title: Posterior cingulate cortex-related co-activation patterns: a resting state FMRI study in propofol-induced loss of consciousness.
abstract: BACKGROUND
  Recent studies have been shown that functional connectivity of cerebral areas is not a static phenomenon, but exhibits spontaneous fluctuations over time. There is evidence that fluctuating connectivity is an intrinsic phenomenon of brain dynamics that persists during anesthesia. Lately, point process analysis applied on functional data has revealed that much of the information regarding brain connectivity is contained in a fraction of critical time points of a resting state dataset. In the present study we want to extend this methodology for the investigation of resting state fMRI spatial pattern changes during propofol-induced modulation of consciousness, with the aim of extracting new insights on brain networks consciousness-dependent fluctuations.
  
  
  METHODS
  Resting-state fMRI volumes on 18 healthy subjects were acquired in four clinical states during propofol injection: wakefulness, sedation, unconsciousness, and recovery. The dataset was reduced to a spatio-temporal point process by selecting time points in the Posterior Cingulate Cortex (PCC) at which the signal is higher than a given threshold (i.e., BOLD intensity above 1 standard deviation). Spatial clustering on the PCC time frames extracted was then performed (number of clusters = 8), to obtain 8 different PCC co-activation patterns (CAPs) for each level of consciousness.
  
  
  RESULTS
  The current analysis shows that the core of the PCC-CAPs throughout consciousness modulation seems to be preserved. Nonetheless, this methodology enables to differentiate region-specific propofol-induced reductions in PCC-CAPs, some of them already present in the functional connectivity literature (e.g., disconnections of the prefrontal cortex, thalamus, auditory cortex), some others new (e.g., reduced co-activation in motor cortex and visual area).
  
  
  CONCLUSIONS
  In conclusion, our results indicate that the employed methodology can help in improving and refining the characterization of local functional changes in the brain associated to propofol-induced modulation of consciousness.
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Faculty of Psychology and Educational Sciences, Department of Data Analysis, Ghent University, Ghent, Belgium.
authors: Enrico
authors: E
authors: Amico
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Francisco
authors: F
authors: Gomez
authors: Department of Neuroradiology, National Neurological Institute C. Mondino, Pavia, Italy.
authors: Carol
authors: C
authors: Di Perri
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Algology and Palliative Care, CHU Sart Tilman Hospital, University of Liège, Liège, Belgium.
authors: Audrey
authors: A
authors: Vanhaudenhuyse
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium.
authors: Damien
authors: D
authors: Lesenfants
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman Hospital, University of Liège, Liège, Belgium.
authors: Pierre
authors: P
authors: Boveroux
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman Hospital, University of Liège, Liège, Belgium; Department of Anesthesia and Intensive Care Medicine, CHR Citadelle, University of Liège, Liège, Belgium.
authors: Vincent
authors: V
authors: Bonhomme
authors: Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman Hospital, University of Liège, Liège, Belgium.
authors: Jean-François
authors: JF
authors: Brichant
authors: Faculty of Psychology and Educational Sciences, Department of Data Analysis, Ghent University, Ghent, Belgium.
authors: Daniele
authors: D
authors: Marinazzo
authors: Coma Science Group, Cyclotron Research Centre, University of Liège, Liège, Belgium; Department of Neurology, University of Liège, Liège, Belgium.
authors: Steven
authors: S
authors: Laureys
mesh_terms: D000328:Adult; D000768:Anesthesia, General; D018686:Anesthetics, Intravenous; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology; D001931:Brain Mapping; D003243:Consciousness / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology; D006179:Gyrus Cinguli / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology*; D015742:Propofol; D013788:Thalamus / Q000033:anatomy & histology / Q000502:physiology; D014474:Unconsciousness / Q000139:chemically induced*; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol