Electrophysiology of Combat‐Related PTSD

One technique that has been applied to the study of posttraumatic stress disorder (PTSD) is the measurement of event-related brain potentials (ERPs).’ ERPs are measured by scalp-electrode recordings of a subject’s electroencephalogram during performance of a task involving discrete stimulus andor response events. Segments of the electroencephalogram following presentations of members of a class of stimuli are averaged, yielding a wave depicting the brain’s average electrical response to that stimulus class. Analyzing the temporal information given by the positive and negative deflections of such a wave and the spatial information provided by an array of electrodes distributed across the scalp yields valuable neurophysiological and functional-anatomical information.2 We explored the neurophysiology of PTSD by measuring ERPs while patients and control subjects viewed threatening and relatively nonthreatening words. In particular, we examined differences between patients and controls that could elucidate whether PTSD is best characterized as an exaggerated neural response specifically to trauma-related stimuli or a general disorder characterized by aberrant brain responses to all stimuli. Sixteen male, right-handed, native English-speaking, Vietnam-era combat veterans participated. Eight were diagnosed with PTSD; the others were well-adjusted veterans (WAV). ERPs were measured with 64 tin electrodes mounted in an elastic cap (referenced to the left mastoid). The stimuli were a sequence of words displayed on a monitor. There were three blocks of words, each consisting of 45 “trauma” words (related to combat experiences in Vietnam, e.g., grenade), 45 comparatively neutral “nontrauma” words (related to school experiences, e.g., pencil), and 18