“How did John Coltrane do it?” Charles Limb wonders. “How did he get up there on stage and improvise his music for an hour or sometimes more? Sure a lot of musicians can throw out a creative little ditty here and there, but to continually produce masterpiece after masterpiece is nothing short of remarkable.”
That question, whether specifically in regard to the iconic jazz saxophonist or any creative genius in general, may never be fully answered. For creativity, next only to love, may be the most enigmatic of human traits, leaving the inner workings of the mind shrouded in mystery.
But in research that is its own shade of remarkable, Limb has started gathering some tantalizing clues about the mind’s activity during music making. With the aid of sensitive imaging equipment, this energetic assistant professor of otolaryngology is literally mapping creative juices as they flow through the brain. Most recently, he and collaborator Allen R. Braun have shown that when jazz musicians improvise, their brains turn off areas linked to self-censoring and inhibition—and turn on those that let self-expression flow.
While there’s undoubtedly a certain “coolness factor” to documenting human creativity in real time, Limb says this work is more than just a novelty act. “We can use music to understand hearing in a broader context,” he says. Moreover, this type of brain activity is crucial for life outside music; people are continually improvising words when they talk, coming up with solutions on the spot. “Without this type of creativity, humans wouldn’t have advanced as a species,” says Limb. “It’s an integral part of who we are.”
It takes only a few seconds to notice that Charles Limb is not your ordinary physician. After all, not all doctors have a small recording booth set up near their office or the latest issues of Bass Player, Downbeat, and Electronic Musician on their desk.
A talented saxophonist who directed a jazz band at Harvard University during college and played at New Haven restaurants during medical school at Yale, Limb is also a composer, studio engineer, and music historian (see p.21). He has extensively examined the creativity of composers such as Beethoven and Smetana, both of whom lost their hearing as adults, and he’s written about Thomas Edison’s invention of the phonograph despite being deaf ( a little-known fact).
And while he does keep some musical things to himself—he’s amassed a personal collection of instruments that includes a Rhodes piano, Hohner clarinet, and the obscure Chapman Stick—Limb has never hesitated to share this passion. In addition to writing numerous magazine articles and making frequent symposia appearances, he holds a joint faculty appointment at Hopkins’ Peabody Institute, where he lectures on using computers to study music.
“Basically, I’m a music addict,” he admits. “And I consider myself extremely fortunate to have found a career that enables me to feed my addiction.”
Limb was a recently minted resident and surgical fellow at Johns Hopkins in 2003, when he began a research fellowship with Braun at the National Institute on Deafness and Other Communication Disorders (NIDCD). Functional magnetic resonance imaging (fMRI) was coming into vogue, and Braun’s lab was using such imaging to track how the brain processes language and how disorders like stroke disrupt speech. “That led me to think that we could use this same approach to study people while they were doing musical things,” Limb says.
It turned out that Braun was also a musical connoisseur, and he quickly fell into step with this idea. “There’s a certain interface between music and language,” Braun says. “In fact, music therapy can aid in stroke recovery, as patients can learn to sing before they recover their speech. It was an idea I was already mulling in my head when Charles came to me with his proposal.”
The two researchers first tested if musical training might affect the brain’s architecture, a hypothesis that proved to hold true. When both musicians and non-musicians were presented with a series of rhythmic patterns, only the musicians activated a portion of the left side of the brain associated with language comprehension. Musicians, it seems, do indeed “hear” music differently than others—almost like a second language.
The pair then came up with a far more ambitious plan. Both jazz lovers, Limb and Braun enjoyed the spontaneity associated with the genre—with its long, impromptu riffs and the tradition of “trading fours” (whereby a pair of musicians alternate four bars apiece, feeding off each other). While other studies had focused on what happens in the brain when a person listens to music, few had looked at brain activity when music is being spontaneously composed.
So, they figured, why not try to analyze jazz improvisation? The logistics were daunting. They needed to figure out how to get a musician to play an instrument containing no magnetic parts while lying inside a cramped MRI tube.
With the help of a California engineer, Limb custom-designed a miniature, non-magnetic keyboard. He also devised a system of mirrors, one behind the test subject and another angled above his head, so the player could see the modified keyboard resting on his knees. The last tricky part: locating trained jazz pianists to serve as volunteers. Limb found three players through his connections at Peabody, and picked up three more through word of mouth in the jazz community.
During the testing, the musicians were asked to perform four different exercises while lying in the fMRI machine. First they played the C-major scale. Then they had to improvise on the scale. Next, they played an original blues melody (composed by Limb) that they had memorized, with a pre-recorded jazz quartet playing in the background. Finally, they were set free to improvise their own tune with the same recorded quartet.
When it came time to analyze the brain scans, Limb and Braun found strikingly similar patterns during improvisation—whether simple improvisation on a C scale or longer riffs with the jazz quartet.
“During improv, the brain deactivates the area involved in self-monitoring and observation, while cranking up the region linked with self-expression,” Limb explains. “So essentially, a musician shuts down his inhibitions and lets his inner voice shine through.”
The scans revealed a wealth of other information that was both unexpected yet unsurprising to anyone who has witnessed a musician close his eyes and seemingly enter a trancelike state as he bares his musical soul on stage. Brain regions involved with all the senses lit up in the improvising test subjects; thus, even though a performing musician may lose track of her actions, she is at the same time in a heightened state of awareness—tasting, smelling, feeling the air around her.
“It’s fascinating because we see these same patterns during deep REM sleep,” Braun notes. “It’s tantalizing to think some connection exists between improvisation and dreaming, which are both spontaneous events. These musicians may in fact be in a waking dream.”
Energized by the test results, which were published in the February 27 Public Library of Science PLoS ONE, Limb is eager to use music in future studies as a means for better understanding other aspects of hearing.
Current hearing studies, whether on animals or human volunteers, are typically approached from a minimal perspective, simplifying the sounds used (blips and pings) and questions asked (i.e., Can you hear a sound? What ear?). But our auditory system is so mechanistically complex, Limb notes, that these rudimentary tests are akin to trying to tease out the potential of a powerful sports car by driving it 10 miles per hour on a straight road.
Music, on the other hand, embodies the pinnacle of hearing: The art form is as complex in structure as language, yet completely abstract and free-flowing. And what better way to shed light on how a human brain processes complex auditory information than through sounds that are inherently human?
Ultimately, Limb envisions applying these research studies to the clinical side of his life as a cochlear implant specialist, where one of his main goals is to improve how deaf individuals with cochlear implants perceive music.
Furthermore Limb proposes that a musical ear exam might be sensitive enough to detect hearing loss at its earliest stages, or detect minor defects in pitch or tone that standard tests may miss.
A music-based diagnostic may even sway musicians, whom Limb notes are surprisingly reluctant to have their hearing assessed. “Musicians often work in environments that are potentially quite damaging to their ears,” and hearing loss and tinnitus (buzzing in the ears in the absence of sounds) are common and on the rise. “Yet so few of the musicians I know have formally checked their hearing,” he says. “They don’t want doctors putting any tubes in their ears for fear of damage, and they definitely don’t want to be seen wearing a hearing aid.”
Before all that, though, Limb and Braun plan to continue imaging the brain to gather clues about other mysteries of creativity. They hope to extend the improv studies to look at art forms—such as writing or painting—that emphasize other senses, to compare the flow of activity and see if spontaneous creativity can be generalized.
“Obviously we won’t expect test subjects to spout out a novel,” says Limb. “But maybe they could put together a haiku.”