Dyslexia Disrupts Brain’s Network Connections The neurological reading disability dyslexia—the most commonly diagnosed learning disability in the United States—occurs when brain regions that process written language don’t function normally, according to a study published Sept. 1 in Biological Psychiatry. Improved understanding of brain organization in dyslexia could lead to better interventions. Most prior work has ... Research in Brief
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Research in Brief  |   November 01, 2014
Dyslexia Disrupts Brain’s Network Connections
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Language Disorders / Reading & Writing Disorders / Research in Brief
Research in Brief   |   November 01, 2014
Dyslexia Disrupts Brain’s Network Connections
The ASHA Leader, November 2014, Vol. 19, 14. doi:10.1044/leader.RIB2.19112014.14
The ASHA Leader, November 2014, Vol. 19, 14. doi:10.1044/leader.RIB2.19112014.14
The neurological reading disability dyslexia—the most commonly diagnosed learning disability in the United States—occurs when brain regions that process written language don’t function normally, according to a study published Sept. 1 in Biological Psychiatry. Improved understanding of brain organization in dyslexia could lead to better interventions.
Most prior work has focused on a small number of brain regions, leaving a gap in the understanding of how multiple brain regions communicate with one another through networks—called functional connectivity—in people with dyslexia.
Non-invasive functional neuroimaging tools have helped characterize how brain activity is disrupted in dyslexia. Neuroscience doctoral student Emily Finn and her colleagues at the Yale University School of Medicine used functional magnetic resonance imaging to conduct a whole-brain functional connectivity analysis of dyslexia.
They recruited and scanned 75 children (mean age 8.9) and 104 young adults (mean age 20.9) with dyslexia and compared the whole-brain connectivity profiles of the dyslexic readers to non-impaired readers.
Readers with dyslexia showed decreased connectivity within the visual pathway and between visual and prefrontal regions; increased right-hemisphere connectivity; reduced connectivity in the visual word-form area; and persistent connectivity to anterior language regions around the inferior frontal gyrus. This altered connectivity profile is consistent with dyslexia-related reading difficulties.
“Compared to typical readers, dyslexic readers had weaker connections between areas that process visual information and areas that control attention, suggesting that individuals with dyslexia are less able to focus on printed words,” Finn says.
Young-adult dyslexic readers also maintained high connectivity to brain regions involved in phonology, suggesting that they continue to rely on effortful “sounding out” strategies into adulthood rather than transitioning to more automatic, visual-based strategies for word recognition.
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November 2014
Volume 19, Issue 11