title: The thalamus and brainstem act as key hubs in alterations of human brain network connectivity induced by mild propofol sedation.
abstract: Despite their routine use during surgical procedures, no consensus has yet been reached on the precise mechanisms by which hypnotic anesthetic agents produce their effects. Molecular, animal and human studies have suggested disruption of thalamocortical communication as a key component of anesthetic action at the brain systems level. Here, we used the anesthetic agent, propofol, to modulate consciousness and to evaluate differences in the interactions of remote neural networks during altered consciousness. We investigated the effects of propofol, at a dose that produced mild sedation without loss of consciousness, on spontaneous cerebral activity of 15 healthy volunteers using functional magnetic resonance imaging (fMRI), exploiting oscillations (<0.1 Hz) in blood oxygenation level-dependent signal across functionally connected brain regions. We considered the data as a graph, or complex network of nodes and links, and used eigenvector centrality (EC) to characterize brain network properties. The EC mapping of fMRI data in healthy humans under propofol mild sedation demonstrated a decrease of centrality of the thalamus versus an increase of centrality within the pons of the brainstem, highlighting the important role of these two structures in regulating consciousness. Specifically, the decrease of thalamus centrality results from its disconnection from a widespread set of cortical and subcortical regions, while the increase of brainstem centrality may be a consequence of its increased influence, in the mildly sedated state, over a few highly central cortical regions key to the default mode network such as the posterior and anterior cingulate cortices.
authors: Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, CF10 3AT, United Kingdom.
authors: Tommaso
authors: T
authors: Gili
authors: Neeraj
authors: N
authors: Saxena
authors: Ana
authors: A
authors: Diukova
authors: Kevin
authors: K
authors: Murphy
authors: Judith E
authors: JE
authors: Hall
authors: Richard G
authors: RG
authors: Wise
mesh_terms: D000328:Adult; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D001931:Brain Mapping; D001933:Brain Stem / Q000098:blood supply / Q000187:drug effects*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000098:blood supply / Q000187:drug effects; D009434:Neural Pathways / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D015742:Propofol / Q000494:pharmacology*; D013788:Thalamus / Q000098:blood supply / Q000187:drug effects*; D014851:Wakefulness; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D010100:Oxygen; D015742:Propofol