Genetic and Environmental Contributions to Regional Cortical Surface Area in Humans: A Magnetic Resonance Imaging Twin Study

Abstract

Cortical surface area measures appear to be functionally relevant and distinct in etiology, development, and behavioral correlates compared with other size characteristics, such as cortical thickness. Little is known about genetic and environmental influences on individual differences in regional surface area in humans. Using a large sample of adult twins, we determined relative contributions of genes and environment on variations in regional cortical surface area as measured by magnetic resonance imaging before and after adjustment for genetic and environmental influences shared with total cortical surface area. We found high heritability for total surface area and, before adjustment, moderate heritability for regional surface areas. Compared with other lobes, heritability was higher for frontal lobe and lower for medial temporal lobe. After adjustment for total surface area, regionally specific genetic influences were substantially reduced, although still significant in most regions. Unlike other lobes, left frontal heritability remained high after adjustment. Thus, global and regionally specific genetic factors both influence cortical surface areas. These findings are broadly consistent with results from animal studies regarding the evolution and development of cortical patterning and may guide future research into specific environmental and genetic determinants of variation among humans in the surface area of particular regions.

Structural MRI reveals cortical thinning in amyotrophic lateral sclerosis

“…Regional cortical volume (figure 2C) is the product of surface area (figure 2B) and average cortical thickness of a given region (figure 2A). Based on our findings, these two variables (thickness and surface area) are independent of each other, as also supported by previous studies on cortical morphology 31 32. Effects found with cortical volume are, therefore, diluted effects, caused either by changes in cortical thickness or surface area.…”

Investigating brain connectivity heritability in a twin study using diffusion imaging data

“…This is consistent with previous findings regarding the heritability of the GM volume and thickness in the frontal and temporal lobes (Eyler et al, 2011; Hulshoff Pol et al, 2006; Joshi et al, 2011; Thompson et al, 2001). The common genetic factor related to schizophrenia was also shown in the pre-frontal (Cannon et al, 2002), frontal and temporal cortices (Cannon et al, 1998, Markov et al, 2010).…”

Association of common genetic variants in GPCPD1 with scaling of visual cortical surface area in humans

“…E-mail: nschork@scripps.edu or amdale@ ucsd.edu. heritable (25-50%) (11,13). These studies reveal that genes have both global and regional effects on cortical surface area, which also seems to be true in mice.…”

“…Human twin studies have shown a significant genetic component to cortical volume (10)(11)(12) and surface area (>80% heritable) (13)(14)(15)(16), and the occipital proportion of cortex is also quite Conflict of interest statement: I.M. has received a speaker's honorarium from Janssen and AstraZeneca.…”