Time course of ERD/ERS. Each figure shows a time course of the relative power decrease (ERD) and increase (ERS) on C3 under each speed and motor load condition. This is a typical result of a participant (Subject G). The horizontal axis indicates the time aligned at the onset of the task period (0 s), and the vertical axis indicates the frequency. The colorbar indicates the percentage of ERD/ERS. The mu-ERD can be observed during the task period. In the Hold condition, the mu-ERD disappears and mu-ERS are alternatively confirmed in the middle of the task period.