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Persistent default-mode network connectivity during light sedation

Authors

  • Michael D. Greicius,

    Corresponding author
    1. Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
    2. Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
    • Department of Neurology and Neurological Sciences, Stanford University Medical Center, 300 Pasteur Drive, Room A343, Stanford, CA 94305-5235
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  • Vesa Kiviniemi,

    1. Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
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  • Osmo Tervonen,

    1. Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
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  • Vilho Vainionpää,

    1. Department of Anesthesia, Oulu University Hospital, Oulu, Finland
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  • Seppo Alahuhta,

    1. Department of Anesthesia, Oulu University Hospital, Oulu, Finland
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  • Allan L. Reiss,

    1. Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
    2. Program in Neuroscience, Stanford University School of Medicine, Stanford, California
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  • Vinod Menon

    1. Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
    2. Program in Neuroscience, Stanford University School of Medicine, Stanford, California
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Abstract

The default-mode network (DMN) is a set of specific brain regions whose activity, predominant in the resting-state, is attenuated during cognitively demanding, externally-cued tasks. The cognitive correlates of this network have proven difficult to interrogate, but one hypothesis is that regions in the network process episodic memories and semantic knowledge integral to internally-generated mental activity. Here, we compare default-mode functional connectivity in the same group of subjects during rest and conscious sedation with midazolam, a state characterized by anterograde amnesia and a reduced level of consciousness. Although the DMN showed functional connectivity during both rest and conscious sedation, a direct comparison found that there was significantly reduced functional connectivity in the posterior cingulate cortex during conscious sedation. These results confirm that low-frequency oscillations in the DMN persist and remain highly correlated even at reduced levels of consciousness. We hypothesize that focal reductions in DMN connectivity, as shown here in the posterior cingulate cortex, may represent a stable correlate of reduced consciousness. Hum Brain Mapp, 2008. © 2008 Wiley-Liss, Inc.

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