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Posted: Sun Feb 21, 2016 5:03 pm
by particleman
Wiring topology: http://onlinelibrary.wiley.com/doi/10.1002/ar.20731/epdf

For vision the case is different. On the one hand the cross over keeps laterality consistent with the rest of the body. But more importantly, the optics of the eye reverse produce a reversed image on the retina. The optics reverse the horizontal on both eyes, so the center of the image is placed on the outside of both images. If the optic nerves did not switch sides there would be a jump in the perceived image: like a photo (upside down) cut in half and the left half placed to the right of the right half. The crossover rights the image order. It also brings together the nerves receiving the binocular overlap region of vision.

Re: nervous system crossover (hard question!)

Posted: Sat Apr 30, 2016 8:54 am
by claudepa
Hi
I discovered by chance (because of a temporary injury at the right arm) that for some activities I am ambidextrous. For instance I play with both hands in tennis (not only the now very general two hands backhand) . In competition this is even an advantage since it is a problem for some opponents and for lengthy matches my right arm is more spared. In the history of tennis some high level players (but not the best ones) were ambidextrous. I had to train to be efficient with the left arm but I remarked that my gestures of the left arm mimick in part gestures of the right one. I should be interested if both right and left arm are commanded from the same hemisphere. Do ambidextrous people have special known connections between both hemispheres.