Disrupted amygdala-prefrontal functional connectivity in civilian women with posttraumatic stress disorder

Abstract

Many features of posttraumatic stress disorder (PTSD) can be linked to exaggerated and dysregulated emotional responses. Central to the neurocircuitry regulating emotion are functional interactions between the amygdala and the ventromedial prefrontal cortex (vmPFC). Findings from human and animal studies suggest that disruption of this circuit predicts individual differences in emotion regulation. However, only a few studies have examined amygdala-vmPFC connectivity in the context of emotional processing in PTSD. The aim of the present research was to investigate the hypothesis that PTSD is associated with disrupted functional connectivity of the amygdala and vmPFC in response to emotional stimuli, extending previous findings by demonstrating such links in an understudied, highly traumatized, civilian population. 40 African-American women with civilian trauma (20 with PTSD and 20 non-PTSD controls) were recruited from a large urban hospital. Participants viewed fearful and neutral face stimuli during functional magnetic resonance imaging (fMRI). Relative to controls, participants with PTSD showed an increased right amygdala response to fearful stimuli (p(corr) < .05). Right amygdala activation correlated positively with the severity of hyperarousal symptoms in the PTSD group. Participants with PTSD showed decreased functional connectivity between the right amygdala and left vmPFC (p(corr) < .05). The findings are consistent with previous findings showing PTSD is associated with an exaggerated response of amygdala-mediated emotional arousal systems. This is the first study to show that the amygdala response may be accompanied by disruption of an amygdala-vmPFC functional circuit that is hypothesized to be involved in prefrontal cortical regulation of amygdala responsivity.

Keywords: Amygdala; Emotion; Functional connectivity; Medial prefrontal cortex; PTSD; fMRI.

Figure 1. Increased amygdala response to fearful stimuli in PTSD subjects

Increased right amygdala response to fearful stimuli in the posttraumatic stress disorder (PTSD) group, relative to the traumatized control (TC) group, p_corr < .05. Results are displayed in neurological orientation on a representative single-subject template brain in MNI space. Bar graph shows the mean contrast estimate across voxels in the right amygdala cluster, for the Fear > Neutral contrast, and error bars show standard error of the mean.

Figure 2. Relationship between amygdala response and trauma or PTSD symptoms

Correlations between the right amygdala response to fearful stimuli, trauma experience, and posttraumatic stress disorder (PTSD) symptoms are shown. The right amygdala response was extracted as the mean of all voxels within the anatomically-defined amygdala ROI, for the fearful > neutral faces contrast. The right amygdala response correlated only with hyperarousal symptoms in the PTSD group.

Figure 3. Differential functional connectivity with amygdala in PTSD vs. Trauma Control

Group differences in functional connectivity with the amygdala, for fearful relative to neutral images are shown. Clusters showing differences in connectivity with either the left or right amygdala seed are overlaid on a representative single-subject template brain, p_corr < .05. Blue-green color scale: significantly decreased connectivity in posttraumatic stress disorder (PTSD) relative to traumatized control (TC) participants. Red-yellow color scale: significantly increased connectivity in PTSD relative to TC participants.