Measurements of the mu/beta ERD and gamma ERS during the imagination of body parts movement

In recent years, many studies shows that the ERS (event-related synchronization) in the gamma band is associated with cortical activation during the imagination of body parts movement. It is also known that the ERD (event-related desynchronization) in the mu and beta band are caused by the imagination of body parts movement. In this study, we investigated the relationship between the gamma ERS and mu/beta ERDs. We recorded 64-channel EEG in order to obtain the power map of the gamma component. Furthermore, we compared the characteristics of the gamma waveform and mu/beta waveforms at the locations where the gamma ERS appeared clearly. As a result, we obtained three conclusions. Firstly, gamma ERS caused by the imagination of body parts movement appears at near somatosensory area and motor area. Gamma ERS caused by the imagination of right arm movement appears at the left side of the somatosenrosy area, that of left arm movement appears at the right side of the somatosensory area, and that of the foot movement appears at the center of the motor area. Secondly, mu/beta ERDs appear simultaneously with the preparation of the imagination, and they continue during the imagination. However, gamma ERS appeared simultaneously with the imagination of body parts movement. Finally, the power of the mu/beta component decrease gradually, but that of the gamma component increases significantly.