The Purpose of Our Eyes' Strange Wiring Is Unveiled
The reverse-wiring of the eyeball has long been a mystery, but new research shows a remarkable structural purpose: increasing and sharpening our color vision
March 18, 2015 |By Erez Ribak and The Conversation UK
The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
The human eye is optimised to have good colour vision at day and high sensitivity at night. But until recently it seemed as if the cells in the retina were wired the wrong way round, with light travelling through a mass of neurons before it reaches the light-detecting rod and cone cells. New research presented at a meeting of the American Physical Society has uncovered a remarkable vision-enhancing function for this puzzling structure.
Before arriving at the cones and rods, light must traverse the full thickness of the retina, with its layers of neurons and cell nuclei.
Credit: Riccardo Cuppini/Flickr
About a century ago, the fine structure of the retina was discovered. The retina is the light-sensitive part of the eye, lining the inside of the eyeball. The back of the retina contains cones to sense the colours red, green and blue. Spread among the cones are rods, which are much more light-sensitive than cones, but which are colour-blind.
Before arriving at the cones and rods, light must traverse the full thickness of the retina, with its layers of neurons and cell nuclei. These neurons process the image information and transmit it to the brain, but until recently it has not been clear why these cells lie in front of the cones and rods, not behind them. This is a long-standing puzzle, even more so since the same structure, of neurons before light detectors, exists in all vertebrates, showing evolutionary stability.
Researchers in Leipzig found that glial cells, which also span the retinal depth and connect to the cones, have an interesting attribute. These cells are essential for metabolism, but they are also denser than other cells in the retina. In the transparent retina, this higher density (and corresponding refractive index) means that glial cells can guide light, just like fibre-optic cables.
Read more here/Leia mais aqui: Scientific American
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NOTA CAUSTICANTE DESTE BLOGGER:
Queria ver a cara do Dawkins ao ler esta notícia na Scientific American falando de teleologia encontrada na visão humana. A Galera dos meninos e meninas de Darwin ficou desprovida de vez do argumento - um engenheiro inteligente não faria a retina desse jeito - visão reversa!
Queria ver a cara do Dawkins ao ler esta notícia na Scientific American falando de teleologia encontrada na visão humana. A Galera dos meninos e meninas de Darwin ficou desprovida de vez do argumento - um engenheiro inteligente não faria a retina desse jeito - visão reversa!
Fui, nem sei por que, rindo feliz da vida por ter sido vindicado mais uma vez por evolucionistas honestos que se rendem às evidências e relatam o que essas evidências dizem: Design Inteligente!!!
