Resting-state Functional Connectivity in Anhedonia: Exploring the Effects of Pramipexole

Abstract: Pramipexole is a medication that normalises dopamine signalling in the brain. Previous studies have suggested that pramipexole is an effective treatment option for depression and anhedonia because it targets the dopaminergic pathways within the brain’s reward network. The nucleus accumbens is a crucial region for dopamine signalling in reward processing. Both task-based and resting-state fMRI evidence have supported the association between anhedonia and abnormal connectivity of the nucleus accumbens. However, no previous research has directly compared how the nucleus accumbens resting-state functional connectivity is altered pre-and post-pramipexole treatment. This study analysed resting-state fMRI data that was collected before and after treatment with pramipexole in a sample of patients with depression and anhedonia (N=9). Bilateral nucleus accumbens seeds were correlated with all other voxels in the brain in a seed- to-voxel functional connectivity analysis. A general linear model was conducted to average the seed-based connectivity maps for main effects of the pre-and post-treatment sessions respectively, and to compare connectivity between the two sessions. Significant differences in resting state functional connectivity of the bilateral nucleus accumbens was found in two regions: the left intracalcarine cortex and the right lingual gyrus. In both regions, resting state functional connectivity had switched from positive pre-treatment to negative post-treatment. The present findings are interpreted taking the study's limitations into account, and suggestions are made for future research.