Eye Works 2: Image: Retina, Optic Nerve and Brain

How the Eye Works 2. Vision. Recording the Image. Retina. Rods and Cones. Optic Nerve. Chiasm. Visual Cortex. Receptive Fields. C Blackwell MD. 2011.

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  Science & Technology

[Kelsey O'Neill]

I know this sounds dumb...but what if I saw 71 instead of 21 or 74??

[Craig Blackwell]

Not dumb. That illustration is just meant to show the concept. By the time the diagram has undergone several reproductions the color fidelity is not that accurate. The Ishihara plates are one of several methods to test color vision. At your next eye check you could ask your eye doctor to check.

[sadie1214]

I am a neuroscience student trying to learn the pathways of the eye and this is the only video that gave me a good, factually based, full picture of what is happening from retina to the primary visual cortex. Thank you so much, you have actually saved my grade for the semester.

[Craig Blackwell]

Glad that helped. If you are a neuroscience person and want a well-written discussion try David Hubel's book, Eye, Brain and Vision. It takes you deeper into the neuroscience, and how research is done. I believe it is accessible free on line.

[GroundZeroHiroshima]

When we see a mirror, the right side flipps to the left, but how come the up-side-down reversion does not occur?

I thought it happens because our two eyes are placed horizontally.

However, the result was the same even when I closed one eye

and tilted my head 90 degree and saw a mirrow like this ' )

Does someone know why?

[Craig Blackwell]

It's tricky, but you can sort it out if you draw a diagram and trace the path of the light rays. For example, the light rays from your feet are coming from below, reflecting about half way up the mirror. Your right eye is looking straight at your right eye. Sorry I can't draw it for you here.

(nonwithstanding Feynman's all pathways)

[GroundZeroHiroshima]

Ah-huh! Thank you so much. You are the first person who gave me the answer. Now I do not have to tilt my head 90 degree in front of the mirror any more.

[stylianos13]

beautiful

[Anup Ghimire]

nice work



[Craig Blackwell]

VC, it is a fascinating subject, and there is quite an extensive literature on the evolution of the eye from the most primitive light sensing structures. If you want to read about it, for starters search for researchers: D-E Nilsson, T Lamb, D Arendt, and J Nathans. Am hoping to do a video on that subject late in the year.

[Viktor Cheban]

The eye if so amazingly complex. I find it hard, honestly, to believe that this one structure could have possibly evolved in the short time span of a couple billion years. Just to have the mutations of the amino acids at the certain places to create the rod instead of another cell in the body, and then have that process repeat itself millions of times, all occurring in the right spots so that the rods aren't positioned before the ganglions. Blows my mind.