Sunday, 17 April 2005

Today's Brain Link

I've been rather busy, doing xtUML work and incidentally being the Simterror05 Australian Prime Monster (not a misprint).

But now it's time to give regular readers what they came here for, rather than a constant diet of Simterror05. I've been saving some goodies to write about (though don't have time to go into great detail), and here's one of them.

Primitive structures deep within the brain may have a far greater role in our high-level everyday thinking processes than previously believed, report researchers at the MIT Picower Center for Learning and Memory in the Feb. 24 issue of Nature.
From the MIT News Office.
The cortex--the "thinking" part of the brain--is highly developed in humans. This is especially true for the prefrontal cortex. Common wisdom suggests that when we learn new things, the prefrontal cortex figures things out first. Then, as our behaviors become familiar and habitual, the more primitive, subcortical basal ganglia take over so that the now-familiar routines can be run off automatically and occupy less of our thoughts.

"What we found was evidence for something very different," Pasupathy said. "We found that as monkeys learn new, simple rules--associations analogous to 'stop at red, go at green'--the striatum of the basal ganglia shows evidence of learning much sooner and faster than the prefrontal cortex. But, an interesting wrinkle is that the the monkeys' behavior improved at a slow rate, similar to that of the slower changes in prefrontal cortex."

This suggests that while the basal ganglia "learn" first, their output forces the prefrontal cortex to change, albeit at a slower rate.

The researchers speculate that perhaps the faster learning in the basal ganglia allows us (and our primitive ancestors who lacked a prefrontal cortex) to quickly pick up important information needed for survival. The prefrontal cortex then monitors what the basal ganglia have learned. Its slower, more deliberate learning mechanisms allow it to gather a more judicious "big picture" of what is going on by taking into account more history and thereby exert executive control over behavior, Miller said.
First stop the Tiger from eating you by running away. Only later plan on how you're going to find the den and kill the cubs. Or try to tame them. But it's the initial don't-get-eaten task you have to accomplish first, and there, presence of mind is good, but absence of body is better.

That appears to be the way we've evolved. Now we're stuck with that kind of thinking apparatus in a world of computers, bureaucracy, nation states, and international trade. It's a wonder that we do as well as we do.

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