Limb and Braun then analyzed the brain scans. Since the brain areas activated during memorized playing are parts that tend to be active during any kind of piano playing, the researchers subtracted those images from ones taken during improvisation.  Left only with brain activity unique to improvisation, the scientists saw strikingly similar patterns, regardless of whether the musicians were doing simple improvisation on the C-major scale or playing more complex tunes with the jazz quartet.

The scientists found that a region of the brain known as the dorsolateral prefrontal cortex, a broad portion of the front of the brain that extends to the sides, showed a slowdown in activity during improvisation. This area has been linked to planned actions and self-censoring, such as carefully deciding what words you might say at a job interview. Shutting down this area could lead to lowered inhibitions, Limb suggests.

The researchers also saw increased activity in the medial prefrontal cortex, which sits in the center of the brain’s frontal lobe.  This area has been linked with self-expression and activities that convey individuality, such as telling a story about yourself.

“Jazz is often described as being an extremely individualistic art form. You can figure out which jazz musician is playing because one person’s improvisation sounds only like him or her,” says Limb. “What we think is happening is when you’re telling your own musical story, you’re shutting down impulses that might impede the flow of novel ideas.”