Cross-Sectional Analysis of the Association Between Age and Corpus Callosum Size in Chimpanzees (Pan troglodytes)

The CC is the major white matter tract connecting the cerebral hemispheres and provides for interhemispheric integration of sensory, motor and higher-order cognitive information. The midsagittal area of the CC has been frequently used as a marker of brain development in humans. Vile report c,first investigation into the development of the corpus callosum and its regional subdivisions in chimpanzees (Pan troglodytes). Magnetic resonance images were collected from 104 chimpanzees (female n = 63, male = 41) ranging in age,from 6 years (pre-pubescent period) to 54 years (old age). Sustained linear growth was observed in the area of the CC subdivision of the genu; areas of the posterior midbody and anterior midbody displayes nonlinear growth during development. After adjusting for total brain size, we observed linear growth trajectories of the, total CC and CC subdivisions of the genu, posterior midbody isthumus and splenium, and nonlinear growth, trajectories of the rostral body and anterior midbody. These developmental patterns ore similar to the development the, CC in humans. As the growth curves of the CC mirrors growth seen in the percentage of white matter in humans, our results suggest chimpanzees show continued white matter development in regions related to cognitive development. (C) 2010 Wiley Periodicals, Inc. Dev 52: 133-141 2010.