Have you ever had your butt kicked by a 12-year old girl? OK, maybe when you were an 8-year old boy perhaps – but I mean as a grown up. Its a humbling experience. I know. For once back in college, I sat for a math contest and was amazed by a young girl who was able to answer each question more quickly and accurately than anyone else (other college students) in the room.
How did she do it? What was different about her brain than mine (illicit substances aside)? Now, as a parent of children who will, themselves, soon start sitting for exams and contests – wouldn’t I like to know. Might I perchance endow my children with brain power? Not likely I imagine, but what is brain power anyway? and what is it about the brain that makes some people perform better in general intelligence assessments? In their new research article, Genetics of Brain Fiber Architecture and Intellectual Performance [doi: 10.1523/jneurosci.4184-08.2009], Paul Thompson’s team of neurobiologists explore this longstanding question.
In this article, the team asks whether the white matter of the brain (the glial cells that ensheath neuronal axons) might be both heritable and correlated with measures of intelligence. To measure white matter integrity, the team uses an imaging method known as diffusion tensor imaging (DTI). It has been shown previously that measures of intelligence are correlated with white matter integrity – presumably because white matter serves as a kind of insulation that speeds up the transmission of action potentials and thus facilitates interhemispheric communication and other long-range forms of neural network processing. The team found that white matter integrity was correlated with performance on intelligence assessments in brain regions such as the cingulum, callosal isthmus, corona radiata, internal capsule and other regions. By imaging 23 pairs of identical and 23 pairs of fraternal twins, the team also found many regions in the brain where white matter integrity was under more than 50% genetic control – particularly in the parietal lobe. Lastly, the team found that in many of these regions, the correlation between white matter integrity and intelligence could be explained by the same genes.
Amazing research findings indeed, that points to where in the brain and what type of physiological processes are related to efficient brain function.