During the study (subscription required), researchers used functional magnetic resonance imaging (fMRI) technology to scan participants' brains as they completed a series of cognitive performance tests and while resting. The brain images were later compared to better understand the relationship between overall brain size and variations in individual intelligence.
Booster Shots reports:
The resulting picture of intelligence is a remarkably simple one: from a single hub in the prefrontal lobes radiates a plethora of brightly lit connections to all corners of the brain. This suggests that when we engage in goal-directed behavior that requires judgment, sustained attention and flexibility, the two sides of the prefrontal lobe coordinate incoming information, send out commands and keep us on task, said the study's lead author, Michael W. Cole of Washington University's cognitive neuroscience department.
To do all that well, it needs to maintain connections throughout the brain that have speed and high capacity.
The latest study underscores a growing appreciation among neuroscientists for the importance of the brain's "white matter" -- fat-covered clusters of axons that string neurons and the brain's two hemispheres together-- in brain function. Our volume of "gray matter" is popularly spoken of as a measure of intelligence. But research increasingly shows that when the "white matter" that ties the gray stuff together is damaged or deficient -- as it can be in patients with brain trauma, autism and schizophrenia -- goal-directed task performance can be very poor.
Photo by Bill McConkey, Wellcome Images