Lab of Medical Informatics, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
PLoS One. 2013 Aug 19;8(8):e71800. doi: 10.1371/journal.pone.0071800. eCollection 2013.
The two core systems of mathematical processing (subitizing and retrieval) as well as their functionality are already known and published. In this study we have used graph theory to compare the brain network organization of these two core systems in the cortical layer during difficult calculations. We have examined separately all the EEG frequency bands in healthy young individuals and we found that the network organization at rest, as well as during mathematical tasks has the characteristics of Small World Networks for all the bands, which is the optimum organization required for efficient information processing. The different mathematical stimuli provoked changes in the graph parameters of different frequency bands, especially the low frequency bands. More specific, in Delta band the induced network increases it's local and global efficiency during the transition from subitizing to retrieval system, while results suggest that difficult mathematics provoke networks with higher cliquish organization due to more specific demands. The network of the Theta band follows the same pattern as before, having high nodal and remote organization during difficult mathematics. Also the spatial distribution of the network's weights revealed more prominent connections in frontoparietal regions, revealing the working memory load due to the engagement of the retrieval system. The cortical networks of the alpha brainwaves were also more efficient, both locally and globally, during difficult mathematics, while the fact that alpha's network was more dense on the frontparietal regions as well, reveals the engagement of the retrieval system again. Concluding, this study gives more evidences regarding the interaction of the two core systems, exploiting the produced functional networks of the cerebral cortex, especially for the difficult mathematics.
两个核心的数学处理系统（数量直觉和检索）及其功能已经为人所知并发表。在这项研究中，我们使用图论来比较在计算困难时皮质层中这两个核心系统的大脑网络组织。我们分别检查了健康年轻人的所有 EEG 频段，发现静息时以及进行数学任务时，所有频段的网络组织都具有小世界网络的特征，这是有效信息处理所需的最佳组织。不同的数学刺激会引起不同频段的图参数发生变化，特别是低频带。更具体地说，在 Delta 频段中，在从数量直觉系统到检索系统的过渡过程中，诱导的网络会增加其局部和全局效率，而结果表明，由于更具体的需求，困难的数学会引起具有更高聚类组织的网络。Theta 频段的网络遵循相同的模式，在进行困难的数学时具有高节点和远程组织。此外，网络权重的空间分布揭示了额顶区域更突出的连接，这反映了由于检索系统的参与而产生的工作记忆负荷。困难的数学也会使大脑 alpha 脑波的皮质网络更有效，无论是局部还是全局，而 alpha 网络在额顶区域更加密集的事实再次揭示了检索系统的参与。总之，这项研究通过利用大脑皮质产生的功能网络，为两个核心系统的相互作用提供了更多的证据，特别是对于困难的数学。
