Why are parts of the brain specialized? -Or- Why doesn't the brain do everything at once?

This post is part of our on-going series of Brain Day Questions, where we answer questions submitted by 7th grade students from Palo Alto and East Palo Alto classrooms. For more on the series, check out our Brain Day Questions kick-off post.

“Why do different parts of the brain function differently instead of having all of the brain do everything at once? Wouldn’t it be more efficient?”

Different parts of the brain function differently so that each area can do its job more effectively. The cells, or the cell networks, in any given area are specialized to perform a particular function as well as possible.

You could say that the whole brain does do everything at once because each area is connected to many other areas and it’s usually hard to say where one area stops and another begins. All of the areas are signaling constantly, simultaneously, so it really is like having one whole network doing everything at once. Some parts of it are just specialized to do particular things (like detect shapes, make emotions, move your eyes).

In one sense it would be more efficient to have the whole brain be filled with identical cells that are all capable of doing the same thing. Then, if one part got damaged, any other part could compensate. Some people think that a big part of the brain (the cortex) works just like that - and any part can take on the job of any other part. For example, sometimes areas are similar enough that one area can takeover the job of a neighbouring area. Many people who experience brain damage, have at least partial recovery.  Also, if one area is not being used, then that part of the brain can sometimes be repurposed for something else. For example, the visual part of the brain of a blind person could be used to process sound. The degree to which the repurposing is successful depends on many different factors, and it’s probably the case that there are both areas that are similar enough share functions and those that are too specialized to do so.