Figure 1.

Alpha-, beta-, and gamma-band amplitudes are positively correlated with visual working memory (VWM) load in fronto-parietal cortical regions during the retention period. (A) A schematic representation of the VWM paradigm in this study. The subjects sustained a memory of the Sample stimulus and indicated with a force-choice response whether the Test stimulus was identical to the Sample or not. The stimuli contained one to six colored squares in random locations and in the 50% of Test stimuli, the color of one square was different from the color in the Sample stimulus. (B) Cortical localization of the memory-load dependence of oscillation amplitudes during the memory retention period (0.4–1 s). The complete cortical surfaces are flattened and oriented so that the anterior–posterior axis corresponds to up–down direction, respectively. The color values indicate the correlation coefficients obtained across subjects of the oscillation amplitude with the number of objects in the stimuli. The correlation values are shown for cortical regions that were significantly correlated with memory-load. Adapted from Palva et al. (2011).