Abstract
Research on genetic and environmental influences on brain function generally focuses on connections between brain areas. A different yet unexplored approach is to examine activity within local brain regions. We investigated the influence of genes and environmental effects on two specific measures of local brain function: regional homogeneity and fractional amplitude of low-frequency fluctuations. Participants were drawn from a sample of adolescent twins on two occasions (mean ages 11.5 and 13.2 yr, n = 278 and 248). Results showed that genetic and environmental factors influenced brain function in almost all 210 cortical regions examined. Moreover, genetic and common environmental factors influencing regional homogeneity and fractional amplitude of low-frequency fluctuation values at wave 1 (9 to 14 yr) also influenced values at wave 2 (10 to 16 yr) for many regions. However, the influence of genetic and common environmental factors varied across the cortex, exhibiting different patterns in different regions. Furthermore, we found new (ie independent) genetic and environmental influences on brain activity at wave 2, again with regional patterns. Exploratory analyses found weak associations between anxiety and depressive symptoms and local brain function in several regions of the temporal lobe. These findings are consistent with similar studies of other resting-state functional MRI metrics (ie functional connectivity).