Functional brain segregation changes during demanding mathematical task.

The neural basis of demanding mathematical problem solving is currently indeterminate and unclear. Mathematical problem solving engages higher order cognition and a complex associative activity of functional neural networks occurs during demanding problem solving. Twenty right handed subjects (mean age: 24.6 years; SD =3.97 years; 50% female) participated in this study. An arithmetic logic puzzle was used as a demanding mathematical task. EEGs were recorded in the eye open rest and eye open task conditions. To clarify functional connectivity of brain networks, clustering coefficient, transitivity, global efficiency, degree and entropy were investigated in two conditions. During problem solving, disrupted brain connectivity and decreased brain segregation were observed in the alpha band. However, in the beta band, increased connectivity, transitivity and clustering associated with higher modularity were observed. Theta exhibited unaltered brain network function. In the demanding problem solving task, decreased local alpha coupling may suggest that default mode network activity is interrupted. Since there is no significant difference within the theta network, the central executive network may not be as strongly involved. Increased segregation of functional brain network (without increasing of integration level) can be discussed in relation of demanding aspects of mathematical problem. We suggest a complex network may involve in the real situation of demanding problem solving.