Thursday, December 18, 2008

Cross-Cultural Musical Phrase Processing

Nan, Yun, and Thomas R. Knösche, Stefan Zysset, and Angela Friedeici. Cross-Cultural Music Phrase Processing: An fMRI Study. Human Brain Mapping 29:312-328 (2008).

Posted by Devon Fornelli

This study used fmri to investigate the neurological basis of musical phrase boundary processing during the perception of music from native and non-native cultures. German musicians performed a cultural categorization task while listening to phrased Western(native) and Chinese (non-native) musical excerpts as well as modified versions of these, where the impression of phrasing has been reduced by removing the phrase boundary marking pause (unphrased). The goals of the investigators was to: 1) specify/locate the neural substrates of musical phrase boundary processing and 2) specify the differences in neural networks underlying the processing of culturally familiar and unfamiliar music, and 3) specify the interaction between 1) and 2) and determining whether and how the processing of musical phrase boundaries might be influenced by the cultural familiarity of the music.
The brain structures the researchers identified as being involved with the tasks:
Bilateral planum temporal was found to be associated with increased difficulty of identifying phrase boundaries in unphrased Western melodies.
Broca’s areas 44 (which is involved with processing musical syntax) and 47 ( which is responsible for linguistic and musical processing)

The networks involved were the frontal and parietal areas since they showed increased activation for phrased condition. The specific structures involved were the orbital part of left inferior frontal gyrus (presumably reflecting working memory aspects of the temporal integration between phrases), and the middle frontal gyrus and intraparietal sulcus (probably reflecting attention processes).
Based on information from other studies, the researchers hypothesize that the right parietal cortex near the inferior parietal lobule and possibly the left parietal lobe and retrosplenial cortex might be associated with familiarity mediated by cultural musical style.
The research participants were 20 female German musicians aged 19-28.
1) Bilateral planum temporal identified as most prominent brain areas for processing of unphrased melodies vs. phrased. Fronto-parietal network consisting of left middle frontal gyri and right intraparietal sulcus was observed in response to phrased melodies.
Listening to unphrased melodies resulted in increased activation in the bilateral supra-temporal plane, comprising the anterior planum temporal and possibly involving the posterior Heschl’s gyrus. In contrast, phrased melodies activated the right intraparietal sulcus, the left middle frontal gyrus, and an area in the orbital part of the left anterior inferior frontal gyrus (which lies in Broca’s area 47 near the border to triangle part and the anterior middle frontal gyrus).

What I was able to gleam from this extensive study was that the subjects displayed that certain structures in their brains showed activity when they were presented with familiar music, foreign music, familiar music with adjusted phrase boundaries, and foreign music with adjusted phrase boundaries.
The observed changes make sense in that the brain would recognize something new or out of place in the phrasing of music it was familiar with. With music that it is unfamiliar with, the brain does not distinguish between changes in phrase boundaries because the music is all new and there is no reference point in order to distinguish whether something is out of place. The perception of phrased melodies in trained musicians is observed by higher activity in the orbital part of the left interior frontal gyrus and lower activity in the bilateral planus temporal.
While observing changes caused by listening to culturally familiar versus culturally foreign music, there was an observed increase in activity in certain parts of the motor system. Basically, there seems to be a connection with the fronto-parietal attention network which is believed to be associated with general cognitive functions when processing differences in phrase boundaries (phrased vs. unphrased stimuli) and familiarity (culturally familiar vs. unfamiliar music).

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