Posterior and prefrontal contributions to the development posttraumatic stress disorder symptom severity: an fMRI study of symptom provocation in acute stress disorder.

Acute stress disorder (ASD) is predictive of the development of posttraumatic stress disorder (PTSD). In response to symptom provocation, the exposure to trauma-related pictures, ASD patients showed increased activation of the medial posterior areas of precuneus and posterior cingulate cortex as well as of superior prefrontal cortex in a previous study. The current study aimed at investigating which activated areas are predictive of the development of PTSD. Nineteen ASD patients took part in an fMRI study in which they were shown personalized trauma-related and neutral pictures within 4 weeks of the traumatic event. They were assessed for severity of PTSD 4 weeks later. Activation contrasts between trauma-related and neutral pictures were correlated with subsequent PTSD symptom severity. Greater activation in, among others, right medial precuneus, left retrosplenial cortex, precentral and right superior temporal gyrus as well as less activation in lateral, superior prefrontal and left fusiform gyrus was related to subsequently increased PTSD severity. The results are broadly in line with neural areas related to etiological models of PTSD, namely multisensory associative learning recruiting posterior regions on the one hand and failure to reappraise maladaptive cognitions, thought to involve prefrontal areas, on the other.

Posterior Midline Activation during Symptom Provocation in Acute Stress Disorder: An fMRI Study.

Functional imaging studies of patients with post-traumatic stress disorder showed wide-spread activation of midline cortical areas during symptom provocation, i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with acute stress disorder (ASD) shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in midline cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus, and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients.

In search of the trauma memory: a meta-analysis of functional neuroimaging studies of symptom provocation in posttraumatic stress disorder (PTSD).

Notwithstanding some discrepancy between results from neuroimaging studies of symptom provocation in posttraumatic stress disorder (PTSD), there is broad agreement as to the neural circuit underlying this disorder. It is thought to be characterized by an exaggerated amygdalar and decreased medial prefrontal activation to which the elevated anxiety state and concomitant inadequate emotional regulation are attributed. However, the proposed circuit falls short of accounting for the main symptom, unique among anxiety disorders to PTSD, namely, reexperiencing the precipitating event in the form of recurrent, distressing images and recollections. Owing to the technical demands, neuroimaging studies are usually carried out with small sample sizes. A meta-analysis of their findings is more likely to cast light on the involved cortical areas. Coordinate-based meta-analyses employing ES-SDM (Effect Size Signed Differential Mapping) were carried out on 19 studies with 274 PTSD patients. Thirteen of the studies included 145 trauma-exposed control participants. Comparisons between reactions to trauma-related stimuli and a control condition and group comparison of reactions to the trauma-related stimuli were submitted to meta-analysis. Compared to controls and the neutral condition, PTSD patients showed significant activation of the mid-line retrosplenial cortex and precuneus in response to trauma-related stimuli. These midline areas have been implicated in self-referential processing and salient autobiographical memory. PTSD patients also evidenced hyperactivation of the pregenual/anterior cingulate gyrus and bilateral amygdala to trauma-relevant, compared to neutral, stimuli. Patients showed significantly less activation than controls in sensory association areas such as the bilateral temporal gyri and extrastriate area which may indicate that the patients' attention was diverted from the presented stimuli by being focused on the elicited trauma memory. Being involved in associative learning and priming, the retrosplenial cortex may have an important function in relation to trauma memory, in particular, the intrusive reexperiencing of the traumatic event.