Structural and Functional Neural Correlates of Non-Symbolic Numerical Magnitude Processing and Mathematical Competency using VBM and fMRI
Freitag, Gabrielle Felice
The development of mathematical competence is an important predictor of academic achievement and later economic success. To date, many studies have explored the association between task-related functional activation and numerical magnitude processing, and few studies have looked at the role of gray matter volume on mathematical ability. However, the overlap between functional and structural correlates of math competence is unknown. The present study serves to address this gap in the literature by studying a sample of 40 typically developing 3rd and 4th grade children using two modalities: 1) functional magnetic resonance imaging (fMRI) to examine neural activation during a non-symbolic number comparison task and its relation to math ability, and 2) voxel-based morphometry to analyze the relation between gray matter volume and math competence. Functional analyses revealed that the right middle frontal gyrus, right inferior frontal gyrus, right IPS, and right posterior-medial frontal gyrus were more active for difficult, large ratio trials. In contrast, the left middle temporal gyrus, left inferior parietal lobe, and right angular gyrus demonstrated greater activity for easy, small ratio trials. After controlling for verbal IQ, the ratio effect negatively correlated with WCJ III math composite scores in only the left primary visual cortex, such that lower math scores were associated with a larger ratio effect. Structural analyses revealed a positive correlation between math competence and gray matter volume in the right inferior middle occipital gyri when controlling for verbal IQ. Together, these results support the notion that performance on the non-symbolic task relates to math competence, ratio-dependent neural activity correlates with individual differences in math ability, and that increased gray matter volume may support functional activity that gives rise to mathematical processing.