Near-Infrared Hemoencephalography for Monitoring Blood Oxygenation in Prefrontal Cortical Areas in Diagnosis and Therapy of Developmental Dyslexia

Abstract

The purpose of this study was to check empirically the relevance of the near-infrared hemoencephalography (NIR-HEG), which assesses local brain blood oxygenation, in facilitation of the diagnosis and behavioral therapy in dyslexics. The study was carried out in children and teenagers with physiologically recognized dyslexia, of three increasing age-groups: 6–7, 9–10, and 19–20 years old. Healthy age- and gender-matched subjects were used as controls. Left and right prefrontal cortical areas were targeted for the NIR-HEG measurements that were taken at baseline in both controls and dyslexics and then after a 10-day course of midriff breathing exercise combined with a standard vocal and writing training in dyslexics. The major finding was that in dyslexics, irrespective of age, the NIR-HEG indices were lower at baseline compared with those in healthy subjects. We further found that the indices improved after the respiratory and behavioral training in the youngest children, but not in the older age-groups. In conclusion, the study shows that deficient blood oxygenation in the prefrontal cortex is germane to shaping dyslexic symptoms in children. Cortical oxygenation improves in response to respiratory and behavioral therapy in a subset of young dyslexics. The NIR-HEG may facilitate the diagnosis of dyslexic disorder and the monitoring of behavioral therapy, particularly at early age.