Women are More Civil

Ian Goddard igoddard at erols.mom
Wed Sep 18 08:32:54 EST 2002


http://www.eurekalert.org/pub_releases/2002-09/uopm-psm091702.php

University of Pennsylvania Medical Center 

Penn study may explain cliche of 'hot-headed' men Penn scientists 
map and measure the seat of impulsive behavior in the brain 

(Philadelphia, PA) -- There is a sound neurological basis for the
cliché that men are more aggressive than women, according to new
findings by scientists at the University of Pennsylvania School of
Medicine.  

Using magnetic resonance imaging (MRI) scans, the Penn scientists
illustrated for the first time that the relative size of the sections
of the brain known to constrain aggression and monitor behavior is
larger in women than in men. 

The research, by Ruben C. Gur, PhD, and Raquel E. Gur, MD, PhD, and
their colleagues in Penn's Department of Psychiatry and the Department
of Epidemiology, is published in the recent issue of the Journal of
the Cerebral Cortex. 

The findings provide a new research path for therapies that may
eventually help psychiatric patients control inappropriate aggression
and dangerous patterns of impulsive behavior. They also bolster
previous work by the Gurs demonstrating that although some gender
differences develop as result of adaptive patterns of socialization,
other distinctions are biologically based and probably innate. 

"As scientists become more capable of mapping the functions of
activity in various parts of the brain, we are discovering a variety
of differences in the way men and women's brains are structured and
how they operate," said Ruben Gur, first author of the study. 

"Perhaps the most salient emotional difference between men and women,
dwarfing all other differences, is aggression," he said. "This study
affords us neurobiological evidence that women may have a better brain
capacity than men for actually 'censoring' their aggressive and anger
responses." 

In the Gurs' work, they relied on established scientific findings that
human emotions are stimulated and regulated through a network that
extends through much of the limbic system at the base of the brain
(the region encompassing the amygdala, hypothalamus and
mesocorticolimbic dopamine systems), and then upward and forward into
the region around the eyes and forehead (the orbital and dorsolateral
frontal area), and under the temples (the parietal and temporal
cortex). 

The amygdala is involved in emotional behavior related to arousal and
excitement, while the orbital frontal region is involved in the
modulation of aggression. 

The Gurs' study measured the ratio of orbital to amygdala volume in a
sample of 116 right-handed, healthy adults younger than 50 years of
age; 57 subjects were male and 59 were female. Once the scientists
adjusted their measurements to allow for the difference between men
and women in physical size, they found that the women's brains had a
significantly higher volume of orbital frontal cortex in proportion to
amygdala volume than did the brains of the men. 

"Because men and women differ in the way they process the emotions
associated with perception, experience, expression, and most
particularly in aggression, 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 'gendered-related' behavior,"
Raquel Gur said.


###
Others Penn investigators participating in the study were Faith
Gunning-Dixon, PhD, and Warren B. Bilker, PhD, of the Department of
Epidemiology.

The study was funded by a grant from the National Institutes of
Health. 


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