By Traci Pedersen
October 23, 2018
People with dyslexia have difficulty decoding the text as they read, meaning they have trouble navigating between the visual form and sounds of a written language.
But a subset of dyslexics, known as “resilient dyslexics,” exhibit remarkably high levels of reading comprehension despite their decoding difficulties.
In a new study, researchers from Tel Aviv University (TAU) and University of California San Francisco identified the exact brain mechanism that accounts for the discrepancy between low decoding skills and high reading comprehension.
The findings, published in PLOS One, show that resilient dyslexics have a larger volume of gray matter in the part of the brain responsible for executive functions and working memory.
This specific region, the dorsolateral prefrontal cortex (DLPFC) of the left hemisphere, is known as the “air traffic controller” or “conductor” of the brain. Gray matter is the darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites.
In the study, the research team observed 55 English-speaking children aged 10-16 with a wide range of reading abilities; half were diagnosed with dyslexia. The children were scanned using magnetic resonance imaging (MRI), allowing the researchers to compare the mapped images of the participants’ brains with their reading skill results.
“We wanted to find whether the brain regions related to language or other regions were responsible,” said Dr. Smadar Patael of TAU’s Department of Communication Disorders. “We found that the region in the left frontal part of the brain known as left DLPFC was directly related to this discrepancy. DLPFC has been shown to be important for executive functions and cognitive controls.”
“We then sought to understand answer a ‘chicken or egg’ question related to dyslexia and the slight enlargement of this brain region,” Patael said. “Do resilient dyslexics have distinct brain structures that allow for better resiliency, or is their success in reading a result of compensation strategies that actually altered the density of neurons in a specific region of the brain?”
To answer this question, the researchers scanned 43 kindergartners, and then three years later tested the children’s reading abilities. The findings show that the density of neurons in the DLPFC predated mature reading ability and predicted the discrepancy, regardless of their initial reading abilities.
“This helps us to understand the brain and cognitive mechanisms these children utilize to enable them to do well despite their relative weakness in decoding. It may help us think about incorporating relatively new strategies into reading interventions,” said Professor Fumiko Hoeft, who is currently at the University of California San Francisco and starts as director of the University of Connecticut’s Brain Imaging Research Center this fall.
Patael added that a lot of the reading readiness curriculum in kindergarten is focused on learning sounds of letter and phonological awareness.
“Our research findings suggest new approaches that emphasize executive functions and working memory. If your child is entering first grade, practicing the alphabet may not be enough. Consider activities that require working memory, such as baking cakes and playing song and strategy games."
“These activities stimulate children’s working memory and may in time foster their ability to comprehend texts well,” said Patael.