Emotion regulation and trait anxiety are predicted by the microstructure of fibers between amygdala and prefrontal cortex

Abstract

Diffusion tensor imaging revealed that trait anxiety predicts the microstructural properties of a prespecified fiber tract between the amygdala and the perigenual anterior cingulate cortex. Besides this particular pathway, it is likely that other pathways are also affected. We investigated white matter differences in persons featuring an anxious or a nonanxious personality, taking into account all potential pathway connections between amygdala and anxiety-related regions of the prefrontal cortex (PFC). Diffusion-weighted images, measures of trait anxiety and of reappraisal use (an effective emotion-regulation style), were collected in 48 females. With probabilistic tractography, pathways between the amygdala and the dorsolateral PFC, dorsomedial PFC, ventromedial PFC, and orbitofrontal cortex (OFC) were delineated. The resulting network showed a direct ventral connection between amygdala and PFC and a second limbic connection following the fornix and the anterior limb of the internal capsule. Reappraisal use predicted the microstructure of pathways to all calculated PFC regions in the left hemisphere, indicating stronger pathways for persons with high reappraisal use. Trait anxiety predicted the microstructure in pathways to the ventromedial PFC and OFC, indexing weaker connections in trait-anxious persons. These effects appeared in the right hemisphere, supporting lateralization and top-down inhibition theories of emotion processing. Whereas a specific microstructure is associated with an anxious personality, a different structure subserves emotion regulation. Both are part of a broad fiber tract network between amygdala and PFC.

Keywords: DTI; PFC; amygdala; reappraisal use; top-down inhibition; trait anxiety.

Figure 1.

A, Illustration of the manually created atlas applied in this study. B, Axial slice of one subject with one exemplary probabilistic track that connects the amygdala with the prefrontal cortex. Voxels selected for the analysis (red) are located within the probabilistic track (green) and the individual skeleton and have FA values higher than 0.4.

Figure 2.

A–D, Left, Three-dimensional sagittal and superior views of tracts between amygdala and PFC regions: A, orbitofrontal cortex; B, ventromedial PFC; C, dorsomedial PFC; D, dorsolateral PFC. Renderings show the normalized number of tracts through each voxel (red). Seed and target regions are displayed in blue. For normalization, each voxel was divided by the amygdala's size. E, Slices illustrating the tracts' localization from medial to lateral. The distance between slices is 5 mm.