Statistical parametric maps of beta power changes by 2-back test trials (random-effect analyses of 10 participants, P < 0.001, uncorrected for the entire search volumes). Statistical parametric maps are superimposed on surface-rendered high-resolution MRI’s, and red indicates an increase of alpha power and blue indicates a decrease (A). Increase of alpha power (B) and decrease of alpha power (C) were shown on sagittal (upper left), coronal (upper right), and axial (lower left) sections. Color bar (lower right) indicates % increase (B) or % decrease (C) of the beta power. R, right; L, left.