Brain images reveal cerebral side of music.

The world may seem brighter with a song in your heart, but what's in your head? Scientists using imaging technology have begun to illuminate how a melody makes a musical impression in the brain.

Brain areas involved in hearing, recall, and even vision--particularly those in the right hemisphere--coordinate musical perception and memory, say Robert J. Zatorre, a neuroscientist at the Montreal Neurological Institute, and his colleagues.

"Depending on how musical information is being processed, one or more sets of brain regions may be activated," Zatorre argues. His group studied 12 right-handed adults, none of whom had played music professionally. Volunteers underwent positron emission tomography (PET) scanning as they performed four tasks: listening to a sequence of noise bursts; listening to a series of unfamiliar, eight-note melodies; listening to the same melodies and determining whether the pitch of the second note was higher or lower than that of the first note; and listening to the melodies once more and noting whether the pitch of the last note rose or fell relative to the first note.

PET images recorded blood flow in participants' brains during each task. The researchers subtracted PET data on the first task from data obtained on the second task to isolate brain activity associated with listening to melodies. They then subtracted that information from the results of each of the pitch-comparison tasks to highlight activity linked to specific musical judgments.

Simply attending to melodies produced blood low increases in the part of the brain's right temporal lobe that plays a role in hearing, as well as in an area at the back of the right hemisphere previously associated with vision, the researchers report in the April JOURNAL OF NEUROSCIENCE.

Since all volunteers kept their eyes closed during the trials, the latter finding may signify the generation of visual images, consciously or unconsciously, in response to the music, Zatorre suggests. Another PET study of musical perception observed no changes in visual structures (SN: 7/11/92, p.21)).

Additional portions of the brain's outer and inner layers, again mainly on the right side, displayed blood-flow jumps during pitch comparisons. First and last note comparisons, which made the greatest demands on volunteers' memory, produced changes in the temporal lobe, suggesting the operation of a brain system devoted to short-term memory for sounds, Zatorre says.