"Obviously, from an ergonomic perspective, it's not ideal," Limb conceded. "They are lying on their backs; they have their head kind of in a cage, which is called a head coil; and they are looking up at a mirror, which is pointed to another mirror, which is pointed at their knees. And then they have a piano keyboard resting on their knees, and they can see their hands through those double mirrors."
The keyboard doesn't make any noise at all, but it sends a signal to a computer that translates the signal into a musical note that is then transmitted back to the musician through specially designed earphones with no metal parts. Each participant went through a series of experiments, beginning with the C-major scale, known by every fledgling musician, followed by a piece each participant had memorized. That gave the researchers images of brain functions during those routine performances.
Finally, the participants were told to improvise as they listened to a recording of a jazz quartet. Under such circumstances, one might expect a pretty weak performance.
"They were fantastic," Limb said. "When they were warming up, wow, they were so good that a couple of times I just let them warm up without starting the project because I was just listening. And I was just shocked at their ability to play on a little dinky plastic keyboard with 35 keys, lying down on their back."
In a report on their research in the Feb. 27 edition of the Public Library of Science (PLoS) One, Limb and Braun revealed that the portion of the brain that is associated with careful planning and self-censorship, the dorsolateral prefrontal cortex, nearly closed down. That's the part of the brain that warns you to tread softly when confronting the boss. It's what makes us inhibited, some more than others.
But the medial prefrontal cortex, the part of the brain linked to self-expression, lit up.
So what appears to happen is that during improvisation, the brain ignores the chance of failure and turns off inhibition, but at the same time it sets the artist free to tell his or her own musical story. As Limb notes, it's probably why some musicians shut their eyes and go into what appears to be a trance as they fly free of the self-censoring part of the brain that might otherwise tell them to stick to the script.
Of course, despite all that, it's still a mystery. Why can some people do it, and others can't? Is it an innate talent that lifts a few above the many, or can anyone learn to do it? For those who can, it must be majestic. For the rest of us, it's simply magic.