title: Intrainsular functional connectivity in human.
abstract: OBJECTIVE
  The anatomical organization of the insular cortex is characterized by its rich and heterogeneous cytoarchitecture and its wide network of connections. However, only limited knowledge is available regarding the intrainsular connections subserving the complex integrative role of the insular cortex. The aim of this study was to analyze the functional connectivity within- and across-insular subregions, at both gyral and functional levels.
  
  
  METHODS
  We performed intracerebral electrical stimulation in 10 patients with refractory epilepsy investigated with depth electrodes, 38 of which were inserted in the insula. Bipolar electrical stimulation, consisting of two series of 20 pulses of 1-ms duration, 0.2-Hz frequency, and 1-mA intensity, was delivered at each insular contact. For each stimulated insular anatomical region, we calculated a rate of connectivity, reflecting the proportion of other insular contacts, showing significant evoked potentials.
  
  
  RESULTS
  Statistically significant evoked potentials were recorded in 74% of tested connections, with an average latency of 26 ± 3 ms. All insular gyri were interconnected, except the anterior and posterior short gyri. Most connections were reciprocal, showing no clear anterior to posterior directionality. No connection was observed between the right and the left insula.
  
  
  CONCLUSIONS
  These findings point to specific features of human insula connectivity as compared to non-Human primates, and remain consistent with the complex integration role devoted to the human insula in many cognitive domains. Periodicals, Inc.
authors.affiliation: Translational and Integrative Group in Epilepsy Research (TIGER), Lyon's Neuroscience Research Centre, INSERM U1028, CNRS 5292, UCB Lyon 1, Lyon, France; Pediatric Epilepsy Department, Hospices Civils de Lyon, Lyon, France; Department of Clinical Physiology, Neurophysiology division, Sultan Qaboos University Hospital, Muscat, Oman.
authors.forename: Talal
authors.initials: T
authors.lastname: Almashaikhi
authors.forename: Sylvain
authors.initials: S
authors.lastname: Rheims
authors.forename: Karine
authors.initials: K
authors.lastname: Ostrowsky-Coste
authors.forename: Alexandra
authors.initials: A
authors.lastname: Montavont
authors.forename: Julien
authors.initials: J
authors.lastname: Jung
authors.forename: Julitta
authors.initials: J
authors.lastname: De Bellescize
authors.forename: Alexis
authors.initials: A
authors.lastname: Arzimanoglou
authors.forename: Pascal
authors.initials: P
authors.lastname: Keo Kosal
authors.forename: Marc
authors.initials: M
authors.lastname: Guénot
authors.forename: Olivier
authors.initials: O
authors.lastname: Bertrand
authors.forename: Philippe
authors.initials: P
authors.lastname: Ryvlin
mesh_terms: D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000503:physiopathology; D005071:Evoked Potentials; D007839:Functional Laterality; D006801:Humans; D009434:Neural Pathways / Q000502:physiology; D012815:Signal Processing, Computer-Assisted
keywords: evoked potential; functional connectivity; human; insular; intra-cranial electrical stimulation
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