Articles

Genetic Contributions to the Midsagittal Area of the Corpus Callosum

Kimberley A. Phillips^a1a2a3 c1, Jeffrey Rogers^a4, Elizabeth A. Barrett^a1, David C. Glahn^a5 and Peter Kochunov^a2a6a7

^a1 Department of Psychology, Trinity University, San Antonio, Texas, USA

^a2 Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA

^a3 Texas Biomedical Research Institute, San Antonio, Texas, USA

^a4 Baylor College of Medicine and Southwest National Primate Research Center, Human Genome Sequencing Center, Houston, Texas, USA

^a5 Yale University, New Haven, Connecticut, USA

^a6 Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA

^a7 Department of Physics, University of Maryland, Baltimore, Maryland, USA

Abstract

The degree to which genes and environment determine variations in brain structure and function is fundamentally important to understanding normal and disease-related patterns of neural organization and activity. We studied genetic contributions to the midsagittal area of the corpus callosum (CC) in pedigreed baboons (68 males, 112 females) to replicate findings of high genetic contribution to that area of the CC reported in humans, and to determine if the heritability of the CC midsagittal area in adults was modulated by fetal development rate. Measurements of callosal area were obtained from high-resolution MRI scans. Heritability was estimated from pedigree-based maximum likelihood estimation of genetic and non-genetic variance components as implemented in Sequential Oligogenic Linkage Analysis Routines (SOLAR). Our analyses revealed significant heritability for the total area of the CC and all of its subdivisions, with h² = .46 for the total CC, and h² = .54, .37, .62, .56, and .29 for genu, anterior midbody, medial midbody, posterior midbody and splenium, respectively. Genetic correlation analysis demonstrated that the individual subdivisions shared between 41% and 98% of genetic variability. Combined with previous research reporting high heritability of other brain structures in baboons, these results reveal a consistent pattern of high heritability for brain morphometric measures in baboons.

(Received May 27 2011)

(Accepted November 04 2011)

Keywords:

• corpus callosum;
• heritability;
• baboons;
• genetics;
• imaging

Correspondence:

^c1 address for correspondence: Kimberley A. Phillips, Department of Psychology, Trinity University, 1 Trinity Place, San Antonio TX 78212. E-mail: Kimberley.Phillips@Trinity.edu