Brain Specialization for Music

New Evidence from Congenital Amusia

ISABELLE PERETZ
Department of Psychology, University of Montreal, Montreal, Quebec, H3C 3J7, Canada

ABSTRACT: Brain specialization for music refers to the possibility that the hu-
man brain is equipped with neural networks that are dedicated to the process-
ing of music. Finding support for the existence of such music-specific networks
suggests that music may have biological roots. Conversely, the discovery that
music may have systematic associations with other cognitive domains or vari-
able brain organization across individuals supports the view that music is a cul-
tural artifact. Currently, the evidence favors the biological perspective. There
are numerous behavioral indications that music-specific networks are isolable
in the brain. These neuropsychological observations are briefly reviewed here
with special emphasis on a new condition, that of congenital amusia (also com-
monly referred to as tone deafness).

KEYWORDS: Music agnosia; Congenital amusia; Music-specific neural net-

works; Tone-deafness

The notion that music might have biological foundations has only recently gained
legitimacy. Over the past 30 years, music has mostly been studied as a cultural prod-
uct. Musicologists have been analyzing each musical system in the context of its spe-
cific culture. Neuroscientists and psychologists have considered music as a
convenient window to the general functioning of the human brain. However, neurop-
sychological observations have consistently and recurrently suggested that music
might well be distinct from other cognitive functions, in being subserved by special-
ized neural networks. As such, music might be viewed as pertaining more to biology
than to culture. The goal of the present paper is to review the neuropsychological ev-
idence that supports the biological perspective.

SPECIALIZED NEURAL NETWORKS FOR MUSIC PROCESSING

If music is biologically determined, then music should enjoy functional and neu-
roanatomical specialization. That is, music should be supported by neural networks
that are dedicated to its processing and that are unresponsive or inadequate for deal-

Address for correspondence: Isabelle Peretz, Department of Psychology, University of Mont-

real, C.P. 6128, succ. Centre-ville, Montreal, Quebec, H3C 3J7, Canada. Voice: 514-343-5840;
fax: 514-343-5787.
isabelle.peretz@umontreal.ca

153
154 ANNALS NEW YORK ACADEMY OF SCIENCES

ing with nonmusical input. Presently, support for the existence of such specialized
neural networks is compelling. Most evidence in this regard derives from the func-
tional examination of individuals whose brain conditions are disturbed in highly se-
lective aspects. The brain anomaly may either disturb or spare musical abilities
exclusively. These disorders are classified as three types of neurological conditions:
acquired disorders, congenital disorders, and brain stimulation.

Acquired Disorders
Acquired disorders refer to sequelae of a brain accident. Such injuries may be di-
verse but most frequently result from a cerebrovascular accident. In such cases, dis-
orders are expected to reveal brain organization due to the fact that the disorders are
constrained by the organization of the undamaged system, which was fully stabilized
prior to the accident. Thus, studying brain-damaged individuals with the objective
of uncovering the functional organization of the normal brain is an endeavor that is
akin to the process of reverse engineering.
This research strategy is facilitated by the recurrent observation that brain dam-
age does not affect cognition in its entirety, but rather, in particular aspects. Cogni-
tive disorders can be highly selective. The selectivity of the disorder can take
spectacular forms such as in brain-damaged composers who may lose their language
and yet remain able to maintain their musical activities at their prior professional
level.
The most famous case is probably that of Shebalin, the Russian composer, who, following
successive vascular accidents occurring in his left hemisphere, suffered from severe distur-
bances of his language abilities. He remained aphasic for the rest of his life; he could neither
understand nor speak intelligibly. Nevertheless, he continued to compose, notably completing
his Fifth Symphony, which Shostakovitch considered to be one of his most brilliant and inno-
vative works.1 Therefore, Shebalin displayed severe language deficits yet retained his musical
skills to a remarkable degree.
This dissociation between language and music cannot simply be explained by the
fact that these professional musicians were “abnormally musical” from the start. In-
deed, the reverse dissociation can also be observed, even in ordinary listeners. That
is, persons devoid of any special talent, linguistic or musical, can experience spec-
tacular losses of musical abilities, like losing the ability to recognize one’s national
anthem, without accompanying language difficulties. I was fortunate to be able to
study in detail three such cases.2,3
One of them, I.R., was a restaurant manager who suffered bilateral brain damage as a result
of successive surgeries in both sides of the brain for the clipping of ruptured aneurysms at the
age of 28. Ten years postonset, I.R. still suffers from severe and irreversible deficits in musical
perception and memory as a consequence to her brain condition.3 Prior to her brain surgeries,
music had great value to her. She was raised in a musically inclined family, her only brother
being a professional musician. Fortunately, I.R. did not lose her language skills. She under-
stands speech perfectly and remains verbally fluent, being able to express herself quite effec-
tively (see her poem recently published in French3).
Such musical disorders—called amusia in neurological terms—are not rare and
are dissociable from disorders of language—that is, aphasia, as reviewed by Brust
(this volume). This recurrent finding suggests that most processing components that
underlie language and music are not shared and are neuroanatomically separate.
PERETZ: BRAIN SPECIALIZATION FOR MUSIC 155

