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Conditioned Fear Extinction and Generalization in Post-Traumatic Stress Disorder

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Annual rept. 1 Aug 2011-31 Jul 2012

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Post-traumatic stress disorder PTSD can affect an individual following exposure to a traumatic event. The exposure to trauma can evoke intense physical and emotional responses. Psychophysiological symptoms of PTSD can include an enhanced startle response an effect that may result from an inability to inhibit fear. Conditioned fear can be measured using paradigms such as fear conditioning and fear extinction. Fear-potentiated startle is the process by which an individual s acoustic startle response is enhanced upon presentation of a conditioned stimulus e.g., a colored shape that was paired with an unpleasant unconditioned stimulus e.g., an aversive airblast to the throat. We have analyzed fear-processing in a population of PTSD patients from recent conflicts in the Middle East and healthy volunteers. One colored shape served as the reinforced conditioned stimulus CS, danger and another colored shape served as the nonreinforced condition stimulus CS-, safety. A 140 p.s.i airblast to the throat was used as the unconditioned stimulus. Subjects were fefear-conditionednd, after a 10 minute interval, the subjects were trained to extinguish the fear. PTSD patients from the OIF theaters displayed greater fear-potentiated startle to the safety cue as well as delayed extinction of fear-potentiated startle in comparison to the healthy volunteers. In addition, combat veterans with PTSD report less discrimination between cues that are similar in nature to the danger cue.

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  • Anatomy and Physiology
  • Medicine and Medical Research
  • Stress Physiology

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