Roberto is 52 years old. He is a dentist and owns a dental clinic. Although, what he really loves is music. He has had a rock group since he was 18 and, apart from rehearsing frequently, they give concerts from time to time. They like to version the Beatles and the Doors. They also have their own songs. However, since Roberto suffered a stroke he has had to leave his musical group. Roberto can move his fingers, he can even take a guitar. In appearance, Roberto leads a functional life, but ... is unable to perceive music. Roberto suffers from amusia.
Music involves a human activity that requires the interaction of different mental processes. It is a complex mental process. For example, to produce music, a correct temporal skill is required for actions that are organized hierarchically. On the other hand, this motor behavior of playing an instrument must interact correctly and accurately with the auditory system. In this way, through the auditory system, the motor orders that are sent to the muscles responsible for playing an instrument can be readjusted.
As you can see, music perception and production is a more complex process than it may seem. Throughout the article both musical perception and the concept of amusia will be addressed. Let's get started!
- 1 Musical perception
- 2 Amusia, what does it consist of?
- 3 Congenital and acquired Amusia
The recognition of music encompasses two modalities. On the one hand, the recognition of the melody and on the other, the temporal component of music. The tempo and variations of the timbre also help in musical recognition, but its importance is less. The identification of a song is based on the "recognition of the correct alternation of the tones at a relative distance between them, which allows discriminating between the most acute and the most serious " (Barquero and Payno, 2007).
As Barquero and Payno (2007) state: "a change in the rate of emission, in the timbre of the instrument or in the rhythm does not produce a significant distortion in the recognition of the piece; an error in the sequence of the tones will be recognized as strange to the score and, if it is quite important, it may prevent its identification ". On the other hand, the tones, rather than being perceived individually, are perceived as grouping units, as a word composed of the grouping of different sounds.
In various studies that have been carried out to study tone discrimination, they have found the activation of the right ventrolateral frontal cortex. However, if what is intended is discrimination between silences and sounds, the same area is activated but bilaterally. On the other hand, the activation of the temporal cortex would be related to the storage of the tones, while the activation of the frontal cortex would be related to activities of working memory.
Amusia, what does it consist of?
Amusia is a concept that designates the failure that occurs in the correct decoding of musical information. It consists of alterations in the performance, perception, writing and musical reading as a result of acquired brain damage, although they do not have to occur all of them at the same time. These alterations are not explained by problems in hearing, or by mental retardation, nor by the lack of exposure to music. Patients suffering from amusia fail in tasks that require discrimination and recognition of music.
The alteration in the proper decoding of the musical information is a consequence of a primary failure in perception and those who suffer from it show an inability to distinguish between different musical components. This type of amusia is called aperceptive amusia and can be seen in lesions in the right hemisphere, specifically, in the superior temporal gyrus.
Another type of friendship is that those who suffer from it they can discriminate the different components of a melody but they cannot recognize the melody itself. It consists of a specific memory alteration for music. This type of amusia occurs because of bilateral lesions that affects the two temporal lobes. In the right hemisphere there is learning and retention of new melodies, but for the recognition of these once learned, activation of the left hemisphere is necessary.
Congenital and acquired amusia
Congenital amusia was studied from deaf subjects for a tone. Ayotte's team (2002), stressed that Congenital amusia is a sensory agnosia, in which the perception of music is abnormal even though hearing and cognition are conserved. The acquired friendship occurs during our life, and may be due to a problem at the cortical level or at the level of the afferent auditory pathway. Some patients who have suffered a stroke or those who have had a cochlear implant have been able to generate amusia.
Ayotte, J., Peretz, I. and Hyde K. (2002). Congenital amusia: a group study od adults afflicted with a music-specific disorder. Brain, 125 (2), 238-251.
Peña-Casanova, J. (2007). Behavioral neurology and neuropsychology. Madrid: Pan American Medical Editorial.