Genetic Influences on Brain Architecture from Multivariate Diffusion Tensor Data

Introduction: In behavioral genetics and medical imaging, twin studies provide a powerful means to assess genetic influences on brain structure and function. Here we used DTI to provide detailed information on white matter fiber in 100 twins. We set out to estimate genetic and environmental contributions to the voxel-wise variance in several DTI-derived measures, to find the most heritable measures. To do this, we fitted an A/C/E structural equation model, using identical and fraternal twin pairs to determine variance components attributable to additive genetic (A), common environmental (C), and unique environmental factors (E) [4]. We computed A, C, and E using the Mx software [4] for ROI-based analyses, and wrote our own software for voxel-wise A/C/E analysis to visualize how each factor contributes to brain microstructure [3]. We expected to see greater influences of A on early-developing regions (occipital lobes), and greater influences of C on protracted maturing regions (frontal lobes).