Brain Canada Brain Canada
FR Donate

Neural indices of a modified auditory oddball task and their symptom correlates in post-traumatic stress disorder dissociative vs. non-dissociative subtypes

Principal Investigator:
  • Sara de la Salle, University of Ottawa Institute of Mental Health Research (IMHR)
  • Seger-van Tol Family

Project Overview

Dr. Hubert van Tol Travel Fellowship

Individuals with post-traumatic stress disorder (PTSD) may experience differences in discriminating between and paying attention to certain types of sounds. These differences can be measured using brain electrical activity. Previous work has shown that PTSD is associated with reductions in the magnitude of response and increases in response processing time to neutral (non-emotional) sounds, and increases in response to trauma-related sounds. As well, there are different sub-types of PTSD that have been identified, including those who have ‘dissociative’ vs. ‘non-dissociative’ types. It is not known how these different sub-types respond to neutral vs. trauma-related sounds. This study assessed differences in brain electrical responses to target, distractor, and trauma-related (e.g. gunshots, screams) sounds, and examined their relationship with symptoms in individuals with dissociative and non-dissociative PTSD sub-types. Twenty-four (N=17 with ‘non-dissociative’ and N=7 with ‘dissociative’ sub-types) current or past members of the Canadian Armed Forces participated in an auditory test where they were instructed to respond (button press) to low-pitch target tones presented alongside frequently occurring, higher-pitched tones. Participants also heard unexpected ‘distractor’ and trauma-related sounds. Self-report measures of mood, anxiety, trauma, and emotional state were also collected. The results indicated that those with the dissociative sub-type had longer response times to the trauma-related sounds. Across the entire sample, the magnitude of the response to the target sounds, the response time to the distractor sounds, and the magnitude of the response to the trauma-related sounds were related to depression symptoms and emotional states. These results suggest that brain electrical responses may be affected by PTSD sub-type, and that there may be more automatic processing of trauma-related sounds in those with a dissociative PTSD sub-type. The data also suggests a relationship between symptoms and brain responses of attention and processing of distractor and trauma-related sounds.