Lower neuron connections associated with higher intelligence
If you are smarter, then your brain has fewer connections - short science articles

Neuroscientists used neuroimaging techniques to look for insights into the wiring of the brain microstructure especially in relation to their intelligence. Participants were brain scanned to quantify the dendrites which are extensions of the neurons which helps them communicate with other neurons. These participants also completed an IQ test and scientists found that higher the intelligence of a person, lower is the number of connections. Usually, larger brains are associated with more neuronal connections and hence considered to have more computation power. However, since the brains of intelligent people show fewer connections, this could mean that intelligent brains are in fact lean and show higher efficient due to lower connections.

Read the full story: Ruhr-Universität Bochum
Scientific publication: Nature Communications