Another Day in the Frontal Lobe by Katrina Firlik

Author:Katrina Firlik
Language: eng
Format: epub
Tags: Non-Fiction
ISBN: 9781588365491
Publisher: Random House Publishing Group
Published: 2009-01-12T16:00:00+00:00

This teenage patient reminded me, as an analogy to the trite “you can’t judge a book by its cover,” that you can’t judge a person’s intelligence by his outward appearance. But can you judge a person’s intelligence by an examination of his brain? I was asked this question recently by a friend and my gut answer, never having studied the question in depth, was no. (This area of inquiry is more a Ph.D. concern than a clinical, practicing M.D. concern.) Obviously, I knew that certain conclusions could be made in the extreme cases—major congenital anomalies or devastating brain damage—but what about in the normal population? Can you look at the brain of, say, someone with an IQ of 90 and see any differences compared to the brain of someone who scored a 130?

Curious about whether my gut response had been correct, I looked around at what’s been written on the topic recently and found out that the answer may actually be yes. I say “may” because I’ve learned not to put definitive faith in any one particular study, and the quality of the work has been variable.

For more than a century, various researchers have looked at overall brain volume and intelligence, and some have found a correlation between larger brains and greater intelligence. My feeling here is that pursuing the question in this very simplistic way is just not that interesting. You might be able to find some sort of trend, but my hunch is that there would be so many exceptions to the rule that the rule wouldn’t be worth much. Einstein’s brain, for example, was apparently slightly smaller than average. Looking at brain volume as a whole, or head size, is far too crude a measurement. I have to admit, though, that I may have a bias here as my own head is not particularly large. Anyway, consider the fact that the brain of a sperm whale is five to six times larger than ours.

What about approaching the question in a more detailed way? What if a pathologist were to hold an isolated brain at autopsy, rotate it around in his hands, look at it from every angle, and examine all the convolutions under a bright light with a magnifying glass? That wouldn’t be good enough either. He still wouldn’t be able to conclude: “I’ve got a genius here!”

You would have to look even closer, and know where to look. Much of the recent work has been based on detailed MRI (magnetic resonance imaging) studies of living volunteers. One study from California, for example, describes numerous focal areas of the cortex, in all four lobes of the brain, in which the presence of more gray matter was correlated with higher IQ.1 Another group, in London, found similar correlations, but in different areas.2

Leaving aside the usual discrepancies between different research studies, a more important point is that examining structure alone has its limitations. Intelligence is a living, fluid entity probably better suited to study by function-based imaging techniques (in

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