TABLE 1. Case reports of selective impairment and of sparing in the recognition of

music
Domain

Speech Environmental
Reports Music (not prosody) sounds Voices Lesions

Peretz et al.2, C.N., and −a + + + Bilateral temporal lobes

G.L. − +b + + Bilateral temporal lobes

Peretz et al.3, I.R. − + + + Bilateral temporal lobes and

right frontal lobe
Griffith et al.6 − + + Posterior right temporal lobe
Laignel-Lavastine et al. 10 + − − Right temporal lobe
Godefroy et al.9,b + − − Right posterior hemisphere
a +, normal recognition; −, impaired recognition.
b After or during recovery.

Although dissociation between music and language has been reported in various
spheres of activities, the two domains are rarely compared in analogous contexts.
Hence, significant association between language and music might have escaped
scrutiny. Thus, it is important to examine music and language in comparable tasks.
One such simple task that the auditory system performs constantly and without ef-
fort, for both music and language, is sound pattern recognition. Yet, it has been
shown that this task is not performed by a single shared auditory device, but by sev-
eral, each being specialized for its particular domain.4,5
For instance, auditory perception of music appears to recruit mechanisms that are
not implicated in speech recognition or in environmental sound recognition. Indeed,
there are brain-damaged persons whose unique symptom is the loss of the ability to
recognize and memorize music. The patients retain the ability to recognize and un-
derstand speech as well as to identify common environmental sounds normally.2,3,6,7
The deficit can be remarkably selective. For example, C.N. was unable to recognize
hummed melodies coming from familiar songs. Yet, she could perfectly recognize
the lyrics accompanying the melodies that she failed to recognize.7 Moreover, C.N.
was able to recognize the voice of speakers2 and the intonation of speech.8 The ex-
istence of such a specific problem with music alongside normal functioning of other
kinds of auditory abilities, including speech comprehension, suggests damage to
processing components that are not only specific to the musical domain but that are
also essential to the normal process of music recognition. We refer to this condition,
which is a particular form of amusia, as music agnosia.7
The reverse condition that corresponds to a selective sparing of music recognition
has been reported (see TABLE 1) but not yet well documented. Nevertheless, in the few
available cases,9,10 the lesion spared music processing relative to both speech compre-
hension and environmental sound recognition, which were both severely disturbed.
Such cases suggest isolated sparing of music recognition abilities, hence complement-
ing the music-specific deficits described above. Thus, the current evidence, summa-
rized in TABLE 1, is indicative of the presence of specialized brain circuits for music
156 ANNALS NEW YORK ACADEMY OF SCIENCES

recognition. These circuits are damaged in the cases of music agnosia and spared in
the few cases of verbal agnosia and associated agnosia for environmental sounds.

