The Semantic System Supports the Processing of Mathematical Principles.

Although numerous studies have shown that brain regions around the intraparietal sulcus play an important role in general mathematical or numerical processing, little is known about the specific neural correlates for processing mathematical principles. In the present study, we compared the activation intensity, multi-voxel activation patterns, and functional connectivity (FC) related to processing mathematical principles (including arithmetic and logic) with those related to arithmetic. Twenty right-handed undergraduates (10 male; aged 18-25 years) participated in the study. Results of whole-brain univariate analysis showed that brain activity in the left angular gyrus (AG) was consistently stronger for mathematical principles than for computation. Multiple-voxel activation patterns at the left middle temporal gyrus (MTG) differed between mathematical principles and arithmetical computation. Additionally, psychophysiological interaction analysis showed that the functional connectivities between (1) the left middle temporal gyrus and the intraparietal sulcus, (2) left middle temporal gyrus and left inferior frontal cortex (IFG), and (3) the intraparietal sulcus (IPS) and left angular gyrus were consistently stronger for mathematical principles than for computation. As the AG, MTG and orbital part of IFG were key regions of the semantic system, these results provided direct evidence that the semantic system plays an important role in the processing of mathematical principles. Although numerous studies have shown that brain regions around the intraparietal sulcus play an important role in numerical processing, little is known about the specific neural correlates for processing mathematical principles. This study determined how processing mathematical principles differs from mathematical computation in the brain in terms of activity levels and functional connections. Results from the univariate, multi-voxel, and functional connectivity analyses consistently revealed that the left angular gyrus, left middle temporal gyrus, and left inferior frontal gyrus were more involved in the processing of mathematical principles than in computation. These regions are connected with the intraparietal sulcus, the core region involved in mathematical processing. As the AG, MTG and orbital part of IFG were key regions of the semantic system, these results provide direct evidence for a crucial role of the semantic system in the processing of mathematical principles.