Inhibitory dysfunction is closely associated to post-traumatic stress disorder (PTSD). The present study investigated the neurophysiological evidence for and the brain regions related to inhibitory dysfunction in PTSD. Fifty patients with PTSD and 63 healthy controls (HCs) participated in a Go/Nogo task combined with electroencephalographic recordings. The N2-P3 complexes of event-related potentials (ERPs) elicited during the Nogo condition were compared between groups. Participants underwent structural magnetic resonance imaging to examine cortical volumes and completed questionnaires. Correlations between altered ERPs and cortical volumes of regions of interest as well as psychological symptoms were analysed. Nogo-N2 latencies at five electrode sites (Fz, FCz, Cz, CPz, and Pz) were significantly delayed in patients with PTSD compared to HCs. Nogo-N2 latency had a significant negative correlation with the volume of gyrus in the inferior frontal cortex, orbitofrontal cortex, amygdala, and medial prefrontal cortex. Nogo-N2 latency was significantly and positively correlated with catastrophizing, anxiety, and perceived threat. These findings show inhibitory dysfunction in patients with PTSD, reflected by the delay in Nogo-N2 latencies. They also indicate that Nogo-N2 latencies are associated with smaller cortical volumes responsible for inhibition as well as with major symptoms of PTSD.
Keywords: Cortical volume; Go/Nogo; N2 latency; PTSD.