Melodies Can Help Heal Disharmonies in Speech

by David Cameron

A lesion on the elderly man’s left frontal lobe, damage from a massive stroke, has robbed him of the ability to speak. The clinician sitting opposite him asks him to repeat a simple phrase: “Happy birthday to you.” The man struggles, but only manages, “En oh en oh en oh.”

The clinician then asks him to sing the phrase. Holding his left hand, moving it rhythmically, she initiates the song. After a few attempts, she’s silent, and he sings it as clearly as anyone carrying a cake with lit candles. The clinician then asks him, again, to speak the phrase. Without a hitch, he repeats, “Happy birthday to you.”

In less than two minutes, an extraordinary feat has occurred. Yet for researchers like Gottfried Schlaug, HMS associate professor of neurology and director of the Music, Neuroimaging and Stroke Recovery Laboratories at Beth Israel Deaconess Medical Center (BIDMC), such events aren’t new. Medical literature going back a century describes stroke victims who have regained aspects of speech through melodic intonation therapy. “The difference,” Schlaug says, “is that now we have the neuroimaging tools to investigate what occurs in the brains of people who relearn language through song.”

These tools reveal substantial overlap between areas of the brain that process music and language. Damage to the left hemisphere significantly impairs speech. And although the right hemisphere has some capacity for language, it responds best to clearly structured information, such as melodies. Layering language over melodies engages the right hemisphere’s latent language capacity.

Schlaug speculates that when people cycle between singing and speaking, the melodic contour and continuous voicing enable the right hemisphere to vocalize words and phrases, creating a kind of language-smuggling Trojan horse. By moving the elderly man’s left hand, the clinician helps him connect sounds to actions, sketching auditory motor maps into the right side. If a patient rehearses this entire process long enough, the brain’s right side eventually compensates for the impaired left—and even changes structure. “Ultimately,” Schlaug says, “we trick the right hemisphere into learning how to speak.”

Neurologists once embraced the theory that the right hemisphere of the brain housed a person’s creativity, while the left hemisphere processed information such as math. Musicians, then, should be highly right brain lateralized. In the early 1990s, Schlaug tested that theory. Using MRI technology to scan the brains of both musicians and nonmusicians, he and his colleagues discovered that the brains’ morphologies revealed the opposite. Musicians, on average, were more left brained; those with perfect pitch were the most left brained of all.

Schlaug has since focused on the planum temporale, which is part of the auditory cortex. The planum temporale has a more pronounced leftward asymmetry in musicians with perfect pitch than in musicians without perfect pitch and in nonmusicians.

“Professional musicians practice their skills many hours a day, for many years,” says Schlaug. “We think of musicians as auditory-motor athletes whose long-term training has an effect on brain function and structure.”

These findings launched Schlaug onto a trajectory of collaborations with researchers such as Psyche Loui, an HMS instructor in neurology at BIDMC and a violinist with perfect pitch, and David Alsop, a musician who is also an HMS associate professor of radiology at BIDMC.

As Schlaug, Loui, Alsop, and colleagues use the latest imaging technologies to study the brains of musicians and nonmusicians, the unanswered questions mount. How, for example, does music affect brain adaptation, reorganization, and even plasticity? The team is also in the last phases of a longitudinal study on the neurobiological effects on children of learning to play an instrument.

And finally, what about professional musicians? Schlaug suspects they are not born with the natural advantage of an auditory-motor system that enables them to play a musical instrument. Instead, given the plasticity of the brain, particularly at a young age, their continued musical practice likely leads to brain changes that can be detected by modern imaging techniques. For many of us this is good news. “Unless you’re tone-deaf,” Loui says, “you probably have some unconscious musical abilities even if you can’t sing in tune.”