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Musical Alexia for Rhythm Notation: A Discrepancy Between Pitch and ...

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1Department of Neurology, Showa University School of Medicine, Tokyo, Japan and ... music are referred to as musical alexia and musical agraphia,.
Neurocase 2003, Vol. 9, No. 3, pp. 232–238

1355-4794/03/0903–232$16.00 # Swets & Zeitlinger

Musical Alexia for Rhythm Notation: A Discrepancy Between Pitch and Rhythm Akira Midorikawa1, Mitsuru Kawamura1 and Machiko Kezuka2 1

Department of Neurology, Showa University School of Medicine, Tokyo, Japan and 2Department of Rehabilitation, Aoyama Hospital, Tokyo, Japan

Abstract In the process of reading music, the reading of rhythm and pitch might be differentiated, although there is no evidence of this to date. There have been cases of disorders restricted to the reading of pitch, but none in which the disorder has been restricted to the reading of rhythm. We present a case of musical alexia and agraphia with Wernicke’s aphasia. An in-depth assessment of the subject’s musical reading ability showed that her musical alexia was restricted to unfamiliar melodies. When a melody was divided into rhythm elements and pitch elements, pitch reading was preserved, but rhythm reading was severely disturbed. This is the first case reported of a disorder restricted to rhythm reading, and suggests the independence of rhythm reading and pitch reading.

Introduction In contrast to simply singing or listening to music, special education is required to read and write music. Accordingly, there have been few neuropsychological reports on the reading or writing of music. Impairment in reading and writing music are referred to as musical alexia and musical agraphia, respectively, and both are encompassed by the term amusia (Benton, 1977). Musical alexia and agraphia have not been studied extensively because they are frequently accompanied by aphasia, and because only a few patients suffer from these deficits (Wertheim, 1969). In recent years, however, isolated cases of musical alexia or agraphia have been reported (Judd et al., 1983; Horikoshi et al., 1997; Cappelletti et al., 2000), and the mechanisms of musical reading and writing have been explored (Scho¨n et al., 2001). There are three types of musical alexia. The first involves an inability to read single notes (Cappelletti et al., 2000); the second involves misreading the pitch of notes more than the rhythm (Brust, 1980 [Case 1]; Judd et al., 1983; Horikoshi et al., 1997; Kawamura et al., 2000); and the third involves an inability to read either pitch or rhythm (Brust, 1980 [Case 2]). The existence of different types of musical alexia implies that there are several processes involved in reading music, although it may merely indicate the severity of the deficit. In fact, musical alexia involving an inability to read either pitch or rhythm is often accompanied by aphasia. It is known that several subsystems are involved in reading language. For example, deep, as opposed to surface, dyslexia

is found in relation to English, and kana (Japanese phonograms), as opposed to kanji (Japanese ideograms), dyslexia occurs in relation to Japanese (Black and Behrmann, 1994). Therefore, it is reasonable to suppose that there are also several subsystems involved in the reading of music. With regard to writing music, it has been suggested that these subsystems consist of a temporal system and a pitch system (Brust, 1980; Kawamura et al., 2000; Midorikawa and Kawamura, 2000). With regard to reading music, it is expected that such systems exist. However, these differences have yet to be observed. Here, we present a case of musical alexia and agraphia that presented with reading disturbances that were restricted to the rhythm dimension. We also show the independence of rhythm reading and pitch reading.

Case report Patient TT was a 62-year-old, right-handed, female piano teacher. After graduating from a music college, she opened her own piano school. In September 1999, she exhibited aphasia following a cerebral infarction and was examined at our hospital. No clear neurological disorders other than Wernicke’s aphasia were observed. Magnetic resonance images (MRI) revealed a regional infarction in an area extending from the left superior temporal gyrus to the angular gyrus in Wernicke’s area (Fig. 1).

Correspondence to: Mitsuru Kawamura, Department of Neurology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan. Tel: +81 3 3784 8710; Fax: +81 3 3784 8710; e-mail: [email protected]

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Fig. 1. MR images of sagittal section (Left) and coronal section (Right). Magnetic resonance images (MRI) revealed a regional infarct in an area extending from the left superior temporal gyrus to the angular gyrus in Wernicke’s area.

