Default mode network mediates low‐frequency fluctuations in brain activity and behavior during sustained attention

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.

Study at a glance

Abstract

The low-frequency (<0.1 Hz) fluctuation in sustained attention attracts enormous interest in cognitive neuroscience and clinical research since it always leads to cognitive and behavioral lapses. What is the source of the spontaneous fluctuation in sustained attention in neural activity, and how does the neural fluctuation relate to behavioral fluctuation? Here, we address these questions by collecting and analyzing two independent fMRI and behavior datasets. We show that the neural (fMRI) fluctuation in a key brain network, the default-mode network (DMN), mediate behavioral (reaction time) fluctuation during sustained attention. DMN shows the increased amplitude of fluctuation, which correlates with the behavioral fluctuation in a similar frequency range (0.01-0.1 Hz) but not in the lower (<0.01 Hz) or higher (>0.1 Hz) frequency range. This was observed during both auditory and visual sustained attention and was replicable across independent datasets. These results provide a novel insight into the neural source of attention-fluctuation and extend the former concept that DMN was deactivated in cognitive tasks. More generally, our findings highlight the temporal dynamic of the brain-behavior relationship.