MR reveals anatomic links to intelligence measures

MRI research is delving deep within the brain to identify connections between brain morphology and brainpower. Presentations at the May International Society for Magnetic Resonance in Medicine meeting used volumetric MRI to establish links between brain structure and problem-solving intelligence in one study and a classical musician's ability to memorize reams of musical composition in another.

Dr. Qi-Yong Gong, a professor of radiology at Huaxi Hospital in Sichuan, China, used well-established MR analytical techniques to confirm the relationship between prefrontal gray matter and problem solving.

Clusters of gray matter in the medial region of the frontal cortex, especially the left anterior cingulate gyrus and dorsomedial prefrontal cortex, strongly correlated with fluid intelligence, which is the ability to perform on-the-spot reasoning without benefit of previous experience. The relationship (p< 0.0001) was even stronger when the data were controlled for age.

The study also established a positive relationship between test scores and gray matter volume in the medial prefrontal cortex, especially the dorsomedial region.

"Whether it is just a size difference or a functional difference that has the greater effect on intelligence may be determined with perfusion MR or MR spectroscopy in the future," Gong said.

Gong's study was conducted at the University of Liverpool in the U.K. At the same institution, senior lecturer Dr. Vanessa Anne Sluming used MRI to investigate how dedication to a cognitively demanding activity affects brain structure.

Sluming performed standard neuropsychology tests and volumetric MRI in 38 musician volunteers from the Royal Liverpool Philharmonic Orchestra and an equal number of subjects from the general public to allow a voxel-by-voxel regression analysis of gray matter concentration.

She found that musicians had significantly larger bilateral hippocampal volumes and larger clusters of gray matter density within the right posterior hippocampus, compared with nonmusicians. Gray matter density in this region increased with the age of male musicians until they reached 50.

No significant differences were observed in the amount of hippocampal gray matter measured in the brains of female musicians compared with women in the general public. Musicians of both sexes scored significantly higher than their counterparts from the general public on visual memory tests.