Definition

Amusia: Amusia refers to a number of disorders which are indicated by the inability to recognize musical tones or rhythms or to reproduce them. Amusia can be congenital (present at birth) or be acquired sometime later in life (as from brain damage). The term "amusia" is composed of a- + -musia which means the lack of music.

WNYC - Soundcheck: Falling On Tone-Deaf Ears? (October 18th, 2005)

"All About Amusia"

Lauren Stewart, a research fellow at University College in London and the University of Newcastle, talks about research into the misunderstood amusia.

Welcome To Amusia...

Steve Martin once said, "talking about music is like dancing about architecture." It is true that for most people, music is a subjective experience that defies description. However, some researchers are trying to do just that: quantify the musical experience in order to explain the rare disorder of amusia, a condition that is characterized by the inability to recognize music in the frequency and/or temporal dimension.

Amusia can be congenital or acquired through trauma to the brain. Until recently, amusia was not recognized as a disorder and warranted little research (Ayotte, Peretz, and Hyde, 2002). If a child was labeled as "tone-deaf" by a music teacher, the parents would probably just shrug it off and sign them up for T-ball instead. If a patient suffered a stroke, it would have been unlikely for the hospital staff to check for recognition of Beethoven's 5th along with vital signs.

The prevalence of congenital amusia is estimated to be about 5% in the United States (Hyde and Peretz, 2004). The prevalence of acquired amusia is trickier to report because of the variability of the symptoms, the unlikelihood that it would be noticed in an acute hospital setting and the ability for those afflicted to recover at any given time (Schuppert et al.).

Music is everywhere and is often taken for granted. What happens to the person who does not have this gift? Why does it happen? Is there a way to get it back? Do those who buy Britney Spears albums have collective amusia? Researchers are now beginning to scratch the surface of this lesser-known disorder.

References

1. Hyde, KL and Peretz, I (2004). Brains That Are out of Tune but in Time. Psychological Science, 15, 356-360:
2. Ayotte, J., Peretz, I., & Hyde, K. (2002). Congenital amusia: a group study of adults afflicted with a music-specific disorder. Brain, 125, 238-251.
3. Schuppert, M., Munte, TF, Wieringa, BM, Altermuller (2000). Receptive amusia: evidence for cross-hemispheric neural networks underlying music processing strategies. Brain, 123, 546-559.

How Is Music Perceived By Someone With Amusia?

"Heard melodies are sweet, but those unheard are sweeter." - John Keats

Music is an important and influential aspect of the human experience. It is a cultural phenomenon and a powerful vehicle for the expression of emotion. Music has the power to bring people together in celebration, mourning and even the repetitions of everyday life. While there are many people on earth that may be indifferent to the presence of music in their own lives, for many it is a valued and appreciated art form.

While there is great variability among cases of amusia, the disorder is characterized by difficulty in perceiving music. With congenital amusia, music can sound like noise or banging. A person with amusia may not be able to recognize familiar tunes or tell the difference between two different tunes. The person may have difficulty judging the direction of pitch, unless the pitches are drastically different and it is suggested that pitch problems can also influence the development of rhythmic and timing abilities. Some people with amusia may avoid situations involving music at all costs while others with a comparable deficit may still find great pleasure in listening to music (Stewart, 2006).

Acquired amusia also differs drastically from case to case. Amusia often co-occurs with aphasia, resulting in impairments in speech and language as well. Amusia can occur in the absence of aphasia and in such cases, most often the site of the lesion is in the right hemisphere. People afflicted have reported hearing musical sounds as “out of tune,” their sense of rhythm being compromised, the loss of the ability to recognize sounds as musical and the sound of voices and music being monotonal (Brust, 2001).


References:

1. Brust, J.C.M. (2001). Music and the neurologist: A historical perspective.
Biological Foundations of Music. 930, 143-152.
2. Stewart, L. (2006). Congenital amusia. Current Biology. 16, R904-R906.

Oliver Sacks - Musicophilia - Amusia

Congenital and Acquired Amusia

"You have Van Gogh's ear for music." - Artemus Ward

Congenital and Acquired Amusia are the two main types of amusia.

Acquired Amusia is the loss of musical ability as a result of a traumatic event, such as an accident or disease. Clinical symptoms are much more variable than those of congenital amusia, and are determined by the location and nature of the lesion.

Acquired amusia often co-occurs with aphasia. Like aphasia, amusia can be categorized as receptive, expressive or mixed. Receptive amusia is sometimes referred to as ‘musical deafness’; symptoms include the inability to recognize familiar melodies or the loss of ability to read musical notation. Clinical symptoms of expressive amusia include the loss of ability to sing, write musical notation, and/or play an instrument (Bautista & Ciampetti, 2003). A mixed disorder would be a combination of expressive and receptive impairment.

