Many grooves and dimples on the surface of the brain are unique to humans, but they’re often dismissed as an uninteresting consequence of packing an unusually large brain into a too-small skull.
But neuroscientists are finding that these folds are not mere artifacts, like the puffy folds you get when forcing a sleeping bag into a stuff sack. The depths of some of the smallest of these grooves seem to be linked to increased interconnectedness in the brain and better reasoning ability.
In a study published May 19 in The Journal of Neuroscience, University of California, Berkeley, researchers show that in children and adolescents, the depths of some small grooves are correlated with increased connectivity between regions of the brain — the lateral prefrontal cortex and lateral parietal cortex — involved in reasoning and other high-level cognitive functions.
The grooves may actually bring those areas closer together in space, shortening the connections between them and speeding communications.
The implication, the researchers say, is that variability in these small grooves, which are called tertiary sulci (pronounced sul’-sigh), may help explain individual differences in cognitive performance, and could serve as diagnostic indicators or biomarkers of reasoning ability or neurodevelopmental disorders.
“The impetus for this study was having seen that sulcal depth correlated with reasoning across children and adolescents,” said Silvia Bunge, professor of psychology and a member of UC Berkeley’s Helen Wills Neuroscience Institute (HWNI). “Given our previous findings, our former postdoctoral fellow Suvi Häkkinen aimed to test if sulcal depth was correlated with reasoning performance and to test if patterns of coordinated activity within a lateral prefrontal-parietal network could explain this relation between sulcal depth and reasoning.”