Dynamic Imaging of Cross-Frequency Phase-Amplitude Coupling during Rhythm Perception and Synchronization in Percussionists

• Main Authors: Jiun-Wei Chen, 陳峻偉
• Other Authors: Li-Fen Chen
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/w565dj

碩士 === 國立陽明大學 === 腦科學研究所 === 107 === Background and Aims: Musicians have better ability of rhythm perception and synchronization. Especially, percussionists expertizing in rhythm processing exhibit superior performance in rhythm-related tasks. However, the effect of specialized musical training on performance in rhythm-related tasks is still controversial. Neuroimaging studies have reported enhanced activation in the prefrontal and parietal regions during rhythm processing in musicians. Moreover, studies have demonstrated that superior abilities of rhythm processing in musicians can be reflected by the neural activities in different frequency bands. Nonetheless, the effect of specialized musical training on functional connectivity between the auditory cortex and other brain regions during rhythm processing is still unclear. We hypothesized that percussionists would perform better in the rhythm-related task as compared with non-musicians and vocalists, which may associate with seeded functional connectivity between the auditory cortex and prefrontal/parietal regions. Moreover, enhanced functional connectivity in musicians would be specifically related to their musical expertise. Materials and Methods: Percussionists (n = 31, male = 12), vocalists (n = 31, male = 9) and non-musicians (n = 29, male = 13) with limited musical experience were recruited in this study. Event-related magnetoencephalographic (MEG) data and tapping responses were recorded during a modified timing detection task, which includes listening to rhythm tones, synchronizing with the perceived rhythm, keeping the rhythm in mind, and two-forced choice for detecting the timing of tone. For behavioral data, the accuracy of timing detection and tapping variability were analyzed and compared among groups using corresponding statistical approaches. For the MEG data of each individual, we first localized the auditory sources at the bilateral superior temporal gyri (STG) as seeds. Then we applied the beamformer-based imaging of cross-frequency phase-amplitude coupling (BIPAC) approach to estimate functional connectivity between the auditory cortex (gamma, 30 - 55 Hz) and other brain regions (theta, 4 - 8 Hz; alpha, 8 - 13 Hz). Monte-Carlo permutation tests (10000 iterations, two-tailed) were conducted to compare between-group differences, including percussionist versus non-musicians, vocalists versus non-musicians, and percussionists versus vocalists. Correlations were further examined between each two factors (musical training background, behavioral performance, and neuroimaging data). Results and Discussion: As compared with non-musicians, both musicians had a higher accuracy rate in delay discrimination and lower tapping variability. Compared with vocalists, percussionists only exhibited significantly higher accuracy rate of delay discrimination in the second probe tone. These findings may indicate that general musical training mainly affects timing detection and rhythm synchronization regardless of specialized musical training. During rhythm perception, the percussionists exhibited the enhanced alpha-phase gamma-amplitude coupling between the right inferior frontal gyrus (IFG) and auditory seed, as compared with non-musicians and vocalists. During rhythm synchronization, the percussionists showed the enhanced theta/alpha-phase gamma-amplitude coupling between the parietal network and auditory seed, as compared with vocalists. Our findings of the increased auditory-seeded functional connectivity with the IFG and parietal cortex in the percussionists implicated that percussion training may shape internal representation of timing while synchronizing rhythmic music and facilitate the updating of sequential movement via sensory feedback. On the other hand, the vocalists displayed the enhanced alpha-phase gamma-amplitude coupling between the medial cortical areas (medial prefrontal cortex (mPFC) and anterior cingulate gyrus (ACG)) and auditory seed, as compared with percussionists and non-musicians, during rhythm synchronization. We speculate that vocalists might engage themselves to monitor the errors between external auditory stimuli and tapping responses to adjust their movements. We also found enhanced theta-phase gamma-amplitude coupling between the left posterior cerebellum and auditory seed during rhythm synchronization, which is related to error correction, in both musician groups. This result may suggest improved ability of error correction in musicians is due to long-term musical training. Conclusion: The dynamic of rhythm processing certainly can be certainly can be investigated using investigated using BIPAC. Moreover, our findings demonstrated that specialized musical training would influence neural mechanisms underlying rhythm perception and synchronization. It suggests potential neuroplasticity of rhythm-based music therapy for the treatment of diseased brains.