Neuropsychological examination

General music ability

TT understood ordinary conversation as long as the content was simple, but she could not sustain the conversation when the topic changed. When several requests were included in one sentence, she only partially understood. TT also had difficulty in understanding a post-positional particle. Although TT spoke fluently, word-finding difficulty and phonological paraphasia were observed, and she sometimes uttered jargon. Repeating a single word that consisted of more than two syllables was difficult for her. She comprehended the meaning of both kana and kanji easily, as long as single words were presented. She could read kana words correctly, but had difficulty reading kanji words. In sentence comprehension, TT understood the general content of a sentence when she read it, but she had difficulty understanding the details of the sentence. When TT was asked to write a sentence, she could write words, but could not construct a sentence. Her ability to write kanji was impaired, but she was able to write them correctly when she was given hints. Errors were observed when she wrote words in kana script, although she could write it more easily than kanji. Copying was performed well. According to the Japanese version of the Western Aphasia Battery (WAB), she scored 13.0/20 points in spontaneous speech, 5.75/10 in auditory comprehension, 0.8/10 in repetition, 0.3/10 in naming, 5.9/10 in reading, and 3.85/10 in writing. TT showed typical Wernicke’s aphasia. In the Raven Colored Progressive Matrices (RCPM) test she scored 22 out of 36 points, and in the WAIS-R her performance IQ was 76; both tests indicated that her intelligence had deteriorated slightly. In the digit span test of the WAIS-R, she was able to recall only two digits, clearly indicating an impaired memory span.

A disorder of pitch was observed when she sang a song. Her pitch was monotonous, even if she could name the notes correctly. However, her piano performance was good, using two hands, as long as she played a familiar melody from wellknown music. When an examiner presented a tune, she could not name the tune, but indicated that she knew the tune by way of gestures and facial expression with paraphasia. When an examiner played a single note or rhythmic pattern and asked her to reproduce it on a piano, she could reproduce the single note correctly, but had difficulty reproducing the rhythmic pattern. If a simple rhythmic pattern was presented, such as half or quarter notes, she reproduced it very well. However, she had difficulty reproducing a complicated rhythmic pattern that consisted of eighth notes or eighth-note rests. TT was able to identify minor and major chords immediately. When two notes were presented continuously, and TT was asked to identify whether the two notes were the same, she was able to identify them correctly up to a minor second. When she was asked to identify the meter of various melodies, she was unable to identify the meter correctly and sometimes counted triple time as quadruple time, using four fingers in order. Therefore, TT’s musical expression ability was good, as long as the piano was used. However, there was obvious impairment in TT’s musical perception, especially in her recognition of rhythm. TT’s musical abilities were examined using a standard musical test (Standard Diagnostic of Musical Ability for Junior-High School). This test includes six subtests: rhythm, melody, harmony, reading, instrument, and listening tests. Each subtest was evaluated using five scales. A score of three is the average score achieved by junior-high school students

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Table 1. The results of a standard musical test Subtests (details of subtest)

TT

Control (n ¼ 2)

Rhythm (discrimination of meter and rhythm, reading) Melody (discrimination of pitch, tonality, scale) Harmony (discrimination of harmony and accompaniment) Reading (reading melody, dictation) Instrument (discrimination of playing section and voice part) Listening (discrimination of chord changes and melody relation)

1

4.5

3

4.5

5

5.0

3

4.0

3

5.0

5

5.0

(Table 1). Comparing age-matched controls (the details are described later), her rhythm function disorder was apparent in this test.

Methods and results In order to clarify TT’s disturbances with respect to musical reading and writing ability, two age-matched control subjects (one was 59-years-old and the other was 60-years-old) participated in this study. Like the patient, the two control subjects were both female, both had graduated from music college, and both had taught piano in a private school for over thirty years.