Congenital Disorders
Further neuropsychological evidence that is indicative of brain specialization for
music comes from congenital disorders. These disorders refer to unexpected failures
or preservation in a particular cognitive domain in comparison to the general level
of intellectual and socioemotional functioning. These deficiencies are termed con-
genital since their presence can be detected very early in development. One such
well-known condition corresponds to the “music-savant syndrome” that can often be
observed in autistic individuals. The etiology of autism is not yet known; however,
its incidence is relatively high, with 1 to 2 cases out of every 1000 births (about the
same rate as Down syndrome). Autism is currently viewed as deriving from some
brain anomaly because of its frequent association with another brain defect (e.g., ep-
ilepsy), its genetic transmission, and its atypical cerebral functioning as measured
by brain imaging studies.11 More interestingly from our perspective, 1 to 10% of au-
tistic individuals might be considered musicians.12 In effect, autistic subjects are
generally more apt in the area of music than in other domains, such as language.13
Several even become musical savants, a term that refers to the observation of high
achievements in musical competence in individuals who are otherwise socially and
mentally handicapped.
A well-known case (described in greater detail by L. Miller12) is that of “Blind Tom.”
Blind Tom was a young blind slave who gave piano concerts at the White House and all around
the world. Although his language repertoire consisted of less than 100 words, his musical rep-
ertoire contained more than 5000 musical pieces. This “music savant” was sold along with his
mother to Colonel Bethune in 1850 during a slavery sale in Georgia. Until age 5, he did not
say a word and manifested no other sign of intelligence than his remarkable interest for the
musical performance given by the colonel’s daughters. At age 4, he was playing Mozart sona-
tas, which he had heard. At age 6, he was able to improvise; and at age 7, he gave his first re-
cital. In 1862, despite the fact that he did not know how to read music, he was able to play
without error 14 pages of an original composition that he had heard just once. Blind Tom gave
recitals until age 53 when, following the colonel’s death, he had to end his career.
The mirror image of this condition corresponds to individuals who are totally mu-
sically inept, despite normal exposure to music, normal intelligence, and social ad-
aptation. Such individuals are sometimes called tone-deaf (see Grant-Allen14 for the
first report).
Che Guevara was known to be “tone-deaf.”15 He was well aware of his handicap, as the
following anecdote illustrates. At a party, by prior arrangement, Alberto, his best friend, was
required to give a poke to Che every time a tango was played. At some point during the party,
the orchestra played an agitated Brazilian shora that had been Alberto’s favorite. Alberto
wished to share his enthusiasm with Che, but Che, with his eyes on a woman across the room,
believed Alberto’s nudge to be a tango signal and took to the floor, dancing a slow and pas-
sionate tango with everyone else jiggling to the shora. Realizing something was wrong, Che
Guevara came over to ask Alberto for advice, who was too convulsed with laughter to be able
to explain.
These individuals have a rare condition called congenital amusia. The term amu-
sia is preferable to tone-deafness to reflect the likelihood that there might be as many
PERETZ: BRAIN SPECIALIZATION FOR MUSIC 157

