It seems to be a bit of brain involved, importantly, in staving off depression, or as Heller notes, in the PNAS open access paper (6-page pdf), Reduced capacity to sustain positive emotion in major depression reflects diminished maintenance of fronto-striatal brain activation,
"While up-regulating positive affect, depressed individuals failed to sustain nucleus accumbens activity over time compared with controls."
Any structure that can help stave off "Major Depressive Disorder" is one I want to know more about. There was a look taken at "the fronto-striatal network in anhedonia" also.
"These findings support the hypothesis that anhedonia in depressed patients reflects the inability to sustain engagement of structures involved in positive affect and reward."
"Our study examines the ability of depressed patients to sustain engagement of the NAcc while enhancing positive affect in response to positive images embedded within a stream of stimuli that included both positive and negative images."
Sounds like depressed people can kind of fake it for a little while, but their/our nucleus accumbens tuckers out easily, can't continuously rejoice over life's simple pleasures. From the paper:
"...in everyday life, individuals do not generally encounter uninterrupted positive stimuli. Negative experiences often intermix with positive ones, and the ability of individuals to heighten and maintain positive affect in the face of negative stimuli is vitally important for health and well-being."
Sheesh, you can say that again. Mine feels as though it is perking up fairly well with the help of increased photons in the suprachiasmatic nucleus. Still a fairly long way to go however.