Congenital amusia, commonly referred to as “tone deafness,” is a lifelong impairment in the perception and production of music. Research findings indicate impairment to be specific to the music domain. Likewise, there are no known effects upon prosody or the recognition of familiar voices or environmental sounds.

In general, people with congenital amusia have deficiency processing pitch variation. This is reflected in both receptive and expressive ability, and extends to the impairment of musical memory and recognition, as well as singing and the ability to tap in time to music. Latest research shows that there is a genetic component to congenital amusia, however, no specific genes have been identified (Peretz et al, 2007).

References:

1. Peretz, I., Cummings, S., Dube, M. (2007). The Genetics of Congenital Amusia (Tone Deafness): A Family-Aggregation Study. The American Journal of Human Genetics, 81, 582-588.
2. Bautista, R., Ciampetti, M. (2003). Expressive Aprosody and Amusia as a Manifestation of Right Hemisphere Seizures. Epilepsia, 44(3), 466-467.

Neural Overview

"Music is auditory cheesecake, an exquisite confection crafted to tickle the sensitive spots of at least six of our mental faculties." - Stephen Pinker

In many research studies of individuals with amusia, there appears to be a number of cortical regions that are involved in processing music. There is some agreement that the primary and secondary auditory cortices and the limbic system are responsible for the appreciation of music. However, recent studies have suggested that
lesions in other cortical areas, abnormality in cortical thickness and deficiency in neural connectivity and brain plasticity, may be other factors causing amusia. While various etiologies of amusia exist, here are some general findings that provide an insight to the brain mechanisms involved in music appreciation.

The right temporal gyrus plays an important role in computing components of frequency, or pitch relations. In particular, the right anterolateral part of Heschl’s gyrus (primary auditory cortex) is concerned with processing pitch information (Tramo et al. 2002). In addition, analysis of pitch change and manipulations of fine tunes are primarily accomplished by the right secondary auditory cortex (Zatorre & Berlin 2001). In melodic tunes, where multiple pitches are involved, the brain recruits contour (pitch directions) and interval (frequency ratios between successive notes) information from auditory input for analysis. It has been found that right superior temporal gyrus is involved in evaluating contour information, while both right and left temporal regions are involved for evaluating interval information (Ayotte, et al. 2000). These studies suggest the right temporal region as the basis for analyzing temporal components of music. Pitch relations also involve musical scales, which are sets of pitches. Because fundamental frequency of musical scale is unequally divided, processing of musical scale is beyond purely analyzing pitch contours and intervals. Although there is evidence to suggest that a specialized area for processing musical harmony and chords exists, the exact location remains undetermined. Listeners often assimilate to what is considered a harmony or chord by passively listening to music. Thus, it could be hypothesized that the ability to analyze harmony is not so much ‘innate’ (Bigand, 2003). Koelsch et al., suggests that through passive listening, children by age five, can recognize harmony to some degree. Given this evidence, congenital amusia may be attributed to the lack of brain plasticity in young children.

In terms of the temporal (rhythmic) relations, there are two components to be addressed: the ability for the brain to segment ongoing sequences of music into temporal events based on duration and to extract the basis of those temporal events to understand the underlying beat to music. In a rhythmic discrimination study performed on individuals with amusia, where they were asked to tap according to either grouping or individually segmenting temporal information, results revealed that the left temporal auditory cortex was responsible for temporal grouping and the right temporal auditory cortex was responsible for individually segmenting (Di Pietro et al, 2004, Wilson, et al, 2002). Thus, it can be hypothesized that one component of temporal relations to music could be spared in the existence of deficits in the other. Other studies have suggested that the cerebellum and basal ganglia may also be involved in processing and controlling perceptual timing (Janata & Grafton, 2003), as well as the participation of motor cortical areas in rhythm perception and production (Halsband, et al, 1993). Given these empirical data, the lack of involvement and networking between bilateral temporal cortices and neural motor centers may be contributing to both congenital and acquired amusia.

Memory is a pertinent aspect in studying the cause of amusia. Because musical events occur over time, a certain amount of memory is required in order to process both melodic and rhythmic aspects of music. The contribution of working memory is also crucial in order to integrate these components and to analyze them on-line. A lesion study, which focused on the working memory for pitch materials in individuals with amusia, has found involvement of the right auditory cortex and frontal cortical areas (Zatorre & Samson, 1991, Gaab, et al., 2003). In a neural imaging study, dorsolateral and inferior frontal areas were activated when working memory load for music was too high for the subject. Both studies suggest that there is a rich interconnection between right temporal gyrus and frontal cortical areas for working memory in music appreciation. Memory is also concerned with the recognition and internal representation of tunes, which helps to identify familiar songs and the ability to, sing a tune in your head. The general findings are that the recognition of a familiar tune is recruited by the activation of superior temporal region and left inferior temporal and frontal areas (Ayotte, et al. 2000), and the right auditory cortex is important for internal representation of tunes because imagery of music requires access to perceptual mechanisms (Zatorre & Halpern, 1993). Again, consolidation of these research findings suggests possible abnormality or lack of interconnectivity between a number of cortical regions in individuals with amusia.

