People with a higher IQ (intelligence quotient) are more likely to have fewer connections between neurons in the outer layer of the brain, according to a recent study published in the journal Nature.
While previous research has suggested that larger brains are actually smarter, a closer look at the microstructural architecture of our thinking organ suggests that it is not just more brain cells, but a more efficient connection. That is, the reason some people are so smart is because they have fewer neural connections but much more efficient than others.
Thus, the international team of neurologists used a non-invasive technique known as multi-layered diffusion tensor imaging in magnetic resonance imaging to get an idea of the density and ramifications of gray matter within the brains of some 260 volunteers - men and women -.
Each participant in the experiment also conducted a culturally fair and complex reasoning test, producing a variety of scores ranging from 7 to 27 correct answers out of a total of 28 possible.
By linking the image data with the test scores, the researchers found that those with higher analytical skills not only had more brain cells, but also tended to have fewer branches between neurons in their cerebral cortex.
They then resorted to a database of nearly 500 neural maps within the Human Connectome Project and found the same pattern of higher IQ and lower neural interconnectivity.
At first, it may seem contradictory, but it seems that the additional neurons do not transmit any more information between them.
In fact, previous research had shown that despite having more neurons to share brain function, smarter brains don't tend to work as hard, showing less metabolic activity when subjected to an IQ test, compared to those who'struggle' to get high scores.
This observation has led to the development of the neural efficiency hypothesis, which suggests that the analytical power of nerve cell groups does not seek to put more pressure on them, but to connect them in a way that minimizes effort. More efficiently.
"Intelligent brains are characterized by a thin but efficient network of neurons. This allows a high level of thinking to be achieved with as little neuronal activity as possible," explains neurologist Erhan Genç of the Ruhr Bochum University (Germany).
It is clear that the brain is an organ as complicated as it is incredible and to understand in detail how individual units can interact to solve problems as efficiently as possible could show us the way to improve the technology that imitates them.
It may not help us all to become geniuses, but it gives us new information about microstructure-level brain wiring.