Monday, September 25, 2006

IQ and brain imaging technology

Sanjay Gupta:

Most scientists say that current brain imaging technology doesn't tell you much more.

"If I showed you two brains side by side, one with an IQ of 150, one with an IQ of 75, I can't tell the difference," says Jay Giedd of the National Institute of Mental Health, one of the most experienced researchers in the field.

But Jung and his colleague Dr. Richard Haier of the University of California, Irvine, claim they are on the verge of refining imaging techniques to a point that would make traditional intelligence tests obsolete.

"We can make quantitative assessments of how much gray matter they have in every single area, and we can use that to predict what their IQ might be," Haier says. "This is in the very early stage, and I think this is going to be very interesting."

Brain imaging remains in some ways as crude a tool as simply cutting open the brain and looking inside. Haier and Jung use magnetic resonance imaging (MRI) to measure various parts of the brain. Then they compare the pictures to intelligence scores on a verbal or pen and paper test.

So far, says Haier, he has found a strong correlation between intelligence and the size and shape of certain brain structures -- including parts of the superior parietal lobe (involved in sensory perception) and parts of the prefrontal cortex (associated with complex thinking, personality, planning, coordination).

Intelligence research is full of surprises. For example, the brains of smarter people, as measured by IQ, tend to be less active but more efficient, Haier says.

In a controversial paper, he contends based on structural MRI scans that men and women think differently. For men in Haier's study, having more gray matter in certain areas corresponds to a higher IQ, while in women, it made no difference.

But with women, the amount of white matter in completely different areas is what corresponds to intelligence. (In both sexes, gray matter is made up of neurons that process information, while white matter is made of the neurons that connect different parts of the brain).

While men and women may use different brain pathways to think, Haier says their average IQ scores are not significantly different.

If confirmed and refined, the discovery could prove tremendously valuable to clinicians, including neurosurgeons.

"If a man and a woman both have a brain injury or a stroke at the same brain area, it could well be they have completely different effects," Haier says.

"Or think about Alzheimer's disease. Alzheimer's disease begins deep in the brain and moves forward to the frontal part of the brain. If the frontal part of the brain is more important for intelligence in women, as it seems to be, then it may be the symptoms of Alzheimer's disease are not apparent until later in the disease process."

If that scenario holds true, it means women risk a delay in getting treatment, unless the changes are captured through some kind of screening.

The MRI is only one of the MIND Institute's research tools. An MRI is static, like a photograph. It's about form, while functional MRI, positron emission tomography (PET) and magnetoencephalography (MEG) reveal the brain's functions.

The MEG scanner works like a rapid-exposure camera, snapping a thousand pictures each second of electrical activity pulsing through the brain and across its surface. You can actually see a thought unfold in real time.

While it happens in the blink of an eye, Haier and Jung say that in more intelligent persons, the process is faster still.

It is an amazing finding, but most of the brain's inner workings are still a mystery --- though perhaps not for long.

Genius has always been the domain of artists and philosophers, but today it is psychiatrists and neuroscientists who seem closest to finding its source -- even as the mind's secrets and the elusive touch of genius remain tantalizingly out of reach.

Human intelligence determined by volume and location of gray matter tissue in brain

Intelligence in men and women is a gray and white matter



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