Byline: Jun-Jie. Sun, Xue-Qun. Pan, Ru. Yang, Zhi-Shuai. Jin, Yi-Hui. Li, Jun. Liu, Da-Xing. Wu
Perceiving pitch is a central function of the human auditory system; congenital amusia is a disorder of pitch perception. The underlying neural mechanisms of congenital amusia have been actively discussed. However, little attention has been paid to the changes in the motor rain within congenital amusia. In this case-control study, 17 participants with congenital amusia and 14 healthy controls underwent functional magnetic resonance imaging while resting with their eyes closed. A voxel-based degree centrality method was used to identify abnormal functional network centrality by comparing degree centrality values between the congenital amusia group and the healthy control group. We found decreased degree centrality values in the right primary sensorimotor areas in participants with congenital amusia relative to controls, indicating potentially decreased centrality of the corresponding brain regions in the auditory-sensory motor feedback network. We found a significant positive correlation between the degree centrality values and the Montreal Battery of Evaluation of Amusia scores. In conclusion, our study identified novel, hitherto undiscussed candidate brain regions that may partly contribute to or be modulated by congenital amusia. Our evidence supports the view that sensorimotor coupling plays an important role in memory and musical discrimination. The study was approved by the Ethics Committee of the Second Xiangya Hospital, Central South University, China (No. WDX20180101GZ01) on February 9, 2019.
Congenital amusia (CA), a lifelong developmental learning impairment and colloquially labelled 'tone deaf', is characterized by difficulty in music perception, production, memory without hearing loss, brain damage, and cognitive deficits (Ayotte et al., 2002; Peretz et al., 2002). This disorder affects about 4% of the population (Kalmus and Fry, 1980). CA-afflicted individuals are unable to detect small pitch variations and are unaware when they (or others) sing out of tune. Psychophysically, these individuals cannot consciously discriminate fine-grained pitches (Peretz et al., 2002). The Montreal Battery of Evaluation of Amusia (MBEA) assessment is the main diagnostic tool for CA, and comprises six sub-tests in four sections that assess melodic, rhythmic, metric, and memory skills. Discrimination is usually measured by three sub-tests in the melodic category (violations of key, pitch contour, and pitch interval) and one sub-test in the rhythmic section (Peretz et al., 2003).
Behavioral studies have linked the music perception and production impairment of CA to deficits in pitch perception (Foxton et al., 2004; Albouy et al., 2016) and pitch memory (Tillmann et al., 2016), which have been associated with changes in brain structure and/or function. Previously, cerebral substrates of CA have been implicated in abnormal activity in the right frontotemporal network, which plays a major role in music perception and memory, particularly for processing pitch-related dimensions (Albouy et al., 2013). CA has been associated with a reduced white matter concentration in the right inferior frontal gyrus and right superior temporal gyrus (Hyde et al., 2006; Albouy et al., 2013), as well as a diminished arcuate fasciculus connecting the two areas (Loui et al., 2009; Zhao et al., 2016),...