Posterior cingulate cortex-related co-activation patterns: a resting state FMRI study in propofol-induced loss of consciousness

PLoS One. 2014 Jun 30;9(6):e100012. doi: 10.1371/journal.pone.0100012. eCollection 2014.

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).

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anesthesia, General
  • Anesthetics, Intravenous*
  • Auditory Cortex / anatomy & histology
  • Auditory Cortex / physiology
  • Brain Mapping
  • Consciousness / physiology
  • Female
  • Frontal Lobe / anatomy & histology
  • Frontal Lobe / physiology
  • Gyrus Cinguli / anatomy & histology
  • Gyrus Cinguli / physiology*
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Neural Pathways / anatomy & histology
  • Neural Pathways / physiology*
  • Propofol*
  • Thalamus / anatomy & histology
  • Thalamus / physiology
  • Unconsciousness / chemically induced*
  • Visual Cortex / anatomy & histology
  • Visual Cortex / physiology
  • Wakefulness / physiology*

Substances

  • Anesthetics, Intravenous
  • Propofol

Grant support

This research was supported by the Belgian Funds for Scientific Research (FRS), European Commission (DECODER), Belgian Science Policy (CEREBNET), McDonnell Foundation, European Space Agency, Wallonia-Brussels Federation Concerted Research Action Mind Science Foundation, University of Liège. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.