The more intelligent a person, the fewer connections there are
between the neurons in his cerebral cortex. This is the result of a
study conducted by neuroscientists working with Dr Erhan Genç and
Christoph Fraenz at Ruhr-Universität Bochum; the study was performed
using a specific neuroimaging technique that provides insights into the
wiring of the brain on a microstructural level.
Together with colleagues from the University of New Mexico in
Albuquerque, Humboldt University of Berlin and the Lovelace Biomedical
and Environmental Research Institute in Albuquerque, the team from the
biopsychology research unit in Bochum published their report in the
journal Nature Communications on May 15, 2018.
Intelligence is determined by the number of dendrites
The researchers analysed the brains of 259 men and women using
neurite orientation dispersion and density imaging. This method enabled
them to measure the amount of dendrites in the cerebral cortex, i.e.
extensions of nerve cells that are used by the cells to communicate with
each other. In addition, all participants completed an IQ test.
Subsequently, the researchers associated the gathered data with each
other and found out: the more intelligent a person, the fewer dendrites
there are in their cerebral cortex.
Using an independent, publicly accessible database, which had been
compiled for the Human Connectome Project, the team confirmed these
results in a second sample of around 500 individuals.
Previously conflicting results are thus explained
The new findings provide an explanation of conflicting results
gathered in intelligence research to date. For one, it had been
previously ascertained that intelligent people tend to have larger
brains. “The assumption has been that larger brains contain more neurons
and, consequently, possess more computational power,” says Erhan Genç.
However, other studies had shown that – despite their comparatively high
number of neurons – the brains of intelligent people demonstrated less
neuronal activity during an IQ test than the brains of less intelligent
individuals.
“Intelligent brains possess lean, yet efficient neuronal
connections,” concludes Erhan Genç. “Thus, they boast high mental
performance at low neuronal activity.”
thecommonchick
