Adolescents with learning disorders have atypical EEG correlation indices. II. Correlation indices during reading

Objective: To find out whether 14–16 year old reading and writing impaired pupils have atypical EEG activation patterns during reading. Methods: EEG correlation indices (EEGCIs), based on the waveform characteristics of two EEG signals, were used as measurers of slow joint activation of cortical regions during reading in pupils with reading and writing impairment. Results: Reading was associated with high EEGCIs within the right hemisphere in reading and writing impaired pupils. The finding is analogous to the results of an earlier study [Byring, Electroencephalogr. Clin. Neurophysiol. 63 (1986) 1] in boys with spelling disabilities. The activation in the right hemisphere might represent a compensation for a left hemisphere dysfunction in pupils with reading and writing impairment during reading, as suggested by a number of functional neuroimaging studies. This interpretation was corroborated by high EEGCIs especially in those impaired pupils who had a good occupational outcome. Conclusions: EEGCIs during reading are high within the right hemisphere in pupils with reading and writing impairment. Significance: High EEGCIs within the right hemisphere during reading might be considered neurophysiological markers for reading and writing impairment.