The ID Report

A Review Of Daniel Levitin's 'This Is Your Brain On Music'

By Robert Deyes

Physicist Emerson Pugh once quipped, "if the human brain were so simple that we could understand it, we would be so simple that we couldn't" [1]. Psychiatrist Jean Goodwin likewise proclaimed that the brain, "is impossible to understand because it is too complex" [1]. The complexity of the human brain is self evident when we consider, as neuroscientist Daniel Levitin does in his book "This Is Your Brain On Music", its one hundred billion neuron content. According to Levitin the number of ways that these neurons can connect with each other is so large that we will never fully comprehend all the thought processes that the brain is capable of. Indeed the number of possible thought states far exceeds the total number of particles that exist in the known universe.

And yet in recent years brain mapping has revealed a lot about the functional regions of the brain. Wernicke's area, for example is involved in language processing, the motor cortex in physical movement, frontal lobes in generating our personality, the temporal lobes in hearing and memory and the cerebellum in determining our emotions. Techniques such as encephalography and MRI have given us key spatial-temporal data about brain function in these regions. But we also find that activities such as listening to music contravene such a simplistic compartmentalization. The perception of pitch, tempo, the emotions invoked by a piece of music and the lyrics of a song, for example, all use different parts of the brain albeit simultaneously. Levitin repeatedly emphasizes the multi-faceted aspects of the music 'experience' noting how a, "precision choreography of neurochemical release and uptake" leads to our appreciation of music [p.188]. The brain is thus a massive parallel device, capable of carrying out several different tasks at once. The mechanism of sound acquisition is likewise a marvel of design. Covered with its tiny hairs that are excited differently depending upon the frequency of a sound, the basilar membrane of the inner ear is what captures the sounds we hear. Our ears are able to compress sounds when they reach dangerously loud levels so as to prevent irreversible damage to our ear drums Electrical signals are then sent to the brain where they are processed by the auditory cortex.

While it is through a lifetime of exposure that our brains become used to the note scales and music styles of our culture, it is during childhood that we are most receptive to learning music rules and note sequences. The finding that children's tastes in music are heavily influenced by the music heard during prenatal development, has forced a shift in the way we think about childhood memory. One area of the brain called the cerebellum has the capacity to recall with precision accuracy the rhythm of a music piece long after it has been heard while the brain stem and dorsal cochlear nucleus are able to distinguish between consonant (harmonious) and dissonant sounds. In fact our brains are able to group sounds without any conscious effort from ourselves. We rarely have difficulty, for example, deconvoluting the sounds of instruments- a trumpet will always sound like a trumpet and a clarinet always a clarinet. Every instrument has its own characteristic 'fingerprint' of tone frequencies many of which can now be copied by electrical synthesizers. Indeed frequency modulation synthesis has allowed musicians to simulate instruments and incorporate their own unique sounds into their music.

Levitin's work at Stanford University has brought to light the amazing capacity of the human brain to faithfully remember music pieces in their original pitch and tempo. In essence the brain can re-deploy ('re-member') the same neurons that were used in the original perception of a music piece. Indeed the brain does not carry a strictly isomorphic representation of the world but instead one particular version of reality that is held in the form of a 'neural code' (rather like the binary code representation of a picture held in our computers). Different sets of neuronal networks give us the myriad of feelings that we experience in our day-to-day lives. According to Levitin, the pitch of a sound is entirely in our heads not in the world out there. It is the end product of a chain of mental events that gives rise to an entirely subjective internal representation of the outside world. And yet for cognitive neuroscientists such as Levitin the anatomy of the brain comes second to understanding how thoughts and emotions arise- that is, how the mind works. What of the mind's origin? For Levitin the quirks of our perception and the optical and auditory illusions that occasionally give us a false impression of reality stand out as evidence that points to the blundering process of evolution. Nevertheless Levitin concedes that the sound separation capabilities of the brain, which allow it to differentiate between concurrent sounds (say two different instruments), are nothing short of remarkable. We are only just beginning to understand how it is that the brain registers the sound signals that cause our ear drums to wiggle at certain frequencies. Feature extraction is the process through which neural networks then 'decompose' the sound signal into information about pitch, timbre and loudness amongst other things. Through repeated exposure, our brains generate 'schemas' of what sounds should go together, what letters will appear in a word and what different types of music will sound like.

