EEG correlation topography in poor spellers

Twenty-three poor spellers (average age 13 years) and 21 matched controls were studied. The EEG from 6 derivations was quantified using Hjorth's parameters 'Activity' and 'Mobility,' from which product-moment correlations were calculated between derivations. Cross-correlations were analogously calculated from EEG amplitude values. In poor spellers higher Mobility local correlation indices (LCIs) occurred in the right fronto-central derivation during reading. Moreover, significantly more right hemisphere dominant Mobility LCIs were seen in the fronto-central regions during reading in poor spellers as well as in the groupings of prepubertal boys and neonatal risk cases. This seems to be the effect of a more right hemisphere dominant activation of the cortical regions during reading. During rest, poor spellers had a less posteriorly accentuated distribution of Activity and cross-correlations than controls, assumed to be the effect of different distributions of alpha activity in the two groups.