Effective Connectivity of the Fronto-Parietal Network during the Tangram Task in a Natural Environment.

Although the neural basis underlying visuospatial reasoning has been widely explored by neuroimaging techniques, the brain activation patterns during naturalistic visuospatial reasoning such as tangram remains unclear. In this study, the directional functional connectivity of fronto-parietal networks during the tangram task was carefully inspected by using combined functional near-infrared spectroscopy (fNIRS) and conditional Granger causality analysis (GCA). Meanwhile, the causal networks during the traditional spatial reasoning task were also characterized to exhibit the differences with those during the tangram task. We discovered that the tangram task in a natural environment showed enhanced activation in the fronto-parietal regions, particularly the frontal cortex. In addition, a strong directional connectivity from the right prefrontal cortex to left angular gyrus was detected for the complex spatial reasoning condition of spatial reasoning task, whereas no effective connectivity was identified between the frontal and parietal cortices during the tangram task. Further correlation analyses showed that the behavioral performance in the spatial reasoning rather than the tangram task manifested the relationship with the connectivity between the frontal and parietal cortex. Our findings demonstrate that the tangram task measures a different aspect of the visuospatial reasoning ability which requires more trial-and-error strategies and creative thinking rather than inductive reasoning. In particular, the frontal cortex is mostly involved in tangram puzzle-solving, whereas the interaction between frontal and parietal cortices is regulated by the hands-on experience during the tangram task.

Causal Cortical Network for Arithmetic Problem-Solving Represents Brain's Planning Rather than Reasoning.

Arithmetic problem-solving whose components mainly involve the calculation, planning and reasoning, is an important mathematical skill. To date, the neural mechanism underlying arithmetic problem-solving remains unclear. In this study, a scheme that combined a novel 24 points game paradigm, conditional Granger causality analysis, and near-infrared spectroscopy (fNIRS) neuroimaging technique was developed to examine the differences in brain activation and effective connectivity between the calculation, planning, and reasoning. We discovered that the performance of planning was correlated with the activation in frontal cortex, whereas the performance of reasoning showed the relationship with the activation in parietal cortex. In addition, we also discovered that the directional effective connectivity between the anterior frontal and posterior parietal cortex was more closely related to planning rather than reasoning. It is expected that this work will pave a new avenue for an improved understanding of the neural underpinnings underlying arithmetic problem-solving, which also provides a novel indicator to evaluate the efficacy of mathematical education.