Quantitative eeg abnormalities in a sample of dyslexic persons

Abstract

Definitions of terms such as dyslexia and specific reading disability commonly recognize a basis in central nervous system dysfunction. Past research has related this dysfunction to both structural and neural timing abnormalities. The present study used QEEG findings to provide further evidence for neural timing/coherence abnormalities in reading disabled persons. Eight children and two adults were diagnosed with specific reading disability based on standard psychoeducational assessment. QEEGís were obtained from each using Lexicor Neurosearch 24 equipment, and analyzed using the Thatcher Life Span Reference Data Base. Standard print-outs depicting coherence, phase, amplitude asymmetry, and relative power abnormalities of each subject were inspected, and tallies made of the most frequently occurring significant deviations from the norms. The following abnormalities were found in 70% or more of the subjects: (1). abnormal coherence between one or more combination of sites P3, T5, T3, O1; (2) an equal to or greater than 1.4/1 ratio of left to right side coherence abnormalities; (3) coherence abnormalities between posterior sites more often involved decreased rather than increased coherence; (4) at least five abnormalities (or any type) involving site P3; (5) at least three abnormalities (coherence, phase, asymmetry) involving frontal/parietal sites. These data appear to have relevance for neurofeedback. Phase/coherence (neural timing) training and emphasis on site P3 may be especially useful in some cases of reading disability. © 1996, Taylor & Francis Group, LLC.