Edited by: Yong He, Beijing Normal University, China
Reviewed by: Jürgen Hänggi, University of Zurich, Switzerland; Xin Di, New Jersey Institute of Technology, USA
*Correspondence: Yul-Wan Sung
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Numerous neuroimaging studies have shown structural and functional changes resulting from musical training. Among these studies, changes in primary sensory areas are mostly related to motor functions. In this study, we looked for some similar functional and structural changes in other functional modalities, such as somatosensory function, by examining the effects of musical training with wind instruments. We found significant changes in two aspects of neuroplasticity, cortical thickness, and resting-state neuronal networks. A group of subjects with several years of continuous musical training and who are currently playing in university wind ensembles showed differences in cortical thickness in lip- and tongue-related brain areas vs. non-music playing subjects. Cortical thickness in lip-related brain areas was significantly thicker and that in tongue-related areas was significantly thinner in the music playing group compared with that in the non-music playing group. Association analysis of lip-related areas in the music playing group showed that the increase in cortical thickness was caused by musical training. In addition, seed-based correlation analysis showed differential activation in the precentral gyrus and supplementary motor areas (SMA) between the music and non-music playing groups. These results suggest that high-intensity training with specific musical instruments could induce structural changes in related anatomical areas and could also generate a new functional neuronal network in the brain.
Structural and functional changes in the human brain resulting from musical training have been noninvasively studied using various imaging modalities, including magnetic resonance imaging (MRI; Schlaug,
Changes in the white matter (WM) of musicians have been demonstrated by DTI (Schlaug et al.,
Changes in the gray matter (GM) have been demonstrated by cortical thickness analysis and VBM. It has been reported that musicians have greater cortical thickness in the superior temporal and dorsolateral frontal regions as a result of their training (Bermudez et al.,
For functional studies, activation of brain areas and functional connectivity among them have been measured to examine neuronal differences between the musicians and non-musicians. A representative functional difference between the musicians and non-musicians in functional MRI (fMRI) studies showed strong activation in auditory and motor areas, which are known to play crucial roles in musical activities (Baumann et al.,
Most previous studies investigating either structural or functional changes in the brain have focused on musicians who play keyboard (Jäncke et al.,
While many previous music-related studies have been conducted, none has examined neuroplasticity relating to wind instruments, which mainly require the mouth (lips and tongue) to play, in contrast to instruments described above, which mainly use other body parts, such as hands. Although the mouth is also used for singing (Sundberg,
In the current study, we hypothesized that similar structural and functional changes would occur in other brain modalities, such as the somatosensory, and examined the effects of musical training with the subjects who play wind instruments (“music playing group”) compared with the subjects who do not play music (“non-music playing group”). Wind instrument players are expected to develop their lips and tongue touches. Therefore, we assumed that the structures of somatosensory areas of the brain that are associated with the lips and tongue would differ between the music and non-music playing groups. In addition, we performed a resting-state fMRI analysis to investigate the possibility of functional connectivity modifications due to musical training.
Fourteen music playing [all female; mean age ± standard deviation (SD), 20.35 ± 1.21 years] and 14 non-music playing subjects (all female; mean age ± SD, 20.14 ± 1.23 years) participated in this study. Those included in the music playing group played wind instruments (woodwinds and brass) for more than 7 years (mean ± SD, 7.93 ± 1.21 years) as members of junior and senior high school and university wind ensembles. In contrast, non-music playing subjects did not have any extra musical experience except for regular music classes in school.
None of the subjects had a history of neurological disease or any medical conditions (i.e., pregnancy, use of a cardiac pacemaker, or claustrophobia). After subjects were given a complete description of the study, written informed consent was obtained in accordance with the Declaration of Helsinki. This study was approved by the Institutional Review Board of Tohoku Fukushi University (Japan).
All subjects were scanned in two sessions that included structural (T1) and functional imaging (resting-state fMRI). Structural images were acquired using the following parameters: repetition time = 1900 ms, echo time = 2.52 ms, matrix size = 256 × 256, in-plane resolution = 1 × 1 mm2, slice thickness = 1 mm, and number of slices = 192. Resting-state fMRI data were acquired using the following parameters: repetition time = 2000 ms, echo time = 30 ms, matrix size = 64 × 64, in-plane resolution = 3.4 × 3.4 mm2, slice thickness = 3.4 mm, and number of volumes = 150. In the resting-state fMRI session, subjects were asked to lie on a bed and try to think about nothing about nothing with closed eyes.
