The Brain on Bop

Dr. Charles Limb researches the neurological miracles behind jazz improvisation

Dr. Charles Limb

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“I must be one of the luckiest surgeons in the world,” began Dr. Charles Limb at the Mansion at Strathmore, an artistic foundation just outside Washington, D.C., on April 26. “I get to get up in front of an audience and talk not about surgery, but about music.”

Limb regularly discusses both-he’s a Baltimore-based neurologist with a passion for music, on faculty at both the Johns Hopkins School of Medicine and the Peabody Conservatory. At Strathmore, he delivered a lecture titled “Your Brain on Jazz: The Neuroscience of Jazz Improvisation,” part of the “Arts and the Brain” series.

Limb’s research interest is artistic creativity, which he believes is a neurological product that can be scientifically studied. Specifically, he regards the process of improvising music as a model for such study; his lecture detailed three experiments that he conducted at the National Institutes of Health by placing jazz musicians (in the first two experiments) or hip-hop freestylers (in the third) into a functional MRI scanner and having them improvise. “No,” he acknowledged, “it’s not a great place to jam.” Limb overcame that hurdle by designing and building a small, 35-key piano that can be played inside the chamber. In all three experiments, the control condition involved repeated performances of original compositions by Limb. “A word of advice,” he said. “If you’re going to do an experiment like this, make sure you write something you don’t mind hearing two thousand times.”

In the first experimental condition, jazz pianists were asked to improvise over Limb’s compositional framework, a C-minor blues. In the second, another group of pianists (including Mike Pope, better known as a bassist) traded fours with Limb over another blues. In the third (“nothing short of hilarious,” said Limb, who infiltrated the Baltimore hip-hop scene to find participants), rappers improvised rhymes using random words from Limb’s written rap. The fMRI machine scanned the musicians using Blood Oxygenation Level Dependent (BOLD) imaging, a technique that measures blood flow to neurons across various regions of the brain, allowing experts to determine which of those regions are activated or inhibited by the stimuli in the experimental conditions.

The results were fascinating. The solo improvisers showed increased activity in the medial prefrontal cortex-the brain’s “autobiography” center-and decreased activity in the lateral prefrontal cortex-the self-monitoring center. Simply put, when musicians improvise, their brain turns up the self-expression, while releasing conscious control of the performance activity. This, Limb explained, leads to “a defocused form of attention that may encourage spontaneous associations and sudden insights.”

The musicians who improvised exchanges with Limb showed even more compelling results: activity in Broca’s area, the brain region associated with language production. This refers not to “language” as jazz theory and technique, but to communication. “Music has an ability to communicate primal, emotional messages that resonate on a noncognitive, noncerebral level,” said Limb. “Seeing this in our experiments, I think we’re on to something.”

Since the freestyle rap experiment was based in language, it showed increased Broca’s area activity even without exchange. However, Limb found that they were substantially more active in freestyling than in reciting the written rap; this, he hypothesized, was “to account for not knowing what comes next. Since they’re creating lines without knowing what the next will be until it comes, they have to pay special attention to the meanings and forms without slowing down to think it through.”

Limb emphasized early in his lecture that “This is the kind of science that has no answer.” Hence, instead of conclusions, he ended with questions for future study: Do the mechanisms of musical creativity generalize to other forms of creativity? What is creative genius? Can creativity be learned? Because funding for such impractical science is hard to come by (and the NIH has expressed disinterest in supporting Limb further), these questions might remain unaddressed. Limb’s current findings, however, are intriguing enough on their own.