Brain Activity in Response to Trauma-specific, Negative, and Neutral Stimuli. A fMRI Study of Recent Road Traffic Accident Survivors.

Andre S Nilsen,Tor Endestad,Laila Skogstad,Siri Leknes,Ines Blix,Trond Heir,Bjørn C Østberg,Øivind Ekeberg

doi:10.3389/fpsyg.2016.01173

Abstract

Most studies of neuro-functional patterns in trauma-exposed individuals have been conducted considerable time after the traumatic event. Hence little is known about neuro-functional processing shortly after trauma-exposure. We investigated brain activity patterns in response to trauma reminders as well as neutral and negative stimuli in individuals who had recently (within 3 weeks) been involved in a road traffic accident (RTA). Twenty-three RTA survivors and 17 non-trauma-exposed healthy controls (HCs) underwent functional MRI while viewing Trauma-specific, Negative, and Neutral pictures. Data were analyzed from four a priori regions of interest, including bilateral amygdala, subcallosal cortex, and medial prefrontal cortex. In addition, we performed a whole brain analysis and functional connectivity analysis during stimulus presentation. For both groups, Negative stimuli elicited more activity in the amygdala bilaterally than did Neutral and Trauma-specific stimuli. The whole brain analysis revealed higher activation in sensory processing related areas (bilateral occipital and temporal cortices and thalamus) as well as frontal and superior parietal areas, for the RTA group compared to HC, for Trauma-specific stimuli contrasted with Neutral stimuli. We also observed higher functional connectivity for Trauma-specific stimuli, between bilateral amygdala and somatosensory areas, for the RTA group compared to controls, when contrasted with Neutral stimuli. We argue that these results might indicate an attentional sensory processing bias toward Trauma-specific stimuli for trauma exposed individuals, a result in line with findings from the post-traumatic stress disorder literature.

Highlights

After experiencing a traumatic event, some individuals develop post-traumatic stress reactions, such as hyper-arousal, intrusive thoughts and memories, avoidance of trauma reminding stimuli, and trauma related memories or thoughts (APA, 2000)
While most previous studies have primarily focused on neuro-functional alterations associated with post-traumatic stress disorder (PTSD), the present study focused on trauma-exposure per se, shortly after the traumatic event
The present results suggest that experiencing a potentially traumatic event alone might not be sufficient to cause the predicted activity levels in amygdala and medial prefrontal cortex (mPFC)

Summary

Introduction

After experiencing a traumatic event, some individuals develop post-traumatic stress reactions, such as hyper-arousal, intrusive thoughts and memories, avoidance of trauma reminding stimuli, and trauma related memories or thoughts (APA, 2000). These symptoms can persist for days, weeks, or years. In line with the fear circuitry model, recent meta-analyses focusing on neuro-functional patterns associated with PTSD, have demonstrated hyperactive amygdala and hypoactive prefrontal regions (Hayes et al, 2012; Patel et al, 2012), as well as hyperactive hippocampus (Patel et al, 2012). Recent studies have shown that PTSD is associated with altered functional connectivity between the amygdala, and medial prefrontal cortex (mPFC), insula, and dCCA (Gilboa et al, 2012; Stevens et al, 2013), suggesting an interplay between prefrontal regions and limbic structures

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