adequately as musicians in their ability to judge modifications of musical ... Psychol Sci 1998; 9: 494±8. Bigand E, Pineau M. Global context effects on musical expectancy. ... Platel H, Baron JC, Desgranges B, Bernard F, Eustache F. Semantic.
Editorial
Neuropsychology of musical perception: new perspectives
For now well over a century, neuropsychologists have investigated the various components of auditory perception. The central disorders of this perception have been a topic of considerable interest, mainly through observations of auditory agnosia or amusia (selective loss of musical abilities). In a remarkable way, it was shown that the disorders of music and language perception could be dissociated. Although it is usual to assert that the perception of music is subserved by the right hemisphere, observations of brain-damaged patients reveal the involvement of both hemispheres. The idea, that amusia follows generally right hemispherical lesions, corresponds in particular to the fact that, in rare cases where musicians have had a left sylvian infarction (e.g. Wernicke's aphasia), they have been able to continue their musical career and follow a quasi normal artistic activity. However, the clinical association of linguistic and musical disorders is also often noted, and the observations of `pure' amusia are extremely rare in the literature. Thus, it remains dif®cult to establish precisely the functional neuroanatomy of musical perception from such clinical studies (Lechevalier et al., 1985). The development of experimental psychology methods applied to healthy subjects and brain damaged patients during the 1960s made it possible to separate, on a functional level, the involvement of each cerebral hemisphere, and contributed to support the distinction between music and language by locating each one of these functions in a different hemisphere. Over the last 20 years, experimental studies have contributed to a more modular conception of musical perception, which is not satis®ed by one simple opposition between music and language, but proposes to approach the perception of music in all its complexity. For example, one may consider the multiple components of music (pitch, timbre, rhythm), each one of which may be differentially lateralized (Peretz, 1993). Thus, the complexity of musical cognition could be revealed in a number of ways as follows: to perceive a melody, to discriminate between the pitch of two notes, to differentiate the timbre of musical instruments, to beat the tempo or to perceive a rhythmic pattern. Such are the many high level cognitive activities, which are based on perceptive skills, and for whom the musicians remain the experts. Beyond the question of independence between music and language, the innate or acquired character of musical ã Oxford University Press 2002
competence, such as the `absolute pitch' capability, is a idea which continues to provoke debate (Zatorre et al., 1998). In a number of experimental conditions, it was clearly shown that non-musician subjects can present musical capabilities as adequately as musicians in their ability to judge modi®cations of musical parameters (Bigand and Pineau, 1997). On the contrary, do we have examples of `naturally' incompetent individuals for music? The research team of I. Peretz provided a new and remarkable insight to these questions by the thorough study of a cognitively neurologically healthy population of subjects, presenting what can be termed as a `congenital amusia'. The work of Ayotte, Peretz and Hyde, published in this volume, is truly a turning point in the research carried out on musical perception in that the authors highlighted a new population of interest. Indeed, clinical research relating to the observation of selective de®cits of musical perception is confronted by the great scarcity of neurological syndromes producing such disorders. For a long time, patients having undergone cortectomy of temporal lobes for intractable epilepsy constituted a privileged population of study for central auditory disorders. However, numerous studies involving these patients have shown frequently a weak deleterious effect of temporal cortectomies on musical abilities (LieÂgeois-Chauvel et al., 1998). As such, clinical research has had to readdress this question and take into account the description of this new and fascinating `pathological' population. This concept, however, is not based primarily on the revelation of the existence of the congenital amusia, which was already described in the literature by the end of the 19th century, but more so on the precise characterization performed by the authors of the observed musical de®cits. Ayotte, Peretz and Hyde are the ®rst to describe precisely the very selective nature of such disturbances. Their selected subjects (chosen using a rigorous methodological approach) presented only disorders of musical perception (in particular the pitch perception), in the absence of linguistic disorders (no dif®culty on prosody) and signi®cant dif®culties with perception of environmental sounds. Moreover, these de®cits did not affect only the perceptive level, but the subjects were also extremely de®cient in their ability to memorize and recall musical information. The main hypothesis, which was proposed to explain these selective musical disorders, is that
