Neural Basis of Acquired Amusia and Its Recovery

In acquired amusia, the healthy music processing system in the brain is disrupted due to focal brain damage. This creates an exceptional opportunity to investigate the critical neural architectures of music processing. Yet, the neural basis of acquired amusia has remained largely unexplored. In this multimodal magnetic resonance imaging (MRI) study of stroke patients with a 6-month follow-up, we systematically explored the neural basis of music processing by determining the lesions patterns, structural grey and white matter changes, and brain activation and functional network connectivity changes associated with acquired amusia and its recovery. We found that damage to the right temporal areas, insula, and putamen forms the crucial neural substrate for acquired amusia after stroke. Longitudinally, persistent amusia was associated with further atrophy in the right superior temporal regions, located more anteriorly for rhythm-amusia and more posteriorly for pitch-amusia. In addition, persistent amusia was associated with structural damage and later degeneration in multiple right frontotemporal and frontal pathways as well as interhemispheric connections. Interestingly, rhythm-amusia was associated with additional deficits in left frontal connectivity. During listening to instrumental music, acquired amusics exhibited dysfunction of multiple frontal and temporal brain regions included in the large-scale music network. Interestingly, amusics showed less activation deficits during listening to vocal music, as compared to instrumental music, suggesting less defective processing of singing. Recovery from acquired amusia was related to increased activation in the right frontal and parietal areas as well as increased functional connectivity in the right and left frontoparietal networks. Overall, the results provide a comprehensive neuroanatomical and functional picture of acquired amusia and highlight the neural structures crucial for normal music perception.