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Possible physiological reason for dyslexia
marymary100 - 18-10-2017 at 15:38

Guardian




Quote:

French scientists claim they may have found a physiological, and seemingly treatable, cause for dyslexia hidden in tiny light-receptor cells in the human eye.
In people with the condition, the cells were arranged in matching patterns in both eyes, which may be to blame for confusing the brain by producing “mirror” images, the co-authors wrote in the journal Proceedings of the Royal Society B.

Jamie Oliver is right: people with dyslexia really do look at things differently
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In non-dyslexic people, the cells are arranged asymmetrically, allowing signals from the one eye to be overridden by the other to create a single image in the brain.
“Our observations lead us to believe that we indeed found a potential cause of dyslexia,” said the study’s co-author, Guy Ropars, of the University of Rennes.
It offers a “relatively simple” method of diagnosis, he added, by simply looking into a subject’s eyes.
Furthermore, “the discovery of a delay (of about 10 thousandths of a second) between the primary image and the mirror image in the opposing hemispheres of the brain, allowed us to develop a method to erase the mirror image that is so confusing for dyslexic people” – using an LED lamp.
Like being left- or right-handed, human beings also have a dominant eye. As most of us have two eyes, which record slightly different versions of the same image, the brain has to select one of the two, creating a “non-symmetry”.
Many more people are right-eyed than left, and the dominant eye has more neural connections to the brain than the weaker one. Image signals are captured with rods and cones in the eye – the cones being responsible for colour.
The majority of cones, which come in red, green and blue variants, are found in a small spot at the centre of the retina of the eye known as the fovea. But there is a small hole (about 0.1-0.15 millimetres in diameter) with no blue cones.
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In the new study, Ropars and colleague Albert le Floch spotted a major difference between the arrangement of cones between the eyes of dyslexic and non-dyslexic people enrolled in an experiment.
In non-dyslexic people, the blue cone-free spot in one eye – the dominant one, was round and in the other eye unevenly shaped. In dyslexic people, both eyes have the same, round spot, which translates into neither eye being dominant, they found.
“The lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities,” said the study’s authors.



It's only one of the possible causes but an interesting one as it will be more easily treatable than the intensive reading recovery programmes. It may also explain why some do better with coloured filters.


Nimuae - 18-10-2017 at 21:41

That is really interesting - thank you.

Never thought of being R or L eyed! I am left footed and was left handed until 11yrs old - then the nuns got me!!


LSemmens - 18-10-2017 at 23:50

They missed your eyes :D

Dominance makes a lot of sense. It would explain why various filters can assist dyslexic people. I'm also wondering if such an anomaly could be 'trained' to the person's advantage. Given that they have no dominant eye, I wonder if they could be "trained" to get a higher quality resolution when observing objects. It might work, say in a surgeon performing microsurgery where a better image would be resented to the brain of the area under consideration. Sort of like a stereo microscope.


John_Little - 19-10-2017 at 08:20

Good news for many who must have wondered what it was,all about. Even better that they may be able to fix it.