You owe your intelligence to your parents

March 18th, 2009 - 4:08 pm ICT by IANS  

Washington, March 18 (IANS) A new kind of brain-imaging scanner has shown that intelligence is strongly influenced by the quality of the brain’s axons, or wiring that sends signals throughout the brain.
The faster the signalling, the faster the brain processes information. And since the integrity of the brain’s wiring is influenced by genes, the genes we inherit play a far greater role in intelligence than was previously thought.

Genes appear to influence intelligence by determining how well nerve axons are encased in myelin - the fatty sheath of “insulation” that coats our axons and allows for fast signalling bursts in our brains. The thicker the myelin, the faster the nerve impulses.

University of California Los Angeles (UCLA) neurology professor Paul Thompson and colleagues scanned the brains of 23 sets of identical twins and 23 sets of fraternal twins.

Since identical twins share the same genes while fraternal twins share about half their genes, the researchers were able to compare each group to show that myelin integrity was determined genetically in many parts of the brain that are key for intelligence.

These include the parietal lobes, which are responsible for spatial reasoning, visual processing and logic, and the corpus callosum, which pulls together information from both sides of the body.

The researchers used a faster version of a type of scanner called a HARDI (high-angular resolution diffusion imaging) that takes scans of the brain at a much higher resolution than a standard MRI.

While an MRI scan shows the volume of different tissues in the brain by measuring the amount of water present, HARDI tracks how water diffuses through the brain’s white matter - a way to measure the quality of its myelin.

“HARDI measures water diffusion,” said Thompson, who is also a member of the UCLA Laboratory of Neuro-Imaging. “If the water diffuses rapidly in a specific direction, it tells us that the brain has very fast connections. If it diffuses more broadly, that’s an indication of slower signalling, and lower intelligence.”

“So it gives us a picture of one’s mental speed,” he said. “The whole point of this research,” Thompson said, “is to give us insight into brain diseases.”

And could this someday lead to a therapy that could make us smarter, enhancing our intelligence? “It’s a long way off but within the realm of the possible,” Thompson said, according to an UCLA release.

The study was published in the Journal of Neuroscience.

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