title: Traumatic Brain Injury as a Disorder of Brain Connectivity.
abstract: OBJECTIVE
  Recent advances in neuroimaging methodologies sensitive to axonal injury have made it possible to assess in vivo the extent of traumatic brain injury (TBI) -related disruption in neural structures and their connections. The objective of this paper is to review studies examining connectivity in TBI with an emphasis on structural and functional MRI methods that have proven to be valuable in uncovering neural abnormalities associated with this condition.
  
  
  METHODS
  We review studies that have examined white matter integrity in TBI of varying etiology and levels of severity, and consider how findings at different times post-injury may inform underlying mechanisms of post-injury progression and recovery. Moreover, in light of recent advances in neuroimaging methods to study the functional connectivity among brain regions that form integrated networks, we review TBI studies that use resting-state functional connectivity MRI methodology to examine neural networks disrupted by putative axonal injury.
  
  
  RESULTS
  The findings suggest that TBI is associated with altered structural and functional connectivity, characterized by decreased integrity of white matter pathways and imbalance and inefficiency of functional networks. These structural and functional alterations are often associated with neurocognitive dysfunction and poor functional outcomes.
  
  
  CONCLUSIONS
  TBI has a negative impact on distributed brain networks that lead to behavioral disturbance.
authors.affiliation: 1National Center for PTSD,VA Boston Healthcare System,Boston,Massachusetts.
authors.forename: Jasmeet P
authors.initials: JP
authors.lastname: Hayes
authors.affiliation: 4Department of Psychology,Brigham Young University,Provo,Utah.
authors.forename: Erin D
authors.initials: ED
authors.lastname: Bigler
authors.affiliation: 2Department of Psychiatry,Boston University School of Medicine,Boston,Massachusetts.
authors.forename: Mieke
authors.initials: M
authors.lastname: Verfaellie
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000070642:Brain Injuries, Traumatic / Q000000981:diagnostic imaging / Q000473:pathology*; D001931:Brain Mapping; D006801:Humans; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology*; D059906:Neuroimaging
keywords: Diffusion tensor imaging; corpus callosum; diffuse axonal injury; fMRI; neural networks; white matter