We acquired an EEG from all participants in an eyes-open state for 5 min, an eyes-closed state for 5 min, and during a visual WM task. Figure 1 illustrates the experimental procedure for EEG acquisition. This WM task was suggested to study alterations in a healthy human EEG [44]. Before the experiment, the task was explained to all participants. All necessary instructions were shown on a monitor screen. Participants were asked to focus on a screen displaying a “+” symbol for 30 s. Three major steps were involved in this WM task. In the first step, 25 images were shown on the screen for 30 s; in the second step, those images were removed from the screen and the participants had to memorize the images in 30 s while their eyes remained closed. In last step, the participants were instructed to open their eyes and recall the images in 30 s. The total number of correct answers was recorded as the WM performance score.