Levitin does a fantastic job in explaining the universal patterns and regularities of musical construction revealing the common music elements that unite apparently disparate pieces of music such as those of Mozart and The Eagles, Prokoviev and Steve Wonder. The non-arbitrary frequency distances between notes are what identify any given piece of music. And yet as Levitin outlines, part of the appeal that comes from listening to groups such as The Beatles or The Police is their deliberate violation of expected rhythm and sound combinations. We see a similar trick with classical composers who use 'deceptive cadence' as a way of surprising the listener. Other contemporary artists such as Joni Mitchell have taken the element of unpredictability to another level by tuning and playing their instruments in unpredictable ways. Establishing a balance between complexity and simplicity- between a sense of adventure and the security of the predictable- is what will eventually determine whether or not a music piece becomes successful. But according to Levitin, expertise in music is just like expertise in anything else albeit with different neurons firing to give us a different end product. There is of course still much debate about how much genetics and the environment contribute to musical talent. Research has revealed some notable differences in the brains of musicians- a larger frontal portion of the mass of fibers that connect the two hemispheres of the brain, a greater number of brain synapses and an increase in the amount of grey matter. Nevertheless what is clear is that even talented musicians require thousands of hours of practice before they truly become experts in their field.

Levitin makes his book that much more exciting by recounting many of his own personal stories both as a musician and a neuroscientist. His work as a record producer with some of the biggest names in the business and some of the best-known artists of contemporary rock provides a unique flavor to his scientific discussion. Nevertheless his conversations on evolutionary biology and its relevance to brain evolution with the greats of molecular genetics, notably Francis Crick and James Watson, are somewhat of a disappointment. Indeed in the last chapter Levitin develops the idea that music has served as a 'vehicle' for social bonding and cohesion citing the tendency of people to identify with others with similar music tastes as supportive evidence. He is quick to dismiss psychologist Steve Pinker's assertion that music was nothing more than 'evolutionary cheesecake' that in humans rode on the back of the more critical adaptation of language. Rather, Levitin sees music and musical appreciation as an adaptation in itself that may have allowed sexual partners to charm each other through their courtship displays (an extension of Darwin's theory of sexual selection). He cites the highly social and musical tendencies of Williams Syndrome patients and the musical and social difficulties of autistic children as clear evidence of an evolutionary connection between music and social integration. But what of the complexity that Pugh so eloquently drew our attention to so many years ago?

Naturalist Jane Goodall expressed her expectation of how the brain had evolved when she wrote of, "a series of vanished brains, each more complex than the one that came before it [that] have forever been lost to science, save for a few imprints on fossil craniums" [2]. And yet without the crucial evidence of the 'how'- the mechanistic meat of evolutionary theory- natural selection remains but a skeleton of speculation. For evolutionary biologists, the challenge lies in explaining the 'how' of brain evolution. Perhaps ironically, Levitin's own illustration brings to light the heart of the problem:

"The average brain consists of one hundred billion (100,000,000,000) neurons. Suppose each neuron was one dollar and you stood on a street corner trying to give dollars away to people as they passed by as fast as you could hand them out- let's say one dollar per second. If you did this twenty-four hours a day, 365 days each year without stopping, and if you had started on the day that Jesus was born, you would by the present day only have gone through about two thirds of your money" (p.85)

Biochemist Erwin Chargraff is quoted as having said that science is wonderfully equipped to answer the question "How?" [3]. And yet for the origin of the human brain and the mind, the answer to that burgeoning question remains as elusive to naturalistic science as the origin of life itself.

Further References
1. Inside The Mind Of God- Images And Words Of Inner Space, Introduction By Sharon Begley, Edited By Michael Reagan, Templeton Foundation Press, New York, p.61

2. Jane Goodall (1999) Reason for Hope: A Spiritual Journey Warner Books Inc, New York, NY, p.126

3. Inside The Mind Of God- Images And Words Of Inner Space, Introduction By Sharon Begley, Edited By Michael Reagan, Templeton Foundation Press, New York, p.68

Copyright (c), 2008, Robert Deyes