Nature Reviews Neuroscience, 2007, vol 8, no. 7, p 547 - 558
Zatorre, Robert J., Chen, Joyce L., and Penhyne, Virginia B. “When the brain plays music: auditory-motor interactions in music perception and production”
Zatorre et al are reviewing and discussing 175 studies or pieces of literature which relate to music – studies pertaining to hearing, timing, sequencing, motor responses, mirror neurons, auditory cortex activity, and particularly any studies that could link musical activity to motor activity. Taken together, they discuss how these studies demonstrate the existence of interactions between the motor and auditory systems of the brain during listening to music, or performing music. They identify three basic motor control functions that are required during a musical performance: timing, sequencing, and spatial organization of movement (p 547). They are aware of many studies which examine these functions separately, and note that “the study of music production requires these systems to be studied in an integrated fashion, thus making it both a challenging and fruitful model system for research into sensory-motor integration” (p 547). Pitch and rhythm activation in the brain has also been studied separately, and scientists have found that the brain can operate separately in each of these two domains.
Zatorre et al note, “neuropsychological and neuroimaging studies have shown that the motor regions of the brain contribute to both perception and production of rhythms … the concept that is emerging from this literature is that the analysis of rhythm may depend to a large extent on interactions between the auditory and motor systems” (p 550). They hypothesize, “the dorsal auditory cortical pathway (which streams from the primary auditory cortex) is relevant for spatial processing, and tracks time-varying events. Therefore, a link to motor systems would make sense, as movements occur in time as well as in space” (p 549).
Zatorre et al cite studies that have found activation in the premotor cortex region (PMC) during listening to music by musicians and by non-musicians, and conclude, “these findings demonstrate that auditory-motor interactions can be elicited in non-musicians spontaneously, or more specifically when there is a direct learned mapping between movement and sound” (p 551). Studies that manipulate feedforward (auditory system influencing the motor output) , and feedback (auditory system responding to motor performance) interactions between the auditory and motor systems suggest that not two, but one “single underlying mental representation” governs this interaction. The authors “propose that the circuitry linking auditory systems to motor systems may be the neural substrate of this cognitive representation” (p 550).
Studies using magnetoencephalography (MEG) and transcranial magnetic stimulation (TMS) “support the notion that the auditory and motor systems are tightly coupled in general, and more so in trained musicians than in untrained people” (p 552). The authors include neuroimaging studies that have detected activity in the supplementary motor area (SMA) and premotor areas when both musicians imagine performing (musical imagery), and when non-musicians imagine listening to music, and recognize “the tight coupling between auditory cortices and the portions of the premotor and supplementary motor system” (p 552).
As a musician, it is no surprise to me that neurological evidence supports a connection between music and movement. Without movement, music would only exist in the imagination. What surprises me, however, is the evidence of SMA and premotor activity observed in non-musicians’ brains as they imagine hearing musical excerpts. Since they do not consciously associate music with performance (movement), why would this area be activated?
The strongest argument to explain this auditory / motor connection would be evolutionary development. Levitin (crediting Miller) claims, “under the conditions that would have existed throughout most of our evolutionary history … music and dance were completely intertwined” (2006, 252). Using Levitin as a reference for considering that evolutionary lag is a minimum of 50,000 years, and based on Zatorre’s findings, it is safe to say that all contemporary humans possess a hard-wired tendency to connect music and movement. If (quoting Levitin again), “the archaeological record shows an uninterrupted record of music making everywhere we find humans, and in every era” (2006, p 256), then there should be a strong connection between movement and music in our brains. Our brains’ adaptations are suited for necessitating movement when we hear music. We would need this “instinctual” connection in order to partake in music / dance activities, which were important enough to be part of every known culture known in human history. Quoting Gloria from her blog, “this is not 'evolutionary theory for dummies'. I can (and we all must) acknowledge the body behind music and recognize that in doing music, we are biological beings performing very physical acts” (Gloria’s blog November 12, 2008).
In any music-making event, whether it is a community celebration, or a personal moment of reflection, creating music involves immediate synchronicity between ear and motor response. Levitin states, “it is only in the last five hundred years that music has become a spectator activity” (2006, p 257). Probably nothing has changed during the past 50,000 years as much as music, and the ways that we use and experience it. Zatorre et al's comment, “therefore, a link to motor systems would make sense, as movements occur in time as well as in space” (p 549), indeed, their whole paper, seems to refer more to present day performance practices instead of the far past. The link between music and movement in the brain makes perfect sense when we take the evolutionary lag into account.
Zatorre et al's suggestion that auditory-motor interactions could be the “link between listening and moving” (p 555) may be true for us in today’s culture, but is less likely a reason for the connection to exist, and more likely a “spandrel”, to use Levitin’s terminology (Levitin 2006, p 248). (A spandrel is a byproduct, an unintentional consequential outcome). If the connection between music and movement is already deeply embedded, and has been for so long, why wouldn’t the brain use it to link music and e-motion, letting us be ‘moved’ by music!? – (metaphors being the more truthful and embodied expressions of our beliefs and feelings).
Levitin, Daniel J. (2006) This is Your Brain on Music, the science of a human obsession. Plume, Penguin Group, New York.
MusicBrainerBlogger, Music, Cognition, Culture, and Evolution, published by Gloria, November 12, 2008