Eeg during Reading

EEGs of extensively screened dyslexics and normal rcadcrs were recorded while they read easy and difficult texts silently and orally, and during two other verbal tasks which also differed in overt spcaking but had m~ reading component: narrative speaking and listening to a story. Mid-temporal, central and parietal leads were referenced to linkcd ears and to ('z. Largc differences bctwecn tasks and between groups were found. With the linked ears reference, power was higher in all bands in oral reading than in silcnl rcading, with the largest change occurring in the temporal leads. In the theta and low beta bands the difference between oral and silent reading was greater for controls than for dyslexics. These effects were not accounted for by differences in reading speed or in difficulty. Similar results wcrc found in two cohorts of subjects. The difference between groups in theta was flmnd only in the reading tasks. In contrast, the group difference in low beta was also found in the change from listening to speaking. This implies that the oral-silent group difference in theta is related to some aspect of the reading tasks other than the presence or absence of overt speaking, and that the low beta group difference is related to some aspect of overt speaking rather than to reading per so. With the Cz reference no group differences were found. It is suggested that the groups differ in the reading strategies they usc, and the degree to which they shift strategy between the silent and oral tasks. We hypothesize that these cognitive differences are reflected in thc thcta activity from the temporal lobe. While there were many differences between the tasks in alpha powcr and assyn'mlch),, no group differences inw)lving alpha were found.