Corpus callosum morphology and intelligence

Abstract

The corpus callosum is the largest fibre tract in the human brain and connects homologous areas of the left and right cerebral hemispheres. The corpus callosum plays an important role in integrating information between the cerebral hemispheres, and is thought to contribute to the allocation of attention between the hemispheres and in maintaining hemispheric arousal. Recently, the size of posterior regions of the corpus callosum has been found to be related to intelligence in a group of healthy adults (Luders et al., 2007) with larger callosal area related to higher intelligence. The current study investigated the relationship between the morphology of the corpus callosum and IQ in a sample of individuals in their late teens and early 20s because recent evidence suggests that maturation of white matter tracts continues through the 20s (Barnea-Goraly et al., 2005; Sowell et al., 2003). Area measurements of seven sub-sections of the corpus callosum, as defined by Witelson (1989), were obtained at the midsagittal slice and correlated with Wechsler Abbreviated Scale of Intelligence scores, while controlling for overall brain volume. The relationship between IQ and callosal size held for individuals in this age range as well, providing further evidence for the relationship between callosal morphology and cognitive task performance.