Genetic analysis of cortical sulci in 1,009 adults

Specific genetic loci related to differences in brain anatomy have recently been discovered through efforts of the ENIGMA consortium and others. Yet different neuroanatomical traits may have different genetic determinants, and their discovery may offer a deeper understanding of genetic factors that shape the human brain. To investigate the degree of genetic contributions to variability in sulcal measures — the fissures within the brain's surface — 1009 healthy young adult Australian twins and siblings were imaged with high-resolution 4-tesla MRI. Length, mean depth, surface area and fold openings for 60 sulci were measured for both hemispheres. We calculated the heritability for each sulcal measure (average h2∼0.3–0.4); genetic correlations determined if there was an overlapping genetic profile across hemispheres for the same trait, or if lateralized genetic influences were statistically distinguishable. In cases with no hemisphere-specific genetic influences, the heritability of the bilateral average was computed for greater stability.