forms of musical disorders that characterize congenital musical deficits as there are
multiple forms of acquired musical disorders (see Brust, this volume, for an illustra-
tion of the heterogeneity of acquired amusias).
Unlike other developmental disorders, such as dysphasia and dyslexia, congenital
amusia has not received much scientific attention. One obvious reason for this ne-
glect is that attention is directed primarily at learning disabilities that affect language
because of their wide educational implications. Moreover, music educators are re-
luctant to suspect the presence of congenital disorders because such a diagnosis may
mean discontinuation of musical studies.16 The other reasons are less pragmatic. As
mentioned at the outset, many scientists conceive music as the product of a general-
purpose brain organization. In that context, amusia is not a developmental disorder
that is expected to occur in isolation. Rather, amusia is expected to result from intel-
lectual and/or socioemotional dysfunctioning. However, as the study of music sa-
vants suggests, music proficiency does not seem to depend on the normal
development of the cognitive and affective system. Musical proficiency can be
achieved while sociocognitive functioning is globally deficient.
Therefore, in an effort to learn more about congenital amusia, we actively adver-
tised and searched for three years for people who were tone-deaf. The early discov-
ery of a textbook case (called Monica, reported in Peretz et al.34 and represented in
FIG . 1) who closely matched the two case descriptions available in the literature (i.e.,
Grant-Allen’s case14 and Geshwind’s case17) has contributed greatly to the advance-
ment of the study. Since then, the presence of amusia has been confirmed in 16 adults
(Ayotte et al., in preparation). All are self-declared tone deaf. Yet, self-report of mu-
sic deficiency requires verification, as this is a frequent complaint in ordinary listen-
ers. Therefore, we selected only subjects who exhibited clear-cut performance
deficits in laboratory tests. Furthermore, in order to exclude extraneous causalities,
we carefully selected participants who had no psychiatric or neurological history and
who possessed a solid level of education. To ensure adequate stimulation and to ex-
clude lack of interest or motivation, only volunteers who had experienced unsuccess-
ful attempts at learning music during childhood were considered.
For all selected persons with congenital amusia, results from a musical screening
battery of tests originally designed for brain-damaged patients gave behavioral evi-
dence for the disorder. This battery has proved to be very effective in identifying
adult nonmusicians with a deficit in music perception and memory.18–20 By experi-
ence, we know that when a score obtained in one of the six tests falls below the low-
est performance obtained by neurologically intact subjects who have reported no
particular musical disorder, the outlier score is indicative of a genuine deficit. In the
present study, we adopted a more conservative criterion and decided to consider par-
ticipants as amusic if their performance fell below three standard deviations from the
mean of a group of 60 unselected nonmusicians, on at least two tests. Their scores
are represented in FIGURE 1 with two tests that allow comparisons of results on the
melodic and temporal dimensions because the tests are very close in structure. One
test serves to evaluate the use of melodic contour and the other to assess the use of
rhythmic contour in the discrimination of two successive short musical sequences as
“same or different.” Each test comprises 30 trials made of two successive synthe-
sized melodies to be compared. The comparison melody is repeated in half the trials.
When different, the comparison melody contains one altered note that modifies the
158 ANNALS NEW YORK ACADEMY OF SCIENCES

FIGURE 1. Number of correct responses obtained by 16 congenital amusics relative to

the normal distribution (constituted by 60 nonmusicians, age range: 14–74 yr; education
range: 7–20 yr) in two screening tests of our musical battery17–19 assessing melodic contour
discrimination (abscissa) and rhythmic contour discrimination (ordinate axis). The dashed
line represents 3 standard deviations below the mean of controls.

pitch directions of the surrounding intervals in the melodic contour condition. In the
rhythmic contour test, the duration of two successive tones was inverted so as to cre-
ate a different rhythmic grouping in the comparison sequence. The original set of
melodies served to construct both tests. The melodies obey the rules of Western mu-
sic and were composed specifically for the battery.
Examination of the data in FIGURE 1 is informative in several aspects. First, most
controls are confined to the right top quarter (B) and show very little overlap with
amusics’ performance, with one exception. Agathe was unimpaired on these two
tests but was nonetheless classified as amusic because her performance was below
the cut-off scores in two other tests that are not illustrated here. Her condition points
to the possible heterogeneity of the congenital amusia syndrome. Another interest-
ing trend is reflected by the subgroup of amusics located in the left top quarter (A).
These amusics perform close to chance on the melodic dimension, whereas they per-
form normally on the rhythmic dimension. Such dissociation, between impaired
melody and spared rhythm, is relatively frequent after brain damage.20,21 Congenital
amusia seems to fractionate along similar lines. Note, however, that the large major-
ity of amusics (88%) have a deficit on the melodic dimension. This deficit seems to
lie on a continuum and may result from a basic auditory problem related to pitch dis-
crimination (Hyde, Peretz, and Ayotte et al., in preparation). Further psychoacousti-
cal work is currently under way with the objective to circumscribe the pitch deficit
experienced by these unmusical individuals.
PERETZ: BRAIN SPECIALIZATION FOR MUSIC 159

