Science has long suspected that overall brain size determines intelligence, accounting for about 6.7 percent of individual variation in populations. More recent research has pinpointed the brain’s lateral prefrontal cortex, a region just behind the temple, as a critical hub for high-level mental processing, with activity levels there predicting another 5 percent of variation in individual intelligence. Now, research from Washington University in St. Louis suggests that another 10 percent of individual differences in intelligence can be explained by the strength of neural pathways connecting the left lateral prefrontal cortex to the rest of the brain. Published in the Journal of Neuroscience, the findings establish “global brain connectivity” as a new approach for understanding human intelligence. “Our research shows that connectivity with a particular part of the prefrontal cortex can predict how intelligent someone is,” suggests lead author Michael W. Cole, PhD, a postdoctoral research fellow in cognitive neuroscience at Washington University. The study is the first to provide compelling evidence that neural connections between the lateral prefrontal cortex and the rest of the brain make a unique and powerful contribution to the cognitive processing underlying human intelligence, says Cole, whose research focuses on discovering the cognitive and neural mechanisms that make human behavior uniquely flexible and intelligent. “This study suggests that part of what it means to be intelligent is having a lateral prefrontal cortex that does its job well; and part of what that means is that it can effectively communicate with the rest of the brain,” says study co-author Todd Braver, PhD, professor of psychology in Arts & Sciences and of neuroscience and radiology in the School of Medicine.