title: Reduced neural activation during an inhibition task is associated with impaired fear inhibition in a traumatized civilian sample.
abstract: BACKGROUND
  Impaired inhibition of fear in the presence of safety cues and a deficiency in the extinction of fear cues are increasingly thought to be important biological markers of Posttraumatic stress disorder (PTSD). Other studies have suggested that there may be altered neural activation during behavioral inhibition tasks in subjects with PTSD. The current study aimed to see whether neural activation during inhibition was reduced in a highly traumatized civilian population, and whether atypical activation was associated with impaired fear inhibition.
  
  
  METHODS
  The participants were 41 traumatized women (20 PTSD+, 21 PTSD-) recruited from Grady Memorial Hospital in Atlanta, GA. We used a Go/NoGo procedure with functional magnetic resonance imaging (fMRI) in a high-resolution 3T scanner. Participants were instructed to press a button whenever an "X" or "O" appeared on the screen, but not if a red square appeared behind the letter. Participants were assessed for trauma history and PTSD diagnosis, and completed a fear-potentiated startle and extinction paradigm.
  
  
  RESULTS
  We found stronger activation in the ventromedial prefrontal cortex (vmPFC) in traumatized subjects without PTSD compared to those with PTSD in the NoGo greater than Go contrast condition. Activation in the vmPFC was negatively correlated with fear-potentiated startle responses during safety signal learning (p = .02) and fear extinction (p = .0002).
  
  
  CONCLUSIONS
  These results contribute to understanding of how the neural circuitry involved in inhibitory processes may be deficient in PTSD. Furthermore, the same circuits involved in behavioral inhibition appear to be involved in fear inhibition processes during differential fear conditioning and extinction.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA 30329, USA.
authors.forename: Tanja
authors.initials: T
authors.lastname: Jovanovic
authors.forename: Tim
authors.initials: T
authors.lastname: Ely
authors.forename: Negar
authors.initials: N
authors.lastname: Fani
authors.forename: Ebony M
authors.initials: EM
authors.lastname: Glover
authors.forename: David
authors.initials: D
authors.lastname: Gutman
authors.forename: Erin B
authors.initials: EB
authors.lastname: Tone
authors.forename: Seth D
authors.initials: SD
authors.lastname: Norrholm
authors.forename: Bekh
authors.initials: B
authors.lastname: Bradley
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Ressler
mesh_terms: D000328:Adult; D001741:Black or African American; D001007:Anxiety / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004576:Electromyography; D005108:Extinction, Psychological / Q000502:physiology; D005239:Fear / Q000523:psychology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000473:pathology / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology*; D013216:Reflex, Startle / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology / Q000523:psychology*; D014505:Urban Population; D055815:Young Adult