Neural response to errors in combat-exposed returning veterans with and without post-traumatic stress disorder: a preliminary event-related potential study

Post-traumatic stress disorder (PTSD) is characterized by sustained anxiety, hypervigilance for potential threat, and hyperarousal. These symptoms may enhance self-perception of one's actions, particularly the detection of errors, which may threaten safety. The error-related negativity (ERN) is an electrocortical response to the commission of errors, and previous studies have shown that other anxiety disorders associated with exaggerated anxiety and enhanced action monitoring exhibit an enhanced ERN. However, little is known about how traumatic experience and PTSD would affect the ERN. To address this gap, we measured the ERN in returning Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans with combat-related PTSD (PTSD group), combat-exposed OEF/OIF veterans without PTSD [combat-exposed control (CEC) group], and non-traumatized healthy participants [healthy control (HC) group]. Event-related potential and behavioral measures were recorded while 16 PTSD patients, 18 CEC, and 16 HC participants completed an arrow version of the flanker task. No difference in the magnitude of the ERN was observed between the PTSD and HC groups; however, in comparison with the PTSD and HC groups, the CEC group displayed a blunted ERN response. These findings suggest that (1) combat trauma itself does not affect the ERN response; (2) PTSD is not associated with an abnormal ERN response; and (3) an attenuated ERN in those previously exposed to combat trauma but who have not developed PTSD may reflect resilience to the disorder, less motivation to do the task, or a decrease in the significance or meaningfulness of 'errors,' which could be related to combat experience.