OBJECTIVE: Previous studies have been inconclusive whether dominant resting state alpha rhythms differ in amplitude in dyslexic subjects when compared to control subjects, being these rhythms considered as a reflection of effective cortical neural synchronization and cognition. Here we used a validated EEG source estimation to test the hypothesis that resting state alpha rhythms are abnormal in dyslexic subjects and are related to reading deficits. METHODS: Eyes-closed resting state electroencephalographic (EEG) data were recorded in 26 dyslexics (12 males, mean age of 11 years ± 0.5 standard error of mean, SEM) and 11 age-matched normal control subjects (8 males, mean age of 11 years ± 0.7 SEM). EEG rhythms of interest, based on individual alpha frequency peak, were the following: about 2-4 Hz (delta), 4-6 Hz (theta), 6-8 Hz (alpha 1), 8-10 Hz (alpha 2), and 10-12 Hz (alpha 3). For the higher frequencies, we selected beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). Cortical EEG sources were estimated by low resolution electromagnetic tomography (LORETA). LORETA solutions were normalized across all voxels and frequencies. RESULTS: Compared to the control children, the dyslexics showed lower amplitude of parietal, occipital, and temporal alpha 2 and alpha 3 sources. In the dyslexics, some of these sources were correlated to reading time of pseudo-words (parietal alpha 2, r=-0.56, p=0.02; parietal alpha 3, r=-0.58, p=0.02; temporal alpha 3, r=-0.57, p=0.02); the higher the alpha power, the shorter the reading time. CONCLUSIONS: Dyslexic children are characterized by limited abnormalities of resting state EEG rhythms as to topography (posterior regions) and frequency (alpha), which were related to phonological encoding (pseudo-words reading). SIGNIFICANCE: Dyslexia may be associated to some functional impairment of cortical neuronal synchronization mechanisms involved in the resting state condition.
OBJECTIVE: Previous studies have been inconclusive whether dominant resting state alpha rhythms differ in amplitude in dyslexic subjects when compared to control subjects, being these rhythms considered as a reflection of effective cortical neural synchronization and cognition. Here we used a validated EEG source estimation to test the hypothesis that resting state alpha rhythms are abnormal in dyslexic subjects and are related to reading deficits. METHODS: Eyes-closed resting state electroencephalographic (EEG) data were recorded in 26 dyslexics (12 males, mean age of 11 years ± 0.5 standard error of mean, SEM) and 11 age-matched normal control subjects (8 males, mean age of 11 years ± 0.7 SEM). EEG rhythms of interest, based on individual alpha frequency peak, were the following: about 2-4 Hz (delta), 4-6 Hz (theta), 6-8 Hz (alpha 1), 8-10 Hz (alpha 2), and 10-12 Hz (alpha 3). For the higher frequencies, we selected beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). Cortical EEG sources were estimated by low resolution electromagnetic tomography (LORETA). LORETA solutions were normalized across all voxels and frequencies. RESULTS: Compared to the control children, the dyslexics showed lower amplitude of parietal, occipital, and temporal alpha 2 and alpha 3 sources. In the dyslexics, some of these sources were correlated to reading time of pseudo-words (parietal alpha 2, r=-0.56, p=0.02; parietal alpha 3, r=-0.58, p=0.02; temporal alpha 3, r=-0.57, p=0.02); the higher the alpha power, the shorter the reading time. CONCLUSIONS: Dyslexic children are characterized by limited abnormalities of resting state EEG rhythms as to topography (posterior regions) and frequency (alpha), which were related to phonological encoding (pseudo-words reading). SIGNIFICANCE: Dyslexia may be associated to some functional impairment of cortical neuronal synchronization mechanisms involved in the resting state condition.
Authors: Gorka Fraga González; Dirk J A Smit; Melle J W van der Molen; Jurgen Tijms; Cornelis Jan Stam; Eco J C de Geus; Maurits W van der Molen Journal: Front Hum Neurosci Date: 2018-08-30 Impact factor: 3.169
Authors: Giuseppina Schiavone; Klaus Linkenkaer-Hansen; Natasha M Maurits; Anna Plakas; Ben A M Maassen; Huibert D Mansvelder; Aryan van der Leij; Titia L van Zuijen Journal: Front Hum Neurosci Date: 2014-09-19 Impact factor: 3.169