While playing spontaneous, improvisational music, the brains of jazz musicians showed activation in areas of the brain traditionally associated with spoken language and syntax, which helps us to understand the construction of phrases and sentences. According to a new study by researchers from Johns Hopkins University, this brain activation also shuts down brain areas linked to semantics, which process the meaning of spoken language.

The team used functional magnetic resonance imaging (fMRI) to gather data on the brain activity of jazz musicians while they "trade fours," a spontaneous back and forth exchange of musical measures by multiple musicians. The performers respond to the improvised music of their counterparts by building on and mortifying the rhymes, much the same way verbal conversation takes place.

The results of the study suggest brain areas that interpret syntax are not limited to spoken language, according to Charles Limb, an associate professor in the Department of Otolaryngology-Head and Neck Surgery at the Johns Hopkins University School of Medicine. He said the brain uses syntactic areas to process communication, which isn't limited to language, according to the press release.

Until now, studies of how the brain processes auditory communication between two individuals have been done only in the context of spoken language," said Limb, the senior author of the report, which was published in PLOS ONE. "But looking at jazz lets us investigate the neurological basis of interactive, musical communication as it occurs outside of spoken language."

"We've shown in this study that there is a fundamental difference between how meaning is processed by the brain for music and language. Specifically, it's syntactic and not semantic processing that is key to this type of musical communication. Meanwhile, conventional notions of semantics may not apply to musical processing by the brain," Limb added.

Limb recruited 11 men aged 25 to 56 who were highly proficient in jazz piano performance. During the "trading four" session, one musician laid on his back inside the fMRI machine with a plastic piano resting on his lap. He was able to view the mirror without moving his head through a series of mirrors set up in the machine.

The musical improvisation activated the inferior frontal gyrus and posterior superior temporal gyrus, which are linked to the syntactic processing for language. Conversely, the improvisation deactivated the angular gyrus and supramarginal gyrus, which are involved in semantic processing.

"When two jazz musicians seem lost in thought while trading fours, they aren't simply waiting for their turn to play," Limb said. "Instead, they are using the syntactic areas of their brain to process what they are hearing so they can respond by playing a new series of notes that hasn't previously been composed or practiced."