Although the exact cause of amusia is still inconclusive, a number of promising findings reveal that lesions in and the absence of rich associations between the right temporal lobe and inferior frontal lobe, may cause an individual to inadequately process music. Continued research in the area of amusia has given rise to new theories that account for other possible causes of amusia. In particular, cortical thickness and reduced white matter have been suggested to cause this disorder, as well as the involvement of parahippocampal gyrus for emotional reaction to music. It is hoped that persistent dedication to amusia research will provide a more comprehensible idea as to the cause of amusia.

References

1. Ayotte, J., Peretz, I.,m Rousseau, I., Bard, C., Bojanowski, M. (2000). Patterns of music agnosia associated with middle cerebral artery infarcts. Brain. 123:1926-1938.
2. Bigand, E. (2003). More about the musical expertise of musically untrained listeners. Annual New York Academy of Science. 999:304-312.
3. Di Pietro, M., Laganaro, M., Leeman, B., Schnider, A. (2004). Receptive amusia: temporal auditory deficit in a processional musician following a left temporo-parietal lesion. Neuropsychologia. 42:868-977.
4. Gaab, N., Gaser, C., Zaehle, T., Jancke, L., Schlaug, G. (2003). Functional anatomy of pitch memory-an fMRI study with sparse temoral sampling. NeuroLmage. 19:1417-1426.
5.Halsband, U., Tanji, J. Feund, H.J. (1993). The role of premotor cortex and the supplementary motor area in the temporal control of movement in man. Brain. 116:243-246.
6. Janata, P., Grafton, S. (2003). Swinging in the brain: shared neural substrates for behaviors related to sequencing and music. Nat. Neuroscience. 6:682-687.
7. Koelsch, S., Grossmann, T., Gunter, T., Hahne, A., Schroger, E., Friederici, A.D. (2003) Children processing music: electric brain responses reveal musical competence and gender differences. Journal of Cognitive Neuroscience. 15:683-693.
8. Peretz, I., Zatorre, R. (2005). Brain Organization for Music Processing. Annual Review ofPsychology. 56: 89-114.
9. Tramo, M., Shah, G.D., Braida, L.D. (2002). Functional role of auditory cortex in frequency processing and pitch perception. Journal of Neurophysiology. 87:122-139.
10. Wilson, S.J., Pressing, J., Wales, R.J. (2002). Modeling rhythmic function in a musician post-stroke. Neuropsychologia. 40:1494-505.
11. Zatorre, R.J., Berlin, P. (2001). Spectral and temporal processing in human auditory cortex. Cerebral Cortex. 11:946-953.
12. Zatorre, R.J., Halpern, R. (1993). Effect of unilateral temporal-lobe excision on percention and imagery of songs. Neuropsychologia. 31:221-32.
13. Zatorre, R.J., Samson, S. (1991) Role of the right temporal neocortex in retention of pitch in auditory short-term memory. Brain. 114:2403-2417.

Global and Local Levels of Music Processing

"Discord: not to be confused with Datcord." - Anonymous

When music is perceived, the brain processes both local information as well as global information. Local information includes identifying specific intervals between pitches and discriminating durational values of sounds. Global information, on the other hand, includes identifying the overall melody and meter of a song. (Peretz and Morais, 1993; Peretz, 1990; Andrade and Bhattacharya, 2003). Researchers have found that healthy non-musicians show auditory activation patterns in the right frontotemporal cortex, whereas professional musicians showed activation in not only this same right hemispheric region but also in the left-hemispheric auditory areas. This lateralization to the left hemisphere in musicians was ascribed to the fact that musical training leads to enhanced perceptual processing of local information, which is predominately based in the left hemisphere (Schuppert et al, 2000). In patients with left-hemispheric lesions, local interval processing has been known to be disordered but global contour perception usually remains intact. In patients with right-hemisphere damage, however, both the local and global processing strategies may be disordered. (Peretz, 1990; Liegeois-Chauvel et al., 1998; Andrade and Bhattacharya, 2003). This finding suggests that global processing of melody is a prerequisite for the decoding of local pitch interval discrimination and can be thought of as a “two-stage processing cascade” (Dowling and Bartlett, 1981; Dowling, 1982; Peretz, 1993; Peretz et al 2002).