Musical reading Reading single notes The subjects were presented with a single note and asked to name it. Material. Twelve notes on the treble clef and twelve notes on the bass clef were presented individually. Results. TT’s responses were 100% (12/12) correct for the treble clef and 83% (10/12) correct for the bass clef. Control subjects scored 100% correct in each task. Therefore, it appeared that although her ability to read notes was not perfect, it had been relatively well preserved. Reading musical signs The subjects were presented with a musical sign and asked to name it. Material. Twenty-four musical signs, including eighth notes and dynamic marks, were presented. Results. TT was completely unable to name the musical signs (0/24), because of word-finding difficulty and paraphasia. However, she was able to describe the meaning of some of the signs. For example, when an eighth note was presented, she answered ‘‘half’’, indicating that this note was half the length of a quarter note, and when the letter ‘‘p’’ was presented, she answered, ‘‘softly’’, which is the correct meaning of this sign. When responses that correctly identified the meaning of the signs were considered to be correct answers,

Fig. 2. Examples of the reading material. The reading task included three types of material: (i) a neutral melody that included changing pitch and rhythm, (ii) a pitch domain that did not include changing rhythms, and (iii) a rhythm domain that did not include changing pitches.

she scored 63% (15/24) correct. The control subjects scored 100% correct. TT’s ability to read musical signs was severely disturbed; however, she could understand their meaning to a certain degree.

Reading unknown melodies I In order to evaluate her ability to read music without instrumental references, the examiner presented a tune using a piano and asked the subjects to choose the correct musical notation representing the tune, from four alternatives. This task included three types of material (Fig. 2): (i) a neutral melody that included changing pitch and rhythm, (ii) a pitch domain that did not include changing rhythm, and (iii) a rhythm domain that did not include changing pitch. Material. The neutral melody task included two types of melody: half consisted of a simple rhythm pattern including quarter and eighth notes, and half consisted of a complex rhythm pattern including dotted notes and sixteenth notes. In order to clarify the nature of her reading disturbance, separate pitch and rhythm domain tasks were designed. In order to minimize the effect of rhythm reading ability, the pitch domain task consisted of eight quarter notes. Conversely, in order to minimize the effect of pitch reading, the rhythm domain task consisted of two bars of several rhythm patterns without pitch changes. In each task, the subjects were presented with four alternatives simultaneously and asked to choose the correct one from the four alternatives, following presentation of the tune. Thirteen items were used for the neutral-melody task, and eight items each were used for the pitch- and rhythm-domain tasks. Results. TT was 62% (8/13) correct in melody reading, 100% (8/8) correct in pitch reading, and 50% (4/8) correct in rhythm reading, while the control subjects scored 100% correct in each task. Apparently, TT had difficulty reading rhythmic patterns. Reading unknown melodies II In order to evaluate sight-reading ability, the subjects were presented with three types of material, similar to those in the task above, i.e. (i) a neutral melody, (ii) a pitch domain, and (iii) a rhythm domain. They were asked to play these items on a piano.

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235

Fig. 3. Example of a musical reading error. The music on the left is the original music, and that on the right is what the patient played. She exhibited difficulty reading eighth notes and rests. She played a quarter note or quarter rest as an eighth note or eighth rest.

Material. In the neutral melody task, we used fourteen items, half of which contained a simple rhythmic pattern, such as quarter or eighth notes, and half of which contained a complex rhythmic pattern, such as dotted notes or sixteenth notes. Eight items were used for the pitch-reading task, and eight were used for the rhythm-reading task. The pitch domain task consisted of eight quarter notes only. The rhythm domain task consisted of two bars of several rhythm patterns without pitch changes. In each item, the subjects were given two attempts to play the music. Up to two trials were evaluated for correct performance by one (AM) of the authors. Results. TT was 50% (7/14) correct in the neutral melody task. She had particular difficulty reading eighth notes or eighth rests, and she played them as quarter notes or quarter rests. She was 100% (8/8) correct in pitch reading, but only 50% (4/8) correct in rhythm reading. She omitted rest notes and played eighth notes as quarter notes (Fig. 3). The control subjects scored 100% correct in each task. In this task, TT again showed a disability in reading rhythm. Reading a well-known melody I Without an instrument, the subjects were asked to read the music of a well-known melody that they had used as lesson material. Material. Mozart’s ‘‘Sonata in C Major, K. 545’’ was used as the reading material. The material was not a piano score, but was a single melody that was gleaned from the original score and was written using MIDI software. Result. TT was able to name each note as do, re, mi, etc. However, because she was unable to read the rhythm of the music, she was unable to identify the music, despite the fact that it was a familiar melody. When the examiner hummed the music, she immediately recognized it as familiar. Although she could not name the melody, she indicated by facial expression

