Electrocortical frequencies in hyperactive, learning-disabled, mixed, and normal children.

Ten boys in each of four groups (hyperactive, learning-disabled, hyperactive/learning-disabled or mixed, and normal) were exposed to a complex visual search task. EEGs were recorded at central and parietal sites, 1-sec prestimulus and 1-sec poststimulus onset, on three types of trials. The resulting wave forms, averaged over trials, were converted to the frequency domain via a fast Fourier transform and factored by principal components. Four components accounting for 87% of the variance were varimax-rotated. Analyses of variance of the component scores revealed that Component 1 differentiated the four groups of boys. This component had highest loadings in frequencies from 16 to 20 Hz and secondary loading in frequencies from 7 to 10 Hz. It was concluded that this multifrequency component is sensitive to parameters deficient in hyperactive and learning-disabled children.