Brain imaging study eliminates differences in visual function as a cause of dyslexia

Posted By News On June 6, 2013 - 4:31pm

WASHINGTON — A new brain imaging study of dyslexia shows that differences in the visual system do not cause the disorder, but instead are likely a consequence. The findings, published today in the journal Neuron, provide important insights into the cause of this common reading disorder and address a long-standing debate about the role of visual symptoms observed in developmental dyslexia.

Dyslexia is the most prevalent of all learning disabilities, affecting about 12 percent of the U.S. population. Beyond the primarily observed reading deficits, individuals with dyslexia often also exhibit subtle weaknesses in processing visual stimuli. Scientists have speculated whether these deficits represent the primary cause of dyslexia, with visual dysfunction directly impacting the ability to learn to read. The current study demonstrates that they do not.

"Our results do not discount the presence of this specific type of visual deficit," says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC) and past-president of the International Dyslexia Association. "In fact our results confirm that differences do exist in the visual system of children with dyslexia, but these differences are the end-product of less reading, when compared with typical readers, and are not the cause of their struggles with reading."

The current study follows a report published by Eden and colleagues in the journal Nature in 1996, the first study of dyslexia to employ functional Magnetic Resonance Imaging (fMRI). As in that study, the new study also shows less activity in a portion of the visual system that processes moving visual information in the dyslexics compared with typical readers of the same age.

This time, however, the research team also studied younger children without dyslexia, matched to the dyslexics on their reading level. "This group looked similar to the dyslexics in terms of brain activity, providing the first clue that the observed difference in the dyslexics relative to their peers may have more to do with reading ability than dyslexia per se," Eden explains.

Next, the children with dyslexia received a reading intervention. Intensive tutoring of phonological and orthographic skills was provided, addressing the core deficit in dyslexia, which is widely believed to be a weakness in the phonological component of language. As expected, the children made significant gains in reading. In addition, activity in the visual system increased, suggesting it was mobilized by reading.

The researchers point out that these findings could have important implications for practice. "Early identification and treatment of dyslexia should not revolve around these deficits in visual processing," says Olumide Olulade, PhD, the study's lead author and post-doctoral fellow at GUMC. "While our study showed that there is a strong correlation between people's reading ability and brain activity in the visual system, it does not mean that training the visual system will result in better reading. We think it is the other way around. Reading is a culturally imposed skill, and neuroscience research has shown that its acquisition results in a range of anatomical and functional changes in the brain."

The researchers add that their research can be applied more broadly to other disorders. "Our study has important implications in understanding the etiology of dyslexia, but it also is relevant to other conditions where cause and consequence are difficult to pull apart because the brain changes in response to experience," explains Eden.

Our work when working at the bio behavioral science dept. at UCONN and looking at n=1120 subjects identified 16 different four sighting patterns. This was looking at two right hand and two left handed sightings. First was pointing to target with right and left and then using a circle made with the thumb and middle finger sighting right and left. This was starting with both eyes open and then closing one at a time. (Exception being 4 left sightings n= 133 n=13% LD) When the first circle right/left sighting came up with two left sightings, n=59 almost 25% of the population were LD identified. When the first sighting came up as right/left on the point test, there were almost no LD. When r/l, r/l and r/l,l/l and r/l/r/r/ was displayed, there was almost no LD. n=103 However r/l/ l/r produced 17% LD n= 17. Anyone wishing to see the complete chart can contact me at the email address above. This could help identify some of the reasons for the above information.

This comment needs to be eliminated. A mistake was made. The first pattern was performed with the circle test and not the point test. We theorize that the wrist position as well as the laterality is causing some of the change of dominance happenings. The information in the second post is correct.

Our work when working at the bio behavioral science dept. at UCONN and looking at n=1120 subjects identified 16 different four sighting patterns. This was looking at two right hand and two left handed sightings. First hand position was using a circle made with the thumb and middle finger sighting right and left. The second position was pointing to target with right and then the left. This was starting with both eyes open and then closing one at a time. When the first circle right/left sighting came up with two left sightings, n=59 almost 25% of the population were LD identified. (Exception being 4 left sightings n= 133 n=13% LD) When the first sighting came up as right/left on the point test, there were almost no LD. When r/l, r/l and r/l,l/l and r/l/r/r/ was displayed, there was almost no LD. n=103 However r/l/ l/r produced 17% LD n= 17. Anyone wishing to see the complete chart can contact me at the email address above. This could help identify some of the reasons for the above information. The test for the procedure can be found in a paper published on line. Psychology
2012. Vol.3, No.1, 36-44
January 2012 in SciRes (http://www.SciRP.org/journal/psych) DOI:10.4236/psych.2012.31006
Physical and Behavioral Markers Help Identify Written Language
Disability (WLD) Related to Attention Deficit Hyperactivity
Disorder (ADHD)

Read:  http://acascipub.com/World%20Journal%20of%20Psychology%20Research/Current%20Issues.php
For more information regarding visual dominance difference and LD connection

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