It is theoretically appealing to consider congenital amusia as arising from a basic

pitch perception defect. Such an account would square rather nicely with the idea
that some disorders in specific cognitive domains can be explained in terms of low-
level auditory mechanisms. Currently a highly popular view of language-specific
disorders involves a basic deficiency in fine temporal resolution.22 Ascribing some
form of congenital amusia to a faulty analysis of pitch variations constitutes an in-
teresting complementary disorder. The pitch-based account is also reasonable be-
cause fine-grained discrimination of pitch is probably required by most musical
systems, but not by speech intonation patterns. Intonation uses rather large variations
in pitch to convey meaningful information. For example, the question, Elle est de-
vant la gare? has a final rising pitch that is about half an octave (5 to 6 semitones)
higher than the final pitch in the assertion Elle est devant la gare. By contrast, mel-
odies mostly use small pitch intervals (on the order of one-twelfth or one-sixth of an
octave).23 Therefore, a degraded pitch perception system may well compromise mu-
sic perception but leave speech intonation unaffected. The available data are consis-
tent with this prediction, since our group of amusics does not exhibit difficulties
discriminating questions from assertions (Ayotte et al., in preparation).
Whatever the exact origin of congenital amusia, it is important to emphasize that,
indeed, the syndrome appears to be music specific. First, all subjects had reached a
high level of education. Thus, if they were having general auditory learning deficien-
cies, they should have had problems learning speech, for example, which, in turn,
should have interfered with normal education, but it did not. To demonstrate this in
a more rigorous fashion, we used another set of tests devised for music agnosic pa-
tients.7 These tests are standard memory recognition tasks that differ only by the do-
main from which the test items are taken. In the music memory test, subjects are
presented with 20 tunes (taken from familiar songs) to memorize. The melodies are
then represented among 20 unstudied (but equally familiar) melodies that are ran-
domly mixed. The subject is requested to indicate which melodies were heard in the
study phase. For comparison purposes, in the lyrics and the environmental sound
tests, subjects are given similar opportunities to learn and recognize 20 spoken lyrics
(taken from the same familiar songs) and 20 environmental sounds (e.g., a barking
dog), respectively. The three tests are performed in different sessions. As can be seen
in FIGURE 2, amusics perform at chance level in the music test, whereas they score
fairly high and within normal limits for nonmusical material, be they song lyrics or
environmental sounds. The results clearly show the music specificity of the learning
disability.
In conclusion, congenital amusia seems to be a true disorder. Affected individuals
appear to be born without the essential wiring elements for developing a normally
functioning system for music, while achieving a high degree of proficiency in their
professional and social lives. This impairment seems to result, at least in some cases,
from a more elemental problem that makes the individual unable to hear the pitch-
relevant variations in music. Although it seems unlikely that a single defective mech-
anism, such as a pitch defect, is responsible for all processing components underly-
ing musical functions, it may be that a single essential defective component brings
the development of the musical system to a halt even if it needs many properly func-
tioning components to work normally.
The existence of congenital amusia coupled with the music-savant syndrome
strongly suggests the presence of early pressures for the development of normal neu-
160 ANNALS NEW YORK ACADEMY OF SCIENCES

FIGURE 2. Number of correct responses obtained by 12 amusics and 20 controls in the

memory recognition of studied melodies, lyrics, and environmental sounds. Error bars rep-
resent standard error of the mean.

ral networks that are dedicated to music. These predispositions would not find a suit-
able neural space in the amusic’s brain, whereas they would find adequate wiring in
the autistic child’s brain. Identification of these neural bases as well as of their asso-
ciated heritability should provide crucial elements in the debate surrounding the ex-
istence of biological foundations for musicality.

Brain Stimulation
Investigations with epileptic patients provides the third source of evidence that
speaks for the existence of neural networks that are dedicated to music. In a few in-
dividuals, music will be the exclusive trigger of the pathological firing of neurons
conductive to the epileptic crisis. This form of epilepsy is called musicogenic
epilepsy24 (see also Brust, this volume) and suggests that the epileptogenic tissue
lies in a neural region that is tied to music processing.
The British neurologist Macdonald Critchley25 describes one regular visit of an epileptic
patient to report progress and to collect medication. The patient explained to him that hearing
music provoked her attacks exclusively. The patient specified that music of the popular type
had no effect, only classical music did, while confessing she had no particular preference for
classical music. She was subsequently admitted to the hospital and, despite her discomfort,
was presented with various kinds of music. The only record of classical music possessed by
the experimenters, which contained “The Walse of the Flowers” by Tchaikovsky, immediately
provoked a seizure with generalized convulsive movements, frothing at the mouth, and
cyanosis.25
During musicogenic epileptic seizures, abnormalities in electrical activity (re-
corded from the scalp) are generally observed at the temporal lobes, with a slight
bias toward the right one (see Wieser et al.24 for a recent review). Thus, some pro-
PERETZ: BRAIN SPECIALIZATION FOR MUSIC 161

