Investigation of Human Brain Parabrachial Nucleus (PBN) - Central Amygdala (CeA) Pathway by Diffusion Tractography

Motivation: The parabrachial nucleus (PBN) to the central amygdala (CeA) is a critical pathway for multiple types of aversive, unconditional threat behaviors including chronic pain states in animals. However, there do not exist connectivity studies on this pathway in the human brain by diffusion tractography. Goal(s): Study of connectivity between PBN and CeA by diffusion tractography. Approach: Probabilistic tractography with the ball-and-stick model (FSL) and multi-shell, multi-tissue constrained spherical deconvolution, and fixel-based analysis (MRTRIX). Results: The study showed the existence of a PBN-CeA pathway in the human brain. Average streamline density of this pathway differs across the subjects while the cross section is comparable. Impact: This study has discovered that a PBN-CeA pathway exists in both hemispheres of the human brain, which is consistent with our previous functional connectivity study. This finding will open up new avenues of research on fear conditioning, anxiety, and pain.