henry copeland:

Mind of blue: Emotional expression affects the brain's creativity network: Study of jazz pianists finds 'happy' and 'sad' music evoke different neural patterns -- ScienceDaily

"There's more deactivation of the DLPFC during happy improvisations, perhaps indicating that people are getting into more of a 'groove' or 'zone,' but during sad improvisations there's more recruitment of areas of the brain related to reward," said McPherson, a classical violist and first-year graduate student in the Harvard-MIT Program in Speech and Hearing Bioscience and Technology. "This indicates there may be different mechanisms for why it's pleasurable to create happy versus sad music."
- www.sciencedaily.com