Figure 2.

Group‐averaged time–frequency spectra during working memory processing. Time (in seconds) is denoted on the x‐axis, with 0 s defined as the onset of the encoding grid. Frequency (Hz) is shown on the y‐axis. All signal power data is expressed as a percent difference from baseline (−0.4 to 0 s), with the color legend shown to the far right. Data represent a group‐averaged gradiometer sensor that was near the parietal–occipital region in each participant (the same sensor was selected in all participants). As is apparent, alpha/beta activity in this brain area strongly decreased (i.e., desynchronized) during the encoding phase, then shifted toward robust increases (i.e., synchronization) in a more narrow (alpha) band during the maintenance phase. Time periods with significant oscillatory activity (relative to baseline) were subjected to beamforming in 0.4 s nonoverlapping time bins. [Color figure can be viewed in the online issue, which is available at http://wileyonlinelibrary.com.]