All data were analyzed with Brainvoyager QX software (Brain Innovation B.V., Maastricht, Netherlands). Structural images were spatially normalized through Talairach transformation with Brainvoyager QX. In the first part of the transformation, we detected the anterior and posterior commissure as landmarks for the y-axis of the Talairach coordinate system. In the anterior commissure, the x-axis runs from the left to the right hemisphere, while the z-axis runs from the inferior to the superior part of the brain. All boundaries were decided manually. After the anterior-posterior commissure transformation, the brain was separated by 12 sub-cuboids. These 12 sub-cuboids were expanded or shrunken linearly to correspond to the size standard Talairach brain sub-cuboids. These normalized T1 images were corrected by an intensity inhomogeneity correction (Sled et al.,
For cortical thickness measurements, we first defined boundary voxels, one at the WM–GM boundary and one at the GM–CSF boundary. The values of those boundary voxels were kept, and the intensities between the GM voxels were smoothed by Laplace's equation (Jones et al.,
Region of interest (ROI)-based analysis is known to be very useful in studies of specific brain areas (Gur et al.,
One subject in the non-music playing group was excluded from the analysis of resting-state functional images because of large head motion. The images of 25 subjects were preprocessed by slice scan time correction, 3D motion correction, and high pass temporal filtering (only signals with relatively high frequency >0.01 Hz). These functional images were smoothed with 6-mm FWHM and coregistered with each structural image. All resting-state functional images were analyzed by seed-based correlation analysis using Brainvoyager QX. In the analysis, the time course of seed ROIs were correlated with whole brain and correlation maps were created. Seed ROIs were those brain regions that showed different cortical thickness between the music and non-music playing groups. Individual correlation maps were made from seed ROIs. Correlation maps were analyzed by two sample
Cortical thickness difference maps for music and non-music playing groups were evaluated using a two sample
Seed-based correlation analysis of tongue-related areas of the brain did not show any significantly different maps between the music and non-music playing groups. Correlation analysis of lip-related areas revealed some significantly different maps between the two groups (higher correlation in the music playing group) (
The aim of our study was to determine how musical training with wind instruments causes structural and functional changes in the brain that could be attributed to specific ways of playing instruments. We mostly focused on somatosensory areas. Participants in this fMRI study were university students who received several years of training on wind instruments in junior and senior high school and are now members of reputable university wind ensembles. Participants chosen as non-music playing were university students with no special musical training. Cortical thickness analysis of structural plasticity in the brain showed significant differences in two areas of the postcentral gyrus associated with the lips and tongue according to previous reports (Pulvermüller et al.,
Along with changes in lip- and tongue-related brain areas, some reports suggest that playing wind instruments could result in physical changes to related body parts (i.e., the tongue and lips). For example, the muscles of the lips and tongue may change while playing a wind instrument (Methfessel,
The thickening of lip-associated brain areas can be explained in the same way as increased GM volume in certain areas associated with other types of training, such as juggling and piano playing. In contrast, the cause of cortical thinning in tongue-related brain areas is not easy to explain. Explanations for the cortical thickness decrease can be found in several previous studies. One explanation stems from previous studies showing sharpening in populations of neurons frequently recruited for a specific function (Desimone,
By resting-state fMRI, the music playing group showed stronger correlations with some areas in the precentral gyrus and SMA, and the relationship between precentral areas and SMAs with music has been found in previous studies. The precentral gyrus has been shown to be involved in musical instrument playing (Schieber,
Unfortunately, the current study is limited in its design. Because the present study was designed to be cross-sectional, we cannot exclude the possibility that the music playing group members' abilities come from certain anatomical advantages over those of the non-music playing group rather than functional changes resulting from musical training. However, the positive correlation between the cortical thickness and years of musical training in lip-related brain areas suggests otherwise. This longitudinal evidence and the appearance of the new functional neuronal network in the music playing group support our interpretation that cortical thickness changes reflect changes in neuronal plasticity by musical training.
In conclusion, we found structural and functional changes in lip- and tongue-related areas in the postcentral gyrus related to longitudinal musical training with wind instruments. These results indicate that high-intensity musical training can change the structure and function of the brain. Furthermore, the current findings support the idea of altered neuroplasticity by musical training.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This study was supported by MEXT-Supported Program for the Strategic Research Foundation at Private Universities 2014–2018 and the National Research Foundation of Korea (NRF) Grant funded by Korea Government (MSIP) (no. NRF-2014M3C7033998).