Science: The Genetics of Thinking Differently

The figure shows the two hemispheres of an inflated brain (light grey: gyral pattern, dark grey: sulcal pattern) viewed from a bird's perspective. This brain represents the average anatomical brain of the whole sample studied. The identical twins and their additional brother had to solve a working memory task with numbers including distraction with an arithmetic task in the scanner. On the surface of the brain two types of information are depicted: red colour indicates areas for which brain activation in the recognition phase of the working memory task was under significant genetic influence. The turquoise colour indicates areas for which activation was significant at the group level. There was only little overlap between both maps. This indicates that the key to understanding genetic influences on brain activation is found in those brain areas where large individual differences in brain activity are present.

[Image courtesy of Jan Willem Koten and Klaus Willmes-von Hinckeldey]

It may be something that you've always suspected and joked about: your brain operates differently than your brother's brain. Now, research published in the 27 March issue of the journal Science can back up that punch line. A study of male twins and their non-twin brothers suggests that individuals may use different areas of the brain to solve a memory problem, and that the differences appear to be genetically controlled.

The twins and their brothers were asked to memorize a short string of digits, after which they were "distracted" by solving simple math problems or sorting a list of fruits and vegetables into separate categories. Functional magnetic resonance images of the brothers' brains show that the siblings then used different neural networks to help them recall specific numbers from the memory task.

Some of the brothers used brain networks related to spatial and numerical tasks, while others activated language-related networks to help them remember the numbers. The more closely genetically related the brothers were, the more likely they were to use the same network to jog their memories.

"This preference seems to be under genetic control, and you can actually see it happening in the brain," said Jan Willem Koten Jr., a neuropsychologist at Aachen University in Germany, who led the Science study.

The findings could help researchers learn more about the role genes play when individual brains come up with different ways to solve the same problem, the researchers concluded. "We cannot find genes for what people are thinking," said Koten, "but we can find genes for how people are thinking."

Becky Ham

26 March 2009