Monday, January 21, 2008
Music and the Brain (my favorite topic and the subject of Oliver Sacks latest book - Musicophilia)
We get married to it, buried to it, come of age to it, finish our schooling in-step to it, put our children to sleep with it, soothe our broken hearts, celebrate our births, pray to our gods, and woo our mates to it. Shakespeare told us it is the "food of love," Nietzsche said without it "Life would be an error." What is it about certain sounds that make them music to our ears and are they merely, as Steven Pinker proclaimed, "a cocktail of recreational drugs that we ingest through the ear," did music's genesis precede spoken language, did it arise from the cadences of the spoken word, is it the by product of motherese - the sing-songy enhancements of the rhythms and pitches of speech that parents use to talk to their babies. Many scientists feel these exaggerations are they way we acquire language. No one can agree about the origins of music but most seem to agree that it really matters to us.
A little primer on some of the basic knowledge we have about music as a form and how it is processed in the brain, since this is a speciality of mine:
Music has existed almost as long as human civilization and across its many cultures. Archeologists discovered a perforated bear bone in Slovenia that is argued to be a "flute" from the Paleolithic ear, making it approximately 36,000 years old. What is it? A complex and conscious use of sound made by humans for humans. Music is generally characterized as having patterns of pitch and meter, but there are, of course, exceptions. Music exists without pitch in drumming, and without meter in chant or alap, an Indian form.
Through its early cognitive processing, it is collected from the environment as any sound would be but scientists do not agree about its exact trajectory through the auditory system. Processing music involves segregating the sounds from their background and analyzing timbre, pitch, both horizontal progress (sounds happening in sequence, i.e. melody) layered simultaneously (chords), and time (meter and rhythm). Interactions with the music's performance - facial expressions of the performer, context of the performance, text, the listener's own associations with superficial features, and their own life events also make up the experience of music.
Individually sequenced pitches are processed in terms of direction and interval size and referenced to a scale, which will vary with culture. Simultaneously presented pitches are references to their conformity to, or violation of, learned combinatory principles. Like the acquisition of syntax for language, these principles are acquired in infancy by musicians and non-musicians alike and require no explicit training. Temporal information is processed in terms of duration of segments and general underlying beat. Whether processing of these components of music happens in music-specific networks of the brain is a hotly debated topic, but brain damage studies have shown that more and more aspects of this process happens in music-specific networks of brain areas. Melody recognition and tonal perception occur in music-specific networks (Peretz & Hyde, 2003). Pitch discrimination appears to occur in separate circuits in the brain from those which process pitch for language (Peretz, 2002) For a while, the story went that language was processed only on the left side of the brain and music on the right but a study by Robert Zatorre (2002) suggests that the right hemisphere specializations are actually specific to detailed spectral discrimination (which happens to be useful for processing melodies) whereas the left is better for rapidly changing temporal information, as is useful for speech. The brain distinguishes between pitch for speech and pitch for tone early on in processing a sound - although this happens differently for tonally based languages like Chinese.
In terms of function there are clear distinctions between music and language. Music must be sound and must have order, but it does not communicate truth or falsity nor can one order a pepperoni pizza with music or schedule a meeting. Language need not be sound at all (as in sign language or in writing) but it is dependent on order, and its function is communicating meaning. Language is remembered for meaning, rarely for it features (its exact words and their sounds) unless word-for-word memorization is the goal. If the meaning of a sentence is recalled, one can sometimes reconstruct the features of language using logic, whereas music can only be remembered for its features. We would be hard pressed to reconstruct notes and rhythms from the sadness they evoked, but if music possess any content aside from the sounds themselves it would seem to be emotion that gives it meaning.
I am crazy about the intersection of music and cognition - it is to be one of my areas of research once I'm out of school. That is why Oliver Sacks' latest book is such, well, music to my ears. Sacks divides his book into four sections - one on people who become suddenly possessed by music without these having been the case before, the second is about degrees of enhanced or impaired skills in the realm of music - from savants to those who have disorders of pitch or rhythm, the third deals with memory and movement in relation to music, and the last with emotion and identity. I am just completing the second section. If you have never read an Oliver Sacks book, his focus is not the neuroscience of music in general, he is a physician (although his scientific skills and interests span a wide range) but as a clinician he encounters individuals with specific problems. His strength as a clinician appears to be his ability to get to know these people as people rather than as problems, and his strength as an artist is his ability to tell their stories with compassion, and with just as much insight as he has but his stories are not all success stories and sometimes his expression is one of admiration for his patient, or awe, or sorrow for the limits of our knowledge and his ability to alleviate the suffering of a person.
The stories he tells are uncanny. Sacks could just parade his patients oddities around as a kind-of modern day freak show, but his writing shows far more humanity than that. In this book we meet a physician who, as a result of being struck by lightening is possessed by a sudden love of/obsession for piano music. Another chapter is devoted to auditory hallucinations and other forms of internally generated auditory perceptions - like mental imagery- and their frequency of occurrence in all sorts of people. I myself pretty much have music playing in my head all day long. When I think about it I can vary the piece, or the artist, or the orchestration - even if I've never heard a version like that before. Sometimes I can get stuck and become the victim of a sort of demon internal-i-pod, but mostly we have a friendly relationship. An entire chapter of Sacks' book is devoted to this and, while the internal generation of perceptions were once thought to be the province only of schizophrenics it is now found that the phenomenon is much more wide-spread. Sacks' tells of of Jerzy Konorski, a Polish neurophysiologist, who argued in the 1960s that hallucinations can occur because the neurological pathways for sensory information flow two ways rather than one. This was a radical concept then but these feedback connections are now a well-known phenomenon and are known to account not only for images and hallucinations but are part of the way we all perceive our environment on a daily basis (Foxe & Simpson, 2002).
Anyway, I can just go on and on when it comes to music and the brain, in fact I have so I'll cut to the chase. I am enjoying Musicophilia tremendously. It is accessibly written, warm and humane in its outlook - the tremendous curiosity for knowledge and the capacity of this brilliant man to be continually awed by human nature is inspiring, yet he never lectures you about it - he communicates it through his own experience of the world. I have found every one of Sacks' books a compulsive read and find this one to be no different. If I hadn't been working so much in the lab over the last few days I'm sure I would already have finished it. More on this book and some of its stories later.