Researchers have long debated whether or not language and music depend on common processes in the mind. Now, researchers at Georgetown University Medical Center have found evidence that the processing of music and language do indeed depend on some of the same brain systems.
Their findings, which are currently available on-line and will be published later this year in the journal NeuroImage, are the first to suggest that two different aspects of both music and language depend on the same two memory systems in the brain.
One brain system, based in the temporal lobes, helps humans memorize information in both language and music— for example, words and meanings in language and familiar melodies in music. The other system, based in the frontal lobes, helps us unconsciously learn and use the rules that underlie both language and music, such as the rules of syntax in sentences, and the rules of harmony in music.
“Up until now, researchers had found that the processing of rules relies on an overlapping set of frontal lobe structures in music and language. However, in addition to rules, both language and music crucially require the memorization of arbitrary information such as words and melodies,” says the study’s principal investigator, Michael Ullman, Ph.D., professor of neuroscience, psychology, neurology and linguistics.
“This study not only confirms that one set of brain structures underlies rules in both language and music, but also suggests, for the first time, that a different brain system underlies memorized information in both domains,” Ullman says. “So language and music both depend on two different brain systems, each for the same type of thing – rules in one case, and arbitrary information in the other.”
Robbin Miranda, Ph.D., currently a post-doctoral researcher in the Department of Neuroscience, carried out this research with Ullman for her graduate dissertation at Georgetown. They enrolled 64 adults. They used a technique called Event-Related Potentials, in which they measured the brain’s electrical activity using electrodes placed on the scalp.
The subjects listened to 180 snippets of melodies. Half of the melodies were segments from tunes that most participants would know, such as “Three Blind Mice” and “Twinkle, Twinkle Little Star.” The other half included novel tunes composed by Miranda. Three versions of each well-known and novel melody were created: melodies containing an in-key deviant note (which could only be detected if the melody was familiar, and therefore memorized); melodies that contained an out-of-key deviant note (which violated rules of harmony); and the original (control) melodies.
For listeners familiar with a melody, an in-key deviant note violated the listener’s memory of the melody − the song sounded musically “correct” and didn’t violate any rules of music, but it was different than what the listener had previously memorized. In contrast, in-key “deviant” notes in novel melodies did not violate memory (or rules) because the listeners did not know the tune.
Out-of-key deviant notes constituted violations of musical rules in both well-known and novel melodies. Additionally, out-of-key deviant notes violated memory in well-known melodies.
Miranda and Ullman examined the brain waves of the participants who listened to melodies in the different conditions, and found that violations of rules and memory in music corresponded to the two patterns of brain waves seen in previous studies of rule and memory violations in language. That is, in-key violations of familiar (but not novel) melodies led to a brain-wave pattern similar to one called an “N400” that has previously been found with violations of words (such as, “I’ll have my coffee with milk and concrete”). Out-of-key violations of both familiar and novel melodies led to a brain-wave pattern over frontal lobe electrodes similar to patterns previously found for violations of rules in both language and music. Finally, out-of-key violations of familiar melodies also led to an N400-like pattern of brain activity, as expected because these are violations of memory as well as rules.
“This tells us that these two aspects of music, that is rules and memorized melodies, depend on two different brain systems – brain systems that also underlie rules and memorized information in language,” Ullman says. “The findings open up exciting new ways of thinking about and investigating the relationship between language and music, two fundamental human capacities.”