Genetic variation of individual alpha frequency (IAF) and alpha power in a large adolescent twin sample

To further clarify the mode of genetic transmission on individual alpha frequency (IAF) and alpha power, the extent to which individual differences in these alpha indices are influenced by genetic factors were examined in a large sample of adolescent twins (237 MZ, 282 DZ pairs; aged 16). EEG was measured at rest (eyes closed) from the right occipital site, and a second EEG recording for 50 twin pairs obtained approximately 3 months after the initial collection, enabled an estimation of measurement error. Analyses confirmed a strong genetic influence on both IAF (h(2)=0.81) and alpha power (h(2)=0.82), and there was little support for non-additive genetic (dominance) variance. A small but significant negative correlation (-0.18) was found between IAF and alpha power, but genetic influences on IAF and alpha power were largely independent. All non-genetic variance was due to unreliability, with no significant variance attributed to unique environmental factors. Relationships between the alpha and IQ indices were also explored but were generally either non-significant or very low. The findings confirm the high heritability for both IAF and alpha power, they further suggest that the mode of genetic transmission is due to additive genetic factors, that genetic influences on the underlying neural mechanisms of alpha frequency and power are largely specific, and that individual differences in alpha activity are influenced little by developmental plasticity and individual experiences.