A Genetic Perspective on the Developing Brain

Abstract

Changes in genetic and environmental influences on electroencephalographic (EEG) and event-related potential (ERP) indices of neural development were studied in two large cohorts of young (N = 418) and adolescent (N = 426) twins. Individual differences in these indices were largely influenced by genetic factors, and throughout development, the stable part of the variance was mainly genetic. Both EEG power (which describes the amount of variability in brain electrical potentials that can be attributed to different frequencies) and long-distance EEG coherence (which is the squared cross-correlation between two EEG signals at different scalp locations and can be regarded as an index for cortico-cortical connectivity) were highly heritable. ERP-P300 latencies and amplitudes were low to moderately heritable. Clear differences between young children and adolescents could be observed in the heritabilities of EEG and ERP indices. The heritabilities of EEG power and EEG coherence were higher in adolescents than in children, whereas the heritabilities of P300 latencies were lower. Both cohorts (young children and adolescents) were measured twice: The children were tested when they were 5 and again at 7 years, the adolescents when they were 16 and again at 18 years. Therefore, within these age ranges a more detailed analysis of age-related changes in heritabilities and in the emergence of new genetic influences could be studied. The heritabilities of EEG powers and P300 amplitudes and latencies did not change much from age 5 to age 7 and from age 16 to 18 years. The heritabilities of a substantial number of connections within the cortex, however, as indexed by EEG coherence, changed significantly from age 5 to age 7, though not from age 16 to 18. The only changes in the heritabilities in adolescents were connections within the prefrontal cortex, which is in agreement with theories of adolescent development. These age-related changes in the heritabilities may reflect a larger impact of maturation on cortico-cortical connectivity in childhood than in adolescence. Evidence was found for qualitative changes in brain electrophysiology in young children: New genetic factors emerged at age 7 for posterior EEG coherences and for P300 latency at some scalp locations. This supports theories of qualitative stage transitions in this age range, as previously suggested using behavioral and EEG data.