No. 95: Sep-Oct 1994
The playing and composition of music has always been considered the near-exclusive province of the brain's right hemisphere. This turns out to be far from the truth. For example, non-musicians use both hemispheres in musical matters; the right side for recognizing melody and intonation, the left for such analytical matters as rhythm and notation. However, professional musicians, as their brain waves demonstrate, use their left hemispheres for just about everything of a musical nature. So much for the right-hemisphere theory!
The comparison of magnetic resonance images of 27 right-handed musicians and 27 right-handed nonmusicians have shown that even their brain structures differ. The corpus callosum -- that inter-hemisphere information highway -- is 10-15% thicker in musicians who began their training while young than it is in nonmusicians. Our brain structure is apparently strongly molded by early training. The corpus callosum in musicians is essential in such things as finger coordination. Like a weight-lifter's biceps, it enlarges to accommodate the increased tasks assigned to it.
(Anonymous; "Music of the Hemispheres," Discover, 15:15, March 1994.)
Comment. It would be interesting to compare the brain structures of mathematicians and nonmathematicians where the dexterity factor is absent.