Brain Activation During Musical Error Detection
Peter Fox,* Lawrence Parsons,* and Don Hodges+
*Research Imaging Center, University of Texas Health Science Center at San Antonio
+Institute for Music Research, University of Texas at San Antonio
Problem
Neural networks for musical processing are not well known. The purpose of this study is to determine those brain areas active during melodic, harmonic, and rhythmic error detection.
Method
Ten professional musicians participated in five tasks, each repeated once for a total of ten trials. The five tasks were:
- Melodic Error Detection: subjects saw a correctly notated Bach chorale in open score (i.e., four staves) and through headphones heard a performance of the same chorale with intentionally implanted errors in the melody only. They were asked to make an internal, mental recognition of visual and aural mismatches. No overt action was required; pre- and posttest behavioral measures outside the pet scanner demonstrated that all subjects were able to complete the task successfully.
- Harmonic Error Detection: subjects saw a correctly notated Bach chorale in open score and heard a performance with intentionally implanted pitch errors dispersed throughout all four voices.
- Rhythmic Error Detection: subjects saw a correctly notated Bach chorale in open score and heard a performance with intentionally implanted rhythmic errors dispersed throughout all four voices.
- Passive Listening: subjects heard a Bach chorale performed correctly while their eyes were visually fixated on a central spot. This was done to activate auditory cortex normally associated with listening to music.
- Rest: subjects rested quietly. This is done to obtain "baseline" data on normal brain activations.
PET imaging was performed with a 15-O, water bolus technique. PET and T1-weighted magnetic resonance images (MRI) were spatially normalized, correcting for differences in brain size. Task induced changes in regional blood flow were detected by Change Distribution Analysis. Response coordinates were interpreted in accordance with Talairach and Tournoux and confirmed with group-mean MRI.
Results
Eight of the ten subjects have been scanned at this writing and data on five have been analyzed. Because data are still in the process of being gathered and analyzed, it would be premature to speculate on the outcome. However, early data analysis lead to several notions: (a) so far, patterns of activation for the three error detection tasks are varying widely; (b) multiple activation patterns are widely dispersed. It is clear that there is no "music center" (i.e., a single location for music processing) and it is also clear that music does not happen only in the right side of the brain. Stay tuned for further results.
Typical Pet Scans