As the brain is the substrate of all mental processes and their behavioral outcome, and as musicianship is certainly a complex of such processes and their resultant behavioral performances, it would seem that the brains of musicians might be different than the brains of non-musicians. What is now known? Although this complex issue can't be covered completely here, we can summarize some interesting findings that do indicate how the brains of musicians and non-musicians differ.
Before we get started, two points should be made. First, there is no strict dividing line between musicians and non-musicians. The former are not all professionals or those with eight years of formal music education, or necessarily any formal musical education. When does a beginning music student become a musician? An initial solution to this problem is to compare groups of people at opposite ends of a continuum of musicality, such as comparing professionals with those who are musically naive.
Second, they might be differences in the brains of the two groups that cannot be discerned yet because of the current state of technology. For example, the stored knowledge of how to transpose to different keys is not yet detectable by brain scans. Thus, failures to find certain differences may not be sufficient reason to categorically reject such differences.
With these points in mind, we begin with the cerebral hemispheres. Overall, and somewhat simplified for present purposes, the left hemisphere (LH) is most important for analytic processes (e.g., details) while the right hemisphere (RH) seems more important for processing global information (e.g., patterns). Notably, most language processes depend on the LH (in right handed individuals). It is often wrongly assumed that all music processing takes place in the RH. Many years ago, Bever and Chiarello discovered that naive listeners depend on the RH for discriminating melodic sequences but musicians use the LH for this task (1). It seems that musicians may process melodies in a more analytic, "language-like" manner than non-musicians.
Are there any anatomical differences between the LH and RH in musicians vs. non-musicians? In a very recent study, Schlaug et al. used magnetic resonance imaging (MRI) to determine the sizes of the "planum temporale" in the left and right hemispheres. This structure includes auditory association cortex. Groups of professional musicians and non-musicians were matched for age, sex and handiness. The authors found that musicians had a larger left vs. right planum temporale than non-musicians. Thus, one could conclude that the brains of musicians show gross anatomical differences from those of non-musicians. However, this difference was due entirely to a subset of musicians who had perfect pitch; other musicians did not differ from the control group. Therefore, the distinction is not "music vs. non-music" but "perfect pitch vs. "non-perfect pitch". These findings underscore the need for thoughtful analysis and restraint against jumping to conclusions but do reveal that perfect pitch may be due to more brain tissue being "allocated" to the auditory cortex.
These anatomical findings also have a physiological counterpart. For example, Barnea et al recorded electrical potentials in the cerebral cortex that are elicited by musical stimuli. They found differences in the extent of cortical areas that respond, between musicians who do have perfect pitch compared to those who do not.
Although these results pertain to perfect pitch, there are neurophysiological differences that distinguish musicians from non-musicians For example, Besson, Faita and Requin studied differences in the processing of melodic material. They presented musical phrases that ended either in a congruous or incongruous note. The brain wave response evoked by this ending note differed between the groups, including a faster brain response by the musicians.
Differences in the way that the brain processes timbre also have been detected. Crummer and co-workers required musicians with and without perfect pitch and non-musicians to perform timbre discrimination tasks. For example, the same pitch was compared for cello vs. viola (easy), wood vs. metal flute (moderate difficulty) and instruments of slightly different size (B-flat vs F tubas), which was most difficult. The amplitude of brain potentials evoked by the notes was greater in musicians vs. non-musicians for the difficult discrimination and the brain potentials occurred fastest for musicians with perfect pitch.
Overall, these studies point to the following conclusions. First, perfect pitch, but not musicality per se, apparently has a cortical anatomical basis. Second, the processing of selected musical elements, as revealed by brain potentials, is facilitated in musicians compared to naive listeners. Third, musicians can process music in a different cognitive mode than naive listeners. The latter two findings suggest that a transition from RH to LH processing of music might be a fundamental aspect of the transition from musically naive to musically adept.
It would be interesting to assess the presumptive development of LH capabilities for relevant elements of music by both behavioral tests and by the recording of brain responses at various stages of musical training. The technology is readily available, present in thousands of medical and college settings, non-invasive and in widespread use for diagnostic and study purposes. Why not apply it to education? This would seem to be a potentially powerful way to join the separate expertise of music educators and relevant neuroscientists in an enterprise that would clearly yield results greater than the sum of its parts.