Abstract:

The experience of musical pleasure is one of the most common psychological phenomena in music activities. It usually refers to the subjective pleasure feelings and reactions induced or aroused by the listeners during music listening. Exploring the underlying neural mechanisms of musical pleasure can help us understand how music acquires its value in human evolution. Here, recent work on the neural substrates of musical pleasure has been reviewed. 
Early imaging studies have shown that musical pleasure experience can activate brain regions such as ventral striatum, suggesting that the reward system of the brain is involved in musical pleasure experience. Recent studies on congenital musical anhedonia reveal that the acquisition of musical pleasure depends on the functional connection between the reward system and the auditory cortex. Evidence from neuropsychology further shows that damage to the frontal, temporal, and parietal cortex may cause acquired musical anhedonia or musicophilia. These findings imply that the experience of musical pleasure is not only related to the core brain regions of the reward system such as the nucleus accumbens, but may also depends on the intricate interactions between the reward system and other cortical regions. In addition, the experience of musical pleasure is thought to be related to the specific release of dopamine in the striatum. There is some evidence that endogenous dopamine delivery in the striatum increases in response to strong emotional experience of music. By manipulating dopaminergic activity, the intensity of music pleasure can also be regulated, suggesting a causal link between musical pleasure and dopamine reward mechanism. 
From the perspective of expectation, reward prediction errors theory and information-theoretic model can both explain the psychological mechanisms underlying musical pleasure. Reward prediction errors theory emphasizes that musical pleasure is based on positive prediction errors. Specifically, people form expectations when they listen to music, and when the actual results are better than expected, the positive prediction error occurs, and the musical pleasure is thus generated. Research evidences supporting reward prediction errors have shown the central role of the nucleus accumbens in musical pleasure. However, the model of music information theory suggests that musical pleasure is regulated by different states in the process of music expectation. Studies in support of this model have revealed that the interaction between the uncertainty of expectations and the degree of surprise modulates the degree of musical pleasure. However, this interaction does not depend on the nucleus accumbens, but on the amygdala, hippocampus, and auditory cortex.
In conclusion, musical pleasure experience can directly activate reward-related brain circuits and induce the release of dopamine neurotransmitters in some subcortical pathways. Moreover, the release of dopamine neurotransmitter affects musical pleasure experience, indicating that the release of dopamine in the reward system has a causal relationship with musical pleasure. Reward prediction errors and information-theoretic model explain the mechanism of musical pleasure from the perspective of expectation. Due to the different theoretical basis, however, their supporting evidence on the neural level diverges obviously. Future studies should further examine the function of the nucleus accumbens and other cortical regions in musical pleasure and integrate different expectation theories. 

Key words: musical pleasure, emotional experience, reward, expectation, musical anhedonia