Daniel J. Levitin's This Is Your Brain on Music -- Cognitive Neuroscience, music and memory

Friedrich Nietzsche said it best, “Without music, life would be a mistake.”  Music is an intrinsic aspect of our every-day lives.  Whether you catch a commercial jingle, listen to the radio while studying, or sing to yourself in the shower, your mind is certain to process music every day.  So what is it that drives humanity’s obsession with music, an art form and expression found across cultures throughout the world and time?  Why do songs get stuck in our head?  How does music have such a profound effect on emotions?  Parallel to language, it seems we possess the innate ability to develop an understanding of musical “language.”  During a child’s development, he or she acquires rules about phonemes and syntax, building an understanding of one’s native language.  Similarly, children also acquire rules about musical structure and tonal sequences of one’s culture, without any conscious awareness of doing so.  As music perception and appreciation are so fundamental to our psyche, it seems worthwhile investigate the neural mechanisms related to music perception.  In This Is Your Brain on Music, Daniel J. Levitin examines the neural faculties tied to humanity’s passion for music.  Further, music, as a universal obsession, is a field that should be made accessible to everyone, and consequently, Levitin sets out to assuage the sense of alienation felt those who may not have a strong background in music theory or neural biology, and delivers his work in a manner accessible to musicians and non-musicians, at a level anyone from our class could appreciate. 

Music, in our most basic conception of it, is the totality of a subset of multiple attributes that alone resemble, at most, mere sounds.  Before diving into the theoretical and empirical content of his book, Levitin describes these fundamental components of music and the roles they play in shaping the perception of song, for it is the perception of the totality of these components and the relations between them that gives rise to the psychical phenomenon of music.  Just as a tree falling in the wood creates no sound if there is no one there to hear it, there can be no music if the attributes that make up music are not perceived.  These basic elements of music include pitch, rhythm, tempo, timbre, loudness, tone, and the spatial qualities of sounds.  From the amalgamation of these attributes, concepts such as key, meter, melody and harmony are born.  Levitin describes the manner in which these components and concepts relate to neural activity and how they are the result of a series of (mostly non-conscious) mental events that give rise to a final representation of the initial series of stimuli; the story constructed by our psyche, music. 

A good example to consider is pitch.  A sound or note produces a series of waves that cause the air to vibrate at multiple frequencies simultaneously.  Consequently, when we hear a note, we are hearing a multitude of pitches that we reduce to a single pitch, the lowest of which is called the fundamental frequency.  Interestingly, the other frequencies, referred to as the overtone series, are typically mathematically related to one another in a simple integer multiple relationship.  For example, the fundamental frequency may be 100 and the overtones would 200, 300, 400 etc. (two, three, four times the fundamental frequency etc.).  The overtone series qualify as a series of harmonics when this simple integer multiple relationship exists.  Pitch, as we know it, is the representation created in our minds of the fundamental frequency of a note.  There is evidence that the brain fires neurons synchronously for each pitch of harmonic heard, which could be the neural basis of the unity of these sounds into a single represented pitch.

Pitch is one of the most important units of music.  What defines music is a series of relations between pitches.  How we define a note, assigning a name such as “B-flat” to a particular frequency, is arbitrary, but the relation between one pitch and the next in our musical scale is proportionally consistent; each successive note follows a 6% increase in frequency (units Hz).  Thus a series of proportional changes between pitches constitutes music.  For example, “Happy Birthday” is recognized as the same song regardless of whether or not it was started on an A or D because the relative change between each note remains the same.  This introduces the concept of melodic transposition, and from here, the concept of music opens up to a whole new realm of theoretical inquiry.  How is it that a song, or more simply, a melody, composed of a series of explicit pitches, retain its character when all the pitches are changed?

