title: Impaired consciousness is linked to changes in effective connectivity of the posterior cingulate cortex within the default mode network.
abstract: The intrinsic connectivity of the default mode network has been associated with the level of consciousness in patients with severe brain injury. Especially medial parietal regions are considered to be highly involved in impaired consciousness. To better understand what aspect of this intrinsic architecture is linked to consciousness, we applied spectral dynamic causal modeling to assess effective connectivity within the default mode network in patients with disorders of consciousness. We included 12 controls, 12 patients in minimally conscious state and 13 in vegetative state in this study. For each subject, we first defined the four key regions of the default mode network employing a subject-specific independent component analysis approach. The resulting regions were then included as nodes in a spectral dynamic causal modeling analysis in order to assess how the causal interactions across these regions as well as the characteristics of neuronal fluctuations change with the level of consciousness. The resulting pattern of interaction in controls identified the posterior cingulate cortex as the main driven hub with positive afferent but negative efferent connections. In patients, this pattern appears to be disrupted. Moreover, the vegetative state patients exhibit significantly reduced self-inhibition and increased oscillations in the posterior cingulate cortex compared to minimally conscious state and controls. Finally, the degree of self-inhibition and strength of oscillation in this region is correlated with the level of consciousness. These findings indicate that the equilibrium between excitatory connectivity towards posterior cingulate cortex and its feedback projections is a key aspect of the relationship between alterations in consciousness after severe brain injury and the intrinsic functional architecture of the default mode network. This impairment might be principally due to the disruption of the mechanisms underlying self-inhibition and neuronal oscillations in the posterior cingulate cortex.
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Centre for Cognitive Neuroscience & Department of Psychology, University of Salzburg, Salzburg, Austria; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Department of Psychology, University of CA Los Angeles, USA. Electronic address: j.crone@neurocognition.org.
authors.forename: Julia Sophia
authors.initials: JS
authors.lastname: Crone
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Centre for Cognitive Neuroscience & Department of Psychology, University of Salzburg, Salzburg, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schurz
authors.affiliation: Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Höller
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bergmann
authors.affiliation: Department of Psychology, University of CA Los Angeles, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Monti
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Schmid
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Eugen
authors.initials: E
authors.lastname: Trinka
authors.affiliation: Neuroscience Institute & Centre for Cognitive Neuroscience, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Centre for Cognitive Neuroscience & Department of Psychology, University of Salzburg, Salzburg, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Kronbichler
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology*; D003244:Consciousness Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000503:physiopathology*; D009434:Neural Pathways / Q000503:physiopathology*; D018458:Persistent Vegetative State / Q000503:physiopathology
keywords: Default mode network; Disorders of consciousness; Dynamic causal modeling; Effective connectivity; Posterior cingulate cortex; Vegetative state