A recent news story tells about a boy who rides a bicycle, runs about, and does other sorts of active things that a child of his age would do. This might not seem like much of a news story—until we realize that this boy was born without a part of his brain, specifically the cerebellum. To anyone who knows anything about brain anatomy, it might seem impossible for someone like this boy to have such a normal range of activity.
The cerebellum (highlighted in purple in the photo) is a part of the brain that seems to be involved in several functions, including emotional regulation and language. However, its best-understood function involves the fine tuning of large-scale body movements, including the keeping of balance, coordination, and timing. The cerebellum is involved in activities like walking, running, and, of course, riding a bike. Adults with damage to the cerebellum often show poorly coordinated movements, and do not walk smoothly. And yet the boy mentioned in the news story seems to have no problems with these kinds of activities—even though there is only fluid where the cerebellum should be. What gives?
The article speculates that the boy’s cerebellum was genetically defective, and its tissues were reabsorbed into the body while the boy was still in the womb. Further, the article speculates that the boy’s brain reorganized itself to distribute the processing of activities involving balance and coordination to other parts of his brain, while he was still developing prenatally.
Recent years have seen much research published that sheds light on the plasticity of the brain, that is, the brain’s capacity to reorganize itself and redistribute its functions as needed (for example, because of injury). Brain plasticity is most easily seen in the brains of very young people, and it appears to be the best explanation for what we see here with this young man.
Of course, this raises all sorts of questions. If a young person's brain shows a great deal of plasticity, why do not adult brains? Is there a way to encourage plasticity in adult brains? But if we do, what is the trade-off, the cost in other brain functions? For that matter, what is the trade-off in the brain function of the young man in the news story?
And, who will answer these questions? Brain researchers—perhaps even you.
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Copyright 2011 Mark E. Koltko-Rivera. All Rights Reserved.
[The image of the human brain (with the cerebellum colored in purple) was produced by the National Institutes of Health (NIH), an agency of the U.S. federal government, and so is in the public domain. It was obtained through Wikipedia.]
Although the child seems to not be affected by the missing cerebellum, is there a chance that as he ages, things could change, and the missing cerebellum could begin to affect him as an adult?
ReplyDelete-Delilah
I can only speak in a salad of metaphors to respond to your excellent question. We are in uncharted territory here. My sense of the situation is that there is indeed some price to be paid. The cerebral assets that are being used to take up the slack of the missing cerebellum are now unavailable for other tasks. However, it may be that there is so much redundancy built into the brain that this young man will merely be able to pay the price out of reserve assets, without showing a deficit in other capacities. Time will tell. I hope that some ambitious group of researchers will arrange to follow this young man over the course of his lifetime to see what happens.
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