Tuesday, December 8, 2009

Is My Brain Getting Too Big For My Skull?

Music and Brain Blog #2
Brian Graiser

Music of the mind, BBC News Online (Health), May 8 2001. http://news.bbc.co.uk/2/hi/health/1319753.stm

Synopsis: Significant evidence has been discovered through brain scanning that the brains of musicians may be physically altered by years of practice. Presented at the 2001 American Academy of Neurology meeting in Philadelphia, this research shows that certain regions of musicians’ brains are packed with a greater number of cells than those of an average person. In a study of 15 musicians and 15 non-musicians, German Professor Gottfried Schlaug used MRI scans to observe the size discrepancies in at least four regions of the brain, including those which process auditory cues and those which control physical responses to visual stimuli. However, at the time of the study it was unclear if this extra brain mass is a result of years of musical training, or if it is a pre-existing condition that routinely pre-disposes people towards pursuing musical careers. According to Professor Schlaug, “additional study is necessary to confirm causal relationships between intense motor training for a long period of time and structural changes in motor and non-motor related brain regions. An alternative explanation may be that these musicians were born with these differences, which may draw them towards their musical gifts."
In a similar study which seems to promote the notion of reshaping the brain, researchers from University College London (UK) scanned the brains of taxi drivers, and found that they had a larger hippocampus (associated with navigation in animals and birds) than average. Furthermore, the researchers noted a correlation between hippocampus size and career length; those who had been taxi drivers the longest had the largest hippocampi. However, according to Dr. Eleanor Maguire (who led the UK research team), it was unknown at the time whether such changes could occur in other areas of the cortex, or only in the hippocampus (thereby neither confirming nor denying the possibility of years of music practice physically altering the brain).

Reflection: It’s important to note that this article is from 2001; following today’s thinking on brain plasticity and development, it seems more apparent that music practice did, in fact, affect the brain (and not the other way around). Based on different recurring personality types one encounters at the average music school, I’d say it’s a safe bet that there are certain psychological and neurological conditions that pre-dispose people towards musical careers. However, the notion that years of practicing music can change the size and shape of my brain is particularly intriguing.
Given how physical percussion performance can be, I’ve long since learned to trust my brain when I practice, in the sense that if I will my muscles to perform a certain task over and over, eventually that motion will be ingrained in my muscle memory so that I don’t need to consciously think about every motion. However, it seems strange to me to equate the thousands upon thousands of such memorized mental commands with added physical mass in my brain. After all, during his autopsy it was found that Albert Einstein’s brain was physically average in size and weight; surely, if thought leads to added brain bulk, wouldn’t Einstein’s brain have to be huge?
I suspect the answer to this problem lies in the nature of what we consider brain plasticity. Rather than simply adding mass to parts of the brain, plasticity would instead reassign certain parts of the brain to tasks other than those for which they were originally intended. I would be interested in finding out if the researchers in this article were able to determine which regions of the brain had “loaned” their mass, or if they had even considered this. On that note, I would also be interested in finding out what, if any, quantifiable relationship there is between mental activity and the amount of mass “reassigned” through brain plasticity; how many years would I have to practice (or drive a cab) in order to add 15 milligrams of mass to my cortex? In extreme cases, could this redistribution of mass theoretically lead to headaches or other physiological problems? Is there a limit to how much of my brain that can be reassigned? Food for thought, to be sure.


Martin Walker said...

London taxi drivers also have bigger brains after learning all of the streets and routes.

We've also seen a correlation in both directions between brain training and music. Musicians tend to be better at the brain exercises and the brain training has a beneficial impact on playing and appreciating music.


Myrtle D. Millares said...

I've just read a chapter, "Neural Bases of Cognitive Development" by Margot J. Taylor, from a book called Lifespan Cognition: Mechanisms of Change (Ellen Bialystok & Fergus I.M. Craik, eds.) that summarized brain growth from infancy to adulthood. At birth, an infant's brain reaches 300 to 500 grams. It grows through late adolescence during which time it reaches the adult brain weight of 1350 to 1500 grams. So brain size appears to stabilize at that point and all neurons and glial cells are already present. So it seems that you're right to think that changes simply happen within the existing structure.

"Pruning" of synapses and gray matter also occurs with age, as synapses that aren't used are lost. Myelination (increase in white matter) continues to increase, so brain volume is pretty stable through adolescence and early adulthood.

I also found out that brain volume decreases in "normal" aging, with a significant change already present at age 30! Though this was seen in a study involving only 272 people. (From "Brain Changes in Aging: A Lifespan Perspective" by Buckner, R.L., Head, D., & Lustig, C. from the same book.