Figure 6: RMS differences in the alpha power estimates resulting from changes in the head position across three different sessions, each session consisting of multiple runs of 130-s duration each. The differences in head position are with respect to the one captured during an initial baseline run acquired at the beginning of the first session. The on-line calculations of alpha power modulations using the reference head position were compared to those obtained offline but with optimal noise attenuation and forward head and inverse source modeling. Colors represent different sessions, and each marker represents a run within a session.