General Intelligence Located In The Brain

There’s an interesting paper called "Distributed neural system for general intelligence revealed by lesion mapping". (It’s open access, so anyone can read it online.)

The paper claims to have found the regions of the brain associated with general intelligence.

Here’s an excepts from ScienceDaily….

A collaborative team of neuroscientists at the California Institute of Technology (Caltech), the University of Iowa, the University of Southern California (USC), and the Autonomous University of Madrid have mapped the brain structures that affect general intelligence.

The study, to be published the week of February 22 [2010] in the early edition of the Proceedings of the National Academy of Sciences, adds new insight to a highly controversial question: What is intelligence, and how can we measure it?

[The Scientists] examine[d] a uniquely large data set of 241 brain-lesion patients who all had taken IQ tests. The researchers mapped the location of each patient’s lesion in their brains, and correlated that with each patient’s IQ score to produce a map of the brain regions that influence intelligence.
[...]
The researchers found that, rather than residing in a single structure, general intelligence is determined by a network of regions across both sides of the brain.

“One of the main findings that really struck us was that there was a distributed system here. Several brain regions, and the connections between them, were what was most important to general intelligence,” explains Gläscher.

“It might have turned out that general intelligence doesn’t depend on specific brain areas at all, and just has to do with how the whole brain functions,” adds Adolphs. “But that’s not what we found. In fact, the particular regions and connections we found are quite in line with an existing theory about intelligence called the ‘parieto-frontal integration theory.’ It says that general intelligence depends on the brain’s ability to integrate — to pull together — several different kinds of processing, such as working memory.”

(Emphasis mine.)

Or in the words of the authors of the paper….

Distributed neural system for general intelligence revealed by lesion mapping

J. Gläschera, D. Rudraufc, R. Colome, L. K. Paula, D. Tranelc, H. Damasiof, and R. Adolphsa

Abstract

General intelligence (g) captures the performance variance shared across cognitive tasks and correlates with real-world success. Yet it remains debated whether g reflects the combined performance of brain systems involved in these tasks or draws on specialized systems mediating their interactions. Here we investigated the neural substrates of g in 241 patients with focal brain damage using voxel-based lesion–symptom mapping. A hierarchical factor analysis across multiple cognitive tasks was used to derive a robust measure of g. Statistically significant associations were found between g and damage to a remarkably circumscribed albeit distributed network in frontal and parietal cortex, critically including white matter association tracts and frontopolar cortex. We suggest that general intelligence draws on connections between regions that integrate verbal, visuospatial, working memory, and executive processes.

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