title: Tools for translational neuroscience: PTSD is associated with heightened fear responses using acoustic startle but not skin conductance measures.
abstract: BACKGROUND
  Posttraumatic stress disorder (PTSD) patients show heightened fear responses to trauma reminders and an inability to inhibit fear in the presence of safety reminders. Brain imaging studies suggest that this is in part due to amygdala over-reactivity as well as deficient top-down cortical inhibition of the amygdala. Consistent with these findings, previous studies, using fear-potentiated startle (FPS), have shown exaggerated startle and deficits in fear inhibition in PTSD participants. However, many PTSD studies using the skin conductance response (SCR) report no group differences in fear acquisition.
  
  
  METHODS
  The study included 41 participants with PTSD and 70 without PTSD. The fear conditioning session included a reinforced conditioned stimulus (CS+, danger cue) paired with an aversive airblast, and a nonreinforced conditioned stimulus (CS-, safety cue). Acoustic startle responses and SCR were acquired during the presentation of each CS.
  
  
  RESULTS
  The results showed that fear conditioned responses were captured in both the FPS and SCR measures. Furthermore, PTSD participants had higher FPS to the danger cue and safety cue compared to trauma controls. However, SCR did not differ between groups. Finally, we found that FPS to the danger cue predicted re-experiencing symptoms, whereas FPS to the safety cue predicted hyper-arousal symptoms. However, SCR did not contribute to PTSD symptom variance.
  
  
  CONCLUSIONS
  Replicating earlier studies, we showed increased FPS in PTSD participants. However, although SCR was a good measure of differential conditioning, it did not differentiate between PTSD groups. These data suggest that FPS may be a useful tool for translational research.
authors: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia 30303, USA. eglover@emory.edu
authors: Ebony M
authors: EM
authors: Glover
authors: Justine E
authors: JE
authors: Phifer
authors: Daniel F
authors: DF
authors: Crain
authors: Seth D
authors: SD
authors: Norrholm
authors: Michael
authors: M
authors: Davis
authors: Bekh
authors: B
authors: Bradley
authors: Kerry J
authors: KJ
authors: Ressler
authors: Tanja
authors: T
authors: Jovanovic
mesh_terms: D000328:Adult; D001741:Black or African American; D003214:Conditioning, Classical / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009488:Neurosciences / Q000379:methods; D013216:Reflex, Startle / Q000502:physiology*; D012720:Severity of Illness Index; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology*; D057170:Translational Research, Biomedical / Q000379:methods