and pantomime that she knew it. By contrast, the control subjects recognized the music within a few seconds. When the examiner asked them the reason for the delay they answered that in order to recognize the tune, solfe`ge was necessary.

Reading a well-known melody II The subjects were asked to read a well-known melody that they had used as lesson material without an instrument. Material. Mozart’s ‘‘Sonata in A Major, K. 331’’ was used as the reading material. The material was part of an original piano score. The title on the score was hidden. Result. As soon as the examiner presented the music, TT indicated by her facial expression that she was familiar with it. When the examiner made her use the piano, she played it with both hands from the music very well, including dotted notes and sixteenth notes. The control subjects also recognized the tune quickly and played it very well. In this task, TT did not exhibit difficulty in reading the music, including rhythm elements.

Writing music Writing single notes The subjects were given the name of a note and were asked to write it on the staff. Material. Twelve notes on the treble clef and twelve on the bass clef were used. Results. TT was 83% (10/12) correct on the treble clef and 92% (11/12) correct on the bass clef. The control subjects were 100% correct. In this task, her ability to write notes was partially preserved. Writing a well-known melody The subjects were asked to write a well-known melody on the staff.

Fig. 4. The results of music writing. TT was asked to write a well-known nursery melody. Above is the original music, and below is what TT wrote. She was unable to write the melody, except for the first two notes.

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Table 2. The results of musical reading and writing tasks Subtests Reading

Musical Notes Musical Signs Unknown Melody I Unknown Melody II

Material

Score of patient TT

Score of control group

Treble clef Bass clef (Naming) (Meaning) Melody Pitch Rhythm Melody Pitch Rhythm

100% 83% 0% 63% 62% 100% 50% 50% 100% 50% Impossible Possible

(12/12) (10/12) (0/24) (15/24) (8/13) (8/8) (4/8) (7/14) (8/8) (4/8)

100% 100% 100% – 100% 100% 100% 100% 100% 100% Possible Possible

(10/12) (11/12) (0/4) (6/8)

100% 100% 100% 100%

Well-known Melody I Well-known Melody II Writing

Musical Notes Well-known Melody Copying

Treble clef Bass clef

83% 92% 0% 75%

 Control subjects were not required to describe the meaning of the musical signs.  Estimation of correct writing was based on each bar.

Material. They were asked to write a well-known Japanese nursery melody ‘‘Takibi’’ (The Fire: lyrics by S. Tatsumi, melody by S. Watanabe), which was familiar to them. Result. TT was unable to write the melody, except for the first two notes (Fig. 4), while the control subjects could write the melody without reference.

Copying music The subjects were asked to copy music that was unfamiliar to them. Material. An eight-bar melody that included dotted notes and sixteenth notes was used as the test material. Result. TT was able to write the melody in this copying task better than in the task that involved writing from memory. However, pitch errors and rhythm errors were apparent; she scored 75% (6/8) correct. The control subjects scored 100% correct.

