igoddard at erols.mom
Tue Feb 12 10:51:56 EST 2002
Brain Part Appears to Accentuate Negativity
Imaging Scans Used To Study Dour Outlook
By Shankar Vedantam
Washington Post Staff Writer
Tuesday, February 12, 2002; Page A08
A region of the brain a few inches behind the bridge of the nose
may hold the key to why some people have a negative outlook on life,
scientists announced yesterday.
The study published yesterday in the Proceedings of the National
Academy of Sciences is the first to examine the neurological roots
of what scientists call "negative affect," a trait that predisposes
people to anxiety, irritability, anger and a range of other
By suggesting that an unconscious disposition toward these emotions
may be molded by a specific area in the brain, the research moves
into previously uncharted waters. It is part of a broad effort by
neuroscientists in recent years to use powerful brain imaging
technology to pinpoint the areas of the brain responsible for
"It touches on an important issue -- the relationship between
individual differences in personality and brain function," said
Marcus Raichle, a professor of radiology and neurology at Washington
University in St. Louis. "There have been for many, many years
attempts to explain the differences we observe among ourselves --
[why] we have different personalities."
"If you believe behavior and brain are related, you would have to
suppose there are differences in brain systems that lead to
differences in personality," Raichle said.
For the study, scientists at Vanderbilt University, the Veterans
Affairs Medical Center in Minneapolis and the University of
Minnesota asked 89 healthy people to take detailed tests that
measured their emotional outlook over the previous month. The tests
were designed to screen out people's mood states on the day they
were evaluated, and look instead for a pattern of emotional
attitudes -- in other words, an outlook or a temperament.
While the subjects rested after the tests, the researchers conducted
brain scans that measured changes in blood flow within their brains.
The scientists found that increased brain activity in one particular
region -- the ventromedial prefrontal cortex -- was associated with
those who reported greater negative affect.
Many factors besides physiology are responsible for personality, and
other parts of the brain are involved in emotions. But researchers
say the circumstantial evidence indicates that the ventromedial
prefrontal cortex acts as a sort of volume knob for emotions. While
the emotions may be produced elsewhere in the brain in response to
stimuli, this region of the brain can make them deafening or muted.
As a result, some people may react sharply in a situation, while
others appear unruffled. The volume knob, in other words, may be
what people interpret as temperament.
Most studies of brain activity have focused on trying to match
regions of the brain with particular moods, or abilities such as
vision, language and physical movement. By focusing on an underlying
trait or a temperament in healthy people, scientists hope to
eventually understand why healthy people react so differently to the
same cues, and why people with mental illnesses have extreme
In turn, this could lead to better treatments of both psychiatric
medicines and psychological therapy. Current treatments for these
emotional disorders may in fact work by affecting these same brain
"There's at least one component of the biology of temperament in the
ventromedial prefrontal cortex," said José V. Pardo, an associate
professor of psychiatry at the University of Minnesota and one of
the researchers who conducted the study.
"In a practical sense, what we know is a person with higher activity
in this area can be predicted to have a high level of negative
affect," Pardo said. "High levels of negative affect have been shown
to have a high risk of depression and anxiety. This may begin to tie
aspects of temperament to disease."
Although negative affect may seem like the opposite of positive
affect, researchers do not find that people with diminished activity
in this part of the brain are "happier." Instead, patients with
damage to the ventromedial prefrontal cortex have previously been
found to lack normal responses to emotional cues, according to the
"What you see in people with brain lesions in this area is they
don't seem to be able to appreciate risk," said David Zald, an
assistant professor of psychology at Vanderbilt University and the
lead author of the study. "They can tell you they are doing
something that has a good chance of failing, but they don't have the
emotional reaction to it -- they don't have visceral arousal."
For example, Zald said, "if you are betting a lot of money, you may
get a feeling in the pit of your stomach -- they won't experience
that, they won't get as upset about it."
The example serves notice to those who might want scientists to find
a way to shut off the brain region in order not to be bothered with
anxious or irritable thoughts.
"Anxiety is often helpful to us -- it is protective," Zald said. "If
you don't have it, you're likely to not detect when you are in
danger or when you are taking too big a risk."
© 2002 The Washington Post Company
"To lengthen thy life, lessen thy meals." Benjamin Franklin
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