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I don't know about changing the brain, but I do believe that music has a powerful effect on both the brain and on mood. I saw a documentary on public television once where the moderator underwent brain scans while listening two different pieces of classical music. The flare ups in the brain were wide spread and very different for each piece with more area of the brain activated and more of the pleasure centers activated for the piece he later said he liked while the one he said he didn't care for had flares in other part of the brain.
Music is powerful and while I'm not sure about it changing the structure of the brain in and of itself, I do believe it helps act as a sort of catalyst or facilitator in increasing learning. I work with disabled kids, many of them autistic, and I almost always play music. Often it's Mozart but sometimes I play quieter music like chants or acoustic earth music for calming. Sometimes I have a kid who is lethargic and I play my christian (I work for a private non-profit in a small southern city so this works without issues) hip-hop/rap music to perk the kids up. I equally believe that dark, angry, violent music can lead to dark, angry, violent behavior and thoughts.
I absolutely believe in the power of music.
The healing powers of music: Mozart and Strauss for treating hypertension
The music of Mozart and Strauss is able to lower blood lipid concentrations and the heart rate. This is the result of a study of the effect of different musical genres on the cardiovascular system. Ref. Source 7t.