The default mode network (DMN), a set of brain regions active at rest, shows higher functional connectivity and stronger low-frequency fluctuations when people keep their eyes open (with or without a fixation point) than when they keep them closed. Although the overall connectivity patterns look similar across conditions, statistical comparisons reveal these differences. An order effect also appears: two eyes-closed sessions differ from each other. These findings suggest that having eyes open during rest may involve more non-specific visual gathering, evaluation, and mind wandering, and that researchers should carefully choose and order resting-state conditions in experimental designs.
Spontaneous low-frequency fluctuations in sustained attention, which cause cognitive and behavioral lapses, originate in the default-mode network (DMN). Analysis of two independent fMRI and behavior datasets shows that neural fluctuations in the DMN mediate behavioral reaction-time fluctuations during sustained attention. The DMN's increased amplitude of fluctuation correlates with behavioral fluctuation specifically in the 0.01-0.1 Hz frequency range, not at lower or higher frequencies. This pattern appears during both auditory and visual sustained attention and replicates across datasets. These findings reveal the DMN as a neural source of attention fluctuation, extending the former view that the DMN is simply deactivated during cognitive tasks.