title: Functional reorganization of neural networks during repeated exposure to the traumatic memory in posttraumatic stress disorder: an exploratory fMRI study.
abstract: BACKGROUND
  Repeated exposure to the traumatic memory (RETM) is a common component of treatments for posttraumatic stress disorder (PTSD). This treatment is based on a fear extinction model; however, the degree to which this treatment actually engages and modifies neural networks mediating fear extinction is unknown. Therefore, the purpose of the current exploratory study was to define the dynamic changes in neural processing networks while participants completed a novel adaptation of RETM.
  
  
  METHODS
  Participants were adult women (N = 16) with PTSD related to physical or sexual assault. Prior to scanning, participants provided written narratives of a traumatic event related to their PTSD as well as a neutral control event. RETM during fMRI consisted of 5 sequential presentations of the blocked narrative types, lasting three minutes each. Self-reported anxiety was assessed after each presentation.
  
  
  RESULTS
  Relative to changes in functional connectivity during the neutral control script, RETM was associated with strengthened functional connectivity of the right amygdala with the right hippocampus and right anterior insular cortex, left amygdala with the right insular cortex, medial PFC with right anterior insula, left hippocampus with striatum and dorsal cingulate cortex, and right hippocampus with striatum and orbitofrontal cortex. Greater PTSD severity generally led to less changes in functional connectivity with the right insular cortex.
  
  
  CONCLUSIONS
  These results provide evidence that RETM engages and modifies functional connectivity pathways with neural regions implicated in fear extinction. The results also implicate the engagement of the right insular cortex and striatum during RETM and suggest their importance in human fear extinction to trauma memories. However, comorbidity in the sample and the lack of a control group limit inferences regarding RETM with PTSD populations specifically.
authors.affiliation: Brain Imaging Research Center, Psychiatric Research Institute, University of Arkansas for Medical Sciences, 4301 W. Markham, #554, Little Rock, AR 72205, USA. Electronic address: josh.cisler@gmail.com.
authors.forename: Josh M
authors.initials: JM
authors.lastname: Cisler
authors.forename: J Scott
authors.initials: JS
authors.lastname: Steele
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Lenow
authors.forename: Sonet
authors.initials: S
authors.lastname: Smitherman
authors.forename: Betty
authors.initials: B
authors.lastname: Everett
authors.forename: Erick
authors.initials: E
authors.lastname: Messias
authors.forename: Clinton D
authors.initials: CD
authors.lastname: Kilts
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008569:Memory Disorders / Q000209:etiology* / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D013313:Stress Disorders, Post-Traumatic / Q000150:complications* / Q000523:psychology; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Exposure therapy; Fear extinction; Neuroimaging; PTSD