Many people sing a melody in tune, many people wistle in tune. Some of them make simple arrangements, but none knows about music theory, or what note they are playing. Put an instrument to those people and no one can play it without exercise and practice. So, i think there is a disconnection between the brain and the instrument. I know the 12 notes, but no reading and no knowledgement about music theory. But sometimes I find myself playing the bass or guitar in front of TV and following the commercial melody without problems. Is there excercises to improve the brain to fret connection ?