Mu rhythm versus central alpha

The appearance of alpha frequencies coincides with eye movements (Eye closure, the Bell's phenomenon, upward movement of the globes), indicative of alpha rhythms. Notice that these are best developed in the central regions and that there is a shift in emphasis from the right to the left-central region in the top image. The same rhythms appear over the parietal and occipital regions, but are lower in amplitude. This illustrates that the extent of alpha rhythm is not always occipitally predominant, and the response to eye opening distinguishes it from mu rhythm, which typically also has a distinctive appearance.