Fig. 2.

Alpha activity per condition on sensor level. (A) Topographic plots showing alpha power (7–14 Hz) modulation per condition, computed on 1-s epochs (rest: alpha power vs. average power in the spectrum [arbitrary 1-s segments]; visual: stimulus [t = 0.5–1.5 s] vs. baseline [t = − 1–0 s]; N-back: 2-back vs. 0-back during retention interval [t = 0.2–1.2 s]). Time–frequency windows used are indicated in C with dashed lines. (B) Power spectra (averaged over sensors marked with asterisks in A) for each of the conditions, showing clear peaks in the alpha band. (C) TFRs showing alpha power modulation per condition (averaged over sensors marked in A). Rest: alpha power increase as compared to average spectral power (arbitrary 1-s epochs); visual: decrease of alpha power during stimulus (t = 0–2 s) as compared to baseline (t = − 1–0 s); N-back: decrease of alpha power for 2-back compared to 0-back (stimulus: t = 0–0.2 s, retention: t = 0.2–2 s). All plots showing grand-averages over 51 subjects.