Somehow the brain is able to distinguish between the aspects of a song that remain consistent with each time we hear it and those aspects that are single-occurrence variations.  If the brain were unable to make such distinctions, we could not recognize Happy Birthday as the same song when sung in a different key or sung at a different volume.  The brain, therefore, isolates those aspects of a song that give it its character or identity.  From here, Levitin goes on to introduce two competing theories of memory.  The constructivist view argues that we store information about relations between objects and ideas (the general picture) but not specific sensory information.  Our memory then uses these relations to construct a representation of reality.  The opposing view, the record-keeping theory, argues that we commit most of our sensory experiences to memory with a high degree of accuracy and reliability. 

Levitin argues that studying music can help resolve the conflict between these theories of memory.  His basis for this comes from the concept of pitch and melody.  Melodies are defined by a set of relations between pitches, which fits the constructivist theory, but these pitches correspond to very specific frequencies, and if these pitches are committed to memory, it supports the record-keeping theory.  Levitin presents empirical data that supports both schools, and then data from studying music and memory, which supports a hybrid theory, the multiple-trace memory model.  According to this model, both abstract and specific information is stored in our memory. 

Research performed by Petr Janata using EEG recordings shows nearly identical patterns of activity when subjects hear/perceive music and when they imagine/remember the music.  These results suggest that perception entails the activation of a set of interconnected neurons, causing them to fire in a particular pattern.  Memory, then, may be the mental process of recruiting and firing these same neural groups to create a reproduction of the previously perceived object.  It is then a matter of encountering the proper cues that initiate the activation of these neural groups that is crucial for memory.  During music listening, the first couple notes (pitch, timbre, etc.) serve as cues to initiate patterns of activity in various regions of the brain.  Included are regions of the brain referred to as “melodic calculation centers,” which keep track of the interval size and space between pitches, the information needed to recognize melodies in transposition.  Also activated is the hippocampus, a structure highly correlated with memory encoding and retrieval.

Levitin explains that memory is so connected to the experience of music, that one could venture to say we wouldn’t have music at all if we didn’t have memory.  With memory, our brains formulate schemas, the patterns, organization and rules of how music goes together.  This occurs non-consciously early in development.  From these schemas, are then born expectations of music.  For instance, we are able to recognize the root of a scale/key of a song we are listening to, and when the notes stray away from this root, we anticipate a return to the root, a resolution (both for the music and for our psyche).  It is anticipation and expectation derived from schemas that is key to the emotional drive of music.  Our brains take enjoyment both in correctly anticipating where music will go, and in being pleasantly surprised when talented composers and musicians defy these anticipations. 

Levitin lays out a possible neural basis for the relation between music and emotions.  Levitin observed that the cerebellum, the most “primitive” part of our brain, typically associated with non-conscious timing and movement, appeared to take an active role in tracking the beat of a song, and more interestingly, the cerebellum becomes active is response to liking or finding music familiar.  The cerebellum has strong connections to the amygdala, associated with memory of emotional events, and the frontal lobe, responsible for executive function.  So how do the cerebellum, music, timing and emotion come together?  How and why does music involve the most primitive and most developed parts of brain, culminating in affections of emotion?  You’ll have to read This Is Your Brain on Music to find out.

I have only outlined a few of the topics covered by Levitin in his book, and the rest are equally, if not more, intriguing.  Levitin goes on to examine what makes a talented musician, the possible evolutionary origin and biological usefulness of music, the basis of music preference, the possibility that music predates and actual lays our the neural connections necessary for language, and the implications of findings on the affects of music on neural development.  For instance, there is evidence that prenatal experiences are encoded into memory and is accessible without language or I-function involvement.  This goes against the commonly accepted notion of childhood amnesia, the belief that we don’t begin to form genuine memories until the age of five.  Many questions in this field remain unanswered, and you can expect more thought provoking discoveries to come from further examination of music and cognition.  This is an excellent book for anyone who has an interest in cognitive neuroscience and/or music.  What makes the motifs of this book even more engaging is their applicability to nearly everyone’s life.  As Levitin explains, regardless if we are musical prodigies or tone-deaf, closet shower singers, “We all have musical brains,” and consequently we can all relate to the ideas laid out by Levitin.