title: The default mode network and the working memory network are not anti-correlated during all phases of a working memory task.
abstract: BACKGROUND
  The default mode network and the working memory network are known to be anti-correlated during sustained cognitive processing, in a load-dependent manner. We hypothesized that functional connectivity among nodes of the two networks could be dynamically modulated by task phases across time.
  
  
  METHODS
  To address the dynamic links between default mode network and the working memory network, we used a delayed visuo-spatial working memory paradigm, which allowed us to separate three different phases of working memory (encoding, maintenance, and retrieval), and analyzed the functional connectivity during each phase within and between the default mode network and the working memory network networks.
  
  
  RESULTS
  We found that the two networks are anti-correlated only during the maintenance phase of working memory, i.e. when attention is focused on a memorized stimulus in the absence of external input. Conversely, during the encoding and retrieval phases, when the external stimulation is present, the default mode network is positively coupled with the working memory network, suggesting the existence of a dynamically switching of functional connectivity between "task-positive" and "task-negative" brain networks.
  
  
  CONCLUSIONS
  Our results demonstrate that the well-established dichotomy of the human brain (anti-correlated networks during rest and balanced activation-deactivation during cognition) has a more nuanced organization than previously thought and engages in different patterns of correlation and anti-correlation during specific sub-phases of a cognitive task. This nuanced organization reinforces the hypothesis of a direct involvement of the default mode network in cognitive functions, as represented by a dynamic rather than static interaction with specific task-positive networks, such as the working memory network.
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, University of Maastricht, Maastricht, The Netherlands; Department of Biomedicine and Clinical Neuroscience, University of Palermo, Palermo, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Piccoli
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, University of Maastricht, Maastricht, The Netherlands.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Valente
authors.affiliation: MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological, Medicine and Clinical Neurosciences, Cardiff University School of Medicine, Cardiff, United Kingdom.
authors.forename: David E J
authors.initials: DE
authors.lastname: Linden
authors.affiliation: Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Re
authors.affiliation: Department of Medicine and Surgery, University of Salerno, Salerno, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Esposito
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, University of Maastricht, Maastricht, The Netherlands.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Sack
authors.affiliation: Department of Medicine and Surgery, University of Salerno, Salerno, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Salle
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology; D063132:Connectome; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term; D055815:Young Adult
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