A functional lesion in developmental dyslexia: left angular gyral blood flow predicts severity

Area of Science:

• Neuroscience
• Cognitive Psychology
• Developmental Disorders

Background:

• Dyslexia is associated with reduced regional cerebral blood flow (rCBF) in specific brain regions.
• The precise relationship between rCBF abnormalities and dyslexia severity remains unclear.

Purpose of the Study:

• To investigate the correlation between reading skill and rCBF in dyslexic individuals and controls.
• To identify specific brain regions where functional differences relate to dyslexia severity.

Main Methods:

• Functional imaging (rCBF measurement) during reading tasks and visual fixation.
• Correlation analysis between reading performance and rCBF in 17 dyslexic men and 14 controls.
• Comparison of functional patterns between dyslexic and control groups.

Main Results:

• The left angular gyrus showed a significant inverse correlation with reading skill in dyslexia (p <.01).
• In controls, higher rCBF in the left angular gyrus correlated positively with reading skill (p <.01).
• This region appears critical, facilitating reading in controls but impairing it in dyslexia.

Conclusions:

• The left angular gyrus is identified as a probable site of functional abnormality in developmental dyslexia.
• Dyslexia may involve altered reliance on the left angular gyrus, impacting reading ability.
• Findings suggest a shared neural basis between developmental dyslexia and alexia.