Discussion In this study, we describe a case of musical alexia and musical agraphia that followed Wernicke’s aphasia. When the melody was divided into rhythm elements and pitch elements, patient TT’s pitch reading was well preserved, but her rhythm reading was severely disturbed. Her reading disturbance was especially apparent for notes that indicate a short time period (e.g. eighth notes), irregular notes (e.g. dotted notes), and short rests (e.g. eighth rests). In contrast, she performed very well at reading a familiar piano score that included eighth and dotted notes, although her ability to read familiar music from a nonpiano score was disturbed. The reported cases of musical alexia can be divided into the following three types: those in which the ability to read single notes was disturbed (Cappelletti et al., 2000); those in which

the ability to read pitch elements was more disturbed than the ability to read rhythm elements (Brust, 1980 [Case 1]; Judd et al., 1983; Horikoshi et al., 1997; Kawamura et al., 2000); and those with complex disturbances that included pitch reading difficulty and rhythm reading difficulty (Brust, 1980 [Case 2]). The first type of musical alexia was combined with musical agraphia, and disturbance was apparent, even for single notes. Therefore, the first type is thought to be a disturbance in understanding the meaning of a note. Reported cases of the second type are accompanied by alexia with agraphia for language as well as musical agraphia; it is therefore thought that the background of the second type may be analogous to that of alexia with agraphia for language. The mechanism of the last type remains unclear. Our patient was unable to name musical signs because of a severe word-finding difficulty, but she was able to name a note and state the meaning of signs. Therefore, we believe that her knowledge of the meaning of notes, including rhythm elements, was preserved. When presented with unfamiliar music, she was able to name the pitch of the notes as do, re, mi, etc., and she was able to strike the right key on the piano. However, she was unable to sing or play a rhythmic melody or rhythmic pattern. Therefore, we believe that our patient differs from the types reported above and represents a case of alexia for rhythm, which reveals independence between the processes of pitch reading and rhythm reading. In the tasks reading a well-known melody I and II, our patient also exhibited another interesting feature. She was able to read music when the music was copied from an original piano score and appeared familiar to her, but she was unable to read music when the notation appeared unfamiliar to her, even though she knew the melody very well. This discrepancy implies that the allocation of notes, i.e. the appearance of notation, mediates a particular tune, and is important in reading music. The control subjects supported

Musical alexia for rhythm notation

this phenomenon. When reading familiar notation, they said that solfe`ge was not required because the notation, as a whole, mediated a particular tune, like a picture. When reading unfamiliar notation, however, in order to understand the tune, even a familiar tune, solfe`ge was required. In our case, this process might be disturbed. Moreover, Kawamura et al. (2000) presented a case of musical alexia, due to left angular infarction, in which the subject misread a trombone part of Elgar’s ‘‘Pomp and Circumstance’’ as a trombone part of Brahms’ ‘‘Hungarian Dances’’, because these two pieces of music happen to be similar in appearance. Therefore, it is thought that the appearance of notation is important in music reading. There have been many cases in which musical reading and writing ability has been preserved, despite the development of Wernicke’s aphasia, (Luria et al., 1965; Assal, 1973; Signoret et al., 1983), similar to that of our patient. In contrast to our patient, however, these other patients were composers or experts in reading and writing music. Our patient’s premorbid ability was limited to teaching piano. Therefore, a subject’s premorbid level of proficiency might be an important factor to consider when exploring such functions. Another feature of our case was that her rhythm performance was well preserved, despite severe disturbances in the reading, writing, and discrimination of rhythm. Polk and Kertesz (1993) reported two cases of rhythm disturbance. One case, with atrophy of the left hemisphere, showed wellpreserved rhythm performance despite disturbances in shortterm rhythm retention. Another case, with atrophy of the right hemisphere, showed severely disturbed rhythm performance with preserved short-term rhythm retention. In experimental psychology, it has been demonstrated that the process of retaining a rhythm pattern, especially when the rhythm was on the beat, is akin to the process of verbal short-term memory (Saito and Ishio, 1998). A similar pattern of difference has been reported in a functional imaging study (Sakai et al., 1999). Thus, it is thought that the short-term retention of rhythm might be related to the left hemisphere, while the performance process of rhythm might be related to the right hemisphere. We believe that such differences between these processes are related to the deficits in our patient. With respect to reading and writing music, Brust (1980), Mavlov (1980) and Scho¨ n et al. (2001) have reported cases similar to the case presented here, of musical alexia with rhythm reading disturbances. All of these cases were instances of conduction aphasia. One of the features of conduction aphasia is the presence of a repetition disturbance, which also occurs in Wernicke’s aphasia (Alexander, 1997). Our patient also had a repetition disturbance. Therefore, the retention of rhythm, and the retention of verbal material, may have a common neural basis, which may be significant with respect to reading rhythm notation. Our patient had complicated disturbances of reading and writing pitch. In relation to the study of short-term retention of pitch (Siegel, 1974), we believe, by analogy, that there are distinct systems for pitch-reading processes. For example,

