Ventral-Dorsal Brain Development in Children’s Symbolic and Nonsymbolic Number Processing: A Longitudinal Study from Kindergarten to Second Grade

Abstract

Numerical ability develops rapidly during early schooling and predicts important academic and life outcomes, yet how it develops in the different brain regions remains unclear. In particular, it remains poorly understood how symbolic number and nonsymbolic numerical processing develop and interact to support numerical cognition. In the present longitudinal fMRI study, we examined the neural development of symbolic and nonsymbolic number processing from kindergarten to second grade. Thirty-nine children who were included in the fMRI analyses were examined using functional regions of interest (fROIs) defined by a group-constrained subject-specific method. We extracted percent signal changes from individual fROIs to characterize developmental trajectories in symbolic and nonsymbolic number comparison tasks. Results showed distinct developmental patterns across ventral temporal regions and dorsal frontoparietal regions. Symbolic responses in ventral temporal cortex (VTC; inferior temporal numeral area) followed a consistent nonlinear trajectory across early schooling, with a transient reduction in first grade followed by an increase by second grade. In contrast, nonsymbolic responses in dorsal cortical regions were more heterogeneous across participants. Together, these findings suggest that symbolic number representation in VTC becomes more specialized during early schooling, whereas dorsal magnitude-related systems exhibit greater variability, with a few regions (right inferior frontal gyrus, right intraparietal sulcus) showing increasing specialization.