title: Differences in graph theory functional connectivity in left and right temporal lobe epilepsy.
abstract: OBJECTIVE
  To investigate lateralized differences in limbic system functional connectivity between left and right temporal lobe epilepsy (TLE) using graph theory.
  
  
  METHODS
  Interictal resting state fMRI was performed in 14 left TLE patients, 11 right TLE patients, and 12 controls. Graph theory analysis of 10 bilateral limbic regions of interest was conducted. Changes in edgewise functional connectivity, network topology, and regional topology were quantified, and then left and right TLE were compared.
  
  
  RESULTS
  Limbic edgewise functional connectivity was predominantly reduced in both left and right TLE. More regional connections were reduced in right TLE, most prominently involving reduced interhemispheric connectivity between the bilateral insula and bilateral hippocampi. A smaller number of limbic connections were increased in TLE, more so in left than in right TLE. Topologically, the most pronounced change was a reduction in average network betweenness centrality and concurrent increase in left hippocampal betweenness centrality in right TLE. In contrast, left TLE exhibited a weak trend toward increased right hippocampal betweenness centrality, with no change in average network betweenness centrality.
  
  
  CONCLUSIONS
  Limbic functional connectivity is predominantly reduced in both left and right TLE, with more pronounced reductions in right TLE. In contrast, left TLE exhibits both edgewise and topological changes that suggest a tendency toward reorganization. Network changes in TLE and lateralized differences thereof may have important diagnostic and prognostic implications.
authors.affiliation: Department of Statistics, Rice University, Houston, TX, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Chiang
authors.affiliation: Department of Neurology, University of California, Los Angeles, CA, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Stern
authors.affiliation: Department of Neurology, University of California, Los Angeles, CA, USA; Department of Neurobiology, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; The Brain Research Institute, University of California, Los Angeles, CA, USA.
authors.forename: Jerome
authors.initials: J
authors.lastname: Engel
authors.affiliation: Department of Physical Medicine, Baylor College of Medicine, Houston, TX, USA; Michael E. DeBakey VA Medical Center, Houston, TX, USA.
authors.forename: Harvey S
authors.initials: HS
authors.lastname: Levin
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Neurology Care Line, VA Medical Center, Houston, TX, USA. Electronic address: zulfi.haneef@bcm.edu.
authors.forename: Zulfi
authors.initials: Z
authors.lastname: Haneef
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008032:Limbic System / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D012146:Rest; D013702:Temporal Lobe / Q000503:physiopathology*; D055815:Young Adult
keywords: Brain imaging; Epilepsy; Functional MRI; Functional reorganization; Graph theory