Sensorimotor plasticity after music-supported therapy in chronic stroke patients revealed by transcranial magnetic stimulation

Abstract

Background: Several recently developed therapies targeting motor disabilities in stroke sufferers have shown to be more effective than standard neurorehabilitation approaches. In this context, several basic studies demonstrated that music training produces rapid neuroplastic changes in motor-related brain areas. Music-supported therapy has been recently developed as a new motor rehabilitation intervention.

Methods and results: In order to explore the plasticity effects of music-supported therapy, this therapeutic intervention was applied to twenty chronic stroke patients. Before and after the music-supported therapy, transcranial magnetic stimulation was applied for the assessment of excitability changes in the motor cortex and a 3D movement analyzer was used for the assessment of motor performance parameters such as velocity, acceleration and smoothness in a set of diadochokinetic movement tasks. Our results suggest that the music-supported therapy produces changes in cortical plasticity leading the improvement of the subjects' motor performance.

Conclusion: Our findings represent the first evidence of the neurophysiological changes induced by this therapy in chronic stroke patients, and their link with the amelioration of motor performance. Further studies are needed to confirm our observations.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Summary of the kinematic parameter for the patients' group (PG) and control group (CG).

Bars represent the mean of frequency (FREQ), number of inversions of velocity (NIV) and the average maximum velocity (Max Vel) for finger tapping (FT), hand tapping (HT) and forearm pronation-supination (PS). Error bars represent the standard deviation of the mean (SEM). Significant differences after training in the MG are indicated (* p<.05 p>

Figure 2. Example of performance of fast diadochokinetic finger.

Detail of the signal recorded from one marker with the 3D movement-analyzer during finger and hand tapping movements of the affected hand of one representative patient (A) and one control subject (B). The marker was attached on the index finger (finger tapping) and from methacarpophalangeal joint (hand tapping). Time courses of the displacement in cm measured in both evaluations are displayed.

Figure 3. Summary of the results of the TMS study.

Bars represent the mean of the motor evoked potential (MEP) amplitude, length of the cortical silent period (CSP), resting motor thresholds (RMT) and active motor thresholds (AMT) of the affected hemispheres for PG and CG. Error bars represent the standard deviation of the mean (SEM). Measurements at the evaluation 1 are colored in white, and measures at the evaluation 2 are colored in gray. An increase of the MEP amplitude on the affected hemisphere in PG can be observed (* p<.>

Figure 4. Summary of the plastic changes observed with the cortical maps.

(A) Displacement of the center of gravity (CoG) across time for the affected and unaffected hemisphere in PG. The origin of each arrow represents the baseline coordinates of the CoG. Arrowheads represent the position of the CoG at evaluation 2. Each arrow is colored differently, corresponding to each subject from PG. (B) Displacement of the medial coordinate of the center of gravity (CoGx) of motor mapping representation through time. In the affected hemisphere (left), almost all patients showed a displacement on the mediolateral edge of the CoG to more temporal regions.

Figure 5. Correlation between changes on the position of the CoG in the mediolateral edge and changes on the number of inversion of velocity (NIV) for hand tapping (HT) from subjects in PG.

Rounded points were considered outlier values after corresponding test and were excluded from the sample.