Researchers use brain-injury data to map intelligence in the brain

A new study found that specific structures, primarily on the left side of the brain, are vital to general intelligence and executive function (the ability to regulate and control behavior). Brain regions that are associated with general intelligence and executive function are shown in color, with red indicating common areas, orange indicating regions specific to general intelligence, and yellow indicating areas specific to executive function. Credit: Aron Barbey

Scientists report that they have mapped the physical architecture of intelligence in the brain. Theirs is one of the largest and most comprehensive analyses so far of the brain structures vital to general intelligence and to specific aspects of intellectual functioning, such as verbal comprehension and working memory.

Their study, published in Brain: A , is unique in that it enlisted an extraordinary pool of volunteer participants: 182 with highly localized brain damage from penetrating .

"It's a significant challenge to find patients (for research) who have brain damage, and even further, it's very hard to find patients who have focal brain damage," said University of Illinois neuroscience professor Aron Barbey, who led the study. Brain damage – from stroke, for example – often impairs multiple brain areas, he said, complicating the task of identifying the cognitive contributions of specific brain structures.

Aron Barbey discusses his work linking specific brain injuries, seen here in a brain scan, to impairment on particular cognitive functions. To view video, return to story and click on link in this cutline. Photo courtesy Aron Barbey

But the very focal brain injuries analyzed in the study allowed the researchers "to draw inferences about how specific brain structures are necessary for performance," Barbey said. "By studying how damage to particular brain regions produces specific forms of cognitive impairment, we can map the architecture of the mind, identifying brain structures that are critically important for specific intellectual abilities."

The researchers took CT scans of the participants' brains and administered an extensive battery of cognitive tests. They pooled the CT data to produce a collective map of the cortex, which they divided into more than 3,000 three-dimensional units called voxels. By analyzing multiple patients with damage to a particular voxel or cluster of voxels and comparing their cognitive abilities with those of patients in whom the same structures were intact, the researchers were able to identify brain regions essential to specific cognitive functions, and those structures that contribute significantly to intelligence.

"We found that general intelligence depends on a remarkably circumscribed neural system," Barbey said. "Several brain regions, and the connections between them, were most important for general intelligence."

These structures are located primarily within the left prefrontal cortex (behind the forehead), left temporal cortex (behind the ear) and left parietal cortex (at the top rear of the head) and in "white matter association tracts" that connect them. (Watch a video about the findings.)

The researchers also found that for planning, self-control and other aspects of executive function overlap to a significant extent with regions vital to general intelligence.

The study provides new evidence that intelligence relies not on one brain region or even the brain as a whole, Barbey said, but involves specific brain areas working together in a coordinated fashion.

"In fact, the particular regions and connections we found support an emerging body of evidence indicating that intelligence depends on the brain's ability to integrate information from verbal, visual, spatial and executive processes," he said.

The findings will "open the door to further investigations into the biological basis of , exploring how the , genes, nutrition and the environment together interact to shape the development and continued evolution of the remarkable intellectual abilities that make us human," Barbey said.

Related Stories

Neuroscientists map intelligence in the brain

Mar 11, 2009

(PhysOrg.com) -- Neuroscientists at the California Institute of Technology (Caltech) have conducted the most comprehensive brain mapping to date of the cognitive abilities measured by the Wechsler Adult Intelligence ...

Brain scans may help guide career choice

Jul 21, 2010

General aptitude tests and specific mental ability tests are important tools for vocational guidance. Researchers are now asking whether performance on such tests is based on differences in brain structure, and if so, can ...

When it comes to intelligence, size matters

Mar 25, 2009

A collaborative study led by researchers at the Montreal Neurological Institute (MNI), McGill University has demonstrated a positive link between cognitive ability and cortical thickness in the brains of healthy ...

Recommended for you

Myelin vital for learning new practical skills

Oct 16, 2014

New evidence of myelin's essential role in learning and retaining new practical skills, such as playing a musical instrument, has been uncovered by UCL research. Myelin is a fatty substance that insulates ...

Reminiscing can help, not hinder, some mind-bending tasks

Oct 16, 2014

To solve a mental puzzle, the brain's executive control network for externally focused, goal-oriented thinking must activate, while the network for internally directed thinking like daydreaming must be turned down to avoid ...

Bio-X scientists develop decoy drug to aid ailing brain

Oct 16, 2014

A team of Stanford Bio-X scientists has restored the ability of adult mice to form new connections in the brain. If the finding works in people, it has the potential to help adults recover from stroke and ...

User comments