The structural integrity of an amygdala-prefrontal pathway predicts trait anxiety

Abstract

Here, we used diffusion tensor imaging (DTI) and showed that the strength of an axonal pathway identified between the amygdala and prefrontal cortex predicted individual differences in trait anxiety. A functional magnetic resonance imaging (fMRI) functional localizer that has been shown to produce reliable amygdala activation was collected in 20 psychiatrically healthy subjects. Voxelwise regression analyses using this fMRI amygdala reactivity as a regressor were performed on fractional anisotropy images derived from DTI. This analysis identified a white matter pathway between the amygdala and ventromedial prefrontal cortex. Individual differences in the structural integrity of this putative amygdala-prefrontal pathway were inversely correlated with trait anxiety levels (i.e., higher pathway strength predicted lower anxiety). More generally, this study illustrates a strategy for combining fMRI and DTI to identify individual differences in structural pathways that predict behavioral outcomes.

Figure 1.

Amygdala–vmPFC pathway identified based on variability in functional activation of the amygdala. Statistical map showing FA voxels that are positively correlated with amygdala reactivity to fearful versus neutral faces (p < 0.05, corrected) in sagittal and coronal slices. The color bars indicate p values.

Figure 2.

Correlation between the structural integrity of an amygdala–vmPFC pathway and trait anxiety. FA values of an amygdala–vmPFC pathway (r = −0.515; p < 0.05), shown in Figure 1, were negatively correlated with trait anxiety.