224
Editorial
the whole of the de®cits observed are the consequence of an initial failure of the system of pitch perception. This assumption, although plausible, will require to be supported by other work. On the other hand, no neuro-functional explanation can be advanced to support a defect of activation of a neural network dedicated solely to a musical process. In addition, the initiation of musical disorders in the history of the subjects must be considered in relation to possible effects of compensation. For these reasons, one may consider that the prolongation of such studies with this population and with functional neuroimaging techniques presents considerable interest. Indeed, the different functional cerebral imaging techniques (metabolic or electrophysiological) have allowed, over the last 15 years, to specify the role of primary and secondary auditory cortex areas. The tonotopic representation of sounds, already described in animal studies, was also found in man (Pantev et al., 1989). However, very few functional neuroimaging studies were directly interested in the investigation of musical processes (Zatorre et al., 1994; Besson et al., 1998). These studies con®rm, however, the complex and composite characteristics of music perception (Platel et al., 1997). Lately, the study of the speci®city of musical memory was addressed, and now constitutes a new ®eld of investigation (Platel et al., 2001). Most of this research work was carried out with normal subjects (musicians or nonmusicians), but very few studies of functional neuroimaging could be carried out on patients presenting central auditory disorders (Engelien et al., 1995). In fact, the opportunity to study this new population, having the double characteristic to present selective disturbances of musical functions in the absence of an established neurological pathology, represents an opening towards new research and makes it possible to readdress the questions about functional independence between language and music, and about the innate or acquired nature of the various levels of expression of these typically human competences. Herve Platel INSERM U.320, University of Caen, France
References Ayotte J, Peretz I, Hyde K. Congenital amusia: a group study of adults af¯icted with a music-speci®c disorder. Brain 2002; 125: 238±51. Besson M, Faita F, Peretz I, Bonnel AM, Requin J. Singing in the brain: independence of lyrics and tunes. Psychol Sci 1998; 9: 494±8. Bigand E, Pineau M. Global context effects on musical expectancy. Percept Psychophys 1997; 59: 1098±107. Engelien A, Silbersweig D, Stern E, Huber W, DoÈring W, Frith C, et al. The functional anatomy of recovery from auditory agnosia. A PET study of sound categorization in a neurological patient and normal controls. Brain 1995; 118: 1395±409. Lechevalier B, Eustache F, Rossa Y. Les troubles de la perception de la musique d`origine neurologique. Paris: Masson; 1985. LieÂgeois-Chauvel C, Peretz I, Babai M, Laguitton V, Chauvel P. Contribution of different cortical areas in the temporal lobes to music processing. Brain 1998; 121: 1853±67. Pantev C, Hoke M, LuÈtkenhoÈner B, Lehnertz K. Tonotopic organization of the human auditory cortex: pitch versus frequency representation. Science 1989; 246: 486±8. Peretz I. Auditory agnosia: a functional analysis. In: Adams SMC, Bigand E, editors. Thinking in sound: cognitive aspects of human audition. Oxford: Oxford University Press; 1993. p. 199±230. Platel H., Price C, Baron JC, Wise R, Lambert J, Frackowiak RS, et al. The structural components of music perception: a functional anatomical study. Brain 1997; 120: 229±43. Platel H, Baron JC, Desgranges B, Bernard F, Eustache F. Semantic and episodic memory of music: a positron emission tomography study. Neuroimage 2001; 13: S727. Zatorre RJ, Evans AC, Meyer E. Neural mechanisms underlying melodic perception and memory for pitch. J Neurosci 1994; 14: 1908±19. Zatorre RJ, Perry DW, Beckett CA, Westbury CF, Evans AC. Functional anatomy of musical processing in listeners with absolute pitch and relative pitch. Proc Natl Acad Sci USA 1998; 95: 3172±7.
