sentences:  Competing activation between the task-positive network and the default mode network at the time of memory encoding has been shown to result in poor long-term memory consolidation.During rest the task-positive network has been claimed to subserve intermittent "external awareness", defined as the conscious perception through different sensory modalities of one's surrounding environment.During performance of attention-demanding tasks, prefrontal and parietal structures that comprise the task-positive network are characterized by increases in activation; in contrast, default mode network structures, including posterior cingulate and medial prefrontal cortices, are characterized by decreased activity.