Brain and Cognition 42, 131–134 (2000) doi:10.1006/brcg.1999.1182, available online at http://www.idealibrary.com on
Toward a Biological Account of Music Experience Isabelle Peretz and Sylvie He´bert University of Montreal; and University Institute of Geriatry of Montreal
Interestingly, neuroscientists working on music no longer need to justify their research enterprise. Most people, from the scientific community as well as from the general population, are keen to know more about music as a brain function. This general interest is likely to carry over to the next millennium. But why do people suddenly consider music worth studying? For more than a century, music has been ignored by both the scientific community and, more recently, by our educational system. This attitude probably reflected the widely shared opinion that music was superfluous. This opinion has changed recently, because it has become increasingly clear over the years, with massive access to the music media, that humans are avid consumers of music. Can neuroscience provide an answer as to why this is so? We contend that studying music as a brain function holds indeed great promises in this regard. Until recently, the study of music cognition in the human brain has relied primarily on clinical case studies. In contrast to other fields such as vision, the study of the neural basis of music cognition cannot be based on animal models. For one thing, it is not clear whether animal vocalization, including bird singing, is the precursor of language or of music in humans. Thus, a major obstacle to generalization across species lies not only in the language specialization of the human brain but also in human inclination for music. Humans possess both language and music as means of auditory–vocal communication while animals possess only one channel, as far as we know. This obstacle to animal modeling can now be overcome with the advent of new methods for the functional exploration of the human brain, such as neuroimaging (e.g., PET, fMRI, high density ERPs, MEG) and brain stimulation (TMS, for Transcranial Magnetic Stimulation) techniques. We no longer The present paper was written while the first author was supported by a grant from the Medical Research Council of Canada and a grant from the Natural Science and Engineering Research Council of Canada. Address correspondence and reprint requests to Isabelle Peretz, De´partement de psychologie, Universite´ de Montre´al, CP. 6128, succ. Centre-ville, Montre´al, Que´bec H3C 3J7, Canada. E-mail:
[email protected]. 131 0278-2626/00 $35.00 Copyright 2000 by Academic Press All rights of reproduction in any form reserved.
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need to wait for a theoretically meaningful accident of nature in clinical cases and work backward, like detectives, to uncover the nature of the musical disorder observed. Although clinical cases will remain a major source of information, they can now be complemented through careful and systematic use of the new brain exploration tools. From now on, the flourishing of these new tools enables us to be proactive by selecting our population of interest and our questions to put at test, and hence advance more rapidly in our research program. Will the rapid advances in the understanding of the neural bases underlying music mean that we will be able to explain why people listen to music? Not directly. The question of the existence of music is not new and has been a subject of controversy since the beginning of the first millennium. However, the scientific study of music organization in the brain should provide us with key elements as to whether music pertains to the area covered by biology, hence fulfilling important needs, or to the area related to human culture, thereby being superfluous. In this perspective, the most important issue is whether or not there exist neural networks that are dedicated to music processing in the mature brain. By ‘‘dedicated neural structures,’’ we mean neural devices that process musical information selectively and exclusively. Support for the existence of such musical modules in the brain entails that music is not a parasite or a byproduct of a more important brain function such as language. Presently, we have strong indications that the human brain is equipped with such musical modules (e.g., see Peretz, 2000, for a review). Finding brain specificity (or modularity) for music does not imply, however, that the human brain is prewired for music and consequently that music fulfills a biological need. Music may recruit any free neural space in infants and modify that brain space so as to adjust it to its processing needs. For instance, early musical training has been found to modify (extend) the brain space dedicated to some aspects of music processing (e.g., Pantev et al., 1998). Hence, brain specificity provides the necessary but not the sufficient conditions for considering music as part of our biological endowment. What other neural aspect would strengthen the claim that music has adaptive significance? Music should correspond to a system that lacks flexibility when stabilized (i.e., in the mature brain). We need to find evidence for a fixed arrangement of the musical neural networks. By fixed arrangement, we mean a particular brain implementation that is shared by humans, nonmusicians and musicians alike, and similarly localized in all brains. This is a very strong prediction, perfectly suited for an application of the new brain imagery techniques. The claim that there is a similar brain organization for music in all humans would seem easy to falsify. However, it is not an easy task. To do so, we need to identify what processing mechanisms are essential for music appreciation, an ability shared by all humans. Then, we can specify where these
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essential processing components are carried out in the brain of musicians and nonmusicians. There is a range of possibilities. Neuropsychology is one of the rare disciplines that can shed light on this issue. First, the lesion method, either naturally produced by a brain accident or experimentally induced by focal TMS, allows one to identify the essential regions of the cortex for music appreciation. The latter technique is likely to play an essential role in the future since it allows direct comparison of musicians and nonmusicians. Second, we need to tap these essential mechanisms with appropriate means. That is, we need to assess the functioning of these musical mechanisms with valid tasks, which usually mimic what people generally do when listening to music. For instance, if we envisage that most people listen to music for emotional purposes, then music processing should be assessed via emotional responses. This is a new endeavor. The neuropsychological study of music as an emotional language has just begun (Blood et al., 1999; Peretz et al., 1998; Peretz & Gagnon, 1999). This new perspective on music and the brain is not, however, accidental and holds great promises for a better understanding of how human brains respond to music. It is probably the study of music, as an emotional language, that is the most likely to tap the universal principles that are responsible for its ubiquity. Until the 1960s, it was believed that languages could vary arbitrarily and without limit. Today, there is a consensus among linguists that there is a universal grammar underlying diversity. Similarly, it was once thought that facial expressions of emotion could vary arbitrarily across cultures until Ekman (e.g., Ekman et al., 1987) showed that a wide variety of emotions are expressed cross-culturally by the same facial movements. Ekman made the important distinction between the expression of emotions and the cultural variation that may exist in the rules for displaying those emotions. Likewise, certain aspects of music are culture-specific, although the general rules and processes subserving parsing, remembering, and producing may be universal. These universal principles may in turn be subserved by neural networks shaped by natural selection. The neurosciences should not be long to provide answers to these assumptions. REFERENCES Blood, A., Zatorre, R., Bermudez, P., & Evans, A. 1999. Emotional responses to pleasant and unpleasant music correlate with activity in paralimbic brain regions. Nature Neuroscience, 2, 382–387. Ekman, P., Friesen, W., O’Sullivan, M., Chan, A., Diacoyanni-Tarltzis, I., Heider, K., Krause, R., LeCompte, W., Pitcairn, T., Ricci-Bitti, P., Sherer, K., Tomita, M., & Tzavaras, A. 1987. Universals and cultural differences in the judgments of facial expressions of emotion. Journal of Personality and Social Psychology, 53, 712–717. Pantev, C., Oostenveld, R., Engelien, A., Ross, B., Roberts, L., & Hoke, M. 1998. Increased auditory cortical representations in musicians. Nature, 392, 811–814. Peretz, I. 2000. Music cognition in the ear of the majority. Modularity of the music recognition
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system. In B. Rapp (Ed.), The handbook of cognitive neuropsychology. New York: Psychology Press. Peretz, I., & Gagnon, L. 1999. Dissociation between recognition and emotional judgment for melodies. Neurocase, 5, 21–30. Peretz, I., Gagnon, L., & Bouchard, B. 1998. Music and emotion: Perceptual determinants, immediacy and isolation after brain damage. Cognition, 68, 111–141.
