title: Offline memory reprocessing: involvement of the brain's default network in spontaneous thought processes.
abstract: BACKGROUND
  Spontaneous thought processes (STPs), also called daydreaming or mind-wandering, occur ubiquitously in daily life. However, the functional significance of STPs remains largely unknown.
  
  
  RESULTS
  Using functional magnetic resonance imaging (fMRI), we first identified an STPs-network whose activity was positively correlated with the subjects' tendency of having STPs during a task-free state. The STPs-network was then found to be strongly associated with the default network, which has previously been established as being active during the task-free state. Interestingly, we found that offline reprocessing of previously memorized information further increased the activity of the STPs-network regions, although during a state with less STPs. In addition, we found that the STPs-network kept a dynamic balance between functional integration and functional separation among its component regions to execute offline memory reprocessing in STPs.
  
  
  CONCLUSIONS
  These findings strengthen a view that offline memory reprocessing and STPs share the brain's default network, and thus implicate that offline memory reprocessing may be a predetermined function of STPs. This supports the perspective that memory can be consolidated and modified during STPs, and thus gives rise to a dynamic behavior dependent on both previous external and internal experiences.
authors.affiliation: National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, People's Republic of China.
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.forename: Chunshui
authors.initials: C
authors.lastname: Yu
authors.forename: Lijuan
authors.initials: L
authors.lastname: Xu
authors.forename: Wen
authors.initials: W
authors.lastname: Qin
authors.forename: Kuncheng
authors.initials: K
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.forename: Tianzi
authors.initials: T
authors.lastname: Jiang
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D013850:Thinking