Scientists at King's College London have been looking at the cerebral cortex, the outermost layer of the human brain known as "gray matter," which plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.
Although previous studies have suggested the thickness of the cerebral cortex closely correlates with intellectual ability, no gene linked to that structural thickness had yet been identified, they said.
In the study, DNA samples and MRI scans from 1,583 healthy 14-year-olds showed those who carried a particular gene variant had a thinner cortex in the left cerebral hemisphere, particularly in the frontal and temporal lobes, and performed less well on tests for intellectual ability.
"The genetic variation we identified is linked to synaptic plasticity -- how neurons communicate," study lead author Sylvane Desrivieres said. "This may help us understand what happens at a neuronal level in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is somehow compromised."
She cautioned against putting too much emphasis on the gene variation in terms of human intellectual performance.
"It's important to point out that intelligence is influenced by many genetic and environmental factors," she said. "The gene we identified only explains a tiny proportion of the differences in intellectual ability, so it's by no means a 'gene for intelligence.'"