In: Neurosciences in Music Pedagogy Neuroscience of Music and Emotion

The chapter discusses recent studies of neural representations of musical emotions. Despite an increasing number of empirical studies on the emotional effects of music, there is paucity of brain research that has identified the underlying neural networks. It is argued that the representation of musical emotions might be based on similar structures as compared to emotions in other domains. Consequently, it is hypothesized that musical emotions recruit networks of emotion processing that are known to be involved in both visual and auditory (speech) perception and that are responsible for psychological as well as physiological responses to emotional stimuli. Beside the provision of theoretic and empirical accounts, the review addresses methodological issues of current imaging techniques that may be particularly detrimental for the study of neural correlates of musical emotions. However, research findings so far support the assumption of largely overlapping networks required for the processing of both general and music-specific emotions. They also corroborate the notion of closely interconnected networks for cognitive and emotional processing even within the same neural structures. Specifically, emotional processing of music most likely involves limbic and paralimbic structures that include amygdala, hippocampus, parahippocampal gyrus, insula, temporal poles, ventral striatum, orbitofrontal cortex, and the cingulate cortex. It is further assumed that the behavioral distinction between perceptual and experiential (or feeling) aspects of musical emotions might be established within these neural structures. More research is needed, for example, to address the generation of musical emotions in the performer as well as developmental aspects and individual differences in neural representations of musical emotions. Gunter Kreutz und Martin Lotze 144 MUSIC, EMOTION, AND THE HUMAN BRAIN Emotions are critical to our understanding of music. They have long been the subject of debate among philosophers, artists and scientists in Western culture and other musical traditions around the world. According to the Greek philosophers, for example, music listening could influence the physiology and character of an individual and even affect subsequent behavior (e.g. Freeman, 2000). These authors not only stressed the therapeutic and educational power of music, but also warned against the negative consequences of musical malpractice for individuals and society. Since the end of the 19th century, research methods in psychology and physiology have been able to elucidate philosophical speculations. For once, the relationship between musical structure and emotional expression has proved a viable approach. Music is thought to convey emotional information via an interactive, communicative process involving composer, performer and listener. It has been shown that the structural cues in musical scores that reflect the intentions of the composer interact with the cues that are under the control of the performer to shape the emotional expression that is communicated to the listener. For example, the expression of ‘sadness’ in a piece of music conveyed by the slow tempi and soft timbres indicated by the composer can be enhanced by the deliberate choices of articulation and nuances of timing made by the performer (e.g. Juslin, 2001). Until recently, the plethora of research on musical emotions has been directed towards the effects of listening to music. More active musical behaviors such as singing, playing musical instruments, or dancing may produce different kinds of emotional response. For example, the extent to which and how emotional experiences might interfere with performance per se, has long been debated, since performers are also listening to themselves, in the first place. This chapter focuses on neuroscientific approaches to music and emotion, which has become an important domain of interdisciplinary research (Juslin & Sloboda, 2001; Kreutz, in press). This relatively new field draws from the philosophical and behavioral research traditions rooted in the social sciences on one hand, and the advances of modern neuropsychological and imaging techniques emerging from the natural sciences on the other. The question arises as to the structure and function of neural correlates in the perception and experience of musical emotions. Some might belong to the auditory modality in the sensorymotor system, while others are neither specific to auditory processing nor the processing of music. Whether the neural basis of emotional appraisal of music is innate or rather acquired through acculturation is subject to ongoing discussion (Peretz & Sloboda, 2005). Beside the nature-nurture problem, there are more puzzling phenomena in relation to musical emotions. For example, on the one hand, the reliable recognition of emotions, unlike the perceptual processing of music per se, appears independent of musical training and occurs in time windows so short that such experiences qualify as reflexes (Peretz, Gagnon & Bouchard, 1998; Bigand, Filipic & Lalitte, 2005). On the other hand, emotions are often seen as dynamically unfolding processes, in which physiological (Krumhansl, 1997) as well as brain activation changes occur over time (Koelsch, Fritz, v.Cramon, Müller & Friederici, 2006). These dynamic changes appear to be associated with the experienced intensity of emotions, Neuroscience of Music and Emotion 145 sometimes culminating in pleasant sensations such as “chills” (Grewe, Nagel, Kopiez & Altenmueller, 2005; Panksepp, 1995) that may indicate the release of endorphins (McKinney, Tims & Kumar, 1997). In another vein, repeated exposure to complete pieces of music often modulates appreciation, giving rise to so-called exposure effects (Samson & Peretz, 2005). Note that recognizing and experiencing musical emotion are different: not only do they involve different temporal aspects of processing, but they also might reflect different modes of processing that interact with time, situation, context, and the musical biographies of individual listeners. Many researchers argue that emotional responses to music should be at least partially similar to emotional responses in other domains such as, for example, vision and speech (Peretz, 2001). To this end, introspective and behavioral approaches as well as peripheral physiological measurements of hemodynamic, respiratory, galvanic skin responses, and other parameters of bodily function have been used (Bartlett, 1996). The precise relationships between subjective experience and physiological concomitants during the processing of emotions are largely unknown. However, it is likely that brain research will provide important new information to reduce the amount of unexplained variances in psychophysiological studies of emotion in general and musical emotion in particular. Moreover, studying musical emotions from a neuroscientific perspective seems particularly promising with respect to the time course and dynamics of human emotion processing (Koelsch, 2006; Grewe et al., 2005; for a review of continuous measurement techniques used in behavioral studies see Schubert, 2001). A recurrent observation is that the same brain structures may serve different roles in functional architectures within and across domains. Features of the brain such as plasticity as the result of learning and its ability to reorganize neural functions in the case of physical damage or disease suggest that any modeling of brain function needs to account for this flexibility. Thus the neuroscientific perspective on music and emotion necessitates interdisciplinary approaches, in which general models and theories of emotion, music theory, and brain research combine (Peretz, 2001). Although the implications of this approach to learning and education will be dealt with in the last chapter at the end of this book, it can be stated from the outset, that emotions – as a means rather than an end – appear to play a major role in modulating human learning processes. Investigating the underlying neural structures and the functions of musical emotion might thus be an important step towards understanding human learning processes within and beyond the domain of music. In the remainder of this chapter, we will first deal with the neural structures that have been implicated in emotion processing. Then we will address empirical evidence relating to the neural correlates of musical emotion. The final goal of this chapter is to summarize our current knowledge of brain structures and functions related to the emotional processing of music, as well as to suggest some possible topics for future research. Gunter Kreutz und Martin Lotze 146 NEURAL CORRELATES OF EMOTION PROCESSING Historically, emotion in the human brain has been considered with respect, first, to hemispheric differences, and, second, to the distinction between high-level cortical structures and deeper-level limbic structures. In fact, as early as 1912, Mills suggested that cognition and emotion were functionally specified and separated, postulating an analytic-cognitive dominance for the left and an emotional dominance for the right hemisphere (Mills, 1912). Later in the first half of the 20th century, McLean (1949) proposed the idea of a structurefunction relationship between the limbic system and the generation of emotions (for an overview of the historical development of this hypothesis, see LeDoux, 1996). Whereas the traditional view on brain processing differentiates the cognitive and emotional domains (Drevets & Raichle, 1998), there are other approaches that integrate the two. Recent studies provide evidence of a substantial overlap between the neural structures involved in both cognition and emotion. Indeed, cognitive and emotive systems might be far more interconnected and indistinct at neuronal levels (Wager & Feldmann Barrett, 2004). Some researchers contend that emotion even precedes cognition as the