Fig. 1.

As the working memory task gets more difficult, EEG frontal theta power increases and parietal alpha power decreases. (Left): 4–14Hz EEG power at frontal (Fz) and parietal (Pz) midline sites measured during an easier (low load -- light line) and more difficult (high load -- dark line) n-back WM task from 80 participants (adapted from Gevins and Smith, 2000). (Right): 120-electrode WM task EEG images for a single participant, mapped onto a cortical model derived from the participant’s MRI (adapted from Gevins et al., 1996). Although such dense electrode arrays improve topographic mapping, practical cognitive neuromonitoring can be accomplished with far fewer electrodes.