Purves, D., Augustine, G. J., Fitzpatrick, D., Hall, W. C., LaMantia, A. S., McNamara, J. O., & White, L. E. (2008). Neuroscience. 4th. Sunderland, Mass.: Sinauer. xvii, 857, 944.

[2] Haines, D. E. (2004). Neuroanatomy: An atlas of structures, sections, and systems (Vol. 153, No. 2004). Lippincott Williams & Wilkins.