Brains in Silicon
<p>Dec 19, 2007 11:22 AM
 
retina  .5% of the brains weight  =  1500 grams *.01 = 15 grams = 7 grams. note: the retina is 72% of a 22mm sphere. wiki.
The retina is an outgrowth of the brain.
100M photoreceptors and 1.2 million axons at its output.
 
3 feedforward cell classes (photorecep, bipolar cells and ganglion cells)
Two lateral networks (horizontal cells and amacrine cells)
 
80 different cells types in all;
why so much?
to create multiple neural representations of visual info, each capturing a unique piece of info embedded in the scene
and to convey it thru parallel paths.
 
page 15:  cones and rods fill 90% of the outer retina.  Only 5% of receptors are cones yet
thier aperures account for 40% of receptor area.  The fovea has only cones -
200,000 per mm2 - no rods.
 
Since rods are repons for night vision, humans develop a blind spot once light intensity falls.
CATS has rods in their foveas.
 
page 29  Retinal OUtput
 
 
 
 
 
 
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