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Tag: dyslexia

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Published on 2 Comments on Is This A Cause of Dyslexia?

Another interesting theory about dyslexia, as well as a great treatment possibility. It is unknown if the study results will hold up with more research (after all, only 60 people were in the study - 30 with dyslexia and 30 without), and whether their suggested treatment really works for larger groups of dyslexics. But what if it helps?

Their main finding is that those who don't have dyslexia have  "asymmetry" in the light-receptor cells in the center of the eye, while dyslexics have symmetry which leads to the brain producing confusing mirror images of letters (e.g."b" and "d"). The researchers conclude that: "the lack of asymmetry might be the biological and anatomical basis of reading and spelling disabilities in people with a normal ocular status but with dyslexia". They found that a flashing LED lamp ("pulse-width modulation light-emitting diode") suppressed the mirror images in those with dyslexia and they could read normally ("restores reading skills"). So this research is definitely worth following. From Medical Xpress:

Scientists may have found a cause of dyslexia

A duo of French scientists said Wednesday 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 reading disability, 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. 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.

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 cornea 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.

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.

Dyslexic people make so-called "mirror errors" in reading, for example confusing the letters "b" and "d". ....The team used an LED lamp, flashing so fast that it is invisible to the naked eye, to "cancel" one of the images in the brains of dyslexic trial participants while reading. In initial experiments, dyslexic study participants called it the "magic lamp," said Ropars, but further tests are required to confirm the technique really works. [Original study.]

 

Cross-section of the human eye. Credit: Wikipedia

Published on

An interesting article that discusses research that finds advantages to being dyslexic. Perhaps think in terms of cognitive diversity. From Scientific American:

The Advantages of Dyslexia

With reading difficulties can come other cognitive strengths.

In our laboratory at the Harvard-Smithsonian Center for Astrophysics we have carried out studies funded by the National Science Foundation to investigate talents for science among those with dyslexia. The dyslexic scientist Christopher Tonkin described to me his sense of this as a sensitivity to “things out of place.”  He’s easily bothered by the weeds among the flowers in his garden, and he felt that this sensitivity for visual anomalies was something he built on in his career as a professional scientist.  Such differences in sensitivity for causal perception may explain why people like Carole Greider and Baruj Benacerraf have been able to perform Nobel prize-winning science despite lifelong challenges with dyslexia.

Why are there advantages in dyslexia?  Is it something about the brains of people with dyslexia that predisposes them to causal thinking? Or, is it a form of compensation, differences in the brain that occur because people with dyslexia read less? Unfortunately, the answer to these questions is unknown.

One thing we do know for sure is that reading changes the structure of the brain. An avid reader might read for an hour or more a day, day in and day out for years on end. This highly specialized repetitive training, requiring an unnaturally precise, split-second control over eye movements, can quickly restructure the visual system so as to make some pathways more efficient than the others.

My colleagues and I suggested that one reason people with dyslexia may exhibit visual talents is that they have difficulty managing visual attention⁠. It may at first seem ironic that a difficulty can lead to an advantage, but it makes sense when you realize that what we call “advantages” and “disadvantages” have meaning only in the context of the task that needs to be performed.

For example, imagine you’re looking to hire a talented security guard. This person’s job will be to spot things that look odd and out of place, and call the police when something suspicious —say, an unexpected footprint in a flowerbed— is spotted. If this is the person’s task, would you rather hire a person who is an excellent reader, who has the ability to focus deeply and get lost in the text, or would you rather hire a person who is sensitive to changes in their visual environment, who is less apt to focus and block out the world?

Tasks such as reading require an ability to focus your attention on the words as your eyes scan a sentence, to quickly and accurately shift your attention in sequence from one word to the next.  But, to be a good security guard you need an opposite skill; you need to be able to be alert to everything all at once, and though this isn’t helpful for reading, this can lead to talents in other areas.

A series of studies by an Italian team led by Andrea Facoetti have shown that children with dyslexia often exhibit impairments in visual attention. In one study,Facoetti’s team measured visual attention in 82 preschool children who had not yet been taught to read. The researchers then waited a few years until these children finished second grade, and then examined how well each child had learned reading. They found that those who had difficulty focusing their visual attention in preschool had more difficulty learning to read.

These studies raise the possibility that visual attention deficits, present from a very early age, are responsible for the reading challenges that are characteristic of dyslexia. If this theory is upheld, it would also suggest that the observed advantages are not an incidental byproduct of experience with reading, but are instead the result of differences in the brain that were likely present from birth.

If this is indeed the case, given that attention affects perception in very general ways, any number of advantages should emerge.  While people with dyslexia may tend to miss details in their environment that require an attentional focus, they would be expected to be better at noticing things that are distributed more broadly.  To put this another way, while typical readers may tend to miss the forest because its view is blocked by all the trees, people with dyslexia may see things more holistically, and miss the trees, but see the forest.

Among other advantages observed, Gadi Geiger and his colleagues at MIT found that people with dyslexia can distribute their attention far more broadly than do typical readers, successfully identifying letters flashed simultaneously in the center and the periphery for spacings that were much further apart. They also showed that such advantages are not just for things that are visual, but that they apply to sounds as well. In one study, simulating the sounds of a cocktail party, they found that people with dyslexia were able to pick out more words spoken by voices widely-distributed in the room, compared with people who were proficient readers.

Whether or not observations of such advantages —measured in the laboratory— have applications to talents in real life remains an open question. But, whatever the reason, a clear trend is beginning to emerge: People with dyslexia may exhibit strengths for seeing the big picture (both literally and figuratively) others tend to miss.  Thomas G. West has long-argued that out-of-the-box thinking is historically part and parcel of dyslexia, and more recently physicians Brock and Fernette Eide have advanced similar arguments. Sociologists, such as Julie Logan of the Cass Business School in London agree.  Logan found that dyslexia is relatively common among business entrepreneurs; people who tend to think differently and see the big picture in thinking creatively about a business.

Whatever the mechanism, one thing is clear: dyslexia is associated with differences in visual abilities, and these differences can be an advantage in many circumstances, such as those that occur in science, technology, engineering and mathematics. It’s only when everything is all the same that nothing productive can get done. Neurological differences similarly drive the engine of society, to create the contrasts between hot and cold that lead to productive work. Impairments in one area can lead to advantages in others, and it is these differences that drive progress in many fields, including science and math.