The New Executive Brain

I read The New Executive Brain yesterday, by Elkhonon Goldberg. It's the closest thing to a professional viewpoint of the brain that you'll find. It can only barely be considered a popular science book. It's just too dense. Goldberg is fiercely intelligent, and he doesn't stint on the vocabulary or the terminology. There were times I'd read through a chapter and have to put the book down because I couldn't absorb any more information.

It's not a book about how people think. In fact, it's explicitly not about people at all; it's about how the brain works. It's a book that explicitly talks about the brain like a car engine; here's the amygdala, there's the frontal lobes, and here's the hippocampus. Put them together and you have a functional human being. Destroy a piece and you end up with a broken toy of a human being that can only ever go around in circles.

Destroy one part of the brain, and there are dozen different ramifications, from Attention Deficit Disorder, to Tourette's, to Obsessive Compulsive Disorder. This is an excellent way to understand the brain as an organ, but it's hard to maintain the idea that these disorders are "brain" and not "personality." But to Goldberg, personality is an outcome of various interactions of the brain. He even complains that when describing flaws in the brain, people absorb it and then ask why the patient's personality has changed -- to Goldberg, he's just explained why.

Much of the book is concerned with the frontal lobes, the "executive" part of the brain that is responsible for making conscious decisions. It turns out that damage in almost any part of the brain can cause malfunctions in the frontal lobes -- this is because the frontal lobes receive input from almost every part of the brain to make decisions. Change the input, and you get output that doesn't make sense. Exactly how the frontal lobes do this is unknown, but we know that both hemispheres of the brain are involved, and interact differently.

Everyone has heard the old story about being "left-brained" or "right-brained" where the left hemisphere is the logical side and the right hemisphere is the intuitive side. The true difference is more subtle than that. The left hemisphere has many neurons that connect to their close neighbors. It can pick up new behavior very quickly. The right hemisphere has many neurons that connect to far off neurons. It picks up new behavior more slowly than the left hemisphere. If the left hemisphere is a tightly woven net, then the right hemisphere is a much larger, courser net, with many scattershot branches.

They both function the same way in recognizing patterns, but when given a new task to learn, the right hemisphere is most active to begin with. New activity is captured and seen using the larger net. Then, as the task is learned and understood, activity migrates from the right hemisphere to the left. What was previously understood in an unformed, loose way, is seen and codified on the left hemisphere, which can recognize the pattern immediately the next time it sees it and deal with it appropriately.

This approach gives the brain the best of both worlds; an immediate loose understanding of a situation, and an efficient grasp of a well known situation. When modelling neural networks on computational platforms, it turns out that this combination gives very effective performance. It also explains how damage in the right hemisphere can be absorbed without obvious incident, while damage in the left can be so crippling; the neural network on the right hemisphere can route around the damage and heal without losing already acquired knowledge.

So. Good book. Recommended. Only read it if you really want to know.