Characteristics of Spatial Synchronization of Encephalograms in Left- and Right-Handed Subjects in Resting State and During Cognitive Testing: a Graph-Theory Analysis

Hand preference is one of the most striking manifestations of functional brain asymmetry. However, the nature of the phenomenon, as well as its interaction with other brain functions has not been fully understood. Therefore, the study of brain peculiarities of left- and right-handed subjects by neuronal network analysis is of particular interest.

The aim of the investigation was to analyze brain network structures according to electroencephalography findings in left- and right-handed subjects in resting state and during cognitive testing (memorizing) using a graph theory.

Materials and Methods. 44 volunteers (20 left-handed, 24 right-handed) took part in the experiment. We used three techniques to calculate the degree of spatial synchronization of EEG-signals: coherence, an imaginary part of coherence, and synchronization likelihood. On basis of the obtained graphs we built minimum spanning trees (MST) and calculated some of their characteristics.

Results. Left-handers compared to right-handers were found to have more linear MST in theta band (coherence-based MST). Memorizing was characterized by the increase of MST regularity structure in alpha band for all three signal measures (coherence, an imaginary part of coherence, and synchronization likelihood). And only right-handers showed the increase in regularity for MST built on the basis of synchronization likelihood and imaginary part of coherence. Regularity increase in alpha band for coherence-based MST was not associated with handedness. Thus, MST based on synchronization li-kelihood and an imaginary part of coherence are more sensitive to differences between left- and right-handers during memorizing.

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Lukoyanov M.V., Grechikhin I.S., Kalyagin V.A., Pardalos P.M., Mukhina I.V. Characteristics of Spatial Synchronization of Encephalograms in Left- and Right-Handed Subjects in Resting State and During Cognitive Testing: a Graph-Theory Analysis. Sovremennye tehnologii v medicine 2014; 6(2): 6