Where in the brain is human intelligence located?

Where in the brain is intelligence located? What causes some people to be more intelligent than others? Is there a brain region for genius? Scientists have been exploring such questions since the mid-19th century. But only in recent years has intelligence been successfully localized within the brain.

In the 19th and early 20th centuries, attempts were made to use anatomical methods to find the causes of intelligence in the brain. For example, in 1955, Albert Einstein's brain was first photographed and then cut into 240 cubes, in an attempt to find abnormalities that distinguished this brilliant brain from the average brain. After many such studies, differences in intelligence were attributed to factors such as brain size, the number and shape of the convolutions, or the ratio of gray to white matter in the brain. None of this led to a truly conclusive result. Only in recent years, through neuroimaging techniques on the one hand and studies on patients with partially damaged brains on the other, have the question of where in the brain intelligence lies been conclusively answered.

Network of Intelligence

In 2007, Richard Haier of the University of California and Rex Jung of the University of New Mexico discovered that intelligence requires neither the entire brain nor a single brain region, but rather that several different brain regions and their interconnectedness are responsible for the expression of intelligence. Since these brain regions are primarily located in the parietal lobe (the area at the back of the head, above the brain) and the frontal lobe (the area below the forehead), the model is now known as the Parieto-Frontal Integration Theory (P-FIT). Intelligence depends on efficient communication.

The P-FIT explains where our intelligence resides, but why is one person more intelligent than another? The characteristics of the individual components, but especially the connection between them, seem to be crucial here. The speed of signal transmission in this network apparently makes the difference between high and low intelligence: "Several studies have measured the speed of neural transmission and found a correlation with IQ test results," says Haier. "EEG recordings show that the conduction speed is higher in smarter people."

Haier and Jung's theory has since been confirmed by numerous other studies and provides direct evidence of the neurobiological basis of intelligence. Perhaps this could one day help us find new ways to promote intelligence or specifically train cognitive abilities.

Source:

Jung, RE, Haier, RJ: The Parieto-Frontal Integration Theory (P-FIT) of intelligence: converging neuroimaging evidence, The Behavioral and Brain Sciences 2007 30(2), pp.135-54