title: Exploring the Neurocircuitry Underpinning Predictability of Threat in Soldiers with PTSD Compared to Deployment Exposed Controls.
abstract: BACKGROUND
  Prior work examining emotional dysregulation observed in posttraumatic stress disorder (PTSD) has primarily been limited to fear-learning processes specific to anticipation, habituation, and extinction of threat. In contrast, the response to threat itself has not been systematically evaluated.
  
  
  OBJECTIVE
  To explore potential disruption in fear conditioning neurocircuitry in service members with PTSD, specifically in response to predictableversusunpredictable threats.
  
  
  METHODS
  In the current study, active-duty U.S. Army soldiers with (PTSD group;n= 38) and without PTSD (deployment-exposed controls; DEC;n= 40), participated in a fear-conditioning study in which threat predictability was manipulated by presenting an aversive unconditioned stimulus (UCS) that was either preceded by a conditioned stimulus (i.e., predictable) or UCS alone (i.e., unpredictable). Threat expectation, skin conductance response (SCR), and functional magnetic resonance imaging (fMRI) signal to predictable and unpredictable threats (i.e., UCS) were assessed.
  
  
  RESULTS
  Both groups showed greater threat expectancy and diminished threat-elicited SCRs to predictable compared to unpredictable threat. Significant group differences were observed within the amygdala, hippocampus, insula, and superior and middle temporal gyri. Contrary to our predictions, the PTSD group showed a diminished threat-related response within each of these brain regions during predictable compared to unpredictable threat, whereas the DEC group showed increased activation.
  
  
  CONCLUSIONS
  Although, the PTSD group showed greater threat-related diminution, hypersensitivity to unpredictable threat cannot be ruled out. Furthermore, pre-trauma, trait-like factors may have contributed to group differences in activation of the neurocircuitry underpinning fear conditioning.
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, AL, USA; Human Dimension Division, HQ TRADOC, 950 Jefferson Ave, Fort Eustis, VA 23604, USA.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Dretsch
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, AL, USA.
authors.forename: Kimberly H
authors.initials: KH
authors.lastname: Wood
authors.affiliation: Department of Psychology, Auburn University, Auburn, AL, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Daniel
authors.affiliation: Department of Psychology, Auburn University, Auburn, AL, USA; AU MRI Research Center, Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, USA.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Katz
authors.affiliation: Department of Psychology, Auburn University, Auburn, AL, USA; AU MRI Research Center, Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, USA.
authors.forename: Gopikrishna
authors.initials: G
authors.lastname: Deshpande
authors.affiliation: Department of Psychology, Auburn University, Auburn, AL, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Goodman
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, AL, USA.
authors.forename: Muriah D
authors.initials: MD
authors.lastname: Wheelock
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, AL, USA.
authors.forename: Kayli B
authors.initials: KB
authors.lastname: Wood
authors.affiliation: Department of Psychology, Auburn University, Auburn, AL, USA; AU MRI Research Center, Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, USA.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Denney
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, AL, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Traynham
authors.affiliation: Department of Psychology, University of Alabama at Birmingham, AL, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Knight
keywords: Amygdala; Fear-conditioning; Hippocampus; Insula; Military; Neuroimaging; PTSD