Quantitative proton MR spectroscopic findings of cortical reorganization in the auditory cortex of musicians

Abstract

Background and purpose: Brain has a capacity for reorganization that enables use-dependent adaptations to acquire skills. Previous studies demonstrated morphometric and functional use-dependent changes in the brains of musicians. The purpose of this study was to investigate the differences in metabolite concentrations in the planum temporale, an area strongly associated with the processing of music perception, between trained musicians and non-musicians. We hypothesized that the microscopic changes leading to use-dependent adaptations in brain might cause neurometabolite changes that could be detected with quantitative proton MR spectroscopy.

Methods: We performed quantitative proton MR spectroscopy in the left planum temporale of 10 musicians (six men and four women; age range, 20-37 years) and in those of 10 age- and sex-matched control subjects who had no musical training. We calculated the major metabolite concentrations in the left planum temporale.

Results: The difference in N-acetylaspartate (NAA) concentrations between the musicians and the non-musician control subjects was statistically significant (P <.01). No significant difference was noted in the choline and creatine concentrations between the musicians and the non-musician control subjects (P >.05). The NAA concentration of the musicians correlated with the total duration of musical training and activity (r=0.733, P <.05).

Conclusion: Long-term, professional musical activity caused significant changes in the neurometabolite concentrations that might reflect the physiologic mechanism(s) of use-dependent adaptation in the brains of musicians.

Fig 1.

T1-weighted MR images (530/20/3) depict examples of voxel placement. A, Coronal MR image shows a voxel placed in the left planum temporale, which is located between the Heschl gyrus medially (arrow) and superior rim of the superior temporal gyrus. B, Sagittal T1-weighted image shows location of the voxel.

Fig 2.

A, Image shows voxel placement for the phantom study. B, Spectrum obtained from the phantom shows the acetate peak and lactate doublet.

Fig 3.

A–D, Proton spectra from the planum temporale in a musician, obtained with TE values of 30 ms (A), 48 ms (B), 135 ms (C), and 230 ms (D).

Fig 4.

A–D, Proton spectra from the planum temporale in a non-musician control subject, obtained with TE values of 30 ms (A), 48 ms (B), 135 ms (C), and 230 ms (D).

Fig 5.

A–C, Graphs show metabolite concentrations in musicians (M) and the non-musician control group (NM) for NAA concentration (A), Cr concentration (B), and Cho concentration (C). Error bars show 95% confidence intervals for the means of the metabolite concentrations.

Fig 6.

A, Graph demonstrates the relationship between NAA concentration in the musicians and total duration of musical training and activity. NAA concentration increases significantly as the duration of total musical training and activity increases (r = 0.733 [Pearson correlation coefficient], P = .016). B, NAA concentration aganist age of commencement (r = −0.463, P = .178). C, NAA concentration aganist time spent for musical activities per week (r = −0.327, P = .357).