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Intelligence is correlated with fewer neural connections, not more, study finds

"The assumption has been that larger brains contain more neurons and, consequently, possess more computational power," researcher Erhan Genç said.

By
Brooks Hays
New research suggests a lower number and density of neural connections, dendrites, in the cerebral cortex is linked with high intelligence. Photo by Erhan Genç, et al./Nature Communications
New research suggests a lower number and density of neural connections, dendrites, in the cerebral cortex is linked with high intelligence. Photo by Erhan Genç, et al./Nature Communications

May 17 (UPI) -- The smartest people may boast more neurons than those of average intelligence, but their brains have fewer neural connections, new research proves.

Neuroscientists in Germany recruited 259 participants, both men and women, to take IQ tests and have their brains imaged. Testing provided a measure of each participant's intelligence, while neurite orientation dispersion and density imaging revealed the number of dendrites, or neural connections, in each participant's brain.

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The research revealed a strong correlation between the number of dendrites in a person's cerebral cortex and their intelligence. The smartest participants had fewer neural connections in their cerebral cortex.

Researchers confirmed the correlation in a followup survey using data sourced from the Human Connectome Project, including IQ scores and brain images of 500 individuals.

"The assumption has been that larger brains contain more neurons and, consequently, possess more computational power," Erhan Genç, a researcher at Ruhr-University Bochum, said in a news release.

However, previous studies have shown the brains of the most intelligent people feature less neuronal activity during test-taking than those of less intelligent individuals.

"Intelligent brains possess lean, yet efficient neuronal connections," concludes Genç. "Thus, they boast high mental performance at low neuronal activity."

The findings, published this week in the journal Nature Communications, are the latest to suggest relatively small differences at the brain's microstructural level can explain significant differences in terms of functionality and performance.

Previous studies have revealed links between the length and insulation of dendrite connections and a person's cognitive abilities.

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