Where I’m at right now (Pre-SMA – and I’ve been here before but I understand it a little better) started from trying to understand “WHERE DOES THE MUSIC IMPROVIZATION COME FROM?”
and it seems to be “motor planning of the hands”.
That makes sense; instruments usually are played with the hands.
Now I seem to have found a three way split they use in neurobiological research:
CHANGE for example, would be the area where one would chose, say, chord inversions while in the middle of playing.
These decisions are voluntary but they are also starting just prior to awareness; so it often feels surprising – like the “muse” taking over with music; but we have control over it too; it straddles what we call unconscious and conscious but it’s both, as I think conscious here would be “ability to tell yourself something about yourself”.