HERITABILITY OF HUMAN BRAIN FUNCTIONING AS ASSESSED BY ELECTROENCEPHALOGRAPHY

To study the genetic and environmental contributions to individual dif ferences in CNS functioning, the electroencephalogram (EEG) was measur ed in 213 twin pairs age 16 years. EEG was measured in 91 MZ and 122 D Z twins. To quantify sex differences in the genetic architecture, EEG was measured in female and male same-sex twins and in opposite-sex twi ns. EEG was recorded on 14 scalp positions during quiet resting with e yes closed. Spectral powers were calculated for four frequency bands: delta, theta, alpha, and beta, Twin correlations pointed toward high g enetic influences for all these powers and scalp locations. Model fitt ing confirmed these findings; the largest part of the variance of the EEG is explained by additive genetic factors. The averaged heritabilit ies for the delta, theta, alpha, and beta frequencies was 76%, 89%, 83 %, and 86%, respectively. Multivariate analyses suggested that the sam e genes for EEG alpha rhythm were expressed in different brain areas i n the left and right hemisphere. This study shows that brain functioni ng, as indexed by rhythmic brain-electrical activity, is one of the mo st heritable characteristics in humans.