Have you ever wondered what structures or areas in your brain allow you to understand language? Read books? Appreciate music? At a basic level, scientists have already correlated discrete brain structures to specific human abilities. As today’s researchers take this understanding further and actually map intellectual ability in the brain, they are discovering that many abilities are not neatly confined to a single area.
Scientists have employed various techniques to delve into this “intracranial cartography.” One method used by Dr. Aron Barbey, professor of neuroscience at the University of Illinois, involved finding patients with highly localized brain injuries and comparing their cognitive abilities and executive functionwith other individuals who had those same structures intact. Barbey’s evidence showed that intelligence relies on localized areas of the brain working together collaboratively as opposed to residing independently in a single region or the brain as a whole. In his own words: "We found that general intelligence depends on a remarkably circumscribed neural system. Several brain regions, and the connections between them, were most important for general intelligence." (2012) Barbey’s research supports the idea that areas of the brain controlling executive function, which governs skills such as self-control and planning, overlap “to a significant extent” with areas that control general intelligence. (2012)
Another method of mapping intellectual ability involves performing brain scans while subjects carry out cognitive tasks, and then indexing the areas of the brain that are engaged in specific types of processes. Using the Wechsler Adult Intelligence Scale(WAIS), a standard index for measuring IQ, Caltech neuroscientist Ralph Adolphs was able to measure subjects’ performance in the four specific areas that the WAIS covers: verbal comprehension, perceptual organization, working memory, and processing speed. (2010)
Interestingly, Adolphs found that even though the WAIS defines verbal comprehension and working memory as separate abilities, areas responsible for each were shown to overlap, suggesting that they represent a similar type of intelligence. Also of note, the study found that processing speed seemed to be a more global function controlled by connections across different areas of the brain as opposed to localized structures.
Barbey’s results support that same finding. “In fact,” he says, “the particular regions and connections we found support an emerging body of neuroscience evidence indicating that intelligence depends on the brain’s ability to integrate information from verbal, visual, spatial and executive processes.” (2012) The implications are intriguing, and support our evolving understanding of human intelligence as a network that can be developed by simultaneously cross-training those regions in the brain that most effectively work together.