Information Processing of the Rorschach's Traumatic Content Index in Trauma-exposed Adults: An Event Related Potential (ERP) Study

Hypervigilance or shutdown? Electrophysiological processing of trauma-unrelated aversive stimuli after traumatic life events

Post-Traumatic Stress Disorder (PTSD) research indicates that hyper-reactivity to trauma-related stimuli reflects reduced prefrontal cortex (PFC) modulation of amygdala reactivity. However, other studies indicate a dissociative "shutdown" reaction to overwhelming aversive stimuli, possibly reflecting PFC over-modulation. To explore this, we used an Event-Related Potential (ERP) oddball paradigm to study P3 responses in the presence of the following: 1. Trauma-unrelated morbid distractors (e.g., "injured bear") related to the Rorschach inkblot test, and 2. Negative distractors (e.g., "significant failure"), among participants with high post-traumatic stress symptoms (PTS; n = 20), low PTS (n = 17), and controls (n = 15). Distractors were presented at 20% frequency amongst the more frequent (60%) neutral standard stimuli (e.g., "desk lamp") and the equally frequent (20%) neutral trauma-unrelated target stimulus ("golden fish"). P3 amplitudes were high in the presence of morbid distractors and low in the presence of negative distractors only amongst the control group. Possible mechanisms underlying the lack of P3 amplitude modulation after trauma are discussed.

The impact of posttraumatic stress disorder on event-related potentials in affective and non-affective paradigms: A systematic review with meta-analysis

Post-traumatic stress disorder (PTSD) is associated with neural processing deficits affecting early automatic and later conscious processing. Event-related Potentials (ERPs) are high resolution indices of automatic and conscious processing, but there are no meta-analyses that have examined automatic and conscious ERPs in PTSD across multiple paradigms. This systematic review examined 69 studies across affective and non-affective auditory and visual paradigms. Individuals with PTSD were compared to trauma-exposed and non-trauma controls on ERPs reflecting automatic (N1, P1, N2, P2) and conscious (P3, LPP) processing. Trauma exposure was associated with increased automatic ERP amplitudes to irrelevant auditory information. PTSD further showed increased automatic and conscious allocation of resources to affective information, reduced automatic attending and classification as well as reduced attention processing and working memory updating of non-affective information. Therefore, trauma exposure is associated with enhanced early processing of incoming stimuli, and PTSD with enhanced processing of affective stimuli and impaired processing of non-affective stimuli. This review highlights the need for longitudinal ERP studies in PTSD, adopting standardized procedures and methodological designs.

Utility of P300 ERP in monitoring post-trauma mental health: A longitudinal study in military personnel returning from combat deployment

Military service members (SMs) returning from combat are at high risk of developing neuropsychiatric conditions such as posttraumatic stress disorder (PTSD) and major depression. Symptom dynamics following reintegration into civilian life may be magnified over time such that some SMs present with delayed onset and may not reach a diagnostic threshold for months to years. Monitoring the trajectory of mental health in the aftermath of combat trauma can therefore be particularly important in enhancing diagnosis. In this study, we investigated the possible utility of the P300 event-related potential (ERP) as an objective marker for monitoring post-trauma mental health. SMs recently returned from a combat deployment were recruited to undergo a baseline assessment, with subsequent follow-up assessment at 6 or 12 months later. At each assessment, ERPs were recorded using a conventional visual oddball task and a set of psychological scores assessing PTSD, depression, and psychosocial functioning were obtained. We observed that the individuals with overall improved psychological scores at follow-up had increased P300 amplitude and shortened P300 latency, and the individuals with overall worsened psychological scores at follow-up had prolonged P300 latency. The degree of change in aggregate psychological score was significantly correlated with the magnitude of change in P300 amplitude (r = -0.72, p < 0.0001) and latency (r = 0.42, p = 0.0201). These findings suggest that the P300 may be utilized as a quantitative biomarker for tracking the changes of mental health longitudinally. It may offer clinicians an objective tool for the assessment of the dynamics of mental health following trauma, and perhaps also for monitoring recovery during treatment.