Key environmental effects on the developing functional connectome: a 3T resting-state fMRI study on young twins

Abstract The brain intrinsic organization into large-scale functional networks, the resting state networks (RSN), shows a complex inter-individual variability, consolidated during development. Nevertheless, the role of genetic and environmental factors on developmental brain functional connectivity (FC) remains largely unknown. Twin design represents an optimal platform to shed light on these effects acting on RSN characteristics. In this study, we applied statistical twin methods to resting-state functional magnetic resonance imaging (rs-fMRI) scans from 50 young twin pairs (age range 10-30 years) to explore developmental determinants of brain FC. FC features at multiple spatial scales were extracted and tested for applicability of classical ACE and ADE twin design. Epistatic genetic effects were also assessed. In our sample, genetic and environmental effects on the brain functional connections largely varied between brain regions and FC features, showing good consistency at multiple spatial scales. Although we found selective contributions of common environment on temporo-occipital connections and of genetics on frontotemporal connections, the predominant effect on FC link- and node-level features was related to unique environment. Our results showed that developmental age is characterized by complex relationships between genetic and environmental factors and functional brain connections, suggesting a predominant role of unique environment on multi-scale RSN characteristics.