White matter microstructure correlates of mathematical giftedness and intelligence quotient

Abstract

Recent functional neuroimaging studies have shown differences in brain activation between mathematically gifted adolescents and controls. The aim of this study was to investigate the relationship between mathematical giftedness, intelligent quotient (IQ), and the microstructure of white matter tracts in a sample composed of math-gifted adolescents and aged-matched controls. Math-gifted subjects were selected through a national program based on detecting enhanced visuospatial abilities and creative thinking. We used diffusion tensor imaging to assess white matter microstructure in neuroanatomical connectivity. The processing included voxel-wise and region of interest-based analyses of the fractional anisotropy (FA), a parameter which is purportedly related to white matter microstructure. In a whole-sample analysis, IQ showed a significant positive correlation with FA, mainly in the corpus callosum, supporting the idea that efficient information transfer between hemispheres is crucial for higher intellectual capabilities. In addition, math-gifted adolescents showed increased FA (adjusted for IQ) in white matter tracts connecting frontal lobes with basal ganglia and parietal regions. The enhanced anatomical connectivity observed in the forceps minor and splenium may underlie the greater fluid reasoning, visuospatial working memory, and creative capabilities of these children.

Keywords: DTI; IQ; adolescents; corpus callosum; fractional anisotropy; fronto-parietal; intelligence; mathematical giftedness; white matter.

Figure 1

Atlas‐based parcellation method. On the left side, anatomically defined fibers in the ICBM‐DTI‐81 white matter labels atlas in MNI space. FA maps of each subject were registered to the template in MNI space. The transformation matrices obtained were inverted and applied to the atlas. On the right side, the resulting atlas transformation in the native space of each subject.

Figure 2

Correlation between FA and IQ in the voxel‐wise analysis. A: Correlation between FA and IQ in the corpus callosum and cingulum in the voxel‐wise analysis (P = 0.05 uncorrected). Significant clusters were overlaid on the mean FA image from all subjects. B: Correlation scatter‐plot from the atlas‐based parcellation with FA obtained from each part of the corpus callosum in native space. Math‐gifted subjects are represented in the graphs in red color circles; controls in blue.

Figure 3

Between‐group contrast in voxel‐wise analysis. The cluster shows significantly increased FA in the math‐gifted group compared with the controls (P < 0.05 corrected for multiple comparisons), after adjustment for IQ. Significant clusters are superimposed on the mean FA image in MNI space. The color bar shows the Z‐score for this contrast. Increased FA was observed bilaterally in the prefrontal lobes, cortico‐striatal tracts, and fronto‐parietal fasciculus in math‐gifted adolescents.

Figure 4

Between‐group differences in the atlas‐based parcellation analysis in native space. The graphs represent anatomical regions in which the math‐gifted group (in red) showed significantly more FA than controls (in blue), after adjustment for the potential effects of IQ.