cessing component that is exclusively related to music must be located in those

regions.
Musicogenic epilepsy is in some sense a natural accident that can be simulated
by direct application of electrical stimulation of the brain. In vivo electrical stimula-
tion of particular areas of the auditory associative cortex of awake patients may pro-
duce highly vivid musical hallucinations.26 These provoked hallucinations suggest
that the stimulation has been applied to circuits that contain memories of musical ex-
periences.
Penfield and Perot report stimulating a particular region of the first right temporal circum-
volution. The patient then said: “I hear music.” The experimenters then repeated the stimula-
tion, without telling the patient, who immediately said, “I hear the music again. It is like the
radio.” When asked what tune she was hearing, she said she did not know but it was familiar.
The stimulation was again repeated and the patient shouted: “I hear it.” The electrode was kept
in place and the patient was asked to describe what she heard. The patient hummed the tune
quite distinctly. The song came out so clearly that one of the nurses recognizes “Rolling along
together.” The patient agreed that this sounded like the words in the song (Penfield and Per-
ot,26 case 5, p. 620).
The left and, slightly more often, right temporal regions are prone to evoke such
musical experiences. The fact that musical memories can be exclusively elicited in
individuals with no musical training underscores once again brain specialization for
music.
In summary, the patient-based approach converges on one precise point: neuronal
networks that are situated in or close to the superior temporal gyrus participate in
music perception and memory in a decisive and exclusive manner. Presently, there is
little evidence for music specificity coming from the study of normal brains (but see
Halpern, this volume, for recent data).

LOCALIZATION OF THE MUSIC-SPECIFIC NETWORKS

Localization of the music-specific networks is essential when biological deter-

minism is at issue. Biological functions are expected to be associated with a fixed
neural organization across individuals. However, finding brain specialization for
music is necessary but not sufficient. Showing brain specialization means that music
possesses a neurofunctional substrate by itself and hence is not a parasite or a by-
product of a more important brain function. Yet, brain specialization does not entail
prewiring.
Brain specialization for music may result from recruitment of any free neural
space in the infant’s brain. Music would simply modify that space and adjust it to its
processing needs. This opportunistic scenario of brain organization for music may
respond to cultural pressure and not biological forces. If this were true, then a highly
variable localization and distribution of the musical networks should be observed
across individuals. Depending on the moment, quality, and quantity of exposure, var-
ious brain spaces might be mobilized. Thus, if music is a “squatter” in the brain, lo-
calization should vary capriciously across members of the same culture.
By contrast, a prewired organization is expected to exhibit consistency in local-
ization. For example, the primary auditory areas (the Heschl’s gyri) are systemati-
cally buried in the sylvian fissure; this holds for all humans. If development of
162 ANNALS NEW YORK ACADEMY OF SCIENCES

