ABNORMAL STIMULUS-PROCESSING IN POSTTRAUMATIC-STRESS-DISORDER

This study investigated event-related potential (EPP) indices of infor mation processing in sufferers of posttraumatic stress disorder (PTSD) . ERPs were obtained from 18 PTSD patients and 20 controls while they performed a target discrimination task requiring the detection of infr equent target tones from a background sequence of frequent and infrequ ent distractor tones. A delayed N2 and an attenuated P3 that failed to differentiate target from distractor tones indicated that patients ha d abnormal difficulty distinguishing task stimuli of differing relevan ce. It is proposed that this difficulty is reflected behaviorally in t he slowed reaction time by patients to target stimuli and may underlie the disturbed concentration and memory impairments found in PTSD. It may also be related to dysfunction in central noradrenaline function, which has been shown to be both crucial in selective attention and abn ormal in PTSD.