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Music agnosia, an auditory agnosia, is a syndrome of selective impairment in music recognition. Three cases of music agnosia are examined by Dalla Bella and Peretz (1999); C.N., G.L., and I.R.. All three of these patients suffered bilateral damage to the auditory cortex which resulted in musical difficulties while speech understanding remained intact. Their impairment is specific to the recognition of once familiar melodies. They are spared in recognizing environmental sounds and in recognizing lyrics. Peretz (1996) has studied C.N.'s music agnosia further and reports an initial impairment of pitch processing and spared temporal processing. C.N. later recovered in pitch processing abilities but remained impaired in tune recognition and familiarity judgments.
The term "agnosia" refers to a loss of knowledge. Acquired music agnosia is the "inability to recognize music in the absence of sensory, intellectual, verbal, and mnesic impairments". Music agnosia is most commonly acquired; in most cases it is a result of bilateral infarction of the right temporal lobes. In his article, Satoh states "when pure word deafness, auditory sound agnosia, and receptive amusia occur simultaneously, the state is called auditory agnosia" (Satoh 2007). However, one must understand the subtle difference between auditory and music agnosia; the former refers to the inability to recognize environmental sounds while the latter refers to the inability to recognize music.
Musical agnosias may be categorized based on the process which is impaired in the individual.
- Apperceptive music agnosia involves an impairment at the level of perceptual analysis involving an inability to encode musical information correctly.
- Associative music agnosia reflects an impaired representational system which disrupts music recognition.
The main symptoms of music agnosia range from the inability to recognize pitch, rhythm, chords, and notes to the inability to discriminate and recognize familiar songs, and judge tonality, and reproduce musical phrases.
Many of the cases of music agnosia have resulted from surgery involving the middle cerebral artery. Patient studies have surmounted a large amount of evidence demonstrating that the left side of the brain is more suitable for holding long-term memory representations of music and that the right side is important for controlling access to these representations. Associative music agnosias tend to be produced by damage to the left hemisphere, while apperceptive music agnosia reflects damage the to right hemisphere.
- ↑ (1999). Music agnosias: Selective impairments of music recognition after brain damage. Journal of New Music Research 28 (3): 209–216.
- ↑ (1996). Can we lose memory for music? A case of music agnosia in a nonmusician. Journal of Cognitive Neuroscience 8 (6): 481–496.
- ↑ Peretz I, Can we lose memory for music? A case of music agnosia in a nonmusician (1996). J Cogn Neuroscience 8:481-96
- ↑ Satoh M. A case of auditory agnosia with impairment of perception and expression of music: cognitive processing of tonality (2007) European Neurology 58(2) 70-77
- ↑ Vignolo L. Music agnosia and auditory agnosia (2003) Annals of the New York Academy of Sciences 999:50-57
- ↑ (2000). Patterns of music agnosia associated with middle cerebral artery infarcts. Brain 123: 1926–1938.