The disclaimer ahead: The grand unknown in all neurophysiological studies about stupidity and intelligence certainly is the exact definition of those terms. It is precisely the question which was not answered in a study of the UCLA Department of Neurology at the University of California/USA published in the Journal of Neuroscience (2009, 29(7):2212-2224). In order to be able to continue with the topic at this point we have to affiliate with the researchers with Professor Paul Thompson and their assumption: Intelligence has something to do the a higher speed of information processing in the brain.
Intelligent is the one who thinks as quickly as his own protons
Thus prepared we are able to appreciate this elegant study Thompson made with a high-resolution diffusion-MR (DTI). He put a total of 92 patients in a MR-scanner. The interesting part was not so much the regular brain anatomy and not the brain function which can be displayed so nicely in fMRT-examinations. The diffusion-MR visualizes something else: It images the movement of protons in the tissue – and that means, in the organism, mainly of water molecules. Depending on speed and direction of the molecule movement there are different color coding which produce motley colorful pictures of the brain which have little in common what you normally would know as a brain-MR. But: What do protons mean which are moving? “If water diffuses quickly in a certain direction it tells us that the brain has very fast connections there”, emphasizes Thompson. If the diffusion is slower and less targeted, it speaks for a rather slower information processing and therefore – see above mentioned definition – for a lower intelligence. “In other words: With the diffusion-MR we can get an idea how fast a person thinks”, explains Thompson.
Show me your myelin and I’ll tell you how quick you think
The clou in Thompson’s study was that he did not examine any quick-witted dude and slow Joe off the street. Those 92 test persons were 46 twin pairs, half of them monozygotic twins, the second half dizygotic twins. Thus the speed of thinking could – so to speak – be compared ‘twin-overlapping’. And since all test persons were siblings growing up together thus having accordingly similar environmental conditions, quite a bit points towards genetics if dizygotic twins differ more in regard to their speed of thinking that monozygotic twins. And – after all the prefacing – it does not come as a surprise that it was the case: The integrity of the myelin, i. e. the morphological correlate for fast flowing protons, was genetically clearly determined in twins. Monozygotic twins had similar myelin, dizygotic showed obvious difference.
And this genetic predisposition of the brain speed becomes particularly clearly visible in some brain areas considered not that irrelevant for higher brain performances. It applies for example for the parietal lobe where visual information is processed and where logic and spatial vision are at home. In the corpus callosum, the great thinking highway between the cerebral hemisperes, the genetic components of the speed of thinking was very prominent as well.
On the look-out for the turbocharger for the brain
So to be quick-witted is genetic. But what do we do with that piece of information? Thompson points out that to him it is not a matter of realization which indeed you might as well want to store in the basket “That was clear anyways”. He emphasizes: “The whole trick of this research is that it is allowing us an insight into brain diseases”. Diseases such as multiple sclerosis and autism for example are associated with malfunctions of the myelin sheaths for quite some time now. Currently the California researchers are working on isolating the genes more precisely which are responsible for the MR-differences in their twin study. The hope: Those genes might provide new starting points for expedient therapy strategies for MS, autism and other disorders. Conversely a medicinal accelerator for thinking would be within reach: “But until then it is still a long way to go, but it would be possible”, says Thompson.