Neural correlates of exposure to traumatic pictures and sound in Vietnam combat veterans with and without posttraumatic stress disorder: a positron emission tomography study

Abstract

Background: Patients with posttraumatic stress disorder (PTSD) show a reliable increase in PTSD symptoms and physiological reactivity following exposure to traumatic pictures and sounds. In this study neural correlates of exposure to traumatic pictures and sounds were measured in PTSD.

Methods: Positron emission tomography and H2[15O] were used to measure cerebral blood flow during exposure to combat-related and neutral pictures and sounds in Vietnam combat veterans with and without PTSD.

Results: Exposure to traumatic material in PTSD (but not non-PTSD) subjects resulted in a decrease in blood flow in medial prefrontal cortex (area 25), an area postulated to play a role in emotion through inhibition of amygdala responsiveness. Non-PTSD subjects activated anterior cingulate (area 24) to a greater degree than PTSD patients. There were also differences in cerebral blood flow response in areas involved in memory and visuospatial processing (and by extension response to threat), including posterior cingulate (area 23), precentral (motor) and inferior parietal cortex, and lingual gyrus. There was a pattern of increases in PTSD and decreases in non-PTSD subjects in these areas.

Conclusions: The findings suggest that functional alternations in specific cortical and subcortical brain areas involved in memory, visuospatial processing, and emotion underlie the symptoms of patients with PTSD.

Figure 1

Percent change in globally normalized regional cerebral blood flow with exposure to traumatic cues (combat slides and sounds) relative to the neutral condition (neutral slides and sounds) in Vietnam combat veterans with PTSD and comparison subjects, showing regions in which there were significant group by condition interactions (p < .001).

Figure 2

Statistical parametric map of areas of significant interaction between PTSD diagnosis and condition. Areas of white and gray represent regions in which there were significant interactions between condition (traumatic versus neutral) and group (PTSD versus comparison subjects) (Z score > 3.00; p < .001). Statistical significance is related to patterns of increased blood flow in PTSD, decreased blood flow in non-PTSD, or some combination of the two. Cer, cerebellum; PH, parahippocampal gyrus; Li, lingual gyrus; PrC, precentral gyrus; IPL, inferior parietal lobule; Ci, posterior cingulate.

Figure 3

Statistical parametric map overlaid on a magnetic resonance image template of areas of significant interaction between PTSD diagnosis and condition. Areas of white and gray represent regions in which there were significant interactions between condition (traumatic versus neutral) and group (PTSD versus comparison subjects) (Z score > 3.00; p < .001). Statistical significance is related to deactivation in the area of medial prefrontal gyrus (area 25) (large white area in frontal cortex) and bilateral middle temporal cortex. Several slices above the large medial frontal deactivation is a smaller area of significant difference in the area of right anterior cingulate (image’s right is patient’s right), which is secondary to activation seen in non-PTSD (but not PTSD). AC, anterior cingulate (area 24 and 32); MPfc, medial prefrontal cortex (area 25); MTG, middle temporal gyrus.