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one of these systems is the naming system, which is a consequence of associated learning. When this system is preserved, it is possible to name notes, i.e. do, re, mi. The second system is a procedural system, which is a consequence of keyboard learning. When this system is preserved, it is possible to tap the keys representing the pitch of a note. The third system is the sense of pitch system. When this system is preserved, it is possible to hum a note with adequate pitch. In the test session, the patient could name a note, which indicates that the first system had been preserved. She could also play a piano using pitch domain music, which indicates that her second system had also been preserved. However, her singing was monotonous, despite the fact that she could name the notes, which indicates that her sense of pitch might have been disturbed. It was thought, therefore, that the patient’s deficit consisted of the inability to imagine the correct pitch of a note from the notation, and that this deficit was bidirectional. In other words, not only could she not imagine the pitch from the notation, but also, she could not transcribe a note from its pitch. Therefore, with regard to the writing of music, her sense of pitch might have affected her writing disturbances.

Acknowledgement This work was supported by Grants-in-Aids for Scientific Research (13680881) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

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Sakai K, Hikosako O, Miyauchi S, Takino R, Tamada T, Iwata NK et al. Neural representation of a rhythm depends on its interval ratio. The Journal of Neuroscience 1999; 19: 10074–81. Scho¨ n D, Semenza C, Denes G. Naming of musical notes: a selective deficit in one musical clef. Cortex 2001; 37: 407–21. Siegel JA. Sensory and verbal coding strategies in subjects with absolute pitch. Journal of Experimental Psychology 1974; 103: 37–44. Signoret JL, Van Eeckhout Ph, Poncet M, Castaigne P. Aphasia without amusia in a blind organist and composer. Verbal alexia and agraphia without musical alexia and agraphia in Braille. Revue Neurologique (Paris) 1983; 143: 172–81. Standard Diagnostic of Musical Ability for Junior-High School. Tokyo: Bunka-kagaku-sya, 1962. Wertheim N. The amusias. In: Vinken PJ, Bruyn GW, editors. Handbook of clinical neurology, vol. 4. Disorders of speech perception and symbolic behavior. Amsterdam: North Holland, 1969: 195–206.

Received on 14 March, 2002; resubmitted on 7 November, 2002; accepted on 19 November, 2002

Musical alexia for rhythm notation: a discrepancy between pitch and rhythm A. Midorikawa, M. Kawamura and M. Kezuka Abstract In the process of reading music, the reading of rhythm and pitch might be differentiated, although there is no evidence of this to date. There have been cases of disorders restricted to the reading of pitch, but none in which the disorder has been restricted to the reading of rhythm. We present a case of musical alexia and agraphia with Wernicke’s aphasia. An in-depth assessment of the subject’s musical reading ability showed that her musical alexia was restricted to unfamiliar melodies. When a melody was divided into rhythm elements and pitch elements, pitch reading was preserved, but rhythm reading was severely disturbed. This is the first case reported of a disorder restricted to rhythm reading, and suggests the independence of rhythm reading and pitch reading.

Journal Neurocase 2003; 9: 232–238

Neurocase Reference Number: NC515/02

Primary diagnosis of interest Musical alexia

Author’s designation of case TT

Key theoretical issue * Dissociation between pitch and rhythm in musical reading

Key words: amusia; musical alexia; musical agraphia; rhythm

Scan, EEG and related measures Magnetic resonance images

Standardized assessment WAIS-R, Western Aphasia Battery, Raven Colored Progressive Matrices, Standard Diagnostic of Musical Ability

Other assessment Musical reading, writing music, copying music

Lesion location * From the left superior temporal gyrus to the angular gyrus in Wernicke’s area

Lesion type Cerebral infarction

Language English