Plasticity and Localization

hardcoverdoidge.jpgIt is New Year’s Eve and I have just completed reading Norman Doidge’s The Brain That Changes Itself – Stories of Personal Triumph from the Frontiers of Brain Science. I read the paperback version, but at the end of his book Doidge notes that the cover of the hardcover “captures, in a single image, what this book is about and even the mood I hope the book creates.” Much in this book intrigued me – there were fascinating ideas to ponder, and brain science to digest. The first seven chapters held me captive for their personal stories; the final four chapters for the science and philosophy.

To have a comfortable grasp of the ideas, be able to discuss them and maybe even remember them, I need to “play” with the ideas, so you know what that means in terms of upcoming blog posts. Especially if anyone has read the book, I hope you will chime in with comments.

Since the book is mainly about plasticity, let’s see if I can explain what that means. Plasticity is not just the brain’s ability to change, for that is what happens all the time when we learn.

Let’s take a look at an old theory of the brain called localization. For many years, it was thought that each area of the brain had its own responsibilities. In fact, my early posts are all about the various parts of the brain, including descriptions of what each area tends to control and monitor. Until the idea of brain plasticity took off, it was thought that specific areas of the brain were responsible for specific functions, in other words, certain functions were localized or hardwired to certain brain areas. If something is hardwired then it is fixed and not capable of change.

The telling words above are “tends to”, because while certain areas of the brain tend to be responsible for specific functions, since the brain is plastic, areas overlap and even can co-opt one another’s functions. Initial maps drawn of our mental system turn out to be not as static as originally thought. If one pathway gets blocked, the brain is very good at finding alternative pathways.

As with any pathway, the more a particular path is used, the more ingrained it becomes, and pathways near one another become associated with each other. If a path is underutilized, over time it will be co-opted by other pathways that are branching out and need more space.

This concept of brain plasticity can be summed up in a few succinct statements revolving around the brain’s ability to reorganize itself, all from chapter 3, Redesigning the Brain:

Neurons that fire together wire together.

Neurons that wire apart fire apart.
This is also stated as Neurons out of sync fail to link.

Use it or lose it.

These statements will become that much more clear in upcoming posts. Meanwhile, here is more information about brain mapping and the idea of localization.

~ Neuroscience for Kids – Functional Divisions

~ Brain Maps: The Study of Brain Function in the Nineteenth Century

~ serendip: Mind, Brain, and Adaptation: the Localizaton of Cerebral Function
The serendip site is a most interesting place to visit and explore. There are a number of simulations and experiments designed to get you thinking!

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