Rauschecker and assistant Stuart Washington measured Graves' brain activity as she lay inside the full-body MRI machine and listened through headphones to three musical selections: opera from Puccini's Tosca, U2's rock hit "With or Without You" and one of Graves' own operatic recordings. This is what they found:

The yellow areas in the scans indicate activity in the regions of the brain that process music. That may be greater for Graves than for a non-musician, according to research by Germany's Dr. Christo Pantev, who now works in Toronto.

Listening to Tosca: The upper-lighted area may indicate a memory-type response, reflecting the singer's familiarity with the tune. This reaction also occurred during Graves' own piece, but not as strongly during the U2 song, which makes sense because Graves admits U2 is not her kind of music.

The middle activated area, which lit up during all three songs, represents the auditory cortex, the site of most sound processing. This is normal and expected. However, during the two opera pieces, the lower-lighted area shows activity in the cerebellum, the center of motor skills, which has only recently been shown to process music by Dr. Lawrence Parsons of the University of Texas in San Antonio. This reaction did not occur while she listened to the U2 piece which could mean Graves showed more cognitive involvement in listening to familiar songs, Rauschecker says.

Listening to U2: In the scan taken during the U2 song, the middle-left lighted area repesents activation in the somatosensory cortex -- a reaction that generally occurs with touch or pain. Was listening to U2 painful to Graves? Until we design a scientific study, with sizeable test and control groups, we may never know.

Left-brain activity: Although music generally is processed on the right, or emotional, side of the brain, Graves also showed some left-brain activity, suggesting that this world-renowned mezzo-soprano listens to music with a finer, more analytical ear.

-- By Frappa Stout