Evaluation of the Short-Term Music Therapy on Brain Functions of Preterm Infants Using Functional Near-Infrared Spectroscopy

Abstract

Music contains substantial contents that humans can perceive and thus has the capability to evoke positive emotions. Even though neonatal intensive care units (NICUs) can provide preterm infants a developmental environment, they still cannot fully simulate the environment in the womb. The reduced maternal care would increase stress levels in premature infants. Fortunately, music intervention has been proved that it can improve the NICU environment, such as stabilize the heart rate and the respiratory rate, reduce the incidence of apnea, and improve feeding. However, the effects of music therapy on the brain development of preterm infants need to be further investigated. In this paper, we evaluated the influence of short-term music therapy on the brain functions of preterm infants measured by functional near-infrared spectroscopy (fNIRS). We began by investigating how premature babies perceive structural information of music by calculating the correlations between music features and fNIRS signals. Then, the influences of short-term music therapy on brain functions were evaluated by comparing the resting-state functional connectivity before and after the short-term music therapy. The results show that distinct brain regions are responsible for processing corresponding musical features, indicating that preterm infants have the capability to process the complex musical content. However, the results of network analysis show that short-term music intervention is insufficient to cause the changes in cerebral functional connectivity. Therefore, long-term music therapy may be required to achieve the deserved effects on brain functional connectivity.

Keywords: Mozart music; functional near-infrared spectroscopy; preterm infants; resting-state functional connectivity; short-term music therapy.

Figure 1

A total of 19 channels covered the cerebral cortex of the frontal, temporal, and parietal regions with the red, yellow, and green colors, respectively. (A) Axial view. (B) Left lateral view. (C) Right lateral view.

Figure 2

Block diagram of the data acquisition and analysis. The purple rectangle with diagonal stripes represents the first sessions of the fNIRS signal during the music stimulus on the first day. The blue diagonal stripe rectangular with white and light-yellow background represents pre-resting state on the first day and the post-resting state on the third day, respectively.

Figure 3

Four categories of the brain networks representing intra- and inter-hemispheric functional connectivity. (A) IntraC-I: connectivity within one hemisphere; (B) IntraC-II: connectivity between two different ROIs within one hemisphere; (C) InterC-III: connectivity between symmetrical ROIs in the two hemispheres; (D) InterC-IV: connectivity between asymmetrical ROIs in the two hemispheres.

Figure 4

Comparison of left–right correlation values between the MTG and the CG in each ROI. MTG-pre: resting state before music therapy in the music therapy group; MTG-post: resting state after music therapy in the music therapy group; CG-pre: resting state before music therapy in the control group; CG-post: resting state after music therapy in the control group.

Figure 5

Intrahemispheric connectivity in the MTG and the CG. The solid lines in red, magenta, blue, and green represent the averaged numbers of resting-state functional connectivity of pre-music therapy in the MTG, post-music therapy in the MTG, pre-music therapy in the CG, and post-music therapy in the CG, respectively. The asterisks and hollow circles represent the values of an individual subject. (A,B) Represents the number of intrahemispheric connectivity within the left and right hemispheres under different thresholds in IntraC-I, respectively. (C,D) Represents the number of intrahemispheric connectivity between different ROIs in the left and right hemispheres under different thresholds in IntraC-II, respectively.

Figure 6

Interhemispheric connectivity in the MTG and the CG. The solid lines in red, magenta, blue, and green represent the averaged numbers of resting-state functional connectivity of pre-music therapy in the MTG, post-music therapy in the MTG, pre-music therapy in the CG, and post-music therapy in the CG, respectively. The asterisks and hollow circles represent the values of an individual subject. (A,B) Represents the number of symmetrical interhemispheric connectivity in frontal and temporal regions in InterC-III, respectively. (C,D) Represents the number of interhemispheric connectivity between frontal and temporal regions in InterC-IV, respectively.