musical networks is under the guidance of early predispositions, then these networks
are expected to have a fixed arrangement. That is, brain implementation of music net-
works should be similar in the vast majority of humans, nonmusicians and musicians
alike. Moreover, this organization is not expected to vary as a function of the musical
culture considered. Musical functions are expected to be similarly implemented in
the brain of an isolated Pacific Islander, a Chinese opera singer, and a Western fan
of rap music. This prediction is quite strong and perfectly suited to the exploitation
of the new brain imagery techniques.
Although clear and straightforward, the demonstration of a similar brain organi-
zation for music in all humans remains elusive. Localization of the brain substrates
underlying music has been an enduring problem for more than a century. In my view,
the only consensus that has been reached today about the cerebral organization un-
derlying music concerns pitch contour processing. The vast majority of studies point
to the superior temporal gyrus and frontal regions on the right side of the brain as the
responsible areas for processing pitch contour information.27 However, it remains to
be determined if this mechanism is music specific, since the intonation patterns of
speech seem to recruit similarly located, if not identical, brain circuitries.8,28
Similarly, assuming comparable brain organization in musicians and nonmusi-
cians may sound controversial, since there is strong evidence that musical training
has a sizable effect on cortical morphology (see Schlaug, this volume) and activity
(see both Pantev and Pascual-Leone, this volume). It remains to be determined to
what extent these changes due to musical training are merely quantitative or rather
represent qualitative modifications. In other words, it will be important to qualify the
effect of training on brain organization. Presently, music training does not seem to
distribute musical modules differently in the neural space of the expert compared to
the ordinary listener, as the parasitic scenario would predict. Yet, the relevant evi-
dence is still scarce.
Clearly, what is needed at the present stage is a grid that allows specification of
the processing mechanisms that are essential for music appreciation, an ability
shared by all humans. Once these essential ingredients have been identified, their re-
spective localization may be tracked down in the brains of musicians and nonmusi-
cians of different musical cultures. The research agenda involved is dense and will
only be briefly sketched in the next section.

WHAT IS THE CONTENT OF THE MUSIC-SPECIFIC

NEURAL NETWORKS?

The music-specific neural networks should correspond to a common core of mu-

sical abilities that are acquired by all individuals of the same culture and that form
the essence of musical competence acquired by members of all cultures. This com-
mon core can probably be reduced to a few essential processing components that
represent the germ of brain specialization for music. In this perspective, there is no
need for all musical abilities to have initial specialization. Brain specialization for a
few mechanisms that are essential to the normal development of musical skills
should suffice.
I am proposing that the two anchors of brain specialization for music are the en-
coding of pitch along musical scales and the ascribing of a regular beat to incoming
PERETZ: BRAIN SPECIALIZATION FOR MUSIC 163

events. The notion that a special device exists for tonal encoding of pitch has been
developed in previous papers29 and will thus not be elaborated further. Similarly, the
notion that regularity might be fundamental to music appreciation is slowly
emerging30 (e.g., Drake, this volume), although its specificity to music is rarely ad-
dressed.
Universality of musical scales and of pulse regularity is another issue that has re-
ceived very little attention from ethnomusicologists. As mentioned earlier, ethnomu-
sicologists cautiously avoid generalization across musical cultures. Yet, the
plausibility of considering pitch scales and regularity as universals of music has in-
creased in recent years.31
By contrast, developmental psychologists have made significant progress in iden-
tifying plausible musical universals. Studies with infants have largely confirmed the
presence of precocious sensitivity to musical scales and to temporal synchronicity in
auditory processing. For example, six- to nine-month-old infants process consonant
intervals better than dissonant intervals32 and exhibit learning preferences for musi-
cal scales.33 In most musical cultures, musical scales make use of unequal pitch
steps. Infants already show a sensitivity bias toward musical scales, since they have
been shown to be better at detecting a small pitch change in an unequal-step scale
than in an equal-step scale (see Trehub, this volume). On the time dimension, infants
prefer music that is subject to an isochronous temporal pulse. For instance, like
adults, four-month-old infants are biased toward perceiving regularity; they exhibit
sensitivity to slight disruptions of temporal isochrony30 (Drake, this volume). All of
these aspects of auditory pattern processing suggest the presence of innate learning
preferences.
In conclusion, appreciation of music fits well with the product of a specialized
cortical arrangement that is present and functional early in human development and
that is shared by the vast majority of ordinary listeners. Hence, music does not seem
to be a mere game for the mind, for the neurons, or for the senses. Music seems to
serve needs that are so important to humans that their brain has dedicated some neu-
ral space to its processing. It remains to demonstrate that these music-specific net-
works are fulfilling needs that are not optional but that have adaptive value.

ACKNOWLEDGMENTS

Parts of the work summarized in this article were done in collaboration with Julie
Ayotte and Krista Hyde. I thank Simone Dalla Bella for editing the figures and mak-
ing insightful comments on the paper and Krista Hyde for language editing. The pa-
per is based on studies supported by grants from the Medical Research Council of
Canada.

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