"Good improvisation communicates harmonic progression melodically. Effective melodies manipulate harmonic content through the use of guide tones and preparatory gravity notes, masterfully woven in systematic tension, release, and transparent harmonic definition."
The TED conference videos are a fascinating resource of current information on technologies and educational philosophies. We were most intrigued by a recent January entry by surgeon Dr. Charles Limb on the impact of improvisation on the brain (or vice versa). Scanning live brain activity of a musician with an MRI reveals curious details on the electrical/blood processes in specific regions while playing memorized passages as compared to improvisational activity. Himself an amateur jazz musician, he even shows video footage of an experiment while "trading fours" with another musician.
What we found striking was the notion that certain parts of the brain become inactive in the heat of maximum heightened creativity. The area that monitors control and inhibition is passive while the region that is expressive and autobiographical increases in activity. This implies that we need to be able to "let loose" cognitively, not only losing our normal conscious inhibitions, but relinquishing control to these creative areas.
Perhaps this is why some musicians actually drool when they play...
We think the analytical approach to jazz, looking under the hood in music theory and mastery of scales is important. That aside, the next step is to be able to transcend the cerebral and make it a motor, "turn off the brain" process. As they say, "Learn your scales so well that you forget them." The cognition needs to get buried and meld with the subliminal.
Learn your FFcPs, your 'ii V7 I's, turnarounds, and your scales, but then go to the next level by making them automatic. That's when creativity can truly take over.