期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：48
页码：13899-13904
DOI：10.1073/pnas.1611743113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe brains default mode network (DMN) is comprised of regions that are highly active during wakeful rest. In the past 15 y, the DMN has been a target of investigation in thousands of basic and clinical neuroscience studies, yet the fundamental role of this network remains debated and unknown. Some studies suggest that DMN activity increases with self-reported mind-wandering away from the present sensory environment, a state in which task performance tends to be highly unstable. However, we show that DMN activity increases with stable, rather than variable, behavior, independent from increases with mind-wandering. Our work urges reinterpretation of the significance of DMN activity fluctuations in daily life and DMN disruption in disease. The brains default mode network (DMN) is highly active during wakeful rest when people are not overtly engaged with a sensory stimulus or externally oriented task. In multiple contexts, increased spontaneous DMN activity has been associated with self-reported episodes of mind-wandering, or thoughts that are unrelated to the present sensory environment. Mind-wandering characterizes much of waking life and is often associated with error-prone, variable behavior. However, increased spontaneous DMN activity has also been reliably associated with stable, rather than variable, behavior. We aimed to address this seeming contradiction and to test the hypothesis that single measures of attentional states, either based on self-report or on behavior, are alone insufficient to account for DMN activity fluctuations. Thus, we simultaneously measured varying levels of self-reported mind-wandering, behavioral variability, and brain activity with fMRI during a unique continuous performance task optimized for detecting attentional fluctuations. We found that even though mind-wandering co-occurred with increased behavioral variability, highest DMN signal levels were best explained by intense mind-wandering combined with stable behavior simultaneously, compared with considering either single factor alone. These brain-behavior-experience relationships were highly consistent within known DMN subsystems and across DMN subregions. In contrast, such relationships were absent or in the opposite direction for other attention-relevant networks (salience, dorsal attention, and frontoparietal control networks). Our results suggest that the cognitive processes that spontaneous DMN activity specifically reflects are only partially related to mind-wandering and include also attentional state fluctuations that are not captured by self-report.
关键词：daydreaming ; default mode network ; sustained attention ; spontaneous thought ; resting state
