title: Preserved modular network organization in the sedated rat brain.
abstract: Translation of resting-state functional connectivity (FC) magnetic resonance imaging (rs-fMRI) applications from human to rodents has experienced growing interest, and bears a great potential in pre-clinical imaging as it enables assessing non-invasively the topological organization of complex FC networks (FCNs) in rodent models under normal and various pathophysiological conditions. However, to date, little is known about the organizational architecture of FCNs in rodents in a mentally healthy state, although an understanding of the same is of paramount importance before investigating networks under compromised states. In this study, we characterized the properties of resting-state FCN in an extensive number of Sprague-Dawley rats (n = 40) under medetomidine sedation by evaluating its modular organization and centrality of brain regions and tested for reproducibility. Fully-connected large-scale complex networks of positively and negatively weighted connections were constructed based on Pearson partial correlation analysis between the time courses of 36 brain regions encompassing almost the entire brain. Applying recently proposed complex network analysis measures, we show that the rat FCN exhibits a modular architecture, comprising six modules with a high between subject reproducibility. In addition, we identified network hubs with strong connections to diverse brain regions. Overall our results obtained under a straight medetomidine protocol show for the first time that the community structure of the rat brain is preserved under pharmacologically induced sedation with a network modularity contrasting from the one reported for deep anesthesia but closely resembles the organization described for the rat in conscious state.
authors.affiliation: F. Hoffmann-La Roche Pharmaceuticals Ltd, Neuroscience Discovery, Basel, Switzerland.
authors.forename: Dany V
authors.initials: DV
authors.lastname: D'Souza
authors.affiliation: Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Jonckers
authors.affiliation: F. Hoffmann-La Roche Pharmaceuticals Ltd, Neuroscience Discovery, Basel, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bruns
authors.affiliation: F. Hoffmann-La Roche Pharmaceuticals Ltd, Neuroscience Discovery, Basel, Switzerland.
authors.forename: Basil
authors.initials: B
authors.lastname: Künnecke
authors.affiliation: F. Hoffmann-La Roche Pharmaceuticals Ltd, Neuroscience Discovery, Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: von Kienlin
authors.affiliation: Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium.
authors.forename: Annemie
authors.initials: A
authors.lastname: Van der Linden
authors.affiliation: F. Hoffmann-La Roche Pharmaceuticals Ltd, Neuroscience Discovery, Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mueggler
authors.affiliation: Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium.
authors.forename: Marleen
authors.initials: M
authors.lastname: Verhoye
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D054810:Deep Sedation; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results