Vol. 8, No. 4, 2002 Page 1
As a group, men are far more aggressive than women, a difference often attributed to social factors. A new study, however, indicates that differences in men's and women's brains—not their upbringing— account for women's greater control over aggressive impulses.
Ruben Gur and colleagues performed MRI scans on 57 men and 59 women between the ages of 18 and 49. The researchers measured the volume of the amygdala, hippocampus, and other limbic areas associated with emotional arousal, as compared to the volume of orbital frontal brain regions that exert control over emotional responses.
After Gur and colleagues adjusted for the difference in overall cranial volume between men and women, they found that hippocampal and amygdala volumes were similar for both sexes. However, women had significantly larger orbital frontal cortex volume than men.
"Because men and women differ in the way they process the emotions associated with perception, experience, expression, and most particularly in aggression," the researchers say, "our belief is that the proportional difference in size in the region of the brain that governs behavior, compared to the region related to impulsiveness, may be a major factor in determining what is often considered 'gender-related' behavior."
"Sex differences in temporo-limbic and frontal brain volumes of healthy adults," Ruben C. Gur, Faith Gunning-Dixon, Warren B. Bilker, and Raquel E. Gur, Cerebral Cortex, Vol. 12, No. 9, September 2002, 998-1003. Address: Ruben C. Gur, Neuropsychiatry Section, Department of Psychiatry, 10th Floor Gates Building, University of Pennsylvania Medical Center, Philadelphia PA 19104.
"Penn study may explain cliché of 'hot-headed' men," Science Daily, September 18, 2002.