“Brain Anatomy and Music”

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concerning the effects of exposure to music on relative size of brain structures in children.

On the other hand, MR has been used to study the size of cerebral regions in musicians compared to non-musicians. In 1995, Schlaug, Jäncke, Huang and Steinmetz studied the brains of professional musicians and compared them to the brains of sex and age-matched non-musicians.1 They focused on auditory regions of the cerebral cortex, an area called the planum temporale (PT~. The authors found a difference between the two groups: the PT was relatively larger in the left vs. right hemisphere of musicians than in non- musicians. However, this was not true of all musicians, but was restricted largely to those who had perfect pitch, i.e., who can exactly identify notes by sound. But perfect pitch is not required to achieve musical skill and musicians who have this ability are not better or more accomplished than those who do not. Thus, while the relative size of a key auditory brain structure is greater in some musicians, this seems to be related to perfect pitch rather than to knowledge or accomplishment in music.’

A recent report indicates that the amount of auditory cortex that is responsive to piano tones vs. non-musical tones is larger in musicians compared to non-musicians. Moreover, the amount of increase was correlated with the age at which the musicians began to study, i.e., greater the younger the age. Also, perfect pitch was not a factor in these findings.

While the auditory sense is very important in

music, the sense of touch is also heavily used by many musicians. For example, string players use the fingers of their left hand intensively, in complex and intricate patterns; the right, bowing-hand involves much less finger movement. There- fore, Elbert, Pantev, Wienbruch, Rockstroh and Taub studied that part of the cerebral cortex which receives sensory input from the fingers.3 They estimated the relative sizes of these regions by measuring tiny changes in magnetic fields caused by responses of brain cells to tactile stimulation of the fingers of the left and right hands. Elbert and co-workers re- ported that the amount of cortex responsive to stimulation of the fingers of the left hand of string players was greater than for the left hands of control subjects. No differences were found for responses to right hand stimulation in musicians vs. controls, which shows that the cortical effects were probably due to intricate use of the left hand. Of particular interest, the amount of increase in the left hand cortical area was related to the age at which the musician had begun to play; it was greatest in those who started about the age of five and less for those who started as teenagers. This relationship suggests that learning to play a string instrument at an early age produces a relative increase in the size of an involved part of the brain.

Of course, extensive use of the fingers does not merely involve touch sensation but also requires the control and coordination of movements of both hands. Schlaug and

colleagues studied the pathways that connect the left and right hemispheres, specifically a structure called the corpus ca/b- sum (CC), One can think of the CC as an information “super- highway” in the brain, sort of like an Internet access; in this case, the two hemispheres have to continually communicate to coordinate the right and left arms and hands. The authors used MR to measure the size of the CC; the basic idea is that the greater the information traffic between the two sides of the brain, the larger the number of connections needed. Two groups were studied: musicians (piano or string players who also had considerable skill at the piano) and matched controls. Schlaug et al found that the part of the CC that carries information between the motor centers of the left and right hemispheres was larger in musicians. The greatest effects were for musicians who started playing before the age of seven. This is another example of a positive relationship between early experience and the relative size of a brain structure.

The cerebellum is another part of the brain that is particularly concerned with motor coordination. In a recent brief report, Schlaug and his colleagues measured the volume of the cerebellum compared to the rest of the brain. They reported that although there was no overall difference in the size of brains between musicians and controls, the cerebellum was relatively larger in musicians than in controls.5 They did not report data concerning the age at which music lessons were started.

In summary, only a small number of studies relate the relative size of brain regions to musical accomplishment. Let’s grant that the few experiments conducted to date do show that the earlier one starts playing an instrument, the larger is a particular brain structure. But now we should return to the question of how best to think about the findings.

Thinking About Music and Brain Size

 Do the findings support the assumption that listening to music increases brain development in infants and young children? The brain anatomy studies to date have studied adults who are musicians and those who are not. So, clearly, there are no direct findings on children. One would have to expose some infants to music in a controlled way and then compare their brain development with that of an appropriate comparison group. This experiment has not yet been done.

Second, the brain anatomy studies with adults concern musicians who are really defined by their ability to per- form music, not merely listen to music. Indeed some of the positive findings concern finger use and hand coordination, that is skills involved in performing music, not limited to listening to music. Therefore, when we think about music, we need to distinguish between listening and playing an instrument. At this time, there is not yet evidence that listening to music in infancy increases brain size in adults. It might do so, but until the appropriate studies are conducted, we simply do not know.

Let us now move away from the issue of listening to the issue of performing music. The argument for a musically- induced increase in relative brain size of children rests on the reports that the effects seen in adults are largest when music lessons were started at an early age, in the range of five to seven

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