Neurophysiological substrates of singing associated with past singing experience and task difficulty
Date
2024
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Publisher
University of Delaware
Abstract
This dissertation examined neurophysiological substrates of singing associated with past singing experience and task difficulty. Individuals trained (singers) and not trained (non-singers) in singing were required to sing difficult and easy melodies inside an MRI scanner. Task difficulty was determined empirically with pilot testing. fMRI and audio data were acquired for later analysis. Brain activity and pitch deviation were compared between singers and non-singers during singing either difficult or easy melodies, as well as within each group, during singing difficult and easy melodies. In addition, correlations were assessed between brain activity and pitch deviation per group and condition. Between groups, differences in brain activity and pitch deviation reached significance for difficult but not easy melodies. Each group sang difficult melodies less accurately than easy melodies. In singers, difficult vs. easy melodies elicited widespread bilateral activation, spanning across brain regions relevant to singing and sensitive to singing training. In non-singers, difficult vs. easy melodies elicited limited activation, circumscribed to the left hemisphere. Correlations between brain activity and pitch deviation were found for singers singing difficult melodies, and for non-singers singing easy melodies. ☐ These results suggest that differences in brain activity and pitch-related singing performance between singers and non-singers become larger with increasing task difficulty. Potentially, singers and non-singers share neural mechanisms for easy and distinctive neural mechanisms for difficult singing tasks. Alternatively, singers might activate singing circuits to a lesser extent for easy than difficult tasks, due to an optimization of neural resources (i.e., neural efficiency), whereas non-singers might engage less brain regions for singing, regardless of task difficulty. Increased activation in singers for difficult vs. easy melodies of right anterior insula, anterior cingulate cortex, Broca’s area and cerebellum supports the notion that singers have optimized neural circuits for singing, presumably developed in time. Increased activation of right anterior insula during singing has been previously linked to greater singers’ reliance on somatosensory feedback relative to auditory feedback. Distinctive increased activation of supplementary motor area for difficult vs. easy melodies in singers (rostral) and non-singers (caudal) might reflect key differences in motor planning of trained and untrained individuals facing a difficult task. Further research is required to better understand brain responses to singing tasks of varying difficulty by trained and untrained individuals, as well as their implications for singing training and voice learning in diverse populations.
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Keywords
Brain activity, Human voice, Pitch deviation, Neural efficiency