Nucleus Accumbens Projections: Validity and Reliability of Fiber Reconstructions based on High-Resolution Diffusion-Weighted MRI

Zielsetzung The N. accumbens (NAc) is a key relay in the mesolimbic dopaminergic reward system. As such, it is a promising target for deep brain stimulation (DBS) in patients with psychiatric diseases. Therefore, we aimed to reconstruct the neural projections connecting the NAc with the medial prefrontal cortex (mPFC), the anterior cingulate cortex (ACC), the amygdala, the hippocampus, the dorsomedial thalamus (dmT) and the ventral tegmental area (VTA) using probabilistic fiber tractography based on DW-MRI.

Material und Methoden MR-data for 11 healthy subjects were acquired in seven sessions on a 3T MRI-scanner. For each subject, the above-mentioned targets were segmented and transformed to the session-specific DW-MRI-space for probabilistic fiber tractography. The results were subject to detailed visual inspection to assess their validity in terms of anatomical plausibility by comparing them with the relevant literature. To quantitatively assess the reliability of the reconstructions, exemplarily the individual fiber-tracts between the NAc and mPFC for each session and subject were clustered and transformed to a main-tract before performing an intra-subject comparison.

Ergebnisse Using MRI data from 11 healthy subjects, we were able to reconstruct neural projections connecting the NAc with the above-mentioned targets. The connectivity patterns formed by the obtained fibers were in good concordance with the literature. Furthermore, the reliability assessment of the NAc ↔ mPFC fiber-tracts yielded to high correlations between the obtained main-tracts.

Schlußfolgerungen We assessed the feasibility and reliability of the in vivo reconstruction of neural fibers connecting the human NAc with the above-mentioned targets from high-resolution DW-MRI data using probabilistic fiber-tractography. In clinical practice, the presented procedure may guide selective electrical stimulation of the mesolimbic fibers using directional lead technology. This could improve for example the efficacy of DBS for the treatment of mental disorders.