Efficiency of the Brain Linked to Intelligence

It is not the size of a brain that is the mark of high intelligence, but how efficiently it works, according to psychiatrist Richard J. Haier of UC Irvine. Haier found that the brains of people who perform well on intelligence tests expend less energy than the brains of poor performers, and may have more efficient neural circuitry.

Haier measured brain activity with a technique called positron emission tomography (PET), which records the amount of a harmless, radioactively labeled sugar taken up by brain cells. The harder cells work, the more sugar they use.

Haier took PET scans of eight subjects while they were performing a difficult test of abstract reasoning: they were required to recognize a pattern embedded in abstract designs and complete the pattern. Those who did best on the test used the least energy.

“Although one might assume that a good performer’s brain would work harder than that of a subject who did poorly, our data suggest that the opposite is true,” Haier said. Haier found no differences in energy uptake, however, when subjects were required only to pay attention to a television screen or to view flashing visual stimuli.