Fig 1. Illustration of our hypothesis that the older subjects may show a decreased δ-θ phase locking index (H1) or β amplitude (H2) since the variability of the motor performance increases with age.

In the upper panel, the dots represent the phase distribution in the δ-θ frequency band across trials in both younger (YS, blue) and older (OS, red) participants. In the lower panels, amplitude changes in the β frequency band (ERD and ERS) are displayed as they may appear in younger (YS, blue) and older (OS, red) subjects.