De novo conditioning in trauma-exposed individuals with and without posttraumatic stress disorder

Differential conditioning was assessed in 15 medication-free individuals me eting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; Ameri can Psychiatric Association, 1994) criteria for chronic posttraumatic stres s disorder (PTSD) and 18 trauma-exposed individuals who never developed PTS D (non-PTSD). Conditioned stimuli (CSs) were colored circles, and the uncon ditioned stimulus was a "highly annoying" electrical stimulus. Individuals with PTSD had higher resting heart rate (HR) and skin conductance (SC) leve ls and produced larger SC orienting responses. During conditioning, the PTS D group showed larger differential SC, HR, and electromyogram responses to the reinforced vs. nonreinforced stimuli (CS+ vs. CS-) compared with the no n-PTSD group. Only PTSD participants continued to show differential SC resp onses to CS+ vs. CS- during extinction trials. Results suggest that individ uals with PTSD have higher sympathetic nervous system arousal at the time o f conditioning and are more conditionable than trauma-exposed individuals w ithout PTSD.