It's a pretty long article but it underlies the mechanisms of anhedonia. It seems the ventral striatum plays a role in anhedonia.
The analyses of anhedonic nonclinical subjects, nonanhedonic depressed patients, and depressed patients with various levels of anhedonia seem to favor the hypothesis that the severity of anhedonia is associated with a deficit of activity of the ventral striatum (including the nucleus accumbens) and an excess of activity of ventral region of the prefrontal cortex (including the ventromedial prefrontal cortex and the orbitofrontal cortex), with a pivotal, but not exclusive, role of dopamine.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181880/
