Age and gender effects in EEG coherence: I. Developmental trends in normal children

Objective: This study investigated intra-hemispheric and inter-hemispheric EEG coherences as a function of age and gender in normal children. Methods: Two groups of 40 boys and 40 girls, each containing 8 normal children in each 1-year band from 8 to 12 years, participated. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intra-hemispheric electrode pairs (4 in each hemisphere), and 8 inter-hemispheric electrode pairs, within each of the delta, theta, alpha and beta bands. Results: There was consistent evidence of coherences developing across this age range, particularly in long-range intra- and inter-hemispheric electrode pairs. Coherences were larger in the left hemisphere than the right. Coherences also appeared to develop further in males than females, across several regions and frequency bands, suggesting that females lag males in this aspect of brain development. Conclusions: EEG coherences in normal children of this age range develop systematically with age. These developmental effects vary substantially with gender, brain region and frequency bands. Significance: The data reported here provide basic norms for coherence development in different brain regions in normal children.