Although current studies support evidence for the location of local and global frequency information processing, there is still disagreement about the hierarchical organization of temporal information processing. While some researchers report that the overall meter of a song must be processed initially before local rhythm recognition occurs (Povel and Essens, 1985), others have found that the global and local processing occur separately (Lerdahl and Jackendoff, 1983; Peretz, 1990; Liegeois-Chauvel et al., 1998). The latter view has been supported by reports of patients having similar deficits in temporal perception regardless of the hemisphere of damage, as well as similar local rhythm and global meter deficits occurring in patients following lesions in either hemisphere (Mavlov, 1980; Fries and Swihart, 1990; Peretz, 1990; Peretz et al., 1994). Researchers are now studying possible underlying neural substrates that may cause cross-hemispheric local and global musical information processing (Schuppert et al, 2000).


References

1. Andrade, P, Bhattacharya, J. Brain Tuned to Music. Journal of the Royal Society of Medicine 2003; 96: 284-287
2. Dowling WJ. Melodic information processing and its development. In: Deutsch D, editor. The psychology of music. New York: Academic Press; 1982. p. 413–29.
3. Peretz I, Morais J. Analytic processing in the classification of melodies as same or different. Neuropsychologia 1987; 25: 645–52.
4. Peretz I, Morais J. Specificity for music. In: Boller F, Grafman J, editors. Handbook of neuropsychology, Vol. 8. Amsterdam: Elsevier; 1993. p. 373–90.
5. Peretz I. Processing of local and global musical information by unilateral brain-damaged patients. Brain 1990; 113: 1185–205.
6. Schuppert M, Munte T, Wieringa B, Altenmuller E. Receptive amusia: evidence for cross-hemispheric neural networks underlying music processing strategies. Brain 2000; 123: 546-559.
7. Liégeois-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.
8. Dowling WJ, Bartlett JC. The importance of interval information in long-term memory for melodies. Psychomusicology 1981; 1: 30–49.
9. Povel DJ, Essens P. Perception of temporal patterns. Music Percept 1985; 2: 411–440.
10. Lerdahl F, Jackendoff R. A generative theory of tonal music. Cambridge (MA): MIT Press; 1983.
11. Mavlov L. Amusia due to rhythm agnosia in a musician with left hemisphere damage: a non-auditory supramodal defect. Cortex 1980; 16: 331–8.
12. Fries W, Swihart AA. Disturbance of rhythm sense following right hemisphere damage. Neuropsychologia 1990; 28: 1317–23.

Emerging Evidence

1. In 2007, a research study of amusic vs. control families showed that 39% of first-degree relatives of the amusic families had the disorder, whereas only 3% had amusia in control families. For further information refer to, "The Genetics of Congenital Amusia (Tone Deafness): A Family-Aggregation Study" by Peretz, Cummings and Dube.

http://download.ajhg.org/AJHG/pdf/PIIS0002929707613548.pdf

2. Krysta L. Hyde, et al. (2007) Cortical thickness in congenital amusia: When less is better than more.

The study reveals that amusia subjects have thicker cortices, with reduced white matter in the right inferior fontal gyrus and the right auditory cortex compared to those who are musically intact. This finding suggests that the presence of cortical malformations have compromised the normal development of the right fronto-temporal pathway and the importance of neural interconnectivity in the appreciation of music.

3. Gosselin, N. et al. (2006) Emotional responses to unpleasant music correlate with damage to parahippocampal cortex.

In order to detect whether emotional reaction to music correlates to a particular brain structure, this paper investigates the role of the parahippocampal gyrus by presenting ‘pleasant’ and ‘unpleasant’ music to patients with medial temporal lobe lesions and matched controls. Results reveal that patients with lesions on the left or right parahippocampal cortex provide atypical judgments to dissonant (unpleasant) music by giving it a slightly pleasant result, while the control group responded to 'pleasant' music as happy and 'unpleasant' music as dissonant.

4. Douglas, KM ande Bilkey, DK (2007). Amusia is associated with deficits in spatial processing. Nature Neuroscience, 10, 915-921.

This article reports that amusia is strongly related to spatial processing deficits in adults. The study indicates that processing pitch in music depends on cognitive mechanisms that are also involved with processing spatial representations in other modalities.

More Emerging Evidence...

Many questions remain in the field of amusia, and it can be challenging to make a correct diagnosis. This is due to the lack of gold standard research, formal diagnostic measures and public awareness. Isabelle Peretz of the University of Montreal has dedicated her laboratory to music and the brain. In 2003, the laboratory created a reliable and valid measure of amusia, called the Montreal Battery of Evaluation of Amusia. This test has 6 musical components, referred to as contour, interval, scale, rhythm, meter and memory tests. Since this test was published, Peretz has received frequent press and consequentially public awareness has increased. Hopefully increased public awareness will promote further research and interest in the field of amusia, and eventually lead to effective treatment of the disorder.

Refer to link to Peretz's Labarotory in upper right corner.