Thursday, January 7, 2010
Dyslexia Theories May Need To Be Changed
For many years now dyslexia researchers have assumed that the differences in brain activity and structure observed by fMRI scans between groups of dyslexics and non-dyslexics have been caused by dyslexia. I've never seen the question raised about whether these differences could be the result of dyslexia.
Granted, scanning many many babies to determine whether or not the babies have dyslexic brains and then retesting them later after school experiences would be an expensive time-consuming study. That would however help answer the question of whether or not the brain differences first existed in the babies or whether the normal readers were the ones that actually changed.
I've always been impressed with researchers that see unique opportunities to answer difficult questions in a much easier way.The following paragraph is from a story in the New York Times.http://www.nytimes.com/2010/01/03/magazine/03Braille-t.html?pagewanted=2&hpw
'Learning to read is so entwined in the normal course of child development that it is easy to assume that our brains are naturally wired for print literacy. But humans have been reading for fewer than 6,000 years (and literacy has been widespread for no more than a century and a half). The activity of reading itself alters the anatomy of the brain. In a report released in 2009 in the journal Nature, the neuroscientist Manuel Carreiras studies illiterate former guerrillas in Colombia who, after years of combat, had abandoned their weapons, left the jungle and rejoined civilization. Carreiras compares 20 adults who had recently completed a literacy program with 22 people who had not yet begun it. In M.R.I. scans of their brains, the newly literate subjects showed more gray matter in their angular gyri, an area crucial for language processing, and more white matter in part of the corpus callosum, which links the two hemispheres. Deficiencies in these regions were previously observed in dyslexics, and the study suggests that those brain patterns weren’t the cause of their illiteracy, as had been hypothesized, but a result.'
There have been studies about what is called brain plasticity showing that the dyslexic brain can become more like the non-dyslexic brain with reading interventions. That seems to be consistent with the above study.
I'm sure more studies need to be done to confirm that it is the literacy that actually changes the brain rather than dyslexia being a neurological brain difference at least as described by most dyslexia researchers today.
It's likely that the present-day thought is not totally off the mark. But it is also likely that the brain differences so often promoted as being the cause of dyslexia are not entirely correct.
My speculation is that there is an as yet unidentified noise filter function of the brain that makes reading more difficult and is what we call dyslexia. There's been recent research that certainly shows that a likely cause of the phonological processing problems of dyslexics is due to their difficulty separating out sounds in a noisy background. The mechanism behind the difficulty has yet to be discovered.
I have long promoted the concept of visual noise as the cause of visual dyslexia and also the mechanism by which my See Right Dyslexia Glasses remove those visual problems by filtering out the wavelengths of light that caused the visual noise.
For a generalized concept of auditory and visual noise generating the dyslexic's primary assorted problems it is probably best to consider it a higher sensitivity to the noise or a filtering problem.
In the final analysis, it looks like another paradigm of what causes dyslexia is going to be needed.