From Alan Levine:
John Hopkins surgeon Charles Limb analyzed brain scans of jazz musicians to try to identify the brain activity indicators of creativity. His results suggest their creativity highs are correlated at times when their self criticism activity is low (they have muffled the voice of the Imposter Syndrome).
"Activity in the lateral prefrontal cortex, an area associated with self-monitoring, dropped dramatically, while that in the medial prefrontal cortex—a structure associated with the self-expression—spiked." (unknown player)
"This is Your Brain on Jazz Improvisation: The Neuroscience of Creativity" from Open Culture link
This is reminiscent of Stephen Krashen's Monitor Hypothesis.