The child's explanation for it's (very clever!!) question: Wouldn't it be faster when visual stimuli were processed in the frontal lobe? (shorter path).
I got this question during a talk about the brain at a Junior Science Café meeting. Does anyone know a good, child friendly answer?
Haha, that's a good one to respond! That will sure make the little boy think :)
One simple answer would be that our brains have evolved from back to front, so the back of the brain where we process visual information is very old (evolutionarily speaking) while front (where we think) is much newer. Thus animals were able to see long before they evolved to pose questions about brain organization.
Hard to believe you Brian... Because if I follow your explanation, we should have our eyes closer to our back head, with an enormous forehead over them. :-)))
Thanks, Laxman.
Philippe: You have to realize that vision does not just take place in the visual cortex. The visual cortex, being very new evolutionarily, is where higher order, complex vision takes place. But there is not just a single, straight pathway to the visual cortex. Rather, the axons from the eyes make many stops along the way to much deeper and older parts of the brain.
As you might imagine, vision in a simple creature such as a gastropod (slug) is not nearly as detailed or refined as it is in mammals. Early vision had inputs exclusively to unconscious, instinctual areas of the brain. So many of the first stops of the axons in the human brain are to these more primitive and much older areas. As the brain evolved, it developed layers. The cerebral cortex is the newest layer and is where the visual cortex is located. Thus the pathway from the eyes makes a number of stops a long the way for various levels of information processing before it ever makes it to the newer, occipital cortex region.
The different types of conscious vs. unconscious vision can be seen in cases of selective brain damage. For instance, there is a phenomenon called "blindsight" in humans that have suffered a stroke or trauma to the visual cortex, but not to other older visual processing centers in the brain. In these people, they are completely blind and have no vision. However, because the axons of they eyes and other visual brain regions are not damaged, these people still have instinctual response to objects. For instance, although they cannot see a ball, they will instinctually catch, or attempt to catch, a ball that is tossed toward their face. This phenomenon demonstrates the evolutionarily old and functional instinctive processing of the brain, while the newer, and conscious processing center of the brain (at the back of the brain) is damaged.
For more on the phenomenon of blindsight, see the Wikipedia article that I have provided a link to.
https://en.wikipedia.org/wiki/Blindsight
Stop shooting Brian! I was not serious. Just mimicing a 11 years old one !
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