The scientists found that people with damage to the left temporal lobe had difficulty recognizing changes only in key, whereas those with damage to the right side struggled to recognize changes in both key and contour. Later imaging studies showed a similar bias toward the right hemisphere¿particularly among nonmusicians¿although Tramo notes that more recent work calls some of this "musical hemisphere" hypothesis into question. "The belt and parabelt areas [of the auditory cortex] in the right hemisphere discriminate local changes in note duration and separation," he writes, "whereas grouping by meter involves mostly anterior parabelt areas in both hemispheres."
From Mind's Eye to Emotion's Seat
Image: NATIONAL MARINE FISHERIES SERVICE
For certain, it is becoming apparent that unexpected and unsophisticated areas of the brain are sometimes involved in interpreting, writing, feeling or performing music. As some research has showed, even the visual cortex sometimes gets into the act. Herv¿ Platel, Jean-Claude Baron and their colleagues at the University of Caen used positron emission tomography (PET) to monitor the effects of changes in pitch. What they found¿much to their surprise¿was that Brodmann's areas 18 and 19 in the visual cortex lit up. These areas are better known as the "mind's eye" because they are, in essence, our imagination's canvas. Any make-believe picture begins there. Thus, Baron suggests that the brain may create a symbolic image to help it decipher changes in pitch.
But music goes much deeper than that¿below the outer layers of the auditory and visual cortex to the limbic system, which controls our emotions. The emotions generated there produce a number of well-known physiological responses. Sadness, for instance, automatically causes pulse to slow, blood pressure to rise, a drop in the skin's conductivity and a rise in temperature. Fear increases heart rate; happiness makes you breathe faster. By monitoring such physical reactions, Carol Krumhansl of Cornell University demonstrated that music directly elicits a range of emotions. Music with a quick tempo in a major key, she found, brought about all the physical changes associated with happiness in listeners. In contrast, a slow tempo and minor key led to sadness.
Robert Zatorre and Anne Blood at McGill University corroborated Krumhansl's findings with PET imaging experiments. They created original melodies containing dissonant and consonant patterns of notes, and played them for a group of volunteers willing to be scanned at the same time. As expected, dissonance made areas of the limbic system linked to unpleasant emotions light up in the PET scans, whereas the consonant melodies stimulated limbic structures associated with pleasure.
That music strikes such a chord with the limbic system¿an ancient part of our brain, evolutionarily speaking, and one that we share with much of the animal kingdom¿is no accident, some researchers assert. In another recent paper in Science, Patricia Gray, head of the Biomusic program at the National Academy of the Sciences, and several colleagues from around the country propose that music came into this world long before the human race ever did. "The fact that whale and human music have so much in common even though our evolutionary paths have not intersected for 60 million years," they write, "suggests that music may predate humans¿that rather than being the inventors of music, we are latecomers to the musical scene."
Humpbacks, Hummingbirds and Human Composers
Image: OHIO STATE UNIVERSITY