Reorganization of functional connectivity during the motor task using EEG time-frequency cross mutual information analysis

Objective: This study investigates the functional organization of cortical networks during self-determinant arm movement using the time sequences of the alpha (8-12. Hz) and beta (16-25. Hz) bands. Methods: The time-frequency cross mutual information (TFCMI) method was used to estimate the EEG functional connectivity in the alpha and beta bands for seven healthy subjects during four functional states: the resting, preparing, movement-onset, and movement-offset states. Results: In the preparing state, the maintenance of the central-executive network (CEN, prefrontal-parietal connection) suppressed the motor network in the alpha band to plan the next movement, whereas the CEN was deactivated in the beta band to retain visual attention (the frontal-occipital connection). A significant decrease of the CEN in the alpha band occurred after a visual cue in the movement-onset state, followed by a significant increase in motor-network connectivity in the beta band until the movement-offset state. Conclusions: The temporal-spectral modulation mechanism allows the brain to manifest multiple functions subject to energy budget. Significance: The TFCMI method was employed to estimate EEG functional connectivity and effectively demonstrate the reorganization process between four functional states. © 2011 International Federation of Clinical Neurophysiology.