Genetic determination of EEG frequency spectra.

Abstract Simultaneous EEG samples were collected under four conditions in one session from 39 pairs of monozygotic and 27 pairs of dizygotic young adult twins of the same sex. The 3 min EEG samples were spectrum analyzed and root mean square differences between pairs of spectra were computed for the two twin samples and also for a group of unrelated pairs obtained from the same samples. Six parameters were defined to characterize the salient features of the individual spectra: delta, theta, alpha, beta, phi (alpha mid-frequency) and kappa (stability of alpha frequency). All six parameters Showed intra-class correlations of about 0.8 for the MZ twins and correlations near zero for the DZ pairs. Comparisons across conditions indicated that, with respect to EEG spectra, the MZ twins resembled their co-twins about 96% as much as they resembled themselves. Holding time and situation constant, most of the variance in the frequency characteristics of the EEG appears genetically determined.