How is it that we’re able to appreciate music? How do our brains assemble the complexities of rhythm, melody, timbre, and pitch into a pleasing whole? Many neuroscientists, influenced by case studies of people with head injuries, have thought that only a few areas in the right hemisphere of the brain are involved. But clinical neuroscientist Richard Frackowiak of the Institute of Neurology in London says there is no single music box in the brain. Instead his research strongly suggests that many different parts of the brain are activated.
To Frackowiak, the studies of brain-damaged patients are unreliable. A head injury, he says, might destroy music perception not by knocking out some central music nexus but by severing connections that are critical to music comprehension. So he chose to study six healthy young men, none of whom were musically trained. He used positron emission tomography scans to observe their brains while they listened to snatches of music. pet scans measure the uptake of radioactively labeled oxygen by various parts of the brain, thus showing which are most active.
While their brains were scanned, the men listened with earphones to four tapes. One tape consisted of 30 short pieces of music, each five to ten notes long, separated by silent gaps of one and a half seconds. Fifteen of these were brief excerpts from popular pieces of classical music, such as Mozart’s Eine kleine Nachtmusik. The others were just random sequences of notes. The subjects pressed the left-hand button on a computer mouse if the sequence was familiar. If it was completely unrecognizable, they pressed the right-hand button.
A second tape consisted of 30 sequences of notes. Fifteen contained a change in timbre. (Timbre refers to the quality of a sound; the same note played on two different instruments--a trumpet and a piano, say-- sounds noticeably different.) The others contained no changes. Of the 30 sequences on the third tape, half contained a change of pitch; a fourth tape had still another 30 sequences, half of which changed in rhythm. For each type, the men were asked to respond to any changes.
The results were intriguing. When the men listened to the well- known pieces on the first tape, the most metabolically active part of the brain was a region in the left hemisphere called Broca’s area. This area is known to be associated with our ability to speak, and Frackowiak says that his results show its functions may include the recognition of all familiar sounds, not just words. Although it’s possible, he adds, that the familiar tunes brought to mind the words of their titles, or prompted a search in the brain for their names. The rhythm tape also activated Broca’s area--not too surprising, says Frackowiak, since the region is also responsible for processing the cadences of spoken language.
When it came to focusing on timbre, the brain’s most active areas were in the right hemisphere. Interestingly, timbre was the only musical component to predominantly activate the right hemisphere. It suggests, says Frackowiak, that the reason people whose right hemisphere is damaged cannot understand music is that they no longer recognize timbre.
The last result was perhaps the most surprising. The pitch tape activated an area on the left side of the back of the brain called the precuneus. Past studies have shown this region to be associated not with hearing but with visual imagery. The suggestion is that as you look for changes in pitch, you may see them in your mind’s eye as shifts up and down a mental stave, says Frackowiak.
This suggests, says Frackowiak, that music appreciation is a complex function that depends partly on memory, partly on mechanisms that have to do with appreciating the sequence of words, timbre, and pitch. These various mechanisms are distributed in different areas of the brain, front and back. It’s a network of specialized areas, out of the coordinated activity of which comes something that we call music appreciation.