Modularity of Music: Evidence from a Case of Pure Amusia

J Neurol Neurosurg Psychiatry 2000;69:541–545 541 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.69.4.541 on 1 October 2000. Downloaded from

SHORT REPORT

Modularity of music: evidence from a case of pure amusia

Massimo Piccirilli, Tiziana Sciarma, Simona Luzzi

Abstract referred to us in December 1997 for the onset A case of pure amusia in a 20 year old left of a sudden and violent left frontotemporal handed non-professional musician is re- headache, which was followed by nausea and ported. The patient showed an impair- vomiting and was associated with a language ment of music abilities in the presence of disorder. The neurological examination per- normal processing of speech and environ- formed at admission showed only aphasia mental sounds. Furthermore, whereas characterised by rare literal paraphasia cor- recognition and production of melodic rected by the patient himself, with impaired sequences were grossly disturbed, both verbal comprehension. Medical history did not the recognition and production of rhythm indicate any noteworthy diseases, with the patterns were preserved. This selective exception of surgery performed when the breakdown pattern was produced by a patient was 3 years old to remove an angioma focal lesion in the left superior temporal from the pulp of the second ﬁnger on his left gyrus. This case thus suggests that not hand. only linguistic and musical skills, but also An emergency cerebral CT showed a left melodic and rhythmic processing are temporal haematoma with a maximum diam- independent of each other. This func- eter of 4.5 cm, surrounded by perilesional tional dissociation in the musical domain oedema. supports the hypothesis that music Angiography of the cerebral circle, per- components have a modular organis- formed immediately after the CT, disclosed a ation. Furthermore, there is the sugges- medium sized arteriovenous malformation in tion that amusia may be produced by a the left temporal region, with an ovoid shaped lesion located strictly in one hemisphere nest with a maximum diameter of 4.5 cm. The and that the superior temporal gyrus arteriovenous malformation seemed to be plays a crucial part in melodic process- supplied mainly by three vessels rising from ing. the temporal branch of the left middle cerebral (J Neurol Neurosurg Psychiatry 2000;69:541–545) artery and it was also supported by the http://jnnp.bmj.com/ anterior choroid artery. Drainage of the Keywords: amusia; melodic processing; superior tempo- angioma occurred exclusively in the surface ral gyrus venous system through a single ectasic venous collector that discharged in the left transverse Music is a complex ability with characteristics sinus. that are unique with respect to other cognitive In January 1998, the patient underwent 1 blocked ﬂow embolisation with NBCA and

abilities : therefore, several issues are still open on October 1, 2021 by guest. Protected copyright. to debate—for example, if music is a faculty particles that completely occluded the arterio- that is independent of the rest of the cognitive venous malformation, leaving all the branches system, and if musical skills are mediated by a of the sylvian artery intact. Departimento Three months after the acute event, a neuro- Medicina Clinica e single mechanism or by a combination of processes that are independent from each other. logical examination and an otological examina- Sperimentale, tion with audiometry were normal. University of Perugia, Moreover, the anatomical correlations of music Via Sicilia 39, 06128 have yet to be clarified.2–6 A cranial MRI showed an area with altered Perugia, Italy We report a case of pure amusia without signals at the left temporal site with a cortical- M Piccirilli subcortical extension. The area was uneven as S Luzzi aphasia, and with selective impairment of melodic processing and precise lesion localisa- both the embolising material and haemoglobin catabolism byproducts were present. Institute of Neurology tion. The clinical picture described here can be T Sciarma considered further evidence supporting the modular interpretation of musical skills, their NEUROPSYCHOLOGICAL EVALUATION Correspondence to: hemispheric lateralisation, and the part played Professor M Piccirilli To investigate the aphasic disorder seen at the [email protected] by the superior temporal gyrus. onset of the patient’s symptoms, a preliminary language evaluation was conducted during the Received 7 July 1999 and in Case report first week after the acute event.6 This examina- revised form 20 March 2000 A 20 year old left handed man who was tion showed fluent oral production character- Accepted 12 April 2000 enrolled in his first year of law school, was ised by dysprosody, anomia, and frequent

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literal paraphasia. Comprehension was well Evaluation of musical ability maintained for interactive communication, but proved to be partially impaired in specific tests a) Preliminary tasks: Grison scale (6) 4 (token test=23). In the written naming tests, Verbal dichotic listening test (40) Left 90% the patient had letter paragraphia which he Recognition of non-musical sounds: Human noises (10) 100% often corrected himself; oral reading, and rep- Animal sounds (10) 100% etition were characterised by the same types of Ambient noises (10) 90% errors seen in oral production. Prosodic emotional tone interpretation: Meaningful sentences (10) 90% Over the next several days, language impair- Meaningless sentences (10) 80% ment improved rapidly and spontaneously. b) Musical perception tasks: One month later, a detailed examination was Recognition of familiar melody (20) 5% 7 Bentley’s test: performed using the BADA battery and this Pitch discrimination (20) 60% disclosed extremely infrequent literal errors Tonal memory (10) 30% that mainly involved inflectional morphemes Chord analysis (20) 75% Rhythmic memory (10) 90% (for example, mamma=mammo). The same Recognition of musical characteristics: battery repeated 3 months after onset was per- Musical instruments (10) 90% formed very well. Intensity (10) 90% Ascending and descending scales (10) 100% A few days after admission, the patient began Familiar rhythms (10) 100% to complain that his music perception had c) Musical production tasks: changed: “I can’t hear any musicality: all the Reproduction of a rhythm with a reflex 80% hummer (10) notes sound the same”. Listening to music gave Stambak test (38) 87% him an unpleasant feeling and he found this Spontaneous singing (10) 0% Reproduction of familiar melody (20) 0% very worrisome because he was an avid music Spontaneous guitar performance (10) 0% lover and devoted most of his free time to this Instrumental reproduction of a familiar 0% hobby. The patient’s father had taught him to melody (10) Instrumental reproduction of a unknown 0% play the guitar when he was 14 years old. He melody (10) did not know how to read music, but he could listen to a musical excerpt and reproduce it. Results are percentage of correct responses (number of trials in Despite the fact that he was left handed, his parentheses). right handed father had taught him to play the instrument and as a result, he would strum pegboard test), and intellectual processes with his right hand and use his left hand on the (Raven 47 coloured progressive matrices, Weigl frets. He and his friends had formed a band in sorting test, Spinnler’s verbal judgement). Per- which he sang and played the guitar, although formance was normal also in semantic fluency, he himself stated that he had no special talent calculation, and somatognosia tests. Further- as a singer. more, the patient did not make any errors in A detailed neuropsychological evaluation the interhemispheric transfer of tactile stimuli, was performed 90 days after the acute event. which was performed to examine callosal 10 The patient reported that he no longer had any function. speech problems, but he continued to com- The Oldfield questionnaire showed that the plain that he had diYculty in perceiving and patient was fully left handed (100%), as did the producing music: “Sounds are empty and cold. eye and foot dominance tests. There was no family history of left handedness. Singing sounds like shouting to me. When I http://jnnp.bmj.com/ hear a song, it sounds familiar at first but I can’t To study the diYculties in music skills, a recognise it. I think I’ve heard it correctly, but musical ability examination was also 11–13 then I lose its musicality. I can recognise the performed. guitar but not the melody.” In tests designed to explore other cognitive EVALUATION OF MUSICAL ABILITY (table) functions,89 the patient’s performance was Preliminary tasks consistently within the normal range. In Grison scale of musical ability before illness14—The

particular, he was administered tests to exam- patient could play an instrument but was not on October 1, 2021 by guest. Protected copyright. ine the following: verbal and non-verbal familiar with music theory and was thus unable memory and learning (WMS digit forward, to read or write music. Consequently, he was Corsi block tapping test, Rey complex A figure, placed at the fourth level of this six level scale Benton visual retention test, Spinnler prose (musicians are considered level six). memory test, Buschke-Fuld verbal learning Verbal dichotic listening tests—Dichotic listen- test, Rey 15 word auditory-verbal learning test, ing to word pairs showed a marked preference Spinnler spatial supraspan learning test, for the left ear (only four answers out of 40 Barbizet-Cany 7/24 test), attention and execu- were for the right ear). These results can be tive functions (Wisconsin card sorting test, interpreted as suggestive of right hemispheric Stroop test, trail making test, Hanoi towers, dominance for language functions. FAS literal fluency, sentence generation, bar- Recognition of non-musical sounds—The task rage of letters, and geometric figures), percep- was proposed as both direct and multiple tual recognition (Poppelreuter test, colour rec- choice recognition. In any case, the patient ognition, and naming), praxis (ideational, appropriately recognised environmental ideomotor, buccofacial and constructional sounds regardless of type—human noises, such tests suggested by De Renzi), visuospatial as coughing and laughing, and animal analysis (Benton line orientation test, behav- sounds—as well as ambient noises such as a ioural inattention test), psychomotor integra- brook or a typewriter, and vehicle noises such tion (Luria test, WAIS digit symbol, grooved as trains and motorcycles.

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Axial (A, B) and coronal (C, D) brain MRI performed 15 months after the event showing a moderate atrophy of the left temporal lobe and focal damage involving the middle and posterior third of the left superior temporal gyrus, including Brodman’s areas 22 (auditory association cortex), 41, and 42 (transverse gyri of Heschl, primary auditory cortex).

Prosodic emotional tone interpretation— ing to the indications of Peretz et al.12 Analysis During this test of recall and recognition of of the scores of subtests disclosed a selective emotional tone, the patient could easily decline in the tonal memory test. identify the mood that matched the tone of a Perception test of musical characteristics—This

sentence. This test was performed using a investigates the patient’s ability to recognise http://jnnp.bmj.com/ meaningful sentence (recall) and a meaning- intensity, timbre (musical instruments), famil- less one composed of neologisms (recogni- iar rhythms (waltz, tango, etc), and ascending tion). He also had no trouble distinguishing and descending scales. This examination did between the characteristics of men’s, women’s, not present any particular diYculties for the and children’s voices; likewise, he found it easy patient. to distinguish foreign accents (French, Eng- lish, German, Spanish). MUSICAL PRODUCTION TASKS

The patient made mistakes only on the longer on October 1, 2021 by guest. Protected copyright. MUSICAL PERCEPTION TASKS sequences in the rhythm reproduction Recognition of familiar melodies—Serious diY- tasks11 16; on all the other tests, listed in the culties were found even with extremely com- table, he experienced such serious diYculty monplace hummed songs such as the national that he refused to do the tests at all. Moreover, anthem and “O sole mio” as well as with musi- he could no longer play the guitar even when he cal pieces chosen from the ones that were pre- was given the chords. Lastly, as far as his sing- viously the patient’s favourites. ing was concerned, because of his undeniably Musical ability examination—Bentley’s test15 poor performance he stopped performing with was used. This test involves four subtests: pitch his band. discrimination (comparison between two notes), tonal memory (comparison between FOLLOW UP two five note motifs that diVer by just one note, The neuropsychological evaluation of musical without any contour changes), chord analysis abilities was repeated after 1 year and did not (two, three, and four note chords), and show any change. rhythmic memory (comparison between two Brain MRI, performed in March 1999 rhythmic figures with four beats and no change (figure), showed focal damage involving the in pitch). The subtests in this battery were set middle and posterior third of the left superior up so that melodic structure and rhythmic temporal gyrus including Brodman’s areas 22 structure could be analyzed separately, accord- (auditory association cortex), 41 and 42

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(transverse gyri of Heschl, primary auditory lesion.4122122 However, it is agreed that the cortex); the images also show moderate atro- superior temporal gyrus plays a crucial part in phy of the left temporal lobe, a feature often the perception of pitch organisation4122123: reported in subjects with bleeding arterio- Results with our patient seem to confirm this venous malformations.17 hypothesis. For the interhemispheric pattern, unilateral Discussion localisation of cerebral damage strongly sup- Recently, data raising the question of the ports, according to previous report of GriYths specificity for music renewed interest about et al,24 but not of Peretz et al,23the hypothesis amusia.1 Comparing our case report with other that strictly unilateral lesions may be able to cases in the literature35suggests several consid- produce an impairment of musical abilities. In erations on musical abilities and their neuro- our patient amusia appeared as a result of a anatomical substrate. lesion in the left hemisphere. As the patient is Our patient manifested a specific disorder left handed, the pattern of functional lateralisa- involving musical ability, without any deficits in tion is unclear. However, the very rapid and other verbal and non-verbal cognitive domains. complete remission of aphasic symptoms His ability to recognise musical sounds seems together with the results of the dichotic listen- to show selective impairment compared with ing tests and the 100% left dominance not only his ability to recognise both linguistic and for handedness, but also for foot and eye pref- ambient sounds. This dissociation between erence suggest that language is likely to be lat- speech and non-speech sounds on the one eralised to right hemisphere. On the basis of hand, and between music and environmental this interpretation, our report seems to support sounds on the other, supports the hypothesis the classic suggestion that the anatomofunc- that music requires a specialised processing tional representation of melodic aspects of channel which is separable from the neural sys- music is carried out by the hemisphere tems subserving the analysis of the other opposite to the one subserving classes of auditory stimuli.1–3 language.56182125 Musical impairment was limited to process- To summarise, our case report, consistently ing melodic structures; on the contrary, rhyth- with the few previous reports in the mic structure and timbre seemed to be literature,2324 seems to provide further evi- processed correctly.11213 This neuropsycho- dence for the modularity of music as well as for logical pattern can be interpreted as a confir- the existence of a specific neural architecture mation of the modular hypothesis proposed by devoted to music. The exact site of lesion con- Peretz et al,312 in which two separate subsys- firms the crucial role of the superior temporal tems mediate the processing of information on gyrus in this music processing system. Moreo- melodic structure (defined by the sequential ver, unilateral localisation of cerebral damage pitch variations) and of information related to strongly supports the hypothesis that pure temporal structure (defined by variations in amusia may be produced by a strictly unihemi- length), respectively. Although the indications spheric lesion that may very well involve the are only suggestive as, to give a direct compari- cerebral structures contralateral to the ones son of performance, melodic, and temporal subserving linguistic skills. components should be assessed using similar 12 tasks, the functional dissociation manifested 1 Peretz I, Morais J. Specificity for music. In: Boller F, http://jnnp.bmj.com/ by our patient supports recent claims for frac- Grafman J, eds. 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