Vocal melody and musical background are simultaneously processed by the brain for musical predictions

Neural Mechanism of Musical Pleasure Induced by Prediction Errors: An EEG Study

BACKGROUND/OBJECTIVES

Musical pleasure is considered to be induced by prediction errors (surprise), as suggested in neuroimaging studies. However, the role of temporal changes in musical features in reward processing remains unclear. Utilizing the Information Dynamics of Music (IDyOM) model, a statistical model that calculates musical surprise based on prediction errors in melody and harmony, we investigated whether brain activities associated with musical pleasure, particularly in the θ, β, and γ bands, are induced by prediction errors, similar to those observed during monetary rewards.

METHODS

We used the IDyOM model to calculate the information content (IC) of surprise for melody and harmony in 70 musical pieces across six genres; eight pieces with varying IC values were selected. Electroencephalographic data were recorded during listening to the pieces, continuously evaluating the participants' subjective pleasure on a 1-4 scale. Time-frequency analysis of electroencephalographic data was conducted, followed by general linear model analysis to fit the power-value time course in each frequency band to the time courses of subjective pleasure and IC for melody and harmony.

RESULTS

Significant positive fits were observed in the β and γ bands in the frontal region with both subjective pleasure and IC for melody and harmony. No significant fit was observed in the θ band. Both subjective pleasure and IC are associated with increased β and γ band power in the frontal regions.

CONCLUSIONS

β and γ oscillatory activities in the frontal regions are strongly associated with musical rewards induced by prediction errors, similar to brain activity observed during monetary rewards.

Potential Benefits of Music Therapy on Stroke Rehabilitation

Stroke is associated with a high rate of disability and mortality, and survivors are usually accompanied with dysphagia, aphasia, motor dysfunction, cognitive impairment, depression, and other complications. In the past decades, many studies have been conducted to reveal the pathogenesis and pathological mechanisms of stroke. Furthermore, treatment methods have been developed that contribute to the elevated survival rate of stroke patients. Early rehabilitation poststroke is starting to be recognized as important and has been receiving increasing attention in order to further improve the quality of life of the patients. As an emerging method of poststroke rehabilitation, music therapy can help attenuate dysphagia and aphasia, improve cognition and motor function, alleviate negative moods, and accelerate neurological recovery in stroke patients. This review helps summarize the recent progress that has been made using music therapy in stroke rehabilitation and is aimed at providing clinical evidence for the treatment of stroke patients.