Brain functional connectivity differentiates dexmedetomidine from propofol and natural sleep

Br J Anaesth. 2017 Oct 1;119(4):674-684. doi: 10.1093/bja/aex257.


Background: We used functional connectivity measures from brain resting state functional magnetic resonance imaging to identify human neural correlates of sedation with dexmedetomidine or propofol and their similarities with natural sleep.

Methods: Connectivity within the resting state networks that are proposed to sustain consciousness generation was compared between deep non-rapid-eye-movement (N3) sleep, dexmedetomidine sedation, and propofol sedation in volunteers who became unresponsive to verbal command. A newly acquired dexmedetomidine dataset was compared with our previously published propofol and N3 sleep datasets.

Results: In all three unresponsive states (dexmedetomidine sedation, propofol sedation, and N3 sleep), within-network functional connectivity, including thalamic functional connectivity in the higher-order (default mode, executive control, and salience) networks, was significantly reduced as compared with the wake state. Thalamic functional connectivity was not reduced for unresponsive states within lower-order (auditory, sensorimotor, and visual) networks. Voxel-wise statistical comparisons between the different unresponsive states revealed that thalamic functional connectivity with the medial prefrontal/anterior cingulate cortex and with the mesopontine area was reduced least during dexmedetomidine-induced unresponsiveness and most during propofol-induced unresponsiveness. The reduction seen during N3 sleep was intermediate between those of dexmedetomidine and propofol.

Conclusions: Thalamic connectivity with key nodes of arousal and saliency detection networks was relatively preserved during N3 sleep and dexmedetomidine-induced unresponsiveness as compared to propofol. These network effects may explain the rapid recovery of oriented responsiveness to external stimulation seen under dexmedetomidine sedation.

Trial registry number: Committee number: 'Comité d'Ethique Hospitalo-Facultaire Universitaire de Liège' (707); EudraCT number: 2012-003562-40; internal reference: 20121/135; accepted on August 31, 2012; Chair: Prof G. Rorive. As it was considered a phase I clinical trial, this protocol does not appear on the EudraCT public website.

Keywords: anaesthesia; cerebrovascular circulation; dexmedetomidine; magnetic resonance imaging; propofol; sleep; slow-wave.

MeSH terms

  • Adolescent
  • Adult
  • Anesthetics, Intravenous / pharmacology
  • Brain / drug effects*
  • Brain / physiology*
  • Brain Mapping / methods
  • Consciousness
  • Dexmedetomidine / pharmacology*
  • Female
  • Humans
  • Hypnotics and Sedatives / pharmacology
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Imaging / methods*
  • Male
  • Neural Pathways / drug effects
  • Propofol / pharmacology*
  • Sleep / physiology*
  • Young Adult


  • Anesthetics, Intravenous
  • Hypnotics and Sedatives
  • Dexmedetomidine
  • Propofol