Brain Organization for Music Processing Review

Review: By Janet Spring
Peretz, I., Zatorre, R. (2005). Brain Organization for Music Processing, Annual Review of Psychology Research Library (56): 89 – 114.

In the article of Peretz and Zatorre (2005), they remark that as the enjoyment and participation in music is a human phenomenon and inherent in all cultures, it is therefore a valuable medium that researchers can employ to study how the brain operates and how music is processed, or how the brain can “reveal the inner workings of music processing” (p. 90). This research review by the authors therefore outlines how the inner workings of the brain have been studied through neuro-imaging and lesion studies and how important musical features such as pitch, rhythm, melody, memory, and emotion can be examined and deciphered. They also discuss evidence related to performing and the training of musicians and how these areas may be studied to obtain a better picture of how the brain functions. Functioning of the brain in a musician versus a non musician is also discussed. The authors conclude with suggestions about the needs for further research and in what direction it should be going. Consequently, it is a valuable paper that provides researchers, musicians and/or students of psychology who wish to link music with brain processes, a comprehensive snapshot into the relation of the two.

The authors begin with the premise that there is a distinct difference between neural networks in relation to music and language, and then discuss how melodic and temporal data are processed with two separate neural systems. Pitch is computed through the right temporal neocortex which determines pitch variation and the relation of one pitch to another. This discovery was performed through the investigation of brain damaged patients where melodic processing was repressed, yet the perception of intervals and melodic contour was not necessarily flawed. The evidence points to the fact that there must be neural networks that are specific to “processing of scale structure in melodies… [yet their] “localization remains to be determined (p. 93). In terms of harmony and dissonance, the authors discuss similar lesion studies that show that dissonance is computed in the temporal gyri by “specialized mechanisms” (p. 94) that are yet to be determined and that harmonic “expectancies” (p. 93) are processed in the inferior frontal regions of the brain. They complete the discussion of pitch with the query, “what stage in auditory processing the computation of the perceptual attribute of dissonance is critical to the perceptual organization of music” (p. 94)?

Lesion studies have shown that when a patient suffered brain damage in the form of lesions on the right temporal cortex, they were unable to tap or clap a steady beat or pulse. However, they were able to tap an irregular short sequence. Neuro-imaging data points to the fact that regular and irregular rhythmic patterns are therefore computed in different areas. The authors conclude that rhythm perception and playing involves the motor cortical areas; the supplementary motor area, premotor cortex and the parietal cortex. (p. 95). Other studies conclude that “a supramodal cerebellar timing system is involved in processing temporally organized events” (p. 95).

The study of memory related to brain processing functions provides researchers with interesting data due to the fact that “music unfolds over time” (p. 95). The authors relate; in terms of maintaining pitch information as compared to speech information, there is evidence that the retention of both is not decoded by the same systems in the brain. Lesion studies point to the fact that the auditory cortex, particularly the frontal cortical and posterior temporal areas are responsible for working memory. Research studies also demonstrate that when there is bilateral damage to the auditory cortex, speech phrases may be recalled, yet when music does not contain lyrics, it is difficult for patients to remember melodies. Patients, who suffered damage in the form of lesions in the medial temporal regions, were unable to remember melodies successfully, and particularly with right sided lesions, the retention of melodies was almost impossible. It has also been found that patients who suffer brain damage can sometimes recognize familiar vocal melodies, yet cannot always recognize familiar instrumental melodies. The secondary auditory cortices are also involved in the rehearsal of melodies and musical imagery (p. 98). In short, the study of memory and how the brain retains information over a period of time can be studied effectively in terms of listening to music, vocal as well as instrumental.

Listening to and performing music evokes different emotions, making music again an important medium to study to find the relationships between music, emotion and the brain. Studies have found that “emotional expression is neurally isolable: (p. 98), and when the human brain has suffered damage, the listener can recognize certain emotions that the music represents, yet cannot identify certain elements within that music. Peretz and Zatorre (2005) therefore relate that music is “cortically mediated” where there is “no direct access to subcortical, limbic structures” (p. 98). Studies that examined the “chill effect” people experience while listening to certain passages of music, found that the following parts of the brain were stimulated: the dorsal midbrain, ventral striatum, insula and the orbitofrontal cortex. The authors also state that these particular parts of the brain are also stimulated by certain drugs or foods that manufacture a “chilling effect”. However, does music play a special role in this area? The authors therefore suggest that further studies will lead to additional information on the “interactions between neocortically mediated cognitive processes and subcortically mediated affective responses” (p. 99).

In the case of musical performance, it is interesting to note that studies have found that people who have suffered brain damage can sometimes sing, yet cannot speak, which proves that an association does not exist between singing and speaking. Also the same holds true for pitch and rhythm where a person may be able to reproduce a group of tones, but cannot reproduce the rhythm associated with the melody. Two independent systems are involved, where the left hemisphere is related to rhythm and the right with melody. Brain lesions in these areas have demonstrated this. In terms of playing performance, the authors relate that more study needs to be completed in this area, for instrumental performance linked to the brain is more difficult to research, due to the fact that few patients with brain damage are able to participate effectively in this area of inquiry.

In the skill of sight reading, brain damage does not always negatively affect the ability to sight read, yet does affect the ability to read words. Therefore a musician may still be able to read music by sight but will not have the ability to read the words associated with the music. Some patients however, struggle to discern certain pitches in relation to another. Studies also prove that pitch and time relations are not connected to reading musical notation as is the same in singing and perception of certain musical ideas. Further study must therefore continue to research the dissociation of certain musical skills from others.

The final category of musical training is one that further research is needed to determine how the degree of expertise in a particular instrument or musical skill impacts the brain. The authors premise that it would be expected that a musician’s brain with extensive musical expertise would in fact have some difference in the motor cortex, the cerebellum and corpus callosum. Some variations have been noted, particularly in regard to string players, where “the cortical reorganization of the representation of the fingers is more pronounced” (p. 102). Other studies, such as (Pantev et al. 2003) note a “use-dependent plasticity phenomenon” (p. 102), for musicians demonstrate that tones related to their individual instruments were more readily pronounced. More research however, is needed to discover“whether the observed brain differences between musicians and non musicians arise from genetic or other predispositions (or talent) as well as from practice and experience” (p. 103). The phenomenon of absolute pitch is another area where further study is needed longitudinally to investigate plasticity and the development of the musician’s brain.

Reflection:

This article has answered a few questions that have intrigued me for a while. Firstly, I have always been interested in the fact that an Alzheimer’s patient that I knew in the past was able to sit at the piano and perform at a local senior citizens’ home with proficiency, provide residents with a solo concert, yet when asked to identify family members, dress herself and/or perform simple tasks, she was unable to do so. She could not at this point in time read a book, magazine; anything that had to do with text. As a musician, this patient demonstrated the dissociation of text and music but was able to maintain pitch and rhythm information. Is this an example that the retention of both is not decoded by the same systems in the brain? As I have not had the opportunity to delve into the topic of Alzheimers, music and the brain, I would be interested to find the answer.

A second question that comes to light is that two teachers that I have team-taught with in past years can effectively play a rhythm, and of course beat a steady pulse, assisting my percussion section with their assigned tasks, yet when asked to tone match and/or sing a familiar tune with the proper pitch, they are unable to do so. Despite their attendance at extra classes such as “raise your voice”, when I work with students who cannot tone match but sing with a monotone drone, they still could not sing, lesson after lesson. What is going on in their brains where they are able to understand and perform basic rhythmic tasks, yet their melodic and tone matching skills are almost nil? What can we learn from studies that focus on tone matching and the brain to effect change in those few students who have difficulties singing in the choir?

Another interesting observation is that, where there was bilateral damage to the auditory cortex, patients could remember lyrics if they were associated with a melody. Perhaps we can use this to our advantage in the literacy classroom. Students who have difficulties remembering important and frequently used sight words, would perhaps develop better spelling recall skills if text were set to music. In other words, students learn language through music. What a novel idea, that can be forgotten